Finally, a remarkable development took place in 1966. Shigeto Ikeda proposed his ideas for construction of a flexible fiberoptic bronchoscope (FOB) to two companies, Machida Endoscope and Olympus.⁵ Meanwhile, in 1967, Peter Murphy ingeniously used a choledochoscope for endotracheal intubation.⁶ In 1968, the Machida company at last produced an extremely “bendable,” guided FOB, which featured an eyepiece for seeing images transmitted along 15,000 glass fibers that were 14 µm in diameter. Clinically, Ikeda’s technique was to insert this very flexible instrument through a rigid bronchoscope. Later that year, Olympus produced a more maneuverable FOB with a working channel that allowed the application of cytology brushes. Ikeda’s new FOB pictures of the distal airway, presented at the International Congress on Disease of the Chest in Copenhagen, were instantaneously news-making revelations. He was able to demonstrate a stand-alone FOB insertion method for endotracheal intubation in many countries, and he published his experiences in 1971.⁷

Initially many clinicians advanced FOB use for diagnostic purposes, for ordinary intubation procedures, and, eventually, for airway management in patients with very challenging airways.⁸^–¹² The inherent characteristic of FOB superiority forged its involvement as an instrument of first choice in difficult intubation (DI) cases, cervical spine risk scenarios, and as a diagnostic and therapeutic tool for patients with hypoxemia, high airway pressure, pulmonary tumors, infection, foreign bodies, airway stenosis, obstructive sleep apnea, tracheomalacia, and many more wide-ranging abnormalities.

Raj advocated the role of FOB assistance in double-lumen tube (DLT) placement ¹¹ while Ovassapian further delineated its advantages in one-lung isolation in 1987.¹³ Through FOB use, Benumof compared bronchial insertions of right and left DLTs to explain why the relationship of bronchial anatomy to DLT construction inevitably resulted in less successful right-sided DLT positioning.¹⁴

In the 1980s, the Asahi Pentax Company’s integration of the FOB with a preexisting invention, the charge-coupled device (CCD), permitted video monitor viewing of the airway and heightened its educational and clinical benefits.¹⁵ FOB construction creativity has continued to evolve, with sizes available for all types of patients, many featuring full-color imaging and a working suction/injection channel. Light-emitting diodes (LED) and micro video complementary metal-oxide semiconductor chips (CMOS) for transmission capability have also been implemented.

Most recently, some flexible bronchoscopes have targeted the idea of being “single-use patient contact instruments,” either as a reusable FOB with a disposable, sheath-like protective barrier or as an entirely disposable “non-fiberoptic” flexible bronchoscope.

Although universal acceptance of FOB use for intubation was somewhat slow for many years, Ovassapian and colleagues were leading and effective pioneers in the educational promotion of its use through workshop training and simulation, eventually popularizing this astonishingly effective technique.¹⁶ Currently, the FOB resides worldwide within all algorithms for DI, and there is a clear, growing tendency to use this technique in combination with other recent advances as a multimodal approach to difficult airway (DA) management.

II Flexible Fiberoptic and Non-Fiberoptic Bronchoscope Design and Care

FOBs and non-fiberoptic flexible bronchoscopes (non-FOBs) are available from a number of manufacturers, including Olympus, Pentax, Karl Storz, Ambu, and Vision Sciences. For simplicity, all “scopes” will be referred to as FOBs, unless indicated. Most FOBs are very expensive and quite delicate. Knowledge of their functionality and care is paramount to prevent damage and loss of clinical availability. Repair costs may reach more than $1000 per instrument per month in teaching hospitals in the United States but can drop to almost one-fiftieth of that with diligent care and training.

A Fiberoptic Bronchoscope Design

Variations in design may seem endless, but all flexible endoscopes have certain commonalities. Differences are described later in this chapter. There are three main parts: handle, insertion tube, and flexible tip (Fig. 19-1).

Figure 19-1 Left, Fiberoptic bronchoscope (FOB) handle (control section) design. 1, Focus adjusting ring; 2, light source connection; 3, video output connection; 4, suction port; 5, valve; 6, working channel; 7, angulation control lever. Right, FOB insertion tube leading to flexible tip: 8, Insertion tube; 9, flexible tip.

At the end of the handle is either a battery-operated light source, which allows for more portability, or an optical cable connection to an external light source. The proximal “visual section” of the handle is the location of an eyepiece and lens, a video output adaptor, or an actual video screen with an integrated camera (depending on the model). FOBs with a CCD or CMOS camera chip at the tip have a wide-angle image and a higher resolution of the picture transmitted, compared with older models, which have a narrower field of view and less optical detail (Fig. 19-2). This makes video fiberscope deployment useful clinically, particularly in teaching.

Figure 19-2 Fiberoptic tip mechanics: Field of view. Insertion tip transmission of light through a lens to the charge-coupled device (CCD) chip.

Many FOBs have a visible black notch in the eyepiece at the 12-o’clock position to aid with orientation. Near the handle, an adjustable focusing ring or diopter can be fine-tuned to sharpen the image. Some models have a venting ethylene oxide sterilization cap nearby.

The handle is attached to the insertion tube (i.e., the section that goes into the patient). The tube’s outer diameter (OD) determines the minimum internal diameter (ID) of the endotracheal tube (ETT) into which the FOB can easily pass. Insertion tubes average 50 to 65 cm in length and are surrounded by a flexible inner stainless steel mesh and a flexible outer, water-impermeable plastic wrap.

Four specific components travel inside the insertion tube along the FOB length (Fig. 19-3). The first allows the transmission of light going toward the tip by way of one or two light guide bundles constructed of noncoherent glass fibers. A high degree of light intensity is focused on the proximal light guide bundle, but heat filters or reflecting mirrors prevent injury to the insertion tube components.

Figure 19-3 Fiberoptic tip components. 1, Working channel; 2, two angulation wires; 3, cladded fiberoptic-lighted bundle.

The eyepiece lens in the handle and the objective lens of the FOB tip are perpendicular to the longitudinal axis of the insertion tube, enabling the second tube component to transmit identical patient images from the distal lens to the proximal one. This component involves 10,000 to 50,000 glass fibers, as low as 8 to 9 µm in diameter, which are arranged in coherent bundles to transmit the image to the visual section in a completely spatially oriented state. (By comparison, human hairs are 17 to 180 µm in diameter.) A secondary glass cladding layer surrounds each strand to reflect light internally and maintain intensity by preventing external absorption or reflection of light from the lateral surface of each fiber. The glass fibers are extremely sensitive to damage. Although many thousands of fibers might seem expendable, when one is broken, a black dot becomes visible within the transmitted image. Excessive FOB bending, dropping, or external pressure (e.g., by teeth) can quickly add up to many dozens of black spots, rendering significant impairment of FOB visual acuity and necessitating costly repair.

On the back of the handle is a bending or angulation lever. Through an up or down movement of the thumb, it causes pulling on the third insertion tube component located along the sagittal plane, the two angulation wires. This initiates movement of the FOB tip in the opposite direction (i.e., down or up, respectively) by as much as 240 to 350 degrees (see Fig. 19-1). These delicate wires can also be broken with excessive pressure, including lever motion if the FOB tip is still within the ETT lumen.

The last component is termed the working channel; it is 1.2 to 2.8 mm in diameter and runs the length of the FOB from the suction or working port on the handle to the FOB tip. When the working port is attached to suction or oxygen tubing, the nearby spring valve can be opened by index finger pressure to allow suctioning or oxygen administration. Alternatively, a syringe with local anesthetic or other medication can be attached to the working port (also called the suction port) or to the biopsy/injection port below the handle (present in some models). When drugs are being given, the operator must make sure the suction is off so that the medication actually goes forward.

The FOB tip or bending section is hinged and has an objective lens (approximately 2 mm in diameter) with a fixed focal point and a short field of view (75 to 120 degrees) (see Figs. 19-1 to 19-3).

Many models are available in sizes from premature infant to large adult and with varying fields of view, video monitors, closed-valve systems, and other features (Table 19-1).

TABLE 19-1 Comparison of Specifications of Flexible Fiberoptic and Endoscopic Intubating Devices

B Fiberoptic Bronchoscope Cleaning

Almost half a million bronchoscopies are performed per year in the United States.¹⁷ Whenever any equipment is reused between patients, there is always a concern for avoiding the transmission of communicable diseases. Although there have not been any reports of infection or cross-contamination caused by fiberoptic intubation for elective or emergency purposes, sporadic references testify to instances of infection or contamination after flexible bronchoscopic procedures such as bronchial washings or bronchoscopic lavage. Between the years 2000 and 2007, the American Association for Respiratory Care (AARC), American College of Chest Physicians (AACP), American Association for Bronchology and Interventional Pulmonology (AABIP), and Association for Professionals in Infection Control (APIC) issued guidelines and consensus statements to assist in the prevention of FOB-associated infection or contamination.¹⁸^–²⁰

Since the 1970s, sources of contamination have included a number of factors: sentinel patients, contaminated water, inadequate sterilization technique (due to insufficient quality or quantity of sterilizing solution), repeated use of cleaning fluid or brushes, automated endoscope reprocessors, and FOB instruments with design errors or damage.²¹^–²⁴ Valves and working channels are usually the most suspect areas for ineffective FOB sterilization. Multiple organisms have been found, including Pseudomonas aeruginosa, non-tuberculosis mycobacteria, Serratia marcescens, Mycobacterium tuberculosis, Stenotrophomonas maltophilia, Legionella pneumophila, Rhodotorula rubra, Klebsiella species, Proteus species, and fungi.^21,²⁵^–²⁸

When an FOB is being used for patient management, involved clinical sites automatically fall under the aegis of mandatory universal precautions. Constant vigilance in FOB care and high-level disinfection are imperative. Once used, an FOB should be directly handed off to trained assistants or placed in a vertical holding tube (e.g., ProShield, Seitz Technical Products, Avondale, PA) for rapid pickup. Holding tubes should be long enough to handle FOBs up to 65 cm in length; they prevent damage and contamination that might occur from contact with other equipment or people.

Disinfection may take up to 45 min (Fig. 19-4). The assistant should carefully insert a cleaning brush into portals entering the working channel. The brush must be advanced fully along the compete span of this conduit to effect early removal of secretions according to the instructions of the manufacturer and the health care organization.

Figure 19-4 Steris machine for sterilization of a fiberoptic bronchoscope. The working channel is flushed out before being carefully placed within the sterilizer.

Next, the FOB has to be diligently inspected for any damage, tears, indentations, or abnormalities along its entire length. A leak test to detect holes in the insertion tube sheath is essential at this point, and failures necessitate sending the FOB for repairs without any further sterilization.

The suction ports and biopsy ports (if present) need to be disassembled from the rest of the FOB. All nondisposable parts must be gently placed in glutaraldehyde, peracetic acid, orthophthaldehyde, hydrogen peroxide gas plasma, or other manufacturer-indicated sterilization solution, and the working channel must be syringe-flushed with this disinfectant conforming to manufacturer and health care organization instructions.²⁹^–³¹

After completion of the specified sterilization time, all parts must be removed to prevent caustic damage to the instrument. The FOB should be gently washed and thoroughly rinsed with sterile water, including flushing of the working channel to prevent toxicity from residual chemicals.³² It is mandatory to dry the channel by suctioning or purging with 70% alcohol and compressed air for a time period in keeping with manufacturer and health care organization instructions.

Most bacteria, fungi, and viruses are susceptible to these sterilization processes, including human immunodeficiency virus (HIV) and hepatitis. FOBs that have been used in patients with contagious diseases (e.g., tuberculosis) may require a lengthy ethylene oxide sterilization and aeration procedure for up to 24 hours, with the venting cap secured to the venting connector. In the case of suspected prion infection (Creutzfeldt-Jakob or variants), it is best to avoid bronchoscopy if possible, because the sterilization process for most medical instruments would be damaging.¹⁸^–²⁰^,³³

Presently, routine surveillance cultures have not been recommended by the AARC, AACP, AABIP, or APIC because of lack of criteria to determine testing frequency, relevance when positive results occur, indeterminate courses of action, and costs of testing procedures.¹⁸^–²⁰

During all handling and sterilization techniques, keeping the FOB as straight as possible is extremely important to avoid damage. Once the device has been cleaned, it is preferable to store it suspended by its handle in a moderately lighted, climate- and humidity-controlled, safe location. Close proximity to radiation should be avoided because of deleterious effects on the FOB material.³⁴

C Disposable Flexible Bronchoscopes

Because efforts toward the production of a truly autoclavable FOB (e.g., Bronchosteril endoscope, Andromis, Geneva, Switzerland) did not lead to a widely accepted device, other solutions aimed at a simplified approach to the prevention of cross-contamination were developed.

1 Sheathed Fiberoptic Bronchoscope

Vision Sciences, Inc. (Orangeburg, NY) has produced two adult-sized, channel-less FOBs for use with a clear, durable, snugly fitting, presterilized flexible, thermoplastic, elastomer EndoSheath that incorporates its own 1.5- to 2.1-mm working channel. The disposable sheath potentially prevents transmission of organisms and may increase FOB availability by requiring no down-time for sterilization. It might also reduce costs in centers where economic factors limit the purchase of more than a minimum number of bronchoscopy systems or limit the availability of sterilization equipment or personnel.^35,³⁶

2 Non-fiberoptic Flexible Bronchoscope

The Ambu aScope (Ambu A/S, Ballerup, Denmark) is a fully disposable, sterile, battery-operated non-FOB with a small (0.8-mm) working channel capable of drug instillation but not suctioning. It has a CMOS chip, a steering button to flex the tip, and a distal LED (Fig. 19-5). Images are transmitted along a cable within the insertion tube and transferred to a small portable monitor by way of a video connection cable at the handle. In its early version, this non-FOB had a timing mechanism allowing it to function for a maximum of 30 minutes during an 8-hour period starting from the initial power startup. A more recent version of this device comes without these time limitations. The monitor can be used for 150 intubations and is connected to an external monitoring system. Apart from routine use of this instrument, a particular advantage may occur in patients with highly contagious disease (e.g., Creutzfeldt-Jakob), in immunosuppressed patients, or in situations in which cheaper devices may be beneficial (e.g., where economic factors limit purchases or where FOB is seldom used).^37,³⁸

Figure 19-5 Disposable Ambu aScope with a button lever to angle the tip down or up.

III Rationale for Fiberoptic Intubation

Airway management failure is a leading cause of patient morbidity and mortality in closed claims analyses.³⁹ During the period 1999 to 2005, failed intubation or DI was the cause of 2.3% of the 2211 anesthesia-related deaths in the United States.⁴⁰ With rigid laryngoscopes (RLs), DI was reported to have a frequency ranging from 1% to 13%.⁴¹^–⁴⁵ Shiga and colleagues performed a meta-analysis of studies on 50,760 patients and estimated the average occurrence of difficult intubation to be 5.8%,⁴⁶ with a range of 4.5% to 7.5% overall^47,⁴⁸ and an even greater incidence in obstetric or obese patients.⁴⁹^–⁵¹ Anesthesia Associates, Inc. (AincA), San Marcos, CA Benumof’s estimate of “cannot intubate, cannot mask-ventilate” scenario was verified by Heidegger and associates at 0.007%,^52,⁵³ whereas Kheterpal and coworkers showed the incidence of impossible mask ventilation to be 0.15% in a prospective series of 53,041 patients.⁵⁴

FOB intubation has always had a place in these scenarios, but this simple technique seems formidable to many. However, despite the increasing availability of less expensive intubating supraglottic airways (SGAs), lighted stylets, video laryngoscopes (VLs), and optical laryngoscopes (OLs), an explosion of improved laryngoscopic views, and greater intubating success rates, there is still a definite need for FOB intubation. A survey of American anesthesiologists by Rosenblatt and colleagues revealed a strong preference for FOB intubation for DA patients.⁵⁵ Avarguès and associates’ survey of French anesthetists in 1999 revealed that 64% of responders expressed the need for more training in FOB intubation.⁵⁶ Furthermore, FOB use was mentioned twice in the revised 2003 DA algorithm by a panel of experts who formulated the American Society of Anesthesiologists (ASA) Practice Guidelines for Difficult Airway Management.⁵⁷ In a 2009 review of the existing algorithms for DA management, Frova and Sorbello affirmed that FOB is universally recognized as the gold standard in the awake, sedated, or anesthetized “difficult to intubate” patient.⁵⁸

Finally and more practically, there have been numerous cases in which older devices and even the most recently developed airway management devices have proved to be inadequate. FOB employment and assistance steadfastly facilitates the execution of successful intubations, often rescuing these failures, either alone or as part of a multimodal approach to the DA.^59,⁶⁰

The FOB has a number of unique, wide-ranging characteristics:

• Its flexible, gliding attributes allow FOB skimming along the most twisted of DA obstacle courses while still posting the highest success rates for intubation.

• During intubation, the FOB is the device least likely to result in any cervical spine motion.⁶¹

• The FOB can be used for intubation in any body position, via oral or nasal routes, in all age groups.

• Under excellent local airway anesthesia, FOB intubation is associated with negligible hemodynamic changes.

• The FOB has multiple diagnostic capabilities for determining abnormal anatomy, assisting with implementation of other airway devices, and trouble-shooting ventilatory problems.

A Indications for Flexible Fiberoptic or Endoscopic Intubation

Although many anesthesiologists routinely carry out FOB intubation on all of their patients, most tend to adhere to specific indications. There is no hard or fast rule for “awake” versus “asleep” fiberoptic intubation. An awake approach is usually chosen to lessen significant patient risk in comparison to other methods, especially rigid laryngoscopy. The awake approach may be more advisable in cases of a very difficult airway or with a somewhat difficult airway in a patient with intolerant comorbidities endangered by the trauma or hypoxemia of non-FOB techniques (e.g., critical coronary artery disease). A list of indications for flexible airway endoscopy is presented in Box 19-1.

Box 19-1 Indications for Use of Flexible Fiberoptic or Endoscopic Intubation

1. Routine intubation

2. Difficult intubation (DI)

a. History of prior DI

b. Suspected DI from patient history or physical examination

c. Rescue of failed intubation attempt

d. Intubating patients with preexisting Combitube or Rüsch EasyTube

3. Prevention of cervical spine motion in at-risk patients

4. Avoidance of traumatic oral or nasal effects of intubation (e.g., loose teeth, nasal polyps)

5. Avoidance of aspiration in high-risk patients

6. Diagnostic purposes

a. Trouble-shooting high airway pressures

b. Trouble-shooting hypoxemia

c. Observation for airway pathology (e.g., stenosis, tracheomalacia, vocal cord paralysis)

d. Removal of airway pathology (e.g., secretions)

7. Therapeutic uses beyond planned FOB intubation

a. Endotracheal tube exchange

b. Assistance with airway placement (e.g., SGA, retrograde intubation, etc.)

c. Positioning of double-lumen tubes or bronchial blockers

d. Positioning of endotracheal tubes at specific depths

e. Intratracheal observation of initial tracheostomy instrument entry

FOB, Fiberoptic bronchoscope; SGA, supraglottic airway device.

B Contraindications: Absolute, Moderate, and Relative

The most important contraindication to FOB use may well be lack of skill of the endoscopist (i.e., FOB operator) due to inadequate training or inadequate maintenance of formerly acquired skills. Any lack of a trained assistant or of available, ready to use, proper equipment may also negate FOB plans. There are few other contraindications to FOB use. These may involve situations in which harm to the instrument may occur (e.g., uncooperative patients), cases in which FOB use is extremely likely to be unsuccessful (e.g., patients with known near-total upper airway obstruction [Fig. 19-6]), or rare instances in which another technique may pose less risk for airway management (e.g., patients who have massive facial trauma with excessive bleeding might do better with a tracheostomy). Contraindications for awake and asleep FOB intubation are listed in Boxes 19-2 and 19-3, respectively.

Figure 19-6 Severe subglottic stenosis appears as a pinpoint tracheal opening.

Box 19-2 Contraindications for Awake FOB Techniques

1. Absolute contraindications

a. A completely wild, uncooperative patient

b. Lack of endoscopist skill, assistance, or equipment

c. Near-total upper airway obstruction unless for diagnostic purposes

d. Massive trauma (but, if retrograde intubation is chosen, FOB may help; see text)

2. Moderate contraindications

a. Relatively uncooperative patient

b. Obstructing or obscuring blood, fluid, anatomy, or foreign body in the airway that might inhibit success

c. Very small entry space

3. Relative contraindications

a. Concern for vocal cord damage that might be caused by blind ETT passage over the FOB

b. With some perilaryngeal masses, blindly advancing the ETT can “cork out” or seed the tumor (this situation should be discussed with the ENT specialist, if possible)

c. Documented or suspected nonconventional infectious agents, agents resistant to multiple drugs, or infectious diseases in the absence of a single-use device

ENT, Ear, nose, and throat; ETT, endotracheal tube; FOB, fiberoptic bronchoscope.

Box 19-3 Contraindications for Asleep FOB Techniques

1. Absolute contraindications

a. Lack of endoscopist skill, assistance, or equipment

b. Near-total upper airway obstruction unless for diagnostic purposes

c. Massive trauma (but, if retrograde intubation was chosen, FOB may help; see text)

2. Moderate contraindications

a. Too high an aspiration risk or too difficult an airway

b. Inability to tolerate even a short period of apnea

c. Obstructing or obscuring blood, fluid, anatomy, or foreign body in the airway that might inhibit success

d. Very small entry space

3. Relative contraindications

a. Concern for vocal cord damage that might be caused by blind ETT passage over the FOB

b. With some perilaryngeal masses, blindly advancing the ETT can “cork out” or seed the tumor (this situation should be discussed with the ENT specialist, if possible)

c. Documented or suspected nonconventional infectious agents, agents resistant to multiple drugs, or infectious diseases in the absence of a single-use device

ENT, Ear, nose, and throat; ETT, endotracheal tube; FOB, fiberoptic bronchoscope.

IV Equipment

A Fiberoptic and Non-fiberoptic Bronchoscope Model Details

FOB specifications and characteristics have been presented in Table 19-1. Some models have eyepieces or video attachments. Others have varying degrees of portability. Sizes and ranges of view are also variable, from the smallest infant to the largest adult size. In 2010, Olympus developed a unique MAF-GM system; it features a lithium rechargeable battery-operated FOB with a fixed, rotatable video screen by the handle––all totally immersible for sterilization. Its CCD camera has a memory card and an xD chip for still photography and video recording.

B Fiberoptic Bronchoscope Cart

Preparation for highly useful FOB techniques is important to increase the likelihood of success. The incorporation of an FOB cart as a movable asset capable of rapid transport to operating rooms, specialty units, or floors is ideal for routine or emergency use. Contents need to be arranged logically in a readily available design so that the composition and organization will be uniform across the facility in the event that more than one cart is needed for an institution. All airway specialists must be familiar with the contents of the FOB cart and know how to have it transported to required patient sites without delay. Preferably, the cart should have two widely separated tubular structures for hanging a clean FOB and, later, a used one (Fig. 19-7). Typically, the FOB cart will also have a light source, a video monitor (ideally), endoscopy masks, bronchoscopy swivel adapters, oral intubating airways, bite blocks, atomizers, tongue blades, cotton-tipped swabs, gauze, soft nasal airways, and local anesthetics (e.g., 2% and 4% lidocaine, 2% lidocaine gel or paste).

Figure 19-7 Mobile fiberoptic cart with a video screen and supplies underneath. The fiberoptic bronchoscope (FOB) is braced in the clean container on the left, and a holding tube for the used FOB is located on the right. The FOB insertion section lies within an endotracheal tube in a warm saline solution.

In addition to clinical use, FOB carts can be used for institutional continuous education programs and teaching workshops. All carts should be organized and upgraded by the anesthesiology team.

Optionally, an FOB cart setup could also be incorporated as part of a more complete DA cart that includes items needed to follow the DA algorithm. Among other items, a DA cart should contain a VL and screen, SGAs, intubating SGAs, ETT introducer/exchangers,^62,⁶³ and percutaneous airway rescue sets.

C Ancillary Equipment

1 Bronchoscopy Swivel Adapters and Endoscopy Masks

Bronchoscopy adapters and endoscopy masks are often used in asleep or awake patients for FOB examination, intubation, diagnosis, or therapy.

Bronchoscopy swivel adapters have the capacity to rotate when placed between the ventilating system and a mask, SGA, or ETT. They look like elbow adapters but are equipped with a “flip-cap port” covering a diaphragm with a central opening (Fig. 19-8). This permits passage of an FOB with virtually no leak during use of the continuous ventilation system on a patient.

Figure 19-8 Bronchoscopy swivel adapter with a snug fiberoptic bronchoscope diaphragm opening that allows ventilation without leaking.

Endoscopy masks differ from regular masks by having at least one larger additional opening whose function is similar to that of a bronchoscopy swivel adapter port (Fig. 19-9). The opening permits both FOB and ETT passage for intubation during continuous mask ventilation. Some masks have recessed one-way, valve-like openings for FOB and ETT entry.

Figure 19-9 Endoscopy mask with connector tubing for ventilation (on the left) and a snug diaphragm (on top) for passage of a fiberoptic bronchoscope within an endotracheal tube.

2 Intubating Oral Airways

Intubating oral airways (IOAs) are often used in unconscious patients or in the topically anesthetized oropharynx of awake patients to act as a conduit through which an FOB is inserted for oral intubation (Fig. 19-10). It is extremely useful when an assistant holds the IOA midline throughout the intubation procedure. These airways should not be jammed fully into the patient if they seem too large for smaller mouth openings. If no IOA is used secondary to inadequate mouth opening or endoscopist preference, a bite block should be placed between the molars or incisors to prevent FOB injury.

Figure 19-10

From left to right, Berman, Ovassapian, and Williams intubating oral airways.

The ideal IOA would have the following advantages: It would protect the FOB from damage caused by the patient’s teeth or jaws, shield the FOB from the tongue and soft tissues, have an ideal length to form a path leading to the glottis, allow passage of an adequate-sized ETT, permit maneuverability of the ETT and FOB within it, possess a breakaway quality for easy removal after intubation, and have the ability to assist with mask ventilation as needed. In a truly ideal world, this ideal IOA would provoke no gag reflex, even without local anesthesia (LA).

Most studies comparing characteristics of different IOA involve non-DA.⁶⁴ No IOA is ideal, and some have disadvantages: Sizes may be too great for patients with small mouth openings; their construction may cause palate or other tissue discomfort or trauma during placement; they may lead the FOB astray (off midline); ETT cuffs may catch and tear on them; and their removal may be slightly intricate. All IOAs are disposable except for the aluminum-made Patil-Syracuse (Anesthesia Associates, Inc. (AincA), San Marcos, CA) oral airway.

The Berman intubating pharyngeal airway (Teleflex Medical Research, Triangle Park, NC) admits ETTs of 8.5 mm or smaller diameter and comes in various adult, child, and neonatal sizes. Its full-length tubular shape does not permit FOB maneuvering, but it has a wide slit the length of its side for breaking away from the ETT after intubation. If kept midline, it provides a better lead to the glottis, assuming its length is appropriate.⁶⁵ If the length is too long, its distal end is usually found in the vallecula; pulling it out 1 to 2 cm may rectify that situation. Lateral breaking away of this airway from the ETT can be difficult, particularly if periglottic ETT impingement has occurred.

The proximal half of the Ovassapian fiberoptic intubating airway (Teleflex Medical Research Triangle Park, NC) has a channel that permits passage of an ETT with a diameter of 9 mm or less. This channel has flexible lateral walls and an opening posteriorly for easy ETT removal. The distal half of the airway has a wide, flat, curved area designed to keep the tongue and soft tissues away from the FOB. Its flatness makes it easier to keep it in the midline, and its openness permits free FOB movement throughout its length. Once the FOB is near the carina and the ETT enters between the teeth, this IOA can be partially broken away to avoid tearing the ETT cuff on its corners. FOB orientation during passage through the device can be assisted by drawing a line with a marker lengthwise down the middle of the concave surface of the IOA.⁶⁶

The Williams airway intubator (Williams Airway Intubator LTD, Calgary, Canada) has two adult sizes that allow passage of an ETT of 8.5 mm diameter or smaller. Proximally, it has a circumferentially closed channel and a distally curved section with a scalloped opening on the lingual surface. The distal area permits free FOB movement. As long as this airway is kept midline and its length is appropriate, it may be the best guide to the larynx.⁶⁷ If it is too long, visualization can be problematic. There may be a concern for more frequent cuff damage with ETT sizes larger than 7.0 mm when using the smaller size of this IOA. For removal, the ETT has to be disengaged from the 15-mm ETT connector. The enclosed channel part should have been liberally prelubricated to accomplish easier ETT release. Sometimes removal can be difficult.⁶⁸

3 Short, Soft Nasopharyngeal Airways

Two techniques have described use of nasopharyngeal airways (NPAs) during FOB intubation. A method to simplify nasal FOB intubation by using a lengthwise, laterally cut NPA for breakaway capability was reported by Lu and colleagues (Fig. 19-11).⁶⁹ The lubricated, modified NPA is gently inserted into one nostril. Afterward, the lubricated FOB is guided through this NPA with the idea that the FOB tip will lead directly toward the glottis. After the FOB has entered just above the carina, the NPA is stripped away, and the ETT is railroaded over the FOB into the trachea.

Figure 19-11 A, A cut breakaway nasopharyngeal airway (NPA). B, Once the carina is visualized, the breakaway NPA is removed from the fiberoptic bronchoscope to allow passage of an endotracheal tube.

A second advantage of NPA use is its role during FOB intubation in oxygen administration and as a conduit for inhalation anesthesia administration (most commonly in pediatric patients).^70,⁷¹ This is particularly advantageous when FOB intubation is preferred to be undertaken unhurriedly in spontaneously breathing patients who need extra anesthesia. An NPA (often with a Murphy eye–type hole cut distally) is placed in one nostril and attached to a breathing circuit by a 15-mm ETT adapter while the FOB intubation procedure is completed orally or nasally through the opposite nostril.⁷²

4 Endotracheal Tubes

Regular polyvinylchloride (PVC) ETTs are used for most FOB intubations. However, the most distal ETT tip area can get caught on the arytenoids, especially the right, causing difficulty for passage into the trachea. Other centrally-curved, soft-tip ETTs have been reported to have greater success rates of passage.⁷³^–⁷⁵ However, Joo and coworkers demonstrated no difference in insertion success rate or number of manipulations required during awake FOB intubation when these two types of ETTs were compared, so long as the correct orientation of the common PVC ETT tip was made. The orientation required during insertion is that in which the Murphy eye of the ETT faces anteriorly with respect to the patient’s body, to avoid arytenoid contact. This represents a 90-degree counterclockwise rotation of the ETT from the normal ETT direction used during rigid laryngoscopy (Fig. 19-12).⁷⁶

Figure 19-12 Comparison of curved-tipped versus straight-tipped endotracheal tubes: 1, Fastrach (LMA North America, San Diego, CA); 2, Parker (Parker Medical, Englewood, CO); 3, polyvinylchloride (PVC) type.

V Clinical Techniques of Fiberoptic Intubation

A Oral Fiberoptic Intubation of the Conscious Patient

FOB intubation techniques tend to be more successful in “awake” circumstances for a number of reasons, even though the airways can be very challenging. In the conscious patient, several factors contribute to this success: The preservation of muscular tone avoids obstructive soft tissue collapse; spontaneous ventilation is more likely to dilate airway structures; and the ability to deep breathe on command can sometimes reveal obscured airway passages.

During awake FOB intubation, the patient’s state of consciousness may vary from completely awake to arousable with moderate stimulation (level 3 or 4 on the Ramsay scale) (Box 19-4).

Box 19-4 Ramsay Sedation Scale

1. Patient is anxious and agitated, restless, or both.

2. Patient is cooperative, oriented, and tranquil.

3. Patient responds to commands only.

4. Patient exhibits brisk response to light glabellar tap or loud auditory stimulus.

5. Patient exhibits a sluggish response to light glabellar tap or loud auditory stimulus.

6. Patient exhibits no response.

Patients should have an awake FOB intubation under any of the following circumstances: anticipated very difficult intubation, a high likelihood of difficult mask ventilation and intubation, a DA with comorbidities likely to result in adverse effects if intubation is not easily accomplished, and after a failed asleep intubation (using any device). Application of excellent local airway anesthesia before endoscopy significantly decreases the odds of hemodynamic changes, severe coughing, laryngospasm, and failure.

B Respiratory Monitoring Methods

The concern for respiratory events, especially after sedative and narcotic administration, has made continuous pulse oximetry a mandatory constant in addition to various monitoring schemes.

One solution involves surveillance by nasal cannula, using a side port for detection of end-tidal carbon dioxide pressure (PETCO₂) detection and setting alarm parameters for PETCO₂ and respiratory rate. There are several drawbacks. First, many FOB operators frown upon this method. Their concern is particularly valid when ETT passage is difficult. They do not want to get into a frantic disconnection of the PETCO₂ sampling tubing from the nasal cannula and then go through a subsequent reconnection to the ventilatory system to verify correct ETT placement, through the presence of PETCO₂. Second, endoscopists complain that this monitoring draws away their attention if they are constantly having to look at the respiratory screen while performing airway maneuvers. Third, alarms may be erroneous when patients breathe through the mouth and not the nose.

Respiratory rate monitoring is also possible on electrocardiographic equipment that measures impedance during thoracic excursion. The drawback to this method is that waveforms are not always reliable, particularly with large body habitus, lack of thoracic impedance, and placement of electrocardiographic leads away from the chest.

C Sedation and Analgesia

As vital as the pharmacologic approach is, a quiet, peaceful, and stress-free atmosphere is of paramount importance when performing an awake FOB intubation. Any external pressure from non-airway experts must be gently but firmly excluded. Other personnel should be advised of the reasoning for the procedure and a realistic waiting time until completion of airway management.

As the FOB process is about to begin, sedation may continue to be titrated with caution. Sedatives tend to be more associated with dysphoria and patient combativeness than narcotics, which can be used to offset discomfort and airway reflexes. In addition to respiratory depression, sedatives and narcotics are associated with increased collapse of airway soft tissues, aspiration, and laryngospasm. One must be on guard for obstruction during sedation, even at low dosages.

Many combinations have been used with expert care, including midazolam (1 to 2 mg) for amnesia and sedation and fentanyl (0.7 to 1.5 µg/kg) for analgesia and antitussive effects. Other agents commonly used include ketamine (0.025 to 0.15 mg/kg) for sedation and analgesia, a combination of ketamine and propofol, propofol (25 to 75 µg/kg/min) for sedation, and remifentanil (0.05 to 0.01 µg/kg bolus followed by 0.03 to 0.05 µg/kg/min infusion) for analgesia.

Ketamine produces less respiratory depression but is longer acting and has no known reversal therapy in humans. One study on ketamine/xylazine use in primates showed reversal with atipamezole (Antisedan), an α-adrenergic antagonist, but because xylazine is a clonidine analogue, it is difficult to say whether the ketamine alone would be reversed to the same extent.⁷⁸

Dexmedetomidine (0.7 to 1.0 µg/kg bolus over 10 minutes followed by 0.5 to 1.0 µg/kg/hr infusion) is associated with hypnosis, amnesia, analgesia, and less respiratory depression. It has been used and titrated so that the patient remains responsive to verbal command. In animal studies, dexmedetomidine has been shown to be reversible by atipamezole, but no human studies are available.⁷⁹

The most appropriate way to administer precisely titrated sedation seems to be with target-controlled infusion. The technique described for nasal FOB intubation has valid principles for oral approaches. Propofol and remifentanil have been studied most extensively.⁸⁰ Mean target plasma concentrations for propofol and remifentanil were 1.3 µg·mL⁻¹ (standard deviation [SD], 0.2 µg·mL⁻¹) and 3.2 ng·mL⁻¹ (SD, 0.2 ng·mL⁻¹), respectively. Rai and colleagues found no difference in patient satisfaction between the two but reported better FOB intubation conditions and a higher incidence of recall with remifentanil than with propofol.⁸¹ Similar results were found by Cafiero and coworkers.⁸² In patients with cervical trauma, a remifentanil effect site concentration as low as 0.8 ng·mL⁻¹ proved to be effective for awake FOB intubation.⁸³ The very short induction and recovery times with remifentanil may represent a major advantage. Nevertheless, the possibility of increased thoracic wall rigidity and laryngospasm should be kept in mind.⁸⁴

D Local Anesthesia Purposes and Preparedness

Ideally, LA application is performed to achieve an excellent state of airway anesthesia to prevent discomfort, psychological distress, hemodynamic changes, and lack of cooperation. When it is appropriately executed, FOB intubation is made markedly easier and more successful. If the patient still has secretions in spite of antisialogogue action, wiping the tongue or directing the patient to suck on gauze can be helpful to soak up excess saliva. Before administration of LA, the relevant anatomy, drug concentrations, appropriate and maximum dosages, time of onset, toxicity, and alternative techniques must be known. Drugs and full resuscitation equipment must be readily available for treatment of toxic reactions. The systemic effects of two or more local anesthetics are additive, and consideration has to be given to the age and size of the patient, the site of application, and combinations of local anesthetics planned. In particular, the tracheobronchial tree is known to have very rapid systemic absorption of these agents. Vasoconstrictors have little effect on duration of action or prevention of toxicity from topical oropharyngeal anesthetics.

1 Innervation of Orotracheal Airway Structures

Cranial nerve IX, the glossopharyngeal nerve (GPN), supplies sensory innervation to the soft palate, the posterior third of the tongue, the tonsils, and most of the pharyngeal mucosa.^85,⁸⁶ Some fibers also supply the lingual surface of the epiglottis.⁸⁷ This nerve controls the afferent component of the gag reflex. Cranial nerve V, the trigeminal, gives sensory supply to the anterior two thirds of the tongue but this area rarely needs anesthesia.

Cranial nerve X, the vagus, also forms part of the pharyngeal plexus, giving motor function to the soft palate and pharyngeal muscles. The superior and inferior laryngeal branches of the vagus carry out sensory supply to the laryngopharynx. The superior laryngeal nerve has an internal division that supplies sensory innervation to the base of the tongue, vallecula, epiglottis, piriform recesses, supraglottic mucosa, and the laryngeal vestibule above the vocal cords. Its external division provides motor control to the adductors/tensors, the cricothyroid muscle, and the cricopharyngeal part of the inferior constrictor of the pharynx. The inferior branch of the vagus, the recurrent laryngeal nerve, receives sensory input below the vocal cords, including the subglottic mucosa.

2 Topical Orotracheal Anesthesia Techniques

Determination of what technique is needed for local airway anesthesia depends on the intended approach for FOB intubation. Relative and perhaps absolute contraindications to these techniques include infection in the area, inability to determine anatomy, lack of patient cooperation, and any comorbidity such as coagulopathy or documented allergy that would pose an unwarranted risk. For a completely insensate oral approach, anesthesia must be provided to some of the soft palate, posterior tongue, posterior wall of the pharynx, vallecula, periglottic area, larynx, and trachea.

LA of the airway can be performed without sedation and should be the method of choice if patients have significant airway compromise. If possible, however, it is more desirable to give sedation before any deep pharyngeal/laryngeal anesthesia, to mask the choking feeling that many patients may experience and avoid this potentially distressing sensation. The bitter taste of the LAs can be somewhat masked by the use of mint strips.

a Glossopharyngeal Anesthesia

In advance of performing a GPN nerve block, give instructions to the patient that he or she may be requested to take deep breaths, gargle, or swallow. It is helpful to vocally mimic gargling so that the patient understands this directive. While pressure is applied on the lateral tongue surface with a tongue depressor, the operator shifts the tongue medially and sprays the LA during inspiration at the anterior tonsillar pillar (Fig. 19-13). After waiting a number of seconds for patient recovery, the process is repeated on the opposite side, then once more on both sides.

Figure 19-13 1, Flexible memory of MADgic atomizer. 2, Glossopharyngeal nerve block in tonsillar fossa.

Advantages include a lower likelihood of provoking gagging and greater cooperation when the tongue pressure is initiated laterally, compared with a midline approach. Also, inhaling and gargling are more likely to maximize anesthetic spread, as opposed to coughing the aerosol at the endoscopist. Optional methods include using a 3-mL syringe of 3% lidocaine on a MADgic atomizer (LMA North America, San Diego, CA) or Exactacain spray (benzocaine 14%, butamben 2%, tetracaine hydrochloride 2%), or alternatively, by touching the pillars for 5 seconds with a swab or pledget soaked in LA. An uncommon and not recommended technique is to actually inject the area with the LA. This last method is fraught with danger to the endoscopist (from biting) and to the patient due to the chance of hematoma formation or toxicity secondary to injection into a very vascular area.

b Alternative Methods of Intraoral Anesthesia

Alternative methods of intraoral anesthesia may anesthetize not only the GPN distribution but also the laryngeal area or even the trachea as drugs are either inhaled or aspirated. With the atomized technique, lidocaine solution is applied via the MADgic to the palate, tonsillar pillars, vallecula, epiglottis, and larynx during deep inspiration by bending the stylet-like applicator in whatever curve is needed.

In the “lollipop” method of LA, 3 cm of lidocaine paste is placed on both sides of one end of a tongue depressor. The operator puts this end on the middle of the patient’s tongue and advises the patient to keep the depressor held in place between the teeth. For the “toothpaste” method, the gel is placed directly down the middle of the tongue, while the tongue tip is held with gauze (Fig. 19-14). In these latter two instances, the lidocaine is left to dissolve over 5 to 10 minutes.

Figure 19-14 Glossopharyngeal nerve block and internal superior laryngeal nerve block. Five percent lidocaine is used for the toothpaste technique of intraoral anesthesia.

With the gargle method, a “slurry” or 4 mL viscous lidocaine is gargled continuously for 5 minutes. Finally, the Tessalon Perle (benzonatate) method involves keeping the Perle in the middle of the tongue so that it dissolves. If the Perle does not start to dissolve within a few minutes, it can be bitten slightly to permit leakage of the drug.

c Superior Laryngeal Nerve Block

The superior laryngeal nerve (SLN) block is advantageous for patients who have limited intraoral cooperation (e.g., perhaps only allowing a quick peritonsillar spray), for those who have no possible oral cavity entry (i.e., requiring nasopharyngeal FOB intubation), or as a rescue method after a failed internal SLN attempt when coughing or hemodynamic changes from sprays are undesirable.

Two techniques are available for the external neck approach to bilateral SLN block. In the simpler technique, attach a 10-mL syringe with 6 mL of 1% lidocaine to a 21- or 22-G needle as an injection system (Video 19-1). Clean the neck area with antiseptic solution and locate both hyoid cornua (Fig. 19-15). Keep the forefinger of the nondominant hand by one cornu for visual reference, and hold the syringe dart-like near the needle hub while advancing the needle perpendicularly toward that cornu. Once bone is felt, shift the nondominant hand to brace against the neck and hold the system near the hub. Aspirate the syringe gently; if no blood returns, inject 3 mL slowly. Repeat the process on the other side.

Figure 19-15 Superior laryngeal nerve block. The assistant holds pressure on the right hyoid cornu while the operator directs the local anesthetic 22-G needle at the left hyoid cornu.

The second external approach to SLN block is more complex and takes longer to perform. The same system is used to hit the cornu. Then the operator walks off anteromedially and caudally 0.1 to 0.4 cm and feels the click of going through the thyrohyoid membrane at a depth of 1 to 2 cm.⁸⁸ The needle is then braced, and the remainder of the technique is identical. The block has to be repeated on the other side.

Internal anesthetization of the SLN can be accomplished by previously mentioned intraoral techniques including spraying toward the “imagined larynx.” An uncommon method involves putting pressure in the piriform fossa with a gauze soaked in local anesthetic; the gauze is held in place by a curved clamp for 10 minutes.

Trouble-Shooting

1. The cervical collar is in the way: Open the collar on one side of the neck and flip its anterior portion over to the other side. Perform both blocks and close the collar when finished.

2. The hyoid is hard to feel with only one hand: It will be more prominent if an assistant presses gently against the opposite hyoid cornu toward the operator’s finger on the side being blocked.

3. Blood is aspirated: The system has to be withdrawn slightly, redirected, and braced until aspiration is negative. (This is particularly important to prevent intracarotid arterial injection and seizures.)

4. Bone is felt but injection is not possible: The needle tip is probably in the periosteum. Using two hands, brace the system constantly, and imperceptibly withdraw 1 mm at a time until negative aspirations are followed by the ability to inject. Excessive distance during withdrawal can cause failure.

d Transtracheal Block

If a collar is in place, locate the cricothyroid area through the anterior collar opening or by flipping the anterior part laterally, as described previously (Video 19-2). Apply antiseptic, and mark the area before refastening the collar. Straddle the trachea with two digits of the nondominant hand. With the dominant hand, direct a 10-mL syringe containing 4 mL of 4% lidocaine attached to a 21- or 22-G needle as a system, aiming posteriorly in the cricothyroid space while aspirating gently (Fig. 19-16). Shift the other hand to keep the system braced on the neck, if possible, and help guide it until many air bubbles are freely obtained. At this point, brace or encircle the system firmly while the dominant thumb is poised to inject. Instruct the patient to breathe in gently and exhale gently but maximally. When exhalation is at completion, rapidly inject the anesthetic. As the LA enters the trachea, the patient may cough, but because exhalation has taken place, a quick breath must be taken to initiate any more cough, and this will help spread the anesthetic. Usually more coughing ensues. By bracing against the neck (or collar) and encircling the system, one need not worry about excessive needle penetration, removal, or breakage even if the patient’s neck moves quite a bit. The system can be removed when finished.

Figure 19-16 Transtracheal block. The operator braces his or her hand on the patient’s chest while aspirating for air through the cricothyroid membrane.

According to Todd, concern about coughing in patients with cervical spine risk is unfounded, because patients cough periodically and those coughing during transtracheal blockade have never been shown to develop secondary neurologic damage.⁸⁹ Some clinicians prefer using a 20-G angiocatheter in lieu of the needle. They perform the technique in a similar fashion, but after air is aspirated they advance the catheter 0.5 to 1 cm, brace the catheter, remove the needle and syringe, disconnect the syringe, connect the syringe to the catheter, aspirate the catheter for air, and proceed in as previously described. The benefit of the needle technique is that it is faster, it is less likely to provoke more coughing caused by hitting the posterior tracheal wall (particularly when the catheter is threaded in too far), and it is more successful (because the needles are shorter, less flexible, and, even if pulled out of the trachea, can be advanced easily). In contrast, with a catheter coming out of the trachea, the needle would have to be reinserted with it, or the angiocatheter would have to be entirely replaced if the plastic is damaged.

Trouble-Shooting

1. The cricothyroid space is impossible to feel: A cricotracheal injection is acceptable.

2. More than a tiny wisp of blood is aspirated: Remove the system and refill the syringe with fresh local anesthetic to avoid injecting blood into the respiratory system.

3. The hyoid bone seems very close to the cricothyroid space: Reassess anatomy or abandon the technique to prevent vocal cord damage.

4. The patient is at very high risk for aspiration: To maintain the patient’s protective reflexes, avoid transtracheal anesthesia. Instead, use the “spray as you go” technique (discussed later) on the visualized vocal cords. Rapidly insert the FOB, and follow immediately with ETT passage and cuff inflation.

The combination of the three blocks described (GPN, SLN, and transtracheal) provides the quietest airway. Any order can be chosen, but usually the oropharynx is anesthetized first because it requires more cooperation on the part of the patient. The external neck approach to the SLN would be next if needed, followed by the transtracheal block, in order to have the procedure that elicits the most patient reaction (i.e., coughing) come last.

e Aerosol Method

The advantage of the aerosol method is that nebulized local anesthetic can be administered without needling and without much cooperation if given by mask. If it works, it is the best method to avoid coughing. This may take up to 15 minutes with some aerosols but can be faster with others such as the Aeroneb Go nebulizer (Dangan, Galway, Ireland). Nebulized lidocaine (5 mL, 4%) can be given via a mouthpiece for oral approaches. Instruct the patient to inhale only through the mouth until nebulization is complete (i.e., to prevent dilution of inhaled anesthetic from breathing through the nose). More cooperation is necessary for success, and the patient needs constant observation to ensure that instructions are actually being followed.

f “spray as You Go” Technique

The “spray as you go” method is used for patients who have partial or no pharyngeal, superior laryngeal, or transtracheal anesthesia. The operator uses an adult FOB with working channels of 2 to 2.5 mm and directs an assistant to give a quick pulse of 1 mL of 2% to 4% lidocaine (4 mL total), when areas with insufficient anesthesia are approached. If the working channel diameter is small (≤1 mm), this permits smaller incremental doses of LA administration (0.2 mL) to jet out as a spray. Do not employ simultaneous suction, because anesthetic will be lost in the suction.

Patients are more likely to react and cough after these pulses, and the FOB view may be obscured for some seconds, after which the FOB can be advanced until another unanesthetized area is reached.⁹⁰ An interesting method to avoid the obscured view is to attach a syringe containing local anesthetic to an epidural catheter (0.5 to 1 mm ID, single distal hole) and pass it through a three-way stopcock attached at the FOB injection port through the working channel. On the second stopcock port, attach the suction tubing for easy use by a simple turn. Extend the catheter tip 1 cm beyond the FOB tip so that as LA is injected, the spray goes a farther distance away, causing less visual disturbance to the FOB. Taping the proximal epidural at the working channel port area keeps its tip a fixed distance.

3 Local Anesthetic Drug Choices

LA dosing for various airway blocks is listed in Table 19-2. Toxicities of these injectable drugs have been described elsewhere, but with regard to the airway, some considerations need clarification.

TABLE 19-2 Oropharyngeal Local Anesthesia

Drug	Form	Appropriate Blocks
Lidocaine	Pacey’s paste (slurry): 7 mL 2% solution + 7 mL 2% viscous in two syringes with 3 mL air each + sweetener (mix back and forth via three-way stopcock); should be swished intraorally in 2 aliquots
	2-4% solution	All blocks except as listed below
	1% solution	Preferred for SLN neck blocks
	4% solution	Preferred for transtracheal blocks
	2% viscous lidocaine	Intraoral or nasopharyngeal
	2-5% gel/ointment/paste	Intraoral
Exactacain (benzocaine, butamben, tetracaine HCl)	Metered spray	Intraoral
Cetacaine (benzocaine, tetracaine HCl, butamben, benzalkonium chloride)	Spray	Intraoral
Hurricaine (benzocaine)	Spray	Intraoral
Tessalon Perle (benzonatate)	200-mg capsule	Intraoral

SLN, Supralaryngeal nerve.

Nydahl and colleagues demonstrated that 20 mL of 2% lidocaine gel in the nasopharynx was mostly swallowed in the stomach. Only one eighth of the described toxic blood level of an equal amount of injected drug resulted. Doubling the volume to 40 mL was equivalent to producing less than one third of the toxic level.⁹¹

Higher dosing and routes are most significant and should depend on a patient’s height and size. Woodall and associates reported symptoms attributable to local anesthetic in 36% of 200 healthy subjects (anesthesiologists attending an FOB course).⁹² Local anesthetics used included nebulized lidocaine (200 mg or 5 mL 4%), nasopharyngeal lidocaine (100 mg or 2 mL 5%), and “spray as you go” lidocaine (600 mg or the equivalent of 15 mL 4%). The maximum dose in their study, 9 mg/kg lidocaine, was somewhat higher than the average dose of 5 mg/kg cited for performance of the described blocks in this chapter whose total dosage is 370 mg (i.e., GPN, 150 mg; SLN, 60 mg; and transtracheal, 160 mg).

Exactacain spray is a metered anesthetic with a six-spray maximum limit in adults to reduce the risk of toxicity. Each spray delivers 9.3 mg of benzocaine. Onset is within 30 seconds, and the duration is 30 to 60 minutes. Care must be taken to avoid use in patients with ester allergies or if the possibility of methemoglobinemia is likely due to patient comorbidities or concomitant drug therapy. Methemoglobinemia is more often associated with unlimited, continuous spraying of the Cetacaine spray (benzocaine 14.0%, butyl aminobenzoate 2.0%, tetracaine hydrochloride 2.0%) or Hurricaine spray (benzocaine 20%), which deliver 28 mg of benzocaine in a 0.5-second spray.⁹³^–⁹⁵ According to Khorasani and colleagues, dosing can be variable with these agents due to the orientation of the container to the patient during spraying or fluctuations in LA canister volume.⁹⁴ Between 1950 and 2005, only 26 of 126 total reported methemoglobinemia cases were related to endotracheal intubation. Transesophageal echocardiography was the procedure with the most frequent association, with a documented incidence of 0.115%.⁹⁵ Some sources consider this to be an underestimation. Because of recent Exactacain straw applicator connection manufacturing changes, care must be taken to use the same straws that come with the local anesthetic canister or to hold them securely while spraying, to prevent “popping off” of straws into a patient.⁹⁶

A general plan of patient preparation is itemized in Box 19-5. Steps that are inappropriate for any specific patient should be eliminated or changed.

Box 19-5 General Plan of Patient Preparation for Awake FOB Intubation

1. Check FOB equipment.

• Choose FOB diameter closest in size to ETT diameter (have lubricant available if very close).

• Plug in electrical outlet, turn on light source, and adjust according to FOB instructions.

• Test lever and FOB tip motion, clarity, and focus by looking at printing on a nearby object.

• Use defogger or insert FOB into warm irrigation bottle.

• Place tested ETT in warm irrigation bottle, choosing at least one-half size smaller if a difficult airway is present.

2. Obtain history and physical examination and discuss the plan with the patient (psychological preparation).

3. Administer antisialogogue.

4. Administer sedative and insert an intravenous line if none is present.

5. Administer sodium citrate if aspiration risk is present.

6. Monitor the patient.

7. Lower the bed maximally.

8. Administer oxygen by cannula.

9. Position patient supine (ideally), or sitting for patients who are unable to lie flat, with the intention of facing the patient during endoscopy (note that anatomy will be inverted in the latter case). See obesity concerns discussed in the text.

10. Titrate sedative/narcotic while local airway anesthesia is applied.

ETT, Endotracheal tube; FOB, fiberoptic bronchoscope.

E Fiberoptic Orotracheal Technique

1 Three Successive Directions for Fiberoptic Guidance

Airway specialists are remarkably familiar with the upper airway configuration as routinely observed during direct laryngoscopy. On the other hand, the different axes successively followed by the structures involved during FOB intubation, and their reciprocal spatial organization, are less a matter of emphasis in the classic teaching programs. Moreover, many sketches or drawings in medical textbooks are inaccurate, showing the upper airways as a regularly curved line joining the oropharynx or nasopharynx to the carina. This is obviously misleading, because three successive directions must be followed in the supine patient in order to reach the trachea through the nasal or the oral route.⁹⁷ These successive directions are (1) downward to the posterior wall of the oropharynx or nasopharynx, (2) upward to the anterior commissure of the vocal cords, and (3) downward again into the laryngeal and tracheal lumen to the carina.

Oral FOB entry is usually midline but a retro-molar entry is possible in some patients with limited openings. When one is performing an FOB intubation via the oral route, it can be difficult to stay in the median sagittal plane, and this problem gets worse when obstructive flaccidity of the pharynx is present. The difficulty can be overcome with the use of a special airway (e.g., the Ovassapian device), help from an assistant, or FOB intubation through a supraglottic airway such as a laryngeal mask airway (LMA; LMA North America, San Diego, CA).

During the second phase of the fiberscope progression, in the upward direction to the anterior commissure of the vocal cords, the posterior part of the glottic aperture comes into view. In the absence of anatomic distortions, the temptation to push the fiberscope unswervingly in this direction should be resisted. It may be better to continue toward the anterior commissure of the cords, keeping the tip of the device in a sharp anterior path (by pushing down with the thumb on the button of the handle). Only when the anterior commissure is approached should the tip be angled correctly downward, toward the middle of the lumen of the larynx. This maneuver aligns the fiberscope with the anatomic axis of the larynx successively in its supraglottic and infraglottic segments, avoiding contact damage to the mucosa and arytenoid cartilages (Fig. 19-17).

Figure 19-17 Three directions in the anatomic approach to fiberoptic intubation (left to right): downward into the pharynx, upward through the vocal cords, and downward into the trachea.

2 Practical Application

Preparation before the FOB procedure should follow in sequence while adjustments are made depending on individual patient concerns: equipment preparation, patient preparation, antisialogogues, sedatives, narcotics, local anesthetics, monitoring, and nasal cannula oxygen (if permitted; see Box 19-5). If there are not enough people available for assistance, the thumb-control port of the suction may be sealed ahead of time with tape, to make it a one-handed tool, which may help in the midst of a busy FOB procedure. The bed or table is moved to its lowest setting while keeping the patient supine. Use a stepstool to keep the FOB straight, if needed; in the case of a sitting, dyspneic patient approach the FOB procedure by facing the patient.

Employ the back-up bed position at whatever height makes the patient’s comfort of breathing better. Traditionally, endoscopists like to “ramp” overweight patients up with many blankets under the upper thorax, neck, and head regions to align the airway when using RL, to decrease soft tissue encroachment on the airway. Rao and colleagues compared ramping with elevating the back of the bed until the patient’s external auditory meatus is at the level of the sternal notch (Fig. 19-18).⁹⁸ There was no difference between the two methods in demographics, time to intubation, grade of glottic view, or number of RL attempts until intubation was successful. There was a significant difference in the added time and effort needed to position patients with blankets and then to remove blankets (and most likely in laundering cost, at 75¢ per blanket, although this was not mentioned in the study). By extrapolation, elevating the back of the bed or using a reverse Trendelenburg position to align the external auditory meatus with the sternal notch may facilitate FOB intubation in obese patients with less wasted resources.

Figure 19-18 Comparison of positions for intubation in patients with increased body mass index. Left, Ramping with multiple blankets, which need to be situated and then removed after intubation. Right, More simplistic back-up bed position. Reverse Trendelenberg or back-up positions are used to align the external auditory meatus with the sternal notch (blue line). Following intubation, the bed is easily returned to normal.

Once oropharyngeal LA is accomplished, many FOB operators direct patients to close their eyes, placing a surgical towel loosely on the upper face as a barrier to avoid injury to the eyes (e.g., from stray liquid agents). The towel can also serve to promote sedation by preventing patient observation of needles and instruments. After the remainder of the airway anesthesia has been completed, gently suction the oropharynx, curving anteriorly and caudally toward the larynx in the midline with a soft suction catheter if the mouth opening is limited, or with a Yankauer suction catheter. If the patient gags, GPN anesthesia is lacking, whereas if coughing occurs, SLN anesthesia is inadequate. This can be rescued by administering the appropriate block, or by using the “spray as you go” technique. Another benefit of suctioning is to remove secretions or blood out of the viewing path of the FOB.

Have an assistant hold the tip of the patient’s tongue with gauze by grasping its anterior and posterior surfaces and extending it carefully so as not to cause tearing of the frenulum linguae. This lifts the tongue off the palate and elevates the epiglottis (Fig. 19-19). Apply 2 cm of 5% lidocaine paste to the distal lingual side of the IOA before gently positioning it, but only if using an Ovassapian or Berman type of airway. The assistant should hold the IOA midline during endoscopy to prevent deviation from the path to the larynx.⁹⁹ Alternatively, use a bite block (e.g., BiteGard [Gensia Automedics, San Diego, CA]) placed between the premolars to protect the FOB from dental trauma (Fig. 19-20).

Figure 19-19 Effects of tongue pull and jaw thrust on epiglottic and glottic views.

Figure 19-20 BiteGard for dental and fiberoptic bronchoscope protection is inserted between the premolars.

Slide the lubricated ETT completely up the FOB, and either tape the connecter there or hold the ETT syringe with a little finger. Many FOB operators recommend holding the FOB handle in the nondominant hand, because thumb movement of the lever or forefinger depression of the suction valve are not as intricate movements as directing the FOB tip with the dominant hand. Control FOB progress into the mouth and keep it midline by using the dominant hand’s thumb and first two fingers, similar to holding a pen. The fourth and fifth fingers are placed on the patient’s upper lip or cheek. This precise anchorage allows for firm stabilization of the FOB to prevent tremulous movement of the view and also prevents eye injuries caused by a stray little finger while the endoscopist’s visual concentration is fixed on the screen or through the eyepiece during advancement. Old-school teaching used the hands in reversed roles, and many still prefer this idea.

To keep the FOB straight and prevent bending damage, rest the hand holding the FOB handle high on that extremity’s ipsilateral shoulder to lessen fatigue. Alternatively, hold the instrument vertically straight adjacent to the patient. The patient’s head and neck normally stay in a neutral position.

Insert the FOB into the patient’s mouth, following the IOA while keeping the demarcation between the color of the IOA and the color of the mucosa in the center of view. Use the lever to look up or down and turn the FOB as a unit to look left or right, always keeping recognizable structures along the desired path in the center of view. Go around unwanted obstacles, such as secretions. If urgency is not a factor, slowly feed the FOB 6 to 8 cm, past the palate and past the uvula, and use the lever to look for the epiglottis, glottis, and tracheal rings. Stop two to three rings above the carina. If nothing is recognizable along the way, back up and look around with slow lever motion until structures are familiar, then proceed again. Do not provoke coughing by getting too close to the carina, which is unlikely to be anesthetized.

Hold the scope immobile and slide the ETT forward with the Murphy eye oriented anteriorly if using a PVC ETT, to prevent it from getting hung up on the arytenoid. Statistically, it gets caught on the right side most often.¹⁰⁰ Do not let the FOB go forward as the ETT advances toward the back of the oropharynx. At this point, look at the patient to judge when the ETT may be near the larynx. Ask the patient to take some deep breaths so that the vocal cords open more widely to admit the ETT. Time the breathing, and when ready, quickly push the ETT forward. After judging that it has gone beyond the vocal cords, look at the FOB tracheal view again, and slide the ETT until it ends up two to three rings above the carina and has just passed the FOB tip. Inflate the ETT, stabilize it, and remove the FOB. Put the FOB in the used vertical holder, or hand it in a straight fashion to an assistant. Attach the ventilating system while checking for PETCO₂, tape the ETT, and continue whatever patient care is anticipated next.

For very difficult airway and ETT insertions, it is worthwhile to check placement with the FOB after taping and patient positioning, which may be a source of ETT dislodgement.

Trouble-Shooting

1. The tongue extended preoperatively, but now, just before FOB insertion, it cannot be fished out for a tongue pull: Have the assistant firmly apply a large suction tubing to the tongue and slowly draw it out enough so that it can be grasped with the gauze. An alternative, especially for larger tongues, is to snag it with a clamp (e.g., ring forceps) or, rarely, with a large-diameter suture.

2. The patient has excessive oropharyngeal secretions or blood, and visualization with the FOB is almost impossible:

• Have an assistant suction the oropharynx, even continuously if necessary. If possible, use an IOA. If not, insert the FOB midline between the fingers of an assistant at the entry point into the mouth. Keep the tip straight while it goes into the mouth a distance equal to two thirds of the distance from the mouth to the ear. Have someone turn off the room lights, and use the FOB similar to a lightwand. With lever manipulation, angle the tip forward and use transillumination to advance the FOB until an extremely bright pretracheal glow is seen. If the light appears off to one side of the neck, retract the FOB slightly and move it away from that side. If the light glow is anterior but less strong and resistance is felt, the tip may be in the submental area. Retract it slightly and redirect it posteriorly. If the glow is very dim, entry into the esophagus is most likely. Again, retract and angle anteriorly until the pretracheal glow brightens. At the glottis, the FOB entry into the trachea is exceedingly bright and visual optics may return. If not, suction via the FOB and continue forward until trachea or carina reaction is observed or those structures are visualized. An epidural catheter could be inserted for confirmatory PETCO₂ monitoring.

• An alternative approach is to insert an IOA or any SGA to seal the periglottic area. One with a gastric access tube may be the best choice. Then the ventilating lumen should be suctioned clear of secretions or blood and tested for PETCO₂. The FOB can be passed through it for intubation, knowing that there is less chance of continued soiling of the FOB or the airway.

• Another alternative is to have a long (≥80 cm) guidewire with a few centimeters extending from the FOB tip that is nestled within an ETT just short of the ETT’s distal end. Secure the wire proximally. With ongoing oropharyngeal suctioning, the FOB may stay clear of the soiling fluids, and the wire may be directed into the trachea. Once the wire is at least 8 cm into the trachea, the FOB and then the ETT can quickly be advanced, with rapid cuff inflation to prevent aspiration.

• Lastly, a retrograde-FOB assisted intubation may be successful (see “Retrograde Incubation”).

• At some point, consider a surgical airway.

3. The optics are not clear; maybe the FOB is fogged: For an unclear view, try turning the focus dial. For fogging, touch the FOB tip on mucosa to clear it (Video 19-3). For secretions, suction with the FOB or use a suction catheter in the oropharynx, or both. Otherwise, FOB removal and cleaning of the tip may be the last choice. To clean, do not jab the FOB tip into anything, because delicate fibers can be broken. Hold the tip still but quite tightly near the very end, and gently wipe with alcohol.

4. It is impossible to look to the left or right because the lever only moves the FOB tip up and down: To look left, loosen the grip on the distal FOB insertion section between the thumb and two fingers while simultaneously rotating the handle section counter-clockwise, to avoid torque. To look right, turn the handle section clockwise in a similar fashion. Alternatively, rotate both hands equally in the same direction.

5. The FOB cannot get under the epiglottis because it is stuck on the posterior pharynx: Ask the assistant to pull the tongue out farther and perform a jaw thrust maneuver to lift the epiglottis (see Fig. 19-19).¹⁰¹ Try moving the FOB more caudally or laterally, to get under the epiglottis.

6. The patient keeps gagging or coughing as the FOB advances: Consider repeating the LA blocks or use the “spray as you go” method.

7. After the FOB enters the trachea, the patient gets agitated and desaturates: In a compromised patient with tracheal stenosis or obstructive pathology, this may be the result of inadequate room around the FOB for the patient to breathe. The intubation process should be sped up, and the FOB should be removed as soon as possible. Be especially wary of starting oxygen insufflation through the working channel in this situation, in case not enough tidal volume can be expelled around the FOB. This sequence of events could precipitate the development of a pneumothorax.

8. The FOB is above the carina, but the ETT will not enter the trachea: Try not to jam the ETT, because it is advancing blindly and could damage perilaryngeal structures. Withdraw the ETT 1 to 2 cm, turn it 180 degrees counter-clockwise, and advance it rapidly after asking for a deep breath. If this is unsuccessful, rotate the ETT 180 degrees clockwise and repeat. If it is still not passing, repeat the other way. Try giving jaw thrust or even releasing jaw thrust. Use cricoid pressure, or neck flexion.⁸⁵ Finally, a rescue may be effected by removing the FOB and trying a smaller ETT; using a centrally curved, soft-tip ETT; inserting an Aintree Intubation Catheter (Cook Medical Inc., Bloomington, IN) on a pediatric FOB; or using a nasopharyngeal approach.

9. While using a pediatric FOB in an adult patient, tracheal rings were seen; the ETT went in, the FOB was removed, and the ETT was attached to the ventilator, but there was no PETCO₂, breath sounds, or chest movement: The tip of the FOB must end up within 2 to 3 cm of the carina in an adult, particularly if a pediatric FOB is being used. If it is only partially down the trachea, pressure against the ETT as it pushes forward in the periglottic area against tissue (e.g., arytenoid) may divert it into the esophagus or bend it back into the oropharynx and cause “flippage.” Flippage may occur when a stiff ETT tip indents into the somewhat flexible insertion section of the FOB as the ETT is diverted into the esophagus or pharynx, causing the short entry of the FOB to flip out of the trachea.

10. A centrally curved, soft-tip ETT was partially inserted into the oropharynx of an adult patient; next, the FOB was inserted through the ETT, and the tip of the adult FOB was positioned 2 to 3 cm above the carina; the ETT was then railroaded over the FOB, but in spite of all maneuvers, it will not pass through the glottis: If time and resources are available, look in the oropharynx with another FOB to diagnose the problem. If the FOB crossed through the Murphy eye, the ETT will never advance into the trachea. Trying to force the ETT forward may cause serious FOB damage and injure the patient. Occasionally, when this happens, the FOB might not even be able to be withdrawn easily, particularly if forceful moves were already made. Strong attempts at removing an FOB stuck in the ETT may result in severe damage due to “sharper” Murphy eye edges digging into the outer plastic wrap of the FOB. If any significant resistance occurs in this “ETT insertion first” type of scenario, remove both devices simultaneously.

11. More than just a few drops of blood are in the trachea after a transtracheal injection: Do not give positive-pressure ventilation (PPV). Attach the oxygen system, and suction the ETT. To avoid coughing, give sedative agents and, if desired, muscle relaxants before suctioning.

F Nasal Fiberoptic Intubation of the Conscious Patient

The patient must be questioned regarding prior coagulation status or anticoagulant therapy, nasal abnormalities, trouble breathing through either side of the nose, and any previous surgery in the area (e.g., recent transsphenoidal surgery). Psychological preparation, monitoring, and pharmacologic therapy concerns are similar to those for oral FOB intubation. Any one-sided nasal pathology should be avoided. If there is a deviated septum, the larger nasal passage should be selected, to steer clear of situations in which the FOB can easily enter the trachea, but the ETT cannot traverse the nasopharyngeal passage.

1 Innervation of Nasopharyngeal Airway Structures

Cranial nerve V, the trigeminal, supplies sensation to the anterior half of the nasopharynx by its first branch. The second branch of the trigeminal nerve forms part of the sphenopalatine ganglion, innervating some of the anterior, superior, and central regions.^85,⁸⁶ Cranial nerve IX, the GPN, supplies parasympathetic innervation, while the carotid plexus supplies sympathetics.¹⁰² Cranial nerve VIII, the facial nerve, has parasympathetic function and forms part of the sphenopalatine ganglion to assist in control of nasopharyngeal reflexes.

2 Topical Nasopharyngeal Local Anesthetic Techniques

A completely insensate nasotracheal FOB intubation approach would involve anesthetization of the nasopharynx, posterior wall of the pharynx, periglottic area, larynx, and trachea. Techniques that work well include a triple combination of nasal, SLN, and transtracheal LA; use of a face mask nebulizer, and the “spray as you go” technique. When administering nonaerosolized agents, apply them to both nasal passages whenever possible in order to find the largest pathway. Another benefit to anesthetizing both passages may result in cases in which it is impossible to complete FOB or ETT entry on one side: there will be no delay due to suddenly having to anesthetize the other route.

Besides anesthetization, the nose requires the addition of a vasoconstrictor to decrease the likelihood of epistaxis (see Table 19-2). Dip four Q-tip swabs into solutions of cocaine or a vasoconstrictor mixed with local anesthetic. Swab insertion gives the FOB operator an idea of the caliber of each nasal passage. Apply a single swab to the outermost part within the nostril. Push it inward with a forefinger, perpendicularly to the plane of the face, until slight resistance is met (Video 19-4). Put the next swab in the opposite nostril, and continue alternating insertion of swabs parallel to previous ones. By the time the last swab is placed, the initial insertions will have caused some vasoconstriction, and slight swab pressure will push each one in further. If desired, midway through the process, spray 0.2 mL of solution with a 20-G angiocatheter (needle removed) in three different directions within each nostril. Continue this process until all swabs are at the back of the nasopharynx. This method uses a total of 2 mL (80 mg) of cocaine. If the possibility of tachycardia is a concern, apply a mixture of lidocaine and a vasoconstrictor instead of cocaine, with swabs positioned as described. Some FOB operators recommend another technique, using lidocaine gel and phenylephrine as a coating on short nasal airways to gauge nasal passage size. Any excess drug that is not absorbed usually drips back to anesthetize the posterior pharyngeal wall.

As an alternative, spray the mixture twice in each nostril, but only in an upright patient. Spraying in supine patients can result in overdoses if the spray becomes a stream. Several case reports have been published in which application of topical phenylephrine or a potent vasoconstrictor resulted in dangerous hypertension. Beta-blocking agents administered in this circumstance may promote the occurrence of pulmonary edema and should be avoided, according to the New York State guidelines on the topical use of phenylephrine in the operating room.¹⁰³

For nasotracheal intubation under GA, vasoconstrictors are very useful to prevent epistaxis.

G Fiberoptic Nasotracheal Technique

Because of the relative narrowness of the nasal passage, an ETT at least one-half size smaller than would be chosen for the oral route should be selected, depending on the patient’s history or size. Some endoscopists erroneously think that inserting progressively larger nasal airways or “trumpets” can mechanically “dilate the passage.” However, Adamson and coworkers reported that use of this method caused increased trauma, hemorrhage, and delay of intubation.¹⁰⁴

Pre-block preparation is similar to that for the oral approach, although antisialogogues are not quite as important if intraoral LA is not planned. The well-lubricated FOB can initially be introduced in one of three ways: (1) by itself for a distance of 12 to 15 cm, (2) within a lubricated short nasal airway that is designed to break away, or (3) after a well-lubricated ETT is first partially inserted into the posterior nasopharynx. After inserting the FOB, steer it to follow the dark conduits or openings of the nasal passage until the epiglottis is seen. As a substitute technique, insert the breakaway nasal airway or partially insert the ETT before FOB entry. This will virtually lead the FOB tip directly toward the larynx. Avoid the “ETT before the FOB” technique in coagulopathic patients and in situations in which bleeding is more likely to occur.

After locating the larynx and entering through the glottis, the remainder of the procedure, including depth of FOB passage, orientation of the Murphy eye, and ETT railroading to the correct depth, is similar to that for oral FOB intubation.

Whether the ETT is inserted before the FOB or after it, direct its leading edge along the septum. Through the left nostril, one may insert the ETT in the usual fashion until the back of the nasopharynx is reached. Through the right side, however, the concave surface of the ETT should face cephalad until the ETT tip reaches the back of the nasopharynx. At this point, the ETT is rotated 180 degrees to align the concavity anteriorly. This may help to prevent evisceration of the turbinates.

A proactive method to avoid trauma is to insert, as a unit, a lubricated and slightly protruding nasogastric or suction tube that almost fills up the lumen of the ETT. This prevents scooping or cutting into tissues by the firm, leading ETT edge. Another option is to use a centrally curved, soft-tip ETT.

Trouble-Shooting

1. The plan was to partially insert the ETT first, but it does not want to pass: Be gentle and do not exert force. Try the other side. If that does not work, try alternative methods listed previously.

2. Partially inserting the ETT caused epistaxis (no FOB yet): Inflate the ETT cuff to tamponade the area, or externally pinch the nose for 5 to 10 minutes. If blood is welling out of the nostril but no blood trickles into the back of the pharynx (i.e., there is no choking, swallowing, or continual need for suctioning), try pulling the deflated ETT a little and reinflating the balloon at what may be the site of injury. To prevent additional trauma, try not to remove the ETT unless blood keeps entering into the back of the pharynx regardless of the number of times these maneuvers were engaged.

H Oral or Nasal Fiberoptic Intubation of the Unconscious Patient

1 Under Routine General Anesthesia

Eyes should always be protected in unconscious patients before any airway manipulation. If mask ventilation is expected to be easy under GA before surgery, a purely elective FOB procedure can always be used to intubate patients if consciousness is not required. This form of achieving intubation is very acceptable. It is considered ethical not to inform the patient of this plan because it is one normally used by many patient caregivers.¹⁰⁵ In some circumstances, “asleep” FOB intubation may have specific indications (e.g., a patient with extensive anterior dental work).

Preparation should include administration of an antisialogogue, complete FOB equipment readiness, premedication, monitoring, and positioning. If the surgery dictates a preference for nasotracheal intubation, nasal vasoconstrictor sprays should be applied while the patient is awake and in the sitting position. Because tissue laxity can obscure the airway in comparison to awake states, a smaller-sized ETT should be used. Positive-pressure face mask oxygenation is standard after induction and muscle relaxant delivery until the drugs have taken effect. At that point, lift the mask off the patient’s face while the assistant performs a tongue pull, places the IOA, or gives a jaw thrust as needed. Insert the FOB and intubate as described previously. If desired, direct someone to keep track of passing time (Video 19-5; see also Video 19-3).

Trouble-Shooting

1. The technique is not succeeding: Careful monitoring and awareness of 2 to 3 minutes’ passage of time, even in the case of technical difficulty, should keep the situation under control. If unsuccessful, always reinstitute face mask ventilation and decide whether the problem is caused by anatomic difficulty, being off-midline, insufficient assistance, or a lack of equipment. Think about giving more anesthetic before another attempt, or use an alternative intubation plan (e.g., intubation with another device). Frequently, combination FOB techniques should be considered (see “Combination Techniques”).

2 After Rapid-Sequence Induction

Although they are not common, scenarios may arise in which patients with high aspiration risk have a DA but are not candidates for the awake intubation technique. An FOB can also be used electively after induction of GA in patients who are too young to understand or in uncooperative patients. In the former situation, the steps involved in an awake FOB intubation might cause an unwanted degree of psychic trauma, whereas in the latter case, the primary concern is risk to the patient or even to the FOB due to fighting or biting. Because of the risk of aspiration or airway loss, only a very experienced endoscopist, who expects a very high chance of success, should embark upon this procedure from the start under GA. Otherwise, initiation of this method during GA is inappropriate, and it is an especially poor choice for patients with very difficult airways.

If the decision is made to proceed, have two operable suctions attached, one on the FOB and the other on a Yankauer or soft suction tubing in case of regurgitation. Choose a smaller-sized ETT. If not contraindicated, preoperative preparation is identical to that used for rapid-sequence GA, with inclusion of an antisialogogue, clear oral antacid, histamine H₂-blocker, and/or gastric motility–inducing agent. After induction and cricoid pressure applied as originally explained by Sellick,¹⁰⁶ use the FOB intubation technique with good assistance. Once the FOB nears the carina, the ETT should be inserted quickly and the cuff inflated immediately.

Sometimes, asleep FOB intubation may be selected as a rescue tactic for patients who have incurred failed intubation with another device. Early use of an FOB for intubations that have gone awry is much less likely to cause the devastation that can result from repeated failed RL attempts.

Trouble-Shooting

1. The epiglottis and periglottic areas are easily seen, but the glottis is very small with closed vocal cords, and the FOB cannot enter: Check the nerve stimulator for degree of muscle relaxation. If this is insufficient and laryngospasm is suspected, spray down the FOB with 4% lidocaine. If the patient is relaxed, ask the assistant to slowly decrease the cricoid pressure to see if things improve, because this pressure can be associated with impaired glottic visualization. If regurgitation occurs, another assistant should suction the oropharynx, and pressure may need to be reinstituted, with a tentative release tried later.

I Fiberoptic Intubation in Unconscious, Unanesthetized Patients

For emergency FOB intubation in unconscious, unanesthetized patients, ideally all equipment is available. The approach must be speeded up, however. Three important caveats must be considered before FOB technique in this situation: a full stomach must be assumed, cricoid pressure must be employed, and the most experienced FOB endoscopist should perform the procedure. More descriptive directions may be required for assistants, who are likely to be less experienced in these urgent cases.

VI Combination Techniques

Whether the patient is awake or under GA, an FOB can be combined with ancillary devices and laryngoscopy instruments to accomplish intubation. FOB combinations have practical utility in realizing improved airway control, assisting in diagnostic and therapeutic efforts, and rescuing failed intubations. In many combination techniques, physical maneuvers (tongue pull and jaw thrust) are very advantageous.

Elective use of an FOB combination with other airway management equipment has a very high rate of success with the added luxury of planning. This may be extraordinarily beneficial in the most difficult airway predicaments. As an illustration, a Fastrach intubating laryngeal mask airway (LMA North America) may be desirable to seal off the laryngeal area from blood and accomplish ventilation in a patient who is difficult to mask ventilate, difficult to intubate, and has significant intraoral bleeding. This intubating airway has a moderately high success rate for blind insertion of its ETT (90% to 96.2% with ≤3 attempts or adjusting maneuvers).¹⁰⁷^–¹⁰⁹ Its use in combination with an FOB, however, can change a blind technique to a more controlled visual one, with a greater chance of success.¹¹⁰

Examples of diagnostic abilities of an FOB often become evident in patients who have undergone prolonged spinal surgery in the prone position. If such a patient’s airway pressure rises intraoperatively, FOB examination through a bronchoscopy swivel adapter can be used to determine the cause (e.g., secretions, endobronchial intubation, a kinked ETT). A therapeutic role periodically occurs at the end of this type of surgery. A degree of indecision as to how well the patient might fare after extubation (due to length of surgery and airway edema) can be remedied by the therapeutic capability of combination use of an FOB with an Aintree catheter through the existing ETT. The Aintree is left as an “airway stent” and then secured in place after the ETT and FOB have been removed. Should the patient appear to be failing the extubation trial, an ETT-fitted FOB is reinserted down the Aintree for reintubation.

A common failed intubation scenario occurs in a morbidly obese patient with redundant intraoral tissues who is undergoing GA and laryngoscopy with an RL that reveals a Cormack-Lehane grade 3 view. Intubation failure despite the use of an intubation guide catheter can result in a deteriorating situation after multiple attempts due to tissue trauma, and it is made notably worse if mask ventilation becomes problematic. Attempts at FOB rescue by itself might be difficult. In combination, however, the RL can be used to elevate tissues out of the way of the FOB in order to obtain the best laryngoscopic view by RL, even if it only reveals the epiglottis. This can offer a much easier route for the FOB to follow to achieve the goal of intubation.

Finally, combining multiple approaches to manage the DA is just another illustration of the general concept of multimodal therapy, in contrast to monotherapy. Multimodal therapy is used in the everyday practice of health caregivers, such as when different classes of drugs are used to provide an overall “tailored” anesthetic, or when combinations of various analgesics are used for chronic pain control. The multimodal approach to the airway, unduly disregarded for a long time, seems to be increasingly accepted as the drawbacks of individual airway devices or techniques become more obvious and the failures of each, when used alone, are more frequently reported.¹¹¹

A Superficial Airway Devices and Flexible Fiberoptic Bronchoscopes

1 Combination with Endoscopy Masks

Very often the FOB-endoscopy mask combination can help to obtain either the objective of anatomic airway examination or actual airway control. These masks may have one or more openings for simultaneous FOB and ETT passage. A model that seals around both is ideal. Be cautious of models having a port that seals only around an FOB, because ETT insertion can result in a leak to the atmosphere with inability to ventilate the patient.

Preparation for use of the FOB-endoscopy mask combination during GA is the same as detailed earlier. The ETT, with its 15-mm connector removed, is placed over the FOB. Keep the connector in a secure spot. After induction, insert an IOA and strap the mask in place with 100% oxygen while an assistant holds the mandible to prevent obstruction. If no muscle relaxant is used, the patient should be relatively deeply asleep to prevent laryngospasm when the larynx is touched. This can be treated by instilling LA in a “spray as you go” technique. With muscle relaxation, the patient does not have to be as deeply anesthetized, but the assistant must be competent enough to maintain positive-pressure mask ventilation.

Insert the ETT-loaded FOB sequentially through the port, IOA, and trachea for subsequent intubation (Fig. 19-21). After ETT intubation, remove the FOB and mask and join the ETT to the ventilation system. If patient conditions warrant urgent ventilation, institute it through the ETT after removal of the FOB. Retire the mask at any time thereafter. One advantage of using this technique for an elective case is that it affords more time for endoscopy, particularly if surgery will not be delayed because the incision site is at the other end of the body.

Figure 19-21 Combination of a fiberoptic bronchoscope with an endotracheal tube through an endoscopy mask.

These masks can also provide a supplementary method for administering oxygen during awake FOB intubation in a patient who is so respiratory-compromised that a nasal cannula might be insufficient. Administer nasal cannula oxygen during mask-lifting periods while LA is being given. After LA administration and airway suctioning, follow the same FOB-endoscopic mask steps detailed earlier.

If an FOB and an ETT are inserted simultaneously into the endoscopy mask port at the beginning of the procedure, FOB manipulation is not a significant problem in the straight forward-aiming oral route to the larynx. For nasotracheal intubation, it is better not to insert both initially, because the ETT might limit FOB maneuverability in entering the nasopharynx. During simultaneous insertion, this transpires when the exiting direction the FOB takes from the ETT is at odds with the entry into the nasal passage. In this case, insert the FOB well ahead of the ETT until the carina is located, and then advance the tube.

2 Combination with Swivel Adapters

A bronchoscopy swivel adapter for FOB examination or intubation can be placed between the ventilation circuit and an ordinary face mask, an SGA, or an ETT.

For intubation purposes, the combined use of an FOB and a swivel adapter can be undertaken under GA or oxygen-enrichment conditions similar to those for FOB-endoscopy mask use. With the patient under GA, insert a pediatric FOB within an Aintree intubation catheter (ID 4.7 mm, OD 6.3 mm) through the swivel adapter port while the patient is breathing spontaneously or being mask ventilated (Fig. 19-22). Once the FOB enters the trachea and nears the carina, slide the Aintree over it until it is two to three rings above the bifurcation. Hold the Aintree securely while noting the depth of insertion, and take out the FOB. Remove the Aintree connector to extract the mask, SGA, or old ETT. Then, slide a lubricated ETT-loaded FOB through the Aintree and down the trachea, stopping again near the carina. Pass the ETT farther down over the Aintree until the ETT tip lies 2 to 3 cm above the bifurcation. While firmly holding the ETT, remove the FOB and the Aintree. Reconnect the ETT to the ventilation circuit.

Figure 19-22 Combination of a fiberoptic bronchoscope with an Aintree catheter through a swivel adapter.

Optionally, apply ventilation via the Aintree 15-mm connector when the device is first placed if urgent respiratory assistance is needed or to confirm PETCO₂ return before attempted ETT passage. This is also an alternative method to ventilate patients in cases where the ETT fails to enter the trachea.

3 Combination Using Short, Soft Nasal Airways

The role of the breakaway soft nasal airway in facilitation of awake FOB intubation was detailed earlier (see “Fiberoptic Nasotracheal Technique”), and the principle can be transferred to generate similar results in patients under GA.

In addition, soft nasal airways may serve a very different function, as a conduit for GA gases while FOB intubation is pursued. In this technique, attach the anesthesia machine to a 15-mm ETT connector inserted into an intact nasal airway in a spontaneously breathing, very deeply anesthetized patient for the FOB manipulation. When the NPA method is used, considerable amounts of anesthetic gases are lost to the atmosphere, which is less than ideal. Nevertheless, it is the best choice in many cases. For example, an NPA is more commonly chosen for pediatric patients, who are prone to desaturate rapidly when intubation attempts are made during stoppages in mask ventilation. For nasotracheal intubation, it is not unusual to see this technique used on one nostril, with a breakaway NPA for intubation on the opposite side. During total intravenous anesthesia, the NPA only supplies oxygen.

B Supraglottic Airways and Flexible Fiberoptic Bronchoscopes

The original LMA for ventilation had obvious airway management benefits from its inception, particularly for difficult mask ventilation and for DI. This device has saved countless lives and is rightfully prominently embedded in the ASA DA algorithm. It can be used in patients who are unconscious, awake with local airway anesthesia, or under GA. Since its development, dozens of SGA and intubating SGA devices have been invented. The idea of performing FOB intubation through the LMA was spawned by the knowledge that, when seated properly, this SGA had to be situated around the glottis and could provide a pathway for an ETT. The combination of FOB-SGA for ETT intubation has been successfully tried with numerous SGA brands (Fig. 19-23).

Figure 19-23 Intubating with the combination of a fiberoptic bronchoscope within an Ambu Aura-i intraoperatively.

The FOB has also been combined with this sort of airway for trouble-shooting SGA insertion problems (e.g., high airway pressures, leak), as described earlier. The combination can also be used for assistance in accomplishing placement of the SGA itself, by having the FOB just recessed within the airway’s “bowl” as the SGA is advanced into the oropharynx.

1 Combination with SGA and Multiple Endotracheal Tube Techniques

If an FOB-SGA combination technique is being used for intubation, ascertain first that the desired lubricated ETT size is able to traverse through the SGA. Of course, the ETT must also be appropriate in size for the FOB. Many SGA have indicators for the maximum tolerated ETT size, and the larger ones permit entry of an adult-sized FOB. For smaller SGAs, a pediatric FOB and a smaller ETT are better choices. With the LMA brand, alignment of the bevel of the ETT in a transverse plane or preemptive cutting of the epiglottic deflectors will avoid situations in which the FOB tip and the ETT tip straddle an aperture bar. ETT sizes usually must be smaller.

Induce GA and position the SGA. While administering 100% oxygen, in a spontaneously breathing, deeply anesthetized patient or a ventilated, muscle-relaxed patient, try to obtain an optimal PETCO₂ waveform with good chest excursions. Disconnect the SGA from the circuit, and slide the ETT-loaded FOB down the SGA until the glottis is visualized. Place the FOB tip near the carina and advance the ETT. Remove the FOB and confirm ETT placement with PETCO₂. Remove the 15-mm ETT connector, and use a smaller ETT as a push rod (similar to the Fastrach pusher rod). With the pusher, keep the first ETT steady, and slide the SGA out until the first ETT can be grasped in the oropharynx. Then remove the second ETT and SGA and connect the first ETT to ventilate the patient.

Trouble-Shooting

1. The only ETT that could pass is small and too short, prompting concern that its cuff will lodge between the vocal cords:

• An option is to cut and discard a 4-cm section of the tubular end of the SGA, allowing for deeper ETT insertion. Push the ETT deeper, using a one-size-smaller ETT, impinging it in the first one’s proximal end like a pusher rod. After pushing in 4 to 5 cm, hold the ETT system steady and withdraw the SGA. After seeing the first ETT in the oropharynx, continue with the same technique described earlier.

• Alternatively, consider wedging a larger ETT circumferentially around the first ETT’s proximal end. Then employ the same technique.

• A very much longer Micro Laryngeal Tube (Rüsch Incorporated, Duluth, GA) (26 to 33 cm long, cuff sizes equivalent to an 8-mm ETT) is a better option. The SGA can be extracted over the Micro Laryngeal Tube with no need for a second ETT. Also, remember that SGA removal is not mandatory; simply leave it in place and deflate its cuff.

2 Combination with SGA and Aintree Catheters

As detailed earlier, intubate with an Aintree-loaded FOB via an SGA. Fix the Aintree, and remove the FOB and SGA. Complete the intubation with the ETT-loaded FOB via the Aintree (Fig. 19-24A).

Figure 19-24 A, Combination of a fiberoptic bronchoscope (FOB), Aintree catheter, and ETT in a laryngeal mask airway. B, The guidewire is shown within the working channel of the FOB.

3 Combination with SGA and Guidewires

Similarly, thread a long guidewire (110 to 145 cm long, 0.38 to 0.97 mm diameter) through the working channel of the FOB far into the trachea by way of the SGA (see Fig. 19-24B). While holding the wire in place, extract both FOB and SGA. Subsequently, thread the near end of the wire through the FOB tip, up the working channel of an ETT-loaded FOB. Use the FOB to visually follow the wire into the trachea for completion of ETT intubation.

4 Concerns

There are some limitations to FOB and SGA combinations:

• Correct SGA placement is not successful in 100% of cases.

• The ETT may not fit or pass through the SGA, so the combination must be prechecked.

• Not all lubricants are equally adept at lubricating the ETT. Viscous lidocaine, Exactacain, and Neosporin (polymyxin B sulfate, neomycin sulfate, bacitracin zinc) ointment achieve a far greater degree of “slickness” than common surgical lubricants.

• Compare the length of the ETT with the length of the SGA, because the distance from the periglottic opening of the SGA to the vocal cords may be 3.5 cm or more. Inattention to lengths may produce a “too short” ETT picture. Trying to cut a 4-cm section of a SGA tube to avert this problem (as mentioned earlier) may lead to problems: the SGA connector may not separate easily from its original seat within the SGA tube, or it may have a poor fit when plugged into the cut-off SGA section.

C Intubating Supraglottic Airways and Flexible Fiberoptic Bronchoscopes

Reports of FOB intubation through the LMA prompted the development of the Fastrach. This silicon-covered, steel-body, intubating SGA comes in three sizes for patients weighing more than 30 pounds and has a moveable epiglottis deflector bar. Its dedicated centrally curved, soft-tip ETT more readily traverses the glottic aperture in comparison to PVC ETTs.

A number of intubating SGA models have now been manufactured. The Ambu Aura-i (Ambu, Glen Burnie, MD) is a soft, rounded PVC SGA available in infant to large adult sizes. It was designed with less of a J-curve, and on its bite block area the maximum ETT size able to pass through it is clearly labeled.

Intubating SGAs were originally designed to act as conduits with high success rates for blind passage of an ETT into the trachea. They are more aptly designed for this purpose than most SGA devices, because larger ETTs can be deployed. When used with an FOB in a similar fashion to FOB-SGA combinations, their intubation success rate soars (Fig. 19-25). In a study by Erlacher and associates, 180 patients were intubated blindly through CobraPLUS (Pulmodyne, Indianapolis, IN), air-Q (Trudell Medical Marketing Limited, London, Ontario, Canada), and Fastrach devices with success rates of 47%, 57%, and 95%, respectively.¹¹² Of the approximately 60 patients for whom blind intubation failed when these intubating SGAs were used alone, FOB insertion for intubation was attempted; the overall success rate for the FOB-intubating SGA combination was greater than 98%.

Figure 19-25 Intubating with a combination of a fiberoptic bronchoscope through a Fastrach.

D Combination with Rigid Laryngoscopes

Occasionally, when an FOB is used as the sole airway device, impediments may prevent entry into the glottis; examples include a nonmobile or floppy, posteriorly directed epiglottis and upper airway edema. An RL can assist in lifting the mandible and moving obstructing tissues out of the way to improve the route for the FOB (Fig. 19-26). The FOB-RL technique requires at least two people: two endoscopists, or one endoscopist and a very knowledgeable assistant. The assistant must be able to hold the RL immobile after it has been placed optimally or to manage the FOB controls.^110,¹¹³ The clinical situation, together with the knowledge and technical abilities of the personnel involved, dictate who handles the RL and who directs the FOB tip or completes glottic insertion of the FOB or both. Successful FOB-aided controlled tracheal extubation and reintubation using the RL-FOB combination has been reported in intensive care unit patients.¹¹⁴

Figure 19-26 Fiberoptic intubation assisted by a rigid laryngoscope with video view of the trachea.

A possible, but not proven, advantage may be reduced nociceptive stress of intubation in response to lower RL blade pressure at the base of the tongue during use of FOB-RL combinations.

1 Nonsoiled Airway Situation

Use the RL to visualize the airway toward the glottis as much as possible, while moving blocking structures out of the way. Ensure that the RL is fixed in place. Before FOB insertion, suction the airway as needed. Endeavor to use the visual features of the ETT-loaded FOB to advance its tip by hand under the epiglottis, toward the larynx, for entry into the trachea and intubation. During maneuvers, direct the assistant to hold the RL steady or to manage the FOB controls.

2 Soiled Airway Situation

If it is impossible to use the visual features of the FOB due to soiling, obtain the best overall view with the RL. Direct an assistant to manage the controls. While holding the RL steady, advance the FOB tip under the epiglottis by looking directly in the mouth, similar to inserting an ETT. Do so by using the light from the RL, not the optical system of the FOB. Once the FOB tip is beyond the epiglottis, monitor its progress by using the FOB visual capability, and advance the insertion section while instructing the assistant to move the tip up or down. Continue until the glottic aperture is reached, while holding the RL firmly in place. When necessary, clear the FOB tip by touching it on mucosa or requesting the assistant to suction the patient, or both. After the trachea has been entered, insert the FOB tip near the carina and ask the assistant to railroad the ETT. Considerable cooperation is important.

Alternatively, after the best view is obtained with the RL, direct the assistant to hold the RL fixed. Introduce the FOB as far as possible under direct vision next to the RL (again, similar to inserting an ETT). Once further insertion under direct vision is impossible, monitor via the FOB and handle the controls until trachea and carina are secured. Then railroad the ETT.

E Combination with Video Laryngoscopes or Optical Laryngoscopes

VLs and OLs are amazing devices that have a firmly rooted place in airway management and definitely should be part of the DA algorithm. Many can give stunning images due to options such as wide-angle camera capability, exceptionally clear optics, and video monitoring. Their learning curves are very fast. In most patients, the 60-degree angulation design with video or optical mirror capability improves Cormack-Lehane views of the larynx by one to two grades over those seen with the RL.¹¹⁵^–¹¹⁷ VL devices will most heavily impact what is now obviously an inferior device for airway management—the RL—and will result in continual declining use of that instrument.¹¹⁸

Despite superior visual capabilities, these devices can have failures in diverse airway cases.¹¹⁷^–¹¹⁹ It is unlikely that VL will replace FOB use because of the very nature of FOB—the flexibility to conform to intricate airway pathology. The VL can optimize laryngoscopy but does not share the FOB’s second most desirable property, the ability to mechanically guide the direction of an ETT into the trachea to a specific end point. Clinicians may be delighted by the improved images from the VL, but they also are disappointed periodically when it remains impossible to intubate a patient despite “a perfect laryngeal view.” Many such failures have been reported with all types of VLs and OLs.^59,¹¹⁹ In addition, pharyngeal perforation (palate or tonsillar pillars) may rarely result from the ETT tip during VL use. The cause is simple to understand. Whereas the ETT is initially advanced under direct vision, at some point it is pushed ahead blindly until it is finally seen again on the video screen.¹²⁰^–¹²² Care taken to directly observe the ETT hugging the tongue and curving it centrally and caudally within the airway greatly lessens this possibility. This type of trauma is unlikely with an FOB system in which the ETT slides over its insertion section.

Even the FOB has limitations compared to VL devices. FOBs have a more narrow-angled field of view, a shorter focal distance, a greater possibility of obscured optics if the airway is soiled, an inability to open the airway, and a degree of inability to maintain a midline position in the pharynx while advancing toward the glottis.¹²³

Ideal circumstances combine an FOB with a VL to employ the strengths of both techniques. Having both FOB and VL screens available would be a situation of truly superior airway management. With this combination, the VL is used to keep the oropharynx open and lift tissues away from the glottis and epiglottis during oropharyngeal or nasopharyngeal FOB intubation. The VL view of the FOB position and the simultaneous FOB view of pharyngeal and later laryngeal anatomy permits better FOB control and a greater range of vision. This combination of an FOB with a VL assists in reaching and entering the larynx by reducing unwanted FOB movements in lateral directions.

VLs can also help diagnose FOB problems. In many cases, the FOB-VL technique provides visualization of the passage of the ETT over the fiberscope into the glottic area, aiding in the resolution of ETT “hang ups” at the arytenoid and other passage difficulties. The combined technique does have a drawback in that it requires both an endoscopist and a very knowledgeable assistant, but management of DI may necessitate two operators in any event. Indeed, use of the combination of FOB and VL has been shown to be advantageous and has been reported in DA patients.¹²⁴

Another virtue of the FOB-VL combination is that it permits the use of a VL to fully observe FOB manipulation by trainees. This can enhance instruction and maximize learning experiences.¹²⁵