Chapter 19 Fiberoptic and Flexible Endoscopic-Aided Techniques
In addition to covering fundamental and advanced aspects of flexible fiberoptic/endoscopic airway management, this chapter focuses on exciting current inventions in airway equipment, related devices, and techniques.
Historically, a wide variety of devices have been employed to visualize the airway in living human subjects. Manuel Garcia, a singing instructor, ingeniously used mirrors to reflect sunlight in 1854, allowing him to examine his own moving vocal cords. He was considered the “first laryngoscopist” after a presentation to the Royal Society of Medicine.1 Using a blind digital technique, William Macewen completed the first endotracheal intubation under anesthesia as well as the first awake intubation for surgery and anesthesia in 1878.2 On hearing of an accidental intratracheal insertion in 1895, Alfred Kirstein used an esophagoscope that incorporated a proximal light source and spatula-like area to perform the first “direct” laryngoscopy.3
Bronchoscopy history began to develop in 1887, when Gustav Killian extracted a foreign body from a farmer’s respiratory tract with a rigid bronchoscope. Chevalier Jackson modified this rigid bronchoscope by inclusion of a distal tungsten light bulb and suction channel in 1904, resulting in the significantly greater likelihood of successful endotracheal intubation.4
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) placement11 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.
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.
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.
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.
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.
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.
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
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.
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
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
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% overall47,48 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
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
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.
Box 19-2 Contraindications for Awake FOB Techniques
Box 19-3 Contraindications for Asleep FOB Techniques
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.
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.
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.
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.
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.
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.