Performance of Rigid Bronchoscopy

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Chapter 29 Performance of Rigid Bronchoscopy

I Historical Background

Rigid bronchoscopy is an invasive surgical technique that is used to visualize the oropharynx, larynx, vocal cords, trachea, and proximal pulmonary branches. The origins of rigid bronchoscopy, like many aspects of modern medicine, can be traced back to Hippocrates (460-370 BC), who advised introducing a pipe into the larynx in a suffocating patient to assess the airways.1 Because of limitations with lighting, the field was largely dormant until the 1800s, when incandescent light bulbs were invented. The development of local anesthesia in 1880 also made bronchoscopy more tolerable. In March of 1897, Gustave Killian passed an endoscope through the larynx and removed a piece of pork bone from the right main stem bronchus using cocaine anesthesia.1 Chevalier Jackson further advanced the field of rigid endoscopy by developing improved lighting, auxiliary instrumentation for removal of foreign objects, and rigid bronchoscopy training programs.2 He is recognized as the father of contemporary rigid endoscopy.3 Since Jackson’s time, many changes have been made to the bronchoscope, so that current rigid instrumentation and ventilation systems allow for more precise and accurate assessment of the aerodigestive tract.3 H. H. Hopkins of England invented the first conventional lens system by using glass rods instead of small lenses, which produced a significantly brighter image, occupied less space, and allowed for greater visualization of an object in a single field.1 This provided the basis for fiberoptic and modern rigid bronchoscopy.

II Indications and Contraindications

The tracheobronchial tree can be directly observed with either rigid or flexible bronchoscopy. Although the advent of flexible bronchoscopy has given physicians improved access to more distal portions of the tracheobronchial tree with a more rapid learning curve and less patient discomfort compared with rigid bronchoscopy,2 there are still several situations in which rigid bronchoscopy is more appropriate. The larger working port and rigid structure make rigid bronchoscopy useful for surgical interventions within the airway, such as the removal of foreign bodies or polyps (see “Foreign Body Removal”).4 At the same time, the bronchoscope can be used in establishing and maintaining airway control in patients with difficult ventilation, such as those with an acute airway obstruction or massive hemoptysis.4 The major advantage of the rigid bronchoscope compared to the flexible one is that it has a ventilation port that can be directly connected to the anesthesia ventilator, allowing for maintenance of an airway and external ventilation while airway procedures are performed. In fact, the latest practice guidelines for the management of a difficult airway (DA) include the use of rigid bronchoscopy because it “reduces airway-related adverse outcomes.”5

Other instances in which rigid bronchoscopy is indicated include deeper diagnostic biopsies when a fiberoptic specimen would be inadequate; dilatation of strictures; bronchial stenting; fracture reduction; application of laser therapy or cryotherapy; tumor removal; and diagnosis of vascular rings. Some of the indications for pediatric rigid bronchoscopy are listed in Box 29-1.

There are few contraindications to rigid bronchoscopy. In practice, most of the factors limiting rigid bronchoscopy are related to the general anesthesia used, such as an unstable cardiovascular or respiratory status.6 One absolute contraindication to rigid bronchoscopy is an unstable cervical spine, because of the hyperextension of the head required during the procedure. In this instance, flexible bronchoscopy is indicated to avoid any further spinal injury during bronchoscopy. Other contraindications include laryngeal stenosis that prevents passage of the bronchoscope; limited range of motion of the mandible; severe kyphoscoliosis; uncontrolled coagulopathy; and extreme ventilatory/oxygenation demands.7,8

III Instrumentation

The Storz endoscope with the Hopkins rod-lens optical system, introduced in 1966, is the most widely used rigid bronchoscope and has largely replaced the Jackson and Holinger endoscopes.9 As described earlier, the rod-lens system provides better illumination, greater visualization, and angled views. The bronchoscope is a hollow, rigid metal tube that is tapered and beveled on the distal end and has a series of different-sized ports on the proximal end that serve different purposes. There are side holes at the end of the bronchoscope to allow for ventilation proximal to the tip.10 The beveled edge of the tip is used to facilitate introduction of the bronchoscope into the airway and for resection of tumors. The inferior port is usually the ventilating port connected to the anesthesia circuit. The superior port connects to the prismatic light deflector and the light source (Figs. 29-1 and 29-2). The main port is the working channel for aspiration and for insertion of instruments such as telescopes, biopsy forceps, laser fibers, balloon devices, cryotherapy probes, and stents. The port can be left open to allow room air into the system or it can be closed to prevent leakage of air or anesthetic gases, depending on the ventilation and type of anesthesia being used.

Bronchoscopes vary in size, in length, and in internal and external diameter. Table 29-1 depicts the different sizes of Storz bronchoscopes used by patient age, although this choice needs to be tailored to the individual patient. The size chosen should maximize the surgeon’s view while causing the least trauma to the airway.9 Telescopes with different angles (0, 30, and 70 degrees), lengths, and diameters can be inserted through the main working port to visualize areas that are difficult to see with the rigid bronchoscope alone, namely the right and left upper bronchial orifices and the right middle bronchial orifice.9 Illumination can be provided either through a light carrier rod that goes down a channel in older endoscopes, through the telescope, or by means of a port that attaches to a prismatic light deflector which subsequently attaches to a light source in newer endoscopes (Figs. 29-3 and 29-4). The last configuration has the advantage that it provides both proximal and distal illumination.

Rigid bronchoscopy should be performed either in an operating room (OR) or an endoscopy suite. As with all procedures that require general anesthesia, the room should be equipped with equipment for oxygen (O2) saturation monitoring, carbon dioxide (CO2) monitoring, blood pressure monitoring, and electrocardiography. A full set of ventilating bronchoscopes (see Table 29-1 for sizes) and a backup light source should be available. The standard adult size rigid bronchoscopy is 8 mm in diameter and 40 cm long. Other instruments such as graspers, biopsy forceps, optical forceps, and suction devices should also be available to the surgeon (Fig. 29-5). Optional items include a flexible bronchoscope that can be passed through the rigid bronchoscope for further examination of the lower tracheobronchial tree. Video capability is also desirable but not required (Fig. 29-6).

IV Preoperative Considerations

A thorough history should be taken to assess previous cardiac disease, such as a recent myocardial infarction or any documented dysrhythmias, or pulmonary disease (e.g., asthma) that may require bronchodilators before bronchoscopy.4 To minimize the risk of bleeding, the patient should have a normal platelet count, prothrombin time, and partial thromboplastin time. Unless a bleeding history is known, a preoperative coagulation workup is not necessary. Because patients with uremia have qualitative platelet abnormalities that can predispose to excessive bleeding, creatinine and blood urea nitrogen values should be relatively normal.4 Patients should also be questioned about aspirin or anticoagulant use and timing of the last intravenous dose. Additional laboratory studies and tests may be ordered depending on the history.

A 12-lead electrocardiogram is required for patients with cardiac risk factors such as smoking, diabetes mellitus, arterial hypertension, or hypercholesterolemia and for those with a significant cardiac history. A chest radiograph may provide information regarding congestive heart failure, pulmonary consolidations, or the presence of chronic obstructive pulmonary disease (COPD). Arterial blood gas analysis can be performed to evaluate the patient’s acid/base status in the setting of pulmonary disease.

Pulmonary function tests are no longer indicated as routine preoperative assessment of respiratory disease but may be useful for determining the postoperative plan.11 For example, patients with a forced vital capacity (FVC) of less than 20 mL/kg is at an increased risk for pulmonary complications postoperatively and may benefit from extended postoperative monitoring.10 Also, patients with forced expiratory volumes of less than 50% are at risk for hypercarbia and hypoxia.12 The clinical predictors of cardiac complications perioperatively or postoperatively with major risk are unstable or severe angina, decompensated congestive heart failure, significant dysrhythmias, and severe valvular disease.13 Cardiac conditions should be evaluated and the medical therapies optimized before the surgery. Perhaps the simplest way to assess the patient’s overall cardiopulmonary status is to inquire about exercise tolerance.

Often, rigid bronchoscopy is performed emergently with limited preoperative evaluation or testing in order to secure an airway, and knowledge and assessment of risk factors for cardiopulmonary mortality, difficult intubation (DI), and difficult mask ventilation (DMV) may be of importance for perioperative and postoperative management. DI may be predicted by weight, head and neck movement, jaw movement, receding mandible, “buck” teeth, Mallampati classification, thyromental distance, sternomental distance, and a history of DI.5,14,15 There are five independent risk factors for DMV: age greater than 55 years, body mass index greater than 26 kg/m2, presence of a beard, lack of teeth, and a history of snoring.14 A careful evaluation of the patient’s jaw and neck mobility should be made, because severe cervical spine disease is a contraindication to rigid bronchoscopy.

V Anesthesia for Bronchoscopy

Because of the nature of the procedure and sharing of the airway, the anesthesiologist and the surgeon must be in constant communication during a rigid bronchoscopy procedure. The goals for anesthesia during bronchoscopy are to provide anesthesia and analgesia, to provide sufficient relaxation, to diminish the reactivity and reflexes of the respiratory tract, to maintain adequate oxygenation, and to achieve prompt awakening at the conclusion of the procedure. General anesthesia is typically used to prevent unnecessary patient movement and possible unintentional damage to the airway. This can be accomplished with deep inhalational anesthesia, total intravenous anesthesia, or a combination of inhalational and intravenous anesthesia with or without neuromuscular blocking (NMB) agents depending on the specifics of the procedure and the preferences of the surgeon and anesthesiologist.

There are several different ventilation techniques that can be used with rigid bronchoscopy. The rigid bronchoscopes have ventilating ports that can be attached to the anesthesia circuit directly, allowing the anesthetic gases to flow concomitantly during the procedure. This is the most common and straightforward manner in which to keep a patient adequately ventilated during rigid bronchoscopy, although ventilation can also be achieved by the use of spontaneous ventilation, positive-pressure ventilation (PPV), apneic oxygenation, jet (Venturi) ventilation, or negative-pressure ventilation (NPV).

Traditionally in the pediatric population, inhalational anesthesia with spontaneous respiration has been used during rigid bronchoscopy, often with switching to a total intravenous anesthetic technique after induction. Disadvantages of inhalational anesthesia with spontaneous respiration include difficulty in maintaining an adequate plane of anesthetic depth and the anesthetic pollution of the surgical environment from a gas leak around the bronchoscope.16 Malherbe and colleagues proposed total intravenous anesthesia with propofol and remifentanil and spontaneous respiration as a reasonable alternative to deep inhalational anesthesia that carries no major complications.16 In the spontaneous respiration technique, the patient is not given an NMB agent and is allowed to breathe spontaneously. The ventilating port of the bronchoscope is attached to the anesthesia circuit with 100% O2 flow (see Fig. 29-1). The advantage of spontaneous ventilation is that it allows for continuous ventilation during the procedure; the main disadvantage is that the depth of anesthesia required for the procedure itself may suppress both cardiac output and the respiratory drive, making spontaneous respirations difficult.17 Another potential disadvantage is that the instrumentation required for the procedure itself provides increased airway resistance and may reduce the efficacy of spontaneous respirations.18

When PPV is used, it is typically achieved by first relaxing the patient with an NMB agent and subsequently connecting the ventilating port of the bronchoscope to the anesthesia circuit. Positive pressure is administered by squeezing the bag or by using the anesthesia ventilator, forcing gas pressure through the rigid bronchoscope.19 Advantages include the prevention of atelectasis, improved oxygenation, and the ability to overcome the increased airway resistance caused by the instrumentation within the rigid bronchoscope.18 A disadvantage to PPV is that a proximal eyepiece must be in place, which hinders the use of suction or other instrumentation during ventilation.20

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