Flexible Scope Intubation Techniques

Partial Disposable—EndoSheath on a Nondisposable Flexible Fiberoptic Scope

The Slide-On EndoSheath is a clear, durable, presterilized flexible thermoplastic elastomer with a working channel (variable size) that snugly fits only its own adult nonchanneled PrimeSight FIS or FIS system. It potentially prevents the transmission of 27-nm-sized organisms and permits FIS availability in one-third of the time needed for sterilizing other FISs. ^, The length of time to check for breaches is unknown but can be done by instilling a methylene blue dye in the used sheath and sinking it in a water bowl. There are no studies on breach probability. Without breaches, this FIS is US Food and Drug Administration (FDA) approved for a wipe-down cleaning with the company’s product, making FOB damage unlikely. Advertised claims for all its various endosheathed devices (including uroscopes) boast “over 5-million sold, zero reported cross-contaminations.” It may reduce costs by requiring fewer FISs and limiting sterilization equipment or personnel needs. This is uncertain because its FIS has a 9-year lifetime, compared with FISs with up to a 15-year lifetime. ^, Presently, use is aimed more at intensive care units (ICUs), but other areas are possibilities; however, the use of these sheaths is becoming more and more obsolete due to the introduction of single-use FISs.

Fully Disposable—Flexible Bronchoscopes

The Ambu aScope is a fully disposable, sterile, battery-operated non-FOB with a working channel. It has a CMOS chip, a steering button lever to flex the tip, and a distal LED ( Fig. 24.1 ). Images are transmitted along the insertion tube’s cable to a small portable monitor by way of a video connection cable at the handle. Its total disposability may be advantageous for patients with highly contagious diseases (e.g., Creutzfeldt-Jakob, Ebola), immunosuppressed patients, or in insufficiently funded sites.

Initial Ambu aScope 2 studies revealed little difference in intubation success rates for normal or DA patients, whereas optic quality and intubation times were better with reusable FISs, although since that study, they do now have a high-quality 12.8-in fully high-definition monitor. Kristensen and colleagues found the button system easy but had worse secretion problems compared with reusable FISs. The Ambu lens needed cleaning twice as often, with two completely blurred episodes after lidocaine instillation requiring FIS replacements.

Studies by Tvede (with his magic number of <22.5 cases/year for disposables to be less expensive), Aïssou, and Reynolds perceived almost no cost saving with it. ^, McCahon and colleagues paper might seem at odds to these studies, as their UK FIS costs per patient were almost double the Danish or French costs and more than triple Liu’s US and Reynolds’ Canadian costs. Mouritsen and colleagues’ systematic review and cost-effectiveness analysis found that single-use FISs are cost-effective and associated with a lower risk of infection. No comparative studies have better results for the Ambu aScope 3, with the exception of perhaps cost benefit.

Two other single-use FISs are now available, the GlideScope BFlex and the Storz single-use video endoscope ( Fig. 24.6 ).

The BFlex is fully disposable and comes in three sizes (3.8 mm, 5.0 mm, and 5.8 mm), all three of which have working channels with 50-mm interval markings on the insertion tube. The internal CMOS camera offers excellent image clarity and the FIS connects via magnetic GlideScope QuickConnect technology to the GlideScope Core monitor, enabling the added advantage of a dual view with the GlideScope videolaryngoscope for viewing multimodal airway procedures. At the time of writing this chapter, there is no published data on this device comparing its performance to other single-use or reusable FISs.

The Storz single-use video endoscopes are also sterile packed and consist of a CMOS sensor and LED illumination to provide high-resolution images with good lighting conditions when attached to the C-MAC monitor or the Tele Pack. There are four sizes available (2.9 mm, 3.5 mm, 5.2 mm, and 6.5 mm), all of which have a working channel and working length of up to 65 cm.

Many professionals are concerned with the hazards of nonrecyclable product use; however, the materials in the aScope 4 Broncho generate less CO ₂ emissions and utilize fewer scarce resources. All three companies involved in producing single-use FIS are working toward reducing CO ₂ emissions, reducing PVC packaging, and increasing to 100% recyclable and compostable packaging.

Bronchoscopy Swivel Adapters and Endoscopy Masks

Bronchoscopy swivel adapters are used for diagnostic examinations, therapeutic maneuvers, or intubation. They can rotate when placed between the ventilating system and a mask, SGA, or ETT. They resemble elbow adapters equipped with a flip-cap port on top, covering a centrally open diaphragm ( Fig. 24.9 ). This facilitates FIS passage with virtually no leak during uninterrupted ventilation. Swivel adapters only permit very small ETT passage (sizes ≤5.5 mm; uncuffed 6.0 mm is very snug). Apart from a ventilation connection, endoscopy masks have more than one larger opening whose design function may be similar to a swivel adapter port ( Fig. 24.10 ). This allows FIS or FIS and ETT (≤8.0 mm) passage during continuous mask ventilation. Some have recessed valvelike openings.

Intubating Oral Airways

For conscious or unconscious patients, IOAs are conduits to keep an FIS midline during oral intubation ( Fig. 24.11 ). They must not be placed too deeply into small mouths.

The ideal IOA (1) protects the FIS from damage; (2) keeps it midline; (3) keeps tissues away; (4) permits FIS maneuverability within; (5) has an ideal length to approach the glottis; (6) allows the passage of larger ETTs; (7) possesses a breakaway quality for easy removal; (8) avoids tissue discomfort (minimizing gagging) or trauma to tissues or ETT cuffs; and (9) has the ability to assist with mask ventilation. If no IOA is used in awake patients (because of unavailability, endoscopist preference, or inadequate mouth opening), a bite block between the molars or incisors may prevent FIS damage.

Most studies comparing IOAs involve non-DA patients. All are disposable, except the aluminum Patil-Syracuse oral airway (Anesthesia Associates, Inc. [AincA], San Marcos, CA).

The Berman Intubating Pharyngeal Airway (Teleflex Medical Research, Triangle Park, NC) in neonatal, child, and adult sizes admits ETTs up to 8.5 mm. Its full-length tubular shape does not help FIS maneuvering, but its wide lateral perforated slits break away from postintubation ETTs (although possibly difficult, particularly with periglottic ETT impingement). Kept midline, it provides a better lead to the glottis if the length is appropriate. If too long, distally, it may lie in the vallecula; 1- to 2-cm withdrawal may rectify the situation. This device has largely been superseded by newer IOAs.

The proximal channel of the Ovassapian Fiberoptic Intubating Airway (Teleflex Medical Research, Triangle Park, NC) permits the passage of ETTs up to 9 mm. It has flexible lateral walls and a posterior opening for easy ETT removal. Its distal half has a wide, flat, open, curved area designed to keep the tongue and soft tissues away, make it easier to stay midline, and permit free FIS movement. A marker line drawn lengthwise down the middle of its concave surface aids FIS orientation upon entry. During ETT insertion between the teeth, the channel can be partially opened to avoid tearing the cuff on its corners.

The Williams Airway Intubator (SunMed Medical Systems, Grand Rapids, MI) has two adult sizes, allowing the passage of an ETT up to 8.5 mm. It has a closed channel proximally and a curved section distally with a scalloped opening on the lingual surface to permit FIS movement. If kept midline and its length is appropriate, it may be the best guide to the larynx. If the length is too long, visualization can be problematic. With smaller sizes, cuff damage is more frequent for ETTs larger than 7.0 mm. During removal, which may be difficult, the enclosed channel part should have been liberally prelubricated. Afterward, reconnect the ETT to its 15-mm ETT connector.

Unexpected Adaptations of Short, Soft Nasopharyngeal Airways

Two nasopharyngeal airway (NPA) techniques may be employed during ATI. One simplifies nasal ATI by making a breakaway NPA with a single full-length slit to permit breakaway capability, as reported by Lu and colleagues. Lubricate the breakaway NPA inside and outside, gently insert it into the largest naris to an appropriate depth, and guide the FIS through it toward the glottis. After maximal entry into the trachea, an assistant strips the NPA away. Advance the FIS until two to three rings above the carina and railroad the ETT into the trachea.

The second technique is where the NPA is used as a conduit for oxygen delivery and possibly for inhalation of volatile anesthetic gases during FSI (most commonly in pediatric patients). ^, This is particularly advantageous in spontaneously breathing patients after cutting a Murphy eye-type hole distally. Place this modified NPA into one nostril, and attach it to a supported breathing circuit via a 15-mm ETT adapter. Perform ATI through a different airway opening.

Endotracheal Tubes: What Is Best?

The appropriate selection of the most appropriate ETT is integral to the success of an ATI. Consideration should be given to the appropriate tube material, size, tip shape and design, and length of the ETT. Regular polyvinylchloride (PVC) ETTs can be used for FSIs. However, the most distal ETT tip area can get caught on the arytenoids, especially the right, causing impingement. Previously, ETTs with soft centrally directed tips had greater successful intubation rates than PVC ETTs. However, Joo and colleagues demonstrated no difference in success rates or manipulation instances required during ATI when comparing these two types of ETTs if the PVC ETT tip was inserted with the Murphy eye facing anteriorly with respect to the patient’s body to avoid arytenoid contact. It represented a 90-degree counterclockwise rotation of the ETT from its normal position during direct laryngoscopy ( Fig. 24.12 ). Reinforced Parker Flex-Tip and the ETTs used with intubating laryngeal mask airways have good clinical evidence to be superior to regular PVC ETTs and are recommended over them.

Location

Planning for the appropriate location and prerequired equipment, drugs, and staffing is essential. Ideally, ATI should be performed in the OR environment as this affords access to DA carts, skilled assistance and nursing, proximity to other anesthesiologists, and surgical skills, as well as providing adequate space for ATI to be performed. Early communication with the OR is important to ensure that sufficient time is planned for DA management. External pressure from nonairway managers must be limited gently but firmly.

Patient Preparation

The importance of building a good patient rapport and psychological preparation cannot be understated. This includes highlighting the importance of advanced airway management in that patient, as well as the risks of the alternative airway management approaches. Specific descriptions regarding the benefits of ATI and the process that the patients are likely to experience should be discussed. Patients should be informed of the unpleasant flavors of local anesthetic; comparing to “tonic water” or “old banana” may be useful. Encouraging the patient to participate in the process by advising them that they will be requested to take deep breaths at certain times or gargle then swallow at others. It may be beneficial to highlight that the procedure may be performed without any sedation if appropriate topicalization is performed, but with conscious sedation, if indicated, patients are often relaxed and may not remember it. Finally, the importance of patient participation and cooperation cannot be understated as it makes the procedure easier, faster, and less worrisome.

Ergonomics

The ergonomics of the clinical workspace have been shown to affect technical procedures and patient safety. ^, Consideration must be given to the placement of the following in the clinical environment: patient, operator, assistant, monitor, bed, airway trolley, anesthetic machine, suction, and infusion pumps. There are benefits and limitations to performing ATI facing the patient or behind the patient, as well as the patient position being supine or semirecumbent, although there are theoretical safety benefits to the latter. Regardless of patient and operator position, it is useful to consider the ergonomics of the clinical workspace ahead of the arrival of the patient ( Fig. 24.14 ).

Equipment and Monitoring

Unless emergency circumstances dictate otherwise, minimum standard equipment should include a DA cart; an oxygen delivery system; suctions; patient monitors; resuscitation equipment; drugs (for topicalization, sedation, GA, reversal agents, and emergency drugs); and drug delivery systems (e.g., target-controlled infusion devices). Equipment for primary and alternative airway management strategies should also be discussed, available, and checked.

Monitoring physiological parameters reduces risks and alerts operators regarding impending complications. Frequently occurring complications that may be avoidable during ATI that may be detected by monitoring are airway obstruction and hypoventilation, which may arise due to oversedation. Thus continuous pulse oximetry should be utilized as a standard. End-tidal carbon dioxide pressure (P etco ₂ ) monitoring may be beneficial with alarm parameters set for P etco ₂ and respiratory rate. There have been modifications to existing devices that can be used to attach one end of the CO ₂ analyzer line from the nasal cannula to the circle breathing circuit, minimizing the burden of disconnecting sampling lines at crucial times during the ATI process ( Fig. 24.13 ). However, this is dependent on the use of a nasal cannula for oxygenation, which might not be ideal. Attachments to high-flow nasal oxygen (HFNO) devices have now been produced, are affordable, and are simple to use, and they may provide an opportunity to undertake continuous waveform capnography in this setting ( Fig. 24.15 ). Regardless of the strategies employed, monitoring for respiratory depression is important during the process of ATI.

Cardiac dysrhythmias or hypotension may occur after the administration of sedation or topicalization agents, and therefore noninvasive blood pressure monitoring cycling frequently (if invasive blood pressure monitoring is not used for separate clinical indications) is mandatory during the performance of ATI.

The use of depth of anesthesia monitors, such as the bispectral index, may be beneficial to monitor sedative drug administration. This may reduce the risk of oversedation, which is known to be one of the most frequently occurring complications during ATI. The benefits of the use of the bispectral index must be weighed against the risks of increasing cognitive load on airway operators.

Innervation of the Orotracheal Airway

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. ^, Some fibers also supply the lingual surface of the epiglottis. It 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, forms part of the pharyngeal plexus, giving motor function to the soft palate and pharyngeal muscles. Its superior and inferior laryngeal branches carry sensory supply to the laryngopharynx. The superior laryngeal nerve (SLN) has an internal division for sensory supply to the tongue base, vallecula, epiglottis, piriform recesses, supraglottic mucosa, and 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.

Innervation of the Nasotracheal Airway

Cranial nerve V, the trigeminal, supplies sensation to the anterior half of the NP via 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. ^, Cranial nerve IX, the GPN, supplies parasympathetic innervation, while the carotid plexus supplies sympathetics. Cranial nerve VIII, the facial nerve, has parasympathetic function and forms part of the sphenopalatine ganglion to assist in the control of nasopharyngeal reflexes.

Noninvasive Techniques

Intraoral Local Anesthesia

These methods may anesthetize everything from the back of the pharynx and posterior tongue to the superficial surface of the vocal cords. In advance, give instructions to the patient about taking deep breaths (rather than coughing out sprays), gargling (to maximize local drug effect), and/or swallowing (to remove LA-mixed saliva before fresh applications).

The simplest and perhaps most effective technique for achieving this is using 10% lidocaine spray to the oropharynx ( Fig. 24.17 ). Each spray delivers 10 mg of lidocaine (0.1 mL), allowing a generous number of sprays before approaching maximum doses. Moreover, the high concentration of local anesthetic affords a rapid onset of topicalization. Operators should spray the tongue, tonsillar pillars, and the base of the tongue (GPN block). Thereafter, asking patients to take a deep breath in while simultaneously spraying will allow the local anesthetic to reach the epiglottis, larynx (SLN block), and trachea. A total of 20–30 sprays should suffice (meaning a dose of 200–300 mg of lidocaine). However, should further LA be required for the larynx and below, using the effective and inexpensive MADgic atomizer (Teleflex Medical, Morrisville, NC, USA) curved to allow careful placement above the glottis with 1–4 mL of lidocaine sprayed and gargled may further contribute to SLN block. This combined technique can often be used as the sole topicalization strategy if delivered appropriately and has been advocated by the Difficult Airway Society (UK).

Other approaches include a lollipop method with 3 cm of 2% to 5% lidocaine paste on one end of a tongue depressor, or a direct toothpaste method (gel down the middle of the tongue) ( Fig. 24.18 ), leaving drugs to dissolve over 5 to 10 minutes. Alternatively, let a Tessalon Perles (benzonatate) dissolve in the middle of the tongue (may need to bite it slightly, once).

“Spray as You Go” Technique

This method is for patients with incomplete or no GPN, SLN, and/or transtracheal block(s). Quick pulses of 1 mL of 2% to 4% lidocaine from a syringe attached to the FIS working channel are injected onto areas requiring further LA. It is best to avoid using suction concomitantly as this will lead to reduced local anesthetic dispersion. To avoid obscured movement views from reactions to sprays, attach the syringe to a three-way stopcock on a taped epidural catheter (0.5- to 1-mm diameter; single distal hole) threaded through the suction port until extending 1 to 2 cm beyond the FIS tip ( Fig. 24.19 ). Epidural catheters mimic the effect of small pediatric FIS channel diameters, causing jet-like flows that require smaller 0.2-mL pulses.

Invasive Techniques

External Approach to Superior Laryngeal Nerve Block

We do not recommend the routine use of invasive approaches to airway topicalization beyond expert hands. This is because they have been associated with higher plasma concentrations of local anesthetic, local anesthetic systemic toxicity, and lower patient comfort, as well as carrying risks of causing hematomas, potentially worsening airway compromise, and increasing the complexity of the entire procedure. Moreover, the effectiveness of minimally invasive techniques means that the necessity for invasive approaches is less apparent. Finally, the use of landmark approaches, while useful, is probably now superseded by ultrasound-guided techniques, allowing the visualization of structures of interest that one hopes to either access or avoid. However, it is useful for readers to have a full understanding of the benefits and landmark-guided techniques of invasive approaches.

The SLN approach is particularly advantageous if intraoral chances of success are less, including in patient situations with no oral cavity entry and that only permit a few quick peritonsillar sprays (e.g., limited cooperation); to rescue failed gel, spray, aerosol, or nebulized internal SLN block; if coughing or hemodynamic changes from FIS “spray as you go” are inadvisable; or to prevent severe laryngospasm episodes that might have been experienced previously with intraoral LA.

The easiest technique is with 6 mL of 1% lidocaine in a 10-mL syringe attached to a 21- or 22-gauge needle as an injection system while aiming for a hyoid cornu ( Fig. 24.20 ). After the needle tip hits the bone, shift the nondominant hand to brace the system at the hub against the neck. Aspirate gently. If no blood returns, inject 3 mL slowly. Repeat on the other side. Constant aspiration and bracing are vital and easily avoid intravascular injection (especially intracarotid), similar to regional blocks (e.g., interscalene). This approach has a lower incidence of complications, such as laryngospasm or gagging, compared with topical LA techniques.

An uncommon intraoral SLN block method involves putting pressure in the piriform fossa with a lidocaine-soaked gauze on a forceps, requiring up to 20 minutes to take effect.

Transtracheal Block

Of all the invasive topicalization techniques, this is probably the most. Of course, transtracheal blocks (TTBs) provide excellent intratracheal anesthesia. However, other benefits include developing expertise in locating the cricothyroid membrane (CTM) by manual assessment (an immediate test for accuracy is the aspiration of many bubbles) or ultrasound (which is more accurate than manual palpation alone ( Fig. 24.21 ). ^,

This skill extends to emergency cricothyrotomy situations, with potential life-saving benefits. Poor ability to detect the CTM was evident in the 4th National Audit Project (NAP4), which reported a 43% to 64% cricothyrotomy failure rate in emergencies. Before this, Elliott and colleagues demonstrated that accurate CTM assessment by the equivalent of experienced residents and attending faculty was only 30%, with poorer estimates mostly dependent on female gender or obesity. Aslani and colleagues later pointed out that 46 of 56 female patients had an incorrect evaluation of the CTM up to 1.6 cm laterally, 2.5 cm superiorly, and 4 cm inferiorly. One in 16 obese patients had correct identification. These results indicate that, as frequently as possible, clinicians should be encouraged to perform TTBs. The use of ultrasound is a significant advancement in this setting, and success rates have increased substantially with the assistance of this imaging modality. ^,

Tips for TTB success include the following: with two hands, aspirate gently with a posterior aim to enter the CTM, to avoid vocal cords; keep aspirating air until after maximal patient exhalation, brace, and continuously inject. It causes a minimal cough, followed by a huge breath that spreads the LA and more coughing. Needle technique advantages: (1) is faster than an angiocatheter method; (2) has fewer steps; (3) is less likely to provoke coughing or injury caused by hitting the posterior tracheal wall while threading the catheter (some like to fully thread it like an IV); and (4) is more successful (needles are shorter, less flexible, and, even if pulled out of the trachea, can be advanced easily). Using a needle rather than an angiocatheter is advocated by various authors.

Is coughing during TTB a problem in cervical spine–risk patients? According to Todd and Crosby, the answer is no. They advise that concern about TTB is unfounded; because of those who coughed, none has ever been shown to develop secondary neurologic damage.

Which technique(s) is/are best? With regard to the occurrence of coughing during FIS insertion, in comparison studies between TTB and “spray as you go,” patients in the TTB group reacted far less, according to Webb and colleagues. Gupta and colleagues demonstrated a better result with TTB as well, when comparing it with nebulized LA. This study was associated with much less gagging and laryngospasm in the TTB group, even though a lidocaine gargle had been used for everyone. Others have also found that a combination translaryngeal, SLN, and GPN block was better than nebulization, with fewer reactions, less grimacing, or fewer hemodynamic changes. ^, El-Boghdadly et al. demonstrated that the use of a spray-only technique in conjunction with MADgic glottic spraying is associated with a high success rate and low complication rate. It is therefore our opinion, as well as that of the Difficult Airway Society, that this noninvasive approach should be the most widely practiced, with more advanced techniques reserved for specialist hands ( Video 24.1 ).

Nasopharyngeal Topicalization Techniques

The route for tracheal intubation should factor in patient anatomy, surgical access, and extubation plan. For example, in patients with limited mouth opening the nasal approach may be the only option, while in patients having nasal surgery, the oral approach may be the preferred route. There is also no evidence favoring the superiority of the oral route when compared with a nasal route, or vice versa. ^, Therefore the nasal approach remains an invaluable route for tracheal intubation that readers should be familiar with.

Topicalization involves the administration of both a local anesthetic agent to render the nasopharynx (NP), posterior pharyngeal wall, and periglottic area insensate and a vasoconstrictor to reduce the risk of bleeding and maximize the caliber of the NP. Oropharyngeal topicalization is still required to ensure the larynx and trachea are also anesthetized. This is most easily achieved with the use of co-phenylcaine spray, which is composed of 2.5-mL lidocaine 5% with phenylephrine 0.5%. This can be delivered using a nasal mucosal atomizing device ( Fig. 24.22 ). First, one should select the nasal passage with the greatest luminal size by asking the patient to sniff through each nare; the one with the least subjective restriction to inspiration should be used in the first instance unless otherwise indicated. Regardless of luminal caliber, when topicalizing, apply them to both nasal passages to avoid delays in having to anesthetize the other side if the first is too small. Then co-phenylcaine is sprayed synchronously to a deep “sniff” by the patient to ensure appropriate dispersion. It is usual for patients to experience a “trickle” of the local anesthetic spray in the back of their throat. This approach is simple, rapid, and well tolerated by patients.

There are alternative approaches to nasopharyngeal topicalization. For example, one may use two Q-tips per nostril dipped in either phenylephrine, in oxymetazoline mixed with lidocaine, or in plain cocaine. Apply every single swab in succession to the outermost part within the nostril, using a fingertip on the stick end to gently push inward perpendicularly to the facial plane until feeling slight resistance ( Video 24.4 ). By the fourth Q-tip, vasoconstriction onset will allow sequential pushing farther in with each in a similar fashion until a point of no resistance posteriorly. This facilitates gauging the NP caliber for ETT passage. Midway through the process, pulse in 0.2 mL of solution with a 20-gauge angiocatheter (needle removed) in each of three different directions per nostril to minimize trauma. This uses a total of 2 mL of solution (e.g., 80 mg of 4% cocaine). It is notable that the use of cocaine for this purpose is reducing given that it is associated with cardiovascular complications and does not lead to a superior effect when compared with phenylephrine or oxymetazoline.

Alternative techniques involve using NPAs coated in lidocaine gel and phenylephrine. Some suggest that inserting progressively larger NPAs can mechanically dilate the NP passage. However, Adamson and colleagues reported that this method only caused increased trauma, hemorrhage, and delay of intubation, and therefore this practice should be avoided.

Local Anesthetic Drug Choices

LA dosing for various airway blocks is listed in Table 24.2 . It is not recommended to use LA brands containing benzocaine because of methemoglobinemia risk (Hurricaine, Exactacain). Although methemoglobinemia instances were much more frequently reported in patients undergoing transesophageal echocardiography, some occurred among FSI-managed patients after unlimited, continuous spraying. Lidocaine is the most commonly used LA for topicalization in this setting and is associated with a safer and more predictable cardiovascular and systemic toxicity risk profile. The dose of topical lidocaine should not exceed 9 mg/kg lean body weight, as higher doses are associated with a significantly increased risk of toxicity. The total dose of all local anesthetics delivered, regardless of the route (e.g., regional anesthesia or surgical infiltration), must also be considered. In terms of selecting the appropriate concentrations of local anesthetic to use there has been some evidence that lower concentrations of lidocaine are as effective as higher concentrations, but higher concentrations may be associated with more rapid onset of airway anesthesia. A high index of suspicion of the rare possibility of local anesthetic systemic toxicity should be in place ( Box 24.4 ).

Antisialagogues

Antisialagogues have traditionally been used to reduce secretions to improve FIS views, dilute LA, and reduce the risk of laryngospasm. However, their use is not mandatory in ATI as they may be associated with undesirable clinical consequences and must be administered well in advance of the ATI ( Table 24.4 ).

Oral Approach

For an oral route, the patient can be asked to open their mouth and protrude their tongue, after which a bronchoscope airway (VBM Medical Inc., Noblesville, IN) or a Berman IOA can be inserted in the midline. If the patient is unable to protrude their tongue, an assistant can grasp the anterior and posterior surfaces of the tongue with gauze to gently pull it outward but not tear the frenulum linguae. This often lifts the tongue off the palate and elevates the epiglottis ( Fig. 24.25 ).

Many experts recommend holding the FIS handle with a nondominant hand, because thumb pressures on the lever and forefinger depression of the suction valve are not as intricate movements as directing the bronchoscope tip with the dominant hand. To prevent the ETT from sliding down, gently snug it fully up the bronchoscope, tape it in place with the connecter, or use an ETT-holding element if the bronchoscope has one ( Fig. 24.26 ). Before you begin, gently warm the tip of the bronchoscope on the patient’s tongue to reduce the risk of misting, then ensure the tip is wiped clean. Control the bronchoscope as it advances through the mouth, keeping it midline with the dominant hand’s thumb and first two fingers, similar to a pen. Brace the fourth and fifth fingers on the IOA, lip, or cheek to avoid tremulous motion and eye injuries.

To reduce endoscopist fatigue, employ a gentle curve in the bronchoscopy by bending the handle control arm’s elbow very near to one’s anterolateral rib cage so that the handle hand is relaxed by the shoulder unless the arm-straight-out style is preferred.

Insert the bronchoscope into the patient’s mouth, down the IOA, while keeping the demarcation between IOA and mucosa colors in the center of view. Use the lever to look up or down while turning the bronchoscope (using both hands in unison) to look left or right; always keeping known anatomy in the center. Go around obstacles, such as secretions, or suction them. Slowly insert the bronchoscope perpendicularly toward the pharynx 6 to 8 cm, past the palate and the uvula, and move the lever to look for the epiglottis and glottis. Jaw thrust or asking the patient to phonate and protrude their tongue often helps lift the epiglottis. ^, For severely limited mouth opening, retromolar entry is often possible. Then consider the three successive directions.

Three Successive Directions for Flexible Bronchoscope Guidance

Airway specialists are familiar with the upper airway configuration, as routinely observed with a laryngoscope. On the other hand, the different axes successively followed plus the structures involved during bronchoscopic intubation and their reciprocal spatial organization are less emphasized in classic teaching programs. Moreover, many medical textbook sketches or drawings are inaccurate, depicting the upper airways as a regularly curved line joining the oropharynx or NP to the carina. This is misleading, because three successive directions must be followed to reach the trachea from the nasal or the oral route. These successive directions in the supine patient are (1) downward to the oropharyngeal or nasopharyngeal posterior wall; (2) upward to the vocal cords’ anterior commissure; and (3) downward again into the laryngeal and tracheal lumen to the carina ( Fig. 24.27 ). That is: down, up, and down again ( Video 24.2 ). These same movements are applicable regardless of patient position.

When performing an orotracheal flexible bronchoscopy, it can be difficult to stay in the median sagittal plane, particularly when pharyngeal obstructive flaccidity is present. The difficulty may be overcome with an IOA, assistant aid, or FIS insertion through an SGA while aiming downward to get to the point of upward tip flexion to view the glottis.

During the second phase, while slowly advancing toward the anterior commissure, the posterior part of the glottic aperture will come into view. Continue toward the anterior commissure by keeping the tip of the device in a sharp upward/anterior path. In the absence of anatomic distortions resist the temptation to push the bronchoscope unswervingly in this direction. When the anterior commissure is very close, angle the tip in the third direction, downward toward the widest opening of the larynx. This maneuver aligns the bronchoscope with the anatomic axis of the larynx successively in its supraglottic and infraglottic segments, avoiding contact damage to the mucosa and arytenoid cartilages.

Follow the third direction into the trachea until the tip lies two to three rings above the carina. Do not provoke coughing by being too close to it (often is not anesthetized), but ensure you are able to visualize the carina.

At this point, stop looking at the screen/eyepiece. Instead, look at the patient to judge when the ETT tip is near the larynx. Hold the bronchoscope immobile in your left hand and, with your right hand, slide the ETT forward with the Murphy eye oriented anteriorly if using a PVC ETT (a 90-degree rotation) to prevent it from getting hung up on the arytenoids (statistically, most frequent on the right). ^, Ask the patient to take a deep breath to open the vocal cords widely, and advance the ETT as you are rotating it. After judging that it is beyond the vocal cords, observe the screen to slide the ETT two to three rings above the carina. Gently inflate the ETT, stabilize it, and remove the bronchoscope by putting it straight into the used vertical holder or hand it to an assistant. Attach the ventilating system, check for P etco ₂ , and secure the ETT. A two-point check is advocated before induction of anesthesia: (1) visualizing the ETT in the trachea and (2) confirming P etco ₂ . Without either of these checks, proceeding with GA might not be safe.

At any point from the mouth to the trachea, if nothing is recognizable, back up slightly to look around with slow lever motions until anatomic structures are familiar, then proceed again. For very difficult ETT insertions, it is worthwhile to recheck the secured ETT with the bronchoscope, especially after patient positioning, which may cause ETT movement.

Here are some scenarios and suggestions on how to deal with issues.

Question. What do I do when the patient is too sleepy before the FIS insertion and I can’t grab the tongue? Reduce the level of sedation and ask the patient to stick out their tongue. You may also consider applying large suction tubing to it. Slowly draw it out, until grasped with gauze.

Question. The bronchoscope view isn’t clear. Is it fog? It may improve with any of the following: touch the tip on the mucosa ( Video 24.3 ); suction via bronchoscope or separate tubing, or both; check the focus dial or eyepiece. If unsolved, remove the bronchoscope and clean the tip by carefully holding the tip tightly near its end and gently wiping it with alcohol.

Question. What if I can’t look laterally because the lever only moves the tip up and down? Rotate both hands equally, clockwise for right (if supine) and counterclockwise for left. Then lever it. As an alternative, loosen the handgrip between the thumb and two fingers on the distal bronchoscope insertion section to avoid bronchoscope torque and damage while simultaneously rotating the handle.

Question. The bronchoscope tip is stuck on the posterior pharynx. What do I do if I can’t get by the epiglottis? Ask the patient to stick out their tongue or the assistant to pull the tongue out more and/or perform jaw thrust ( Fig. 24.25 ). As an alternative, try moving the tip more laterally and caudally to angle in under the epiglottis or assist with another airway device to lift the epiglottis (see combo with DL [25], ETT [24], stylet).

Question. What do I do if the patient keeps gagging or coughing as the bronchoscope advances? Consider correcting inadequate LA blocks, or use the “spray as you go” technique.

Question. What do I do if the patient has too many secretions and/or blood and I can’t see? Use one or two suctions continuously. Direct a straightened FIA midline and posterior, equal to two-thirds of the mouth-to-ear distance. Turn the room lights down or off, angle the tip caudally, and use FIS light transillumination, similar to a lighted stylet ( Fig. 24.28 ). Once in the trachea, suction via the bronchoscope until tracheal or carina reaction is observed or those structures are visualized. If unsure, insert an epidural catheter down the working channel for P etco ₂ analysis. There are a number of alternatives. (1) Use a VAL for ATI instead, allowing a wider field of view, easier ability to suction, and a lower probability of the image becoming obstructed. (2) Insert a second-generation SGA to seal the periglottic area. Suction the ventilating lumen of the SGAs, ventilate, and check the P etco ₂ waveform. Advance a bronchoscope until near the carina. (3) Insert a long (≥80 cm) guidewire into the bronchoscope to extend it 3 cm past its tip. Tape it proximally. Tape the ETT to the FIS so that the FIS tip ends just before the ETT tip. With simultaneous oral suctioning, the FIS may stay clear of the soiling, and the wire may be directed to the glottis. Once it goes 8 cm past the glottis, quickly advance the FIS and then the ETT. Rapidly inflate and suction the ETT. (4) Use retrograde-flexible scope–assisted intubation (see Combinations). (5) At any point, if oxygenation, ventilation, or aspiration threatens, consider a surgical airway.

Question. What do I do if the bronchoscope passes the glottis and I can see rings? The airway is getting very narrow and the patient is getting agitated and desaturating a bit. It may be a compromised airway. Tracheal stenosis or obstructive pathology causes inadequate room around the bronchoscope for ventilation. Do not insufflate oxygen through the bronchoscope in case ventilation volumes cannot exit (pneumothorax risk). Speed up the process to intubation and remove the FIS as soon as possible. Alternatively, if an adult FIS was used, remove it and use a pediatric one.

Question. What do I do if the bronchoscope is clearly right above the carina but I can’t slide the ETT into the trachea? Withdraw the ETT 1 to 2 cm, keep the convex side right, and advance with a rotational movement while asking the patient to take a deep breath. If unsuccessful, apply tongue pull/jaw thrust, repeat, and/or rotate the ETT 180 degrees clockwise the other way. Han’s study found that these maneuvers could double success rates for first-attempt ETT passage with an FIS; oddly, sometimes, even releasing jaw thrust helps. Alternatives include trying slight cricoid pressure or neck flexion ; removing the FIS and trying a smaller ETT or a centrally curved, soft-tip ETT; inserting a pediatric FIS on an Aintree Intubation Catheter (Cook Medical Inc., Bloomington, IN) and sliding the ETT over both (lessens diameter disparity); or using a nasotracheal approach.

Question. I pushed the ETT forward after successfully placing an FIS. Despite every maneuver, the ETT wouldn’t enter. What should I do? Back the bronchoscope out. If more than minimal resistance is felt, withdraw the bronchoscope/ETT carefully as a unit. The bronchoscope may have exited through the Murphy eye. Strong attempts at removing the FIS can damage the outer skin as a result of catching sharp Murphy eye edges ( Fig. 24.29 ). However, the ETT may be too big. In this case remove the scope and start again using a different approach.