Difficult airway management for intensivists

Before the procedure

Anatomy

Though there are a variety of SGAs that occupy the periglottic area and surround the glottic opening with a cuff, most models differ very little except in the manufactured materials, their flexibility or rigidity, ease of use, weight, and effectiveness. Most, but not all (e.g., I-gel: Intersurgical and air-Q SP: Cookgas), have an inflatable cuff that lies in the hypopharynx and essentially seals the supraglottic region from the epiglottis down the cricopharyngeal sphincter. A sealed airway allows positive-pressure ventilation to be delivered but is limited by the effectiveness of the cuff seal/periglottic mucosal surface interface. Many will allow effective airway pressurization to 10–25 cm H ₂ O pressure before leaking, whereas other models are specifically designed to allow much higher sealing thresholds (25–35 cm). These latter models are particularly effective in generating ventilatory support for the obese and morbidly obese patient and when confronted by low pulmonary compliance situations (congestive heart failure, acute respiratory distress syndrome, abdominal distention, pregnancy, ascites, and pulmonary fibrosis). The recently published Difficult Airway Society guidelines recommend the second-generation SGA based on higher cuff leak thresholds, improved intubating potential, and the presence of a bite block and gastric drainage capabilities. Many manufacturers now offer SGA models with a portal that allows passage of a suction catheter or nasogastric tube (NGT) to assist with evacuation of air or gastric contents from the esophagus and stomach (second-generation SGA). Although handy, access to the aerodigestive tract is not guaranteed, nor is the emptying process. Thus the assumption that these SGA models are acceptable in nonfasting patients or those at risk for aspiration is not supported by published literature. Despite this, any patient who has a failed airway may benefit from SGA placement even if the risk of aspiration is elevated.

In general, placement of the SGA can be performed in the exaggerated “sniff” position to the other extreme, a neutral cervical spine. Many SGA models are flexible (e.g., classic LMA-Teleflex) or foreshortened, semirigid, and curved to replicate the oro-hypopharyngeal curvature (e.g., ProSeal, Fastrach, Supreme LMA, or Aura-Once-Ambu). The SGA generally can be placed effectively when faced with little to no neck flexibility. The SGA is lubricated and then passed toward the roof of the mouth across the hard to soft palate, encouraging smooth advancement along the posterior throat so as to minimize getting hung up on the epiglottis. It typically comes to lie with its distal tip in the cricopharyngeal region. Unfortunately, the cuff end may buckle over on itself, come to lie over the glottic opening, or be displaced in a contorted position that impedes effective ventilation and oxygenation. The SGA may indeed be placed incorrectly but still function in near-perfect form with effective ventilation; it is a peculiar airway device. It can be forgiving, yet it still requires skill and finesse to place it properly in most situations. Guidance by a skilled and frequent user is the best method to learn the details of its proper use. Ideally, it lies just over the glottic opening and allows access to the trachea. However, the SGA is frequently malpositioned or the epiglottis is folded over to a lesser or greater degree, partially or completely blocking the pathway to the glottic opening, yet ventilation and oxygenation remain unabated. This may be adequate for airflow to and from but not for the passage of an ETT into the glottic opening. Hence, most generic SGA models do require fiber-optic–guided placement of an ETT because of the uncertain position of the SGA and its adjacent airway structures.

After the procedure

Outcomes and evidence

The LMA design offers a relatively short learning curve for the airway novice and affords fewer episodes of desaturation, less difficulty in maintenance of a patent airway, larger tidal volume than mask ventilation, and decreased arm and hand fatigue when compared with a conventional face mask. Its value in the ICU setting for assistance during emergency airway management is undeniable, especially during difficult intubation or when ventilation is not possible with a standard bag-mask assembly. Blind or fiber-optic–assisted tracheal intubation is an extremely attractive asset that the SGA device offers the clinician and provides an entirely novel rescue approach when conventional laryngoscopy and tracheal intubation prove troublesome or impossible. It is also useful in maintaining airway support in the ICU setting for patients who require repetitive general anesthetic or heavy sedation-analgesia for brief procedures, fiber-optic bronchoscopy, or diagnostic visualization of the airway. Recent work suggests that the SGA is better tolerated and produces fewer cardiovascular side effects than tracheal intubation. Insertion in the patient with an unstable cervical spine may be far easier than direct laryngoscopy because its insertion does not absolutely require neck manipulation.

The device may be difficult to place into the hypopharynx in the presence of a small mouth, a large tongue or tonsils, hypertrophied lingual tissue, or a posteriorly displaced pharynx. However, the SGA often proves easier to use than conventional methods of airway control such as direct laryngoscopy. The threat of gastric dilatation and regurgitation/aspiration may lead some to avoid its use in the critically ill, but its excellent track record and very low incidence of regurgitation/aspiration (1/1126 emergency insertions, Hartford Hospital, TCM) support its role as a primary airway rescue device when conventional methods fail. The role of the SGA as a rescue device in the elective and emergency setting is unparalleled, but further studies into its use in the emergency setting are needed to solidify its standing as the premier rescue airway device, regardless of which model is used. All recognized algorithms and airway management guidelines include the SGA as an integral component of management. Its multiple roles as a rescue device for difficult bag-mask ventilation and difficult intubation, as a conduit for bronchoscopic-assisted intubation, and as an oxygenation/ventilation bridge during front of neck access (FONA, surgical airway) support their recommendations.

Before the procedure

Anatomy

Though the bougie is capable of assisting intubation in nearly all airway situations except when “no view” is possible, it is most commonly used as an adjunct with grade IIb, IIIa, and IIIb laryngeal views. Even when the laryngoscopy reveals a full view (grade I), the bougie may be useful when the mouth opening is small or narrow and/or the hypopharyngeal opening is narrow (OSA, obesity, swelling) and passing the ETT may actually obstruct the view of the glottic opening. In this case, the narrower, more colorful tracheal tube introducer can be passed into the trachea with little visual obstruction taking place. Conversely, the floppy epiglottis is a challenge that may be technically difficult with many different airway adjuncts. The bougie may either be used to elevate the floppy epiglottis or be maneuvered around by virtue of the Coude tip. Though useful, the success rate is often less than 50%, and other airway device alternatives may be needed (intubating laryngeal mask airway [ILMA], VAL, flexible fiber-optic bronchoscope [FFB] ( Fig. E1.7 ).

Procedure

• The bougie is grasped in the intubator’s right hand at the 20- to 25-cm mark.

• It is passed alongside the laryngoscope with the 30-degree angled tip (Coude) anteriorly.

• The tip is advanced anterior to the arytenoids and into the larynx (grade IIa, IIb).

• The tip is then advanced underneath the epiglottis and past the vocal cords blindly (grade IIIa).

• The tip lifts the floppy epiglottis and is then advanced blindly past the vocal cords (grade IIIb).

• Advancement into the trachea to a depth of 22–26 cm in an average adult

  • Tip may “bounce” or “click” past the tracheal rings, suggesting tracheal placement.

  • This is a helpful sign but does not guarantee intratracheal placement.

  • Conversely, the lack of “clicks” does not guarantee the position of the bougie, nor does it rule out location within the trachea.

  • Ten to fifty percent of bougies passed into a grade III airway may enter the esophagus

    • Grade IIIa: 5%–12% may enter the esophagus

    • Grade IIIb: 30%–50% may enter the esophagus

      • Quickly deploy backup strategy (SGA, FFB, VAL)

      • Some may consider the bougie a poor choice in grade IIIb view

  • Tip may be gently advanced farther (28–36 cm) to contact carina/mainstem bronchus of second bronchi

    • Tip hang-up provides tactile feedback during blind passage

    • Detection of carina/bronchus is reassuring to operator

    • Advancement past 35–40 cm without hang-up strongly suggests the bougie is in the esophagus

    • Using hang-up or Cheney sign lowers the incidence and dangers of passing the ETT into the esophagus, bougie should be retracted to 23-25 cm depth, held securely then ETT may be advanced over the bougie

    • Eliminates the delay of verifying the ETT location by insufflation, capnography, auscultation

  • Decision time: passing the ETT

    • If time permits, generously lubricate the ETT

    • Smaller-sized ETTs pass over the bougie more easily than larger ones

    • Maintain tongue displacement with laryngoscopy/hand grasp

    • Pass the ETT, but do not force the advancement (an assistant should grasp the proximal end of the bougie to stabilize it)

    • Anticipate resistance at 16- to 17-cm depth because of impingement on arytenoid/vocal cord (two methods to remedy this) ( Fig. E1.8 ).

      • Preemptively advance ETT while rotating in the counterclockwise (CCW) direction to allow ETT bevel tip to avoid impingement on the glottic structure.

      • If resistance is encountered, stop and withdraw ETT 1–2 cm and then rotate CCW and advance the ETT into the airway.

      • If ETT fails to pass, the patient may be ventilated and oxygenated with bag-mask ventilation (move the bougie to the corner of the mouth).

      • Change to a smaller-diameter ETT (to ease advancement over the bougie) and assume the glottic opening may be swollen, impeding entry.

      

After the procedure

Outcomes and evidence

The simplicity of the trachea tube introducer makes it an attractive option for assisting with trachea intubation in the situation when a restricted laryngeal view is available with laryngoscopy. A variety of uses for the bougie make it a desirable addition to the difficult airway cart or bag, made accessible at the bedside in the ICU and other remote locations in the hospital. The bougie is a suggested option in the management algorithms offered by anesthesiology societies in the United States, Canada, the United Kingdom, Germany, and many other countries.

Before the procedure

Anatomy

The ILMA is similar to other SGA devices that occupy the periglottic area and surround the glottic opening with a cuff. Passing the ILMA into the oral cavity is easier than the comparative standard LMA, because it is designed with an intrinsic curve easing passage into the hypopharynx. The inflatable cuff lies in the hypopharynx and essentially seals the supraglottic region from the epiglottis down to the cricopharyngeal (upper) sphincter. The rigid construction of the ILMA is limited by its diameter, so adequate mouth opening is a prerequisite. The sealed ILMA allows positive-pressure ventilation to be delivered. Occasionally, the ILMA will afford effective ventilation if the standard LMA model fails, and vice versa (as could other brands).

In general, placement of the ILMA can be performed in the exaggerated “sniff” position or the other extreme, a neutral cervical spine. In the presence of cervical spine immobility, it is best to maintain stabilization yet remove the front collar to improve oral access. After cuff deflation, the ILMA is lubricated and then passed along the roof of the mouth across the hard to soft palate, encouraging smooth advancement along the posterior throat so as to minimize getting hung up on the epiglottis or causing its down-folding. The distal tip of the ILMA typically comes to lie in the cricopharyngeal region. Unfortunately, the cuff end may buckle over on itself, come to lie over the glottic opening, or be displaced in a contorted position that impedes effective ventilation and oxygenation ( Figs. E1.9–E1.16 ) .

Procedure

• The ILMA is placed into the airway in a similar fashion as other SGA products. However, the shortened length of the ILMA model and its handle may be easier to place than the standard SGA model. Placement is augmented by passing it along the hard to soft palate posteriorly into the hypopharynx, posterior to the epiglottis. It too comes to lie with its tip atop the cricopharyngeal area posterior to the arytenoids/glottis. The tip may fold over or under and impede air exchange or be sensed by an incomplete cuff seal (leak). This can be remedied by performing the “in-and-out” or “up-and-down” maneuver (simply moving the ILMA slightly inward and outward to free up the distal tip). Cuff inflation is followed by positive-pressure oxygen delivery. Successful placement allows the chest to rise and ETCO ₂ detection, with no audible air leak, to approximately 15–25 cm H ₂ O pressure applied to the ILMA. Always confirm ventilation before attempting ETT advancement via the ILMA.

• Two maneuvers are handy to improve success in ILMA placement and intubation:

  • After ILMA placement, the Chandy maneuver #1 involves using the ILMA handle to optimize the positioning of the ILMA within the airway, with the goal of maximizing tidal volume, ETCO ₂ , and the feel of “bagging.” The ILMA is held in this position in preparation for passing a lubricated ETT. The included LMA brand wire-reinforced ETT is an excellent ETT for passing, but it is suboptimal for long-term use in the ICU airway (if duration of intubation is >24–48 hours, one should consider changing the ETT over an airway exchange catheter to the standard ICU ETT model).

  • Limiting SGA insertion attempts to two to three is suggested by several sources. Once effective ventilation/oxygenation is established, passing an ETT may be the next objective. With the ILMA in the best ventilating position (Chandy #1), the Chandy maneuver #2 involves using the ILMA handle to slightly elevate or “lift” the ILMA (handle toward forehead, ILMA distal tip anteriorly) to improve the success rate of passing the ETT into the trachea, based on the ILMA portal being tilted toward the glottic opening and away from the esophagus. This lift increases seal pressure and improves the alignment of the ILMA to the glottic opening and corrects any flexion the mask has undergone after its placement. Malposition or flexion of the mask while in the ventilating position may alter the pathway of the ETT as it exits the ILMA. Generous lubrication of the ETT to ease passage through the ILMA lumen is absolutely essential. Intubation of the trachea may be performed blindly or with fiber-optic assistance. The skill to successfully intubate the trachea is attained by practice coupled with instruction by an experienced individual. Practicing the technique before an emergency situation arises is in the best interest of patient care.

• Troubleshooting in the event of failure to intubate (typically caused by a down-folded epiglottis, ETT impaction on the periglottic tissues, too large or too small ILMA, or patient is resisting intubation because of inadequate sedation/analgesia/muscle relaxation/anesthesia).

  • If resistance is felt approximately 2 cm beyond the black transverse line marked on the ILMA ETT (or 15–16 cm marking on a standard ETT), the down-folded epiglottis may be blocking ETT advancement, as may the vestibular wall. Rotation of the ETT may allow passage if impeded by the vestibular wall. A down-folded epiglottis may need to be addressed by performing the “up-and-down” maneuver. This is a partial withdrawal of the inflated ILMA to a maximum of 6 cm, followed by reinsertion. This often frees the epiglottis from its down-folded position. Otherwise, FFB assistance is needed, or a different size ILMA may be tried.

  • If the ETT meets immediate resistance at 15–16 cm (black mark) or at a 4- to 5-cm depth past the black mark, then the ILMA is too large, and downsizing may help.

  • If resistance is encountered at 3 cm past the black mark, the ILMA may be too small. If an alternative-size ILMA is not available, external manipulation of the larynx either downward or caudally may assist with passing the ETT. Likewise, ETT rotation may be helpful.

  • The ILMA has an “epiglottis elevator bar” to assist in lifting the epiglottis up to afford improved ETT passage into the laryngeal inlet. When using bronchoscopic-guided ETT advancement, using the ETT tip to elevate the bar is best because the bronchoscope typically is not rigid enough to do so by itself.

  • Another miscellaneous yet quite important clinical situation that may prohibit intubation is excessive periglottic/glottic edema when viewing with the FFB. Massive airway edema may preclude advancement of the FFB-ETT owing to the inability to clearly identify the glottic opening; caution must be exercised to not advance the FFB tip into unrecognizable tissue planes. Excessive force on the FFB or ETT may lead to tissue injury and thus threaten the current airway patency by inducing further bleeding, edema, or swelling. Attaching a bronchoscopic swivel adapter to the ILMA itself or via the ETT may allow active application of positive pressure to the airway and promote lateralization of the edematous glottic tissues. This is analogous to the use of CPAP in OSA patients. The bronchoscopic adapter is too narrow to allow an ETT to pass through it. To remedy this, an Aintree catheter (bougie-type catheter with a lumen that allows a proper-sized FFB to be placed within the catheter) is sized to fit through the adapter and its diaphragm. The Aintree-FFB assembly may be passed through the bronchoscopic adapter, down the ILMA, and used to visualize the glottic opening. Once advanced into the trachea, the Aintree remains within the trachea as the FFB is withdrawn. The ILMA is then removed over the Aintree, and the ETT is advanced over the Aintree catheter in similar fashion to a bougie, tube exchanger, or FFB.

• Blind intubation via the ILMA is useful and generally successful (90% within three attempts in the Hartford Hospital database for emergency intubations). Recent guidelines have leaned toward deploying bronchoscopic guidance for intubation so as to avoid blind insertion in the difficult airway situation. Moreover, recent societal recommendations have moved away from the ILMA toward the second-generation SGA models, despite an impressive track record of success with the classic SGA model (LMA) and the ILMA model design.

After the procedure

Outcomes and evidence

• The use of the ILMA has revolutionized airway management, especially in the emergency setting. It is an accepted component in the ASA airway management algorithm, in addition to all other algorithms offered by medical societies throughout the world. The presence of VAL has potentially altered the ILMA’s role as a logical and rational first step toward airway rescue when conventional methods fail or are inappropriate. However, the clinician must be familiar with this device and have it readily available as a backup for VAL difficulties or failures.

• In the elective setting, the ILMA has an excellent track record for a high level of successful ventilation coupled with blind and FFB-assisted intubation. Its successful deployment in the acute care setting in the ICU, emergency department, or other remote locations outside of the operating room has been well received, though the success rate for both ventilation and intubation is tempered to a more realistic success rate of nearly 8–9 out of 10 patient encounters (Hartford Hospital database, TCM). Thus a backup plan must be in place to deal with ILMA failure and establish effective ventilation/oxygenation, and ultimately tracheal intubation, either blindly or with FFB assistance.

Before the procedure

Anatomy

The cricothyroid membrane is located between the superior thyroid cartilage and the inferior cricoid ring. The cricothyroid membrane is located just 1.5–2 cm below the vocal cords, so care must be practiced when advancing a needle caudad, as the underside of the vocal cords could be impaled. Passing the ETT over the wire or obturator/wire may be met with resistance at the 16- to 17-cm depth, as the ETT tip may impinge on the vocal cords or arytenoids. This is the inherent danger of passing the ETT blindly over the wire or obturator/wire assembly. The location of the distal tip (having met resistance) may or may not be at the position below the vocal cords. This is the challenge of the retrograde wire method; knowing the location of the ETT tip is unknown when the decision is made to remove the wire. If the ETT tip is erroneously positioned above the glottis, then the access to the airway is denied with wire removal; hence, the advantage of using the FFB as an intubation guide ( Fig. E1.17 ).

Procedure

• Retrograde tracheal intubation

  • Needle insertion directed cephalad; operator should approach with dominant hand more caudad (e.g., right-handed operator on right side of patient)

  • Puncture cricothyroid membrane with needle directed cephalad ( Fig. E1.18 ). Aspirate air with syringe to locate air column (1–2 mL of saline in syringe; allow bubbles to percolate to verify the air column).

    

  • Pass the guidewire through the needle aimed superiorly so that the distal end of the wire may be retrieved from the mouth (or if desired, nose) of the patient. Withdraw needle off wire.

    • Pull majority of wire out of the mouth (or naris)

    • Secure distal end of wire by clamping hemostat at the level of the cricothyroid membrane ( Figs. E1.19 and E1.20 ).

      
      

• Three choices to pass ETT down the wire into the airway (nasal or oral): (1) wire assisted, (2) wire with obturator to reinforce wire, (3) flexible bronchoscope (loaded with ETT) passed over wire into airway

  • Wire assisted

    • Load lubricated ETT over oral (or nasal) end of wire, passing wire into tube through the Murphy eye.

    • Pull wire relatively taut and straight.

    • Advance ETT over wire into trachea to cricoid area and then, gradually relaxing cricothyroid end of wire, advance ETT to appropriate intratracheal location.

    • Release cricothyroid end of wire, and withdraw wire out of ETT.

    • Confirm ETT position (auscultation/capnography).

• Wire with obturator to reinforce wire ( Fig. E1.21 )

  • Pass obturator over wire into airway until resistance is felt.

  • See manufacturer’s instructions for Cook retrograde intubation kit.

  • Load lubricated ETT over oral (or nasal) end of wire/obturator.

  • Advance ETT into trachea to cricoid area.

  • Remove wire from cricothyroid membrane end, and then advance obturator distally into trachea.

  • Advance ETT to appropriate intratracheal location.

  • Confirm ETT position (auscultation/capnography).

  

• FFB (loaded with smaller-sized ETT [6–7 mm]) ( Fig. E1.22 )

  • Advance wire through the suction portal of the FFB.

  • Grasp wire end from top of FFB.

  • Advance FFB down wire, observing the airway structures as you advance ( Fig. E1.23 ).

    

  • Advancing the FFB to distal end of wire will occlude view and appear “pink” (backside of cricothyroid membrane). Correct position may be verified by darkening the room to transilluminate the cricothyroid membrane puncture site ( Fig. E1.24 ).

    

  • Once the FFB is below the vocal cords, the cricothyroid end of wire may be released as the fiberscope is advanced to the carina and wire and then pulled out of the fiberscope.

  • Or the wire may be pulled out inferiorly through the cricothyroid puncture and fiberscope and advanced into the trachea.

  • Advance the FFB tip into distal trachea, and advance the ETT into position and confirm.

  

After the procedure