Troubleshooting and Managing the Difficult Airway

Diane M. Birnbaumer, MD, and Charles V. Pollack Jr., MA, MD.

Disclosures

Semin Respir Crit Care Med. 2002;23(1) 

In This Article

Rescue Devices

Fiberoptic Intubation Devices

Fiberoptic intubation, which allows for direct visualization of the airway during intubation, is a viable alternative in the patient with airway obstruction, obesity, and distorted anatomy. The fiberoptic intubating endoscope is expensive and requires care and skill when being used. Care using the device and maintenance and cleaning of the device are also crucial.

Fiberoptic intubation can be performed orally or nasally; when it is performed orally a bite block should be used to prevent the patient from biting on the scope and damaging its fragile fiberoptic fibers. Adequate anesthesia is critical in the use of this device; a straightforward approach utilizes topically applied tetracaine or lidocaine both intranasally and intraorally. The preferred approach for nasal intubation over the fiberscope involves introducing the endotracheal tube into the chosen nare and prepositioning it in the hypopharynx. The endoscope is then passed through the endotracheal tube into the trachea, and lastly the endotracheal tube is advanced over the scope until positioned appropriately in the trachea. When intubating the patient orally, devices such as the Berman Airway facilitate placement of the tube and protect it from the patient's bite. Although there is a learning curve to using this approach, data indicate that patients can be successfully intubated emergently with these scopes. Fiberoptic intubation may be the method of choice in some patients, particularly obese patients, those with limited mouth opening, and those with restricted peroral visualization of the hypopharynx.[10]

The Laryngeal Mask Airway (LMA) was developed by the British anesthesiologist Dr. Archie Brain in the 1980s. It was originally designed to permit ventilation and maintain a patent airway, intermediate in intensity and invasiveness between the facemask and the endotracheal tube. Brain envisioned the LMA as a physical junction between the artificial and anatomical airways, allowing some maintenance of protective reflexes and less dead space ventilation (and greater reliability) than with a facemask, but without assumption of complete control of the patient's airway by the operator.[11]

The LMA is considered a primary option for the management of difficult and failed airway patients in algorithms published by both the American Society of Anesthesiologists and the European Resuscitation Council.[12,13,14] It is a familiar option for most anesthetists and anesthesiologists, and emergency physicians and intensivists are increasingly comfortable with its use. The LMA can also be used as a conduit for passing a formal endotracheal tube, but the preferred means for that intervention is the intubating LMA (LMA-Fastrach). Of particular interest to emergency physicians and emergency medical service users of this latter device is, compared with the standard LMA, a greatly diminished need for manipulation of the head and neck, making the device more useful for patients in whom cervical spine injury is suspected.[15] The intubating LMA (Fig. 2) further differs from the LMA in that the former's rigid handle acts as an insertion tool and provides a conduit for a larger ETT (up to 8.0) than the standard LMA. The sole functional purpose of the shaft of the standard LMA is to serve as a gas conduit for ventilation. After basic training with the device, successful insertion may be expected in greater than 95% of patients within two passes.[16] Insertion techniques for the LMA and intubating LMA are described in detail elsewhere.[17]

Figure 2.

(A) Features of the LMA-Fastrach. (B) Rub the lubricant over the anterior hard palate with the device in position as shown here. (From Walls et al[5] with permission.)

Figure 2.

(A) Features of the LMA-Fastrach. (B) Rub the lubricant over the anterior hard palate with the device in position as shown here. (From Walls et al[5] with permission.)

The most important issue mitigating use of the LMA in the resuscitation setting is the risk of aspiration of gastric contents; unlike an ETT with an inflated cuff, the device does not physically separate the respiratory and alimentary tracts. An additional concern arises in patients with the need for high pulmonary inflation pressures due either to increased airway resistance or to very low lung compliance. Inadequate ventilation due to air leakage and gastric distension is the predictable adverse effect of attempting positive pressure ventilation on "tight" asthmatics with the LMA.[18] On the other hand, complications resulting from use of the LMA are known to be rare. In a series of more than 11,000 patients of all ages over a 2-year period, there was a 0.15% airway management complication rate, and none of these 18 patients required intensive care.[19] The primary complications known to be associated with the LMA use are aspiration of gastric contents; local irritation that can cause coughing and bucking; trauma to upper airway structures; pressure-induced lesions such as palsy of the twelfth cranial nerve; and, with positive pressure ventilation through the LMA, bronchoconstriction and pulmonary edema or other hemodynamic compromise.

The Bullard and Woo laryngoscopes are rigid fiberoptic-enhanced laryngoscopes that may facilitate intubation in patients with limited mouth opening or neck movement. These devices are extremely reliable and easy to use.[20] Their utility is limited to patients with midline airways (because they are dependent upon normal supraglottic anatomy) and manageable secretions (because suctioning through suction channels in these devices is suboptimal). In ED studies of the Bullard scope, successful tube placement was achieved in at least 90% of patients and exceeded 80% on the first pass in patients deemed prospectively to have difficult airways.[21] The design of the device allows the operator to see the glottis via the fiberoptic eyepiece, and physical alignment of the oral, pharyngeal, and laryngeal axes for direct visualization of the glottis -- a necessity with traditional direct laryngoscopy -- is not required.

In some instances orotracheal intubation using direct laryngoscopy may be impossible and the lighted stylet technique may be useful. This technique is performed blindly and, when successful, provides intubation with airway protection. It is particularly helpful in patients with limited mouth opening because the only object that must be introduced into the mouth is the endotracheal tube.

Lighted stylets are available in several forms. One device is a simple battery source that attaches to a firm wire stylet with a bright halogen light at the end of the stylet. An alternative device, called the TrachLight, utilizes a reusable battery-powered handle with a reusable or disposable stylet and a retractable internal wire, facilitating placement of the tube. Success rates using the lighted stylet range from 70 to 100%, and most patients are intubated within 30 to 45 seconds using these devices.[22,23,24]

Frequently, using either blind nasotracheal or orotracheal intubation, the endotracheal tube can be advanced to near the glottic opening but may be difficult to advance through the cords. Particularly useful in this situation is the gum elastic bougee. This firm but flexible device is advanced through an endotracheal tube that is near the patient's glottic opening with the distal angled portion aiming anteriorly. It will pass into the trachea and the operator can feel the "bumping" of the bougee along the ridges of the tracheal rings. Once the bougee is in the trachea the endotracheal tube can be advanced over the bougee into the airway.[5]

There are several surgical approaches to airway establishment: cricothyrotomy, percutaneous transtracheal jet ventilation, and tracheostomy are those most often employed during resuscitation. For patients 10 to 12 years of age (an adultlike body size is more important than actual age) and older, cricothyrotomy is typically the fastest and most often successful surgical approach. Cricothyrotomy is the introduction of a cuffed tube via a surgical opening in the airway through the cricothyroid membrane. The surgical opening may be made sharply and directly using a scalpel and a tracheal dilator, or it may be made via serial dilations from a needle puncture and introduction of a guidewire using one of a variety of commercially available "cricotome" kits. There have been no clinical studies comparing the "surgical" and "cricotome" techniques, and the choice between these two options should be based on operator experience and preference. Regardless of this choice, successful cricothyrotomy requires familiarity with airway and neck anatomy and comfort with the equipment used.

The cricothyroid membrane is best identified by direct palpation; it lies in an indentation one or at most two fingerbreadths below the laryngeal prominence (Fig. 3). In morbidly obese patients and in patients with subcutaneous emphysema in the neck, an alternative means of identifying the desired landmark is to place the four fingers of the operator's right hand in the patient's sternal notch, while standing on the patient's right side. Orient the fingers vertically up the anterior midline of the neck; the index finger will typically lie over or very nearly over the membrane. Once the landmarks are identified, the neck is rapidly prepared with a topical antiseptic solution and, if the patient is conscious, with infiltration of local anesthetic. The mechanics of the remainder of the procedure depend upon whether the procedure is performed with a scalpel or with a cricotome, and the variations are too numerous to discuss in detail here. The reader is referred to an excellent summary.[5]

Figure 3.

Anatomy of the larynx. The cricothyroid membrane (arrow) is bordered above by the thyroid cartilage and below by the cricoid cartilage. (From Walls et al[5] with permission.)

Surgical airway management is properly viewed as the "ultimate" rescue approach in failed intubation. It should not, however, be approached with trepidation. Patients who have reached this "fork" in the road of airway management require decisive and efficient management. Critical care physicians should regularly update their experience with surgical airways and should always be familiar with the "kits" and "trays" stocked by the hospital in the areas where they work. It is disheartening, to say the least, to encounter an unfamiliar piece of airway equipment only when a patient lies before the physician dying for lack of an airway.

In essence, the esophageal-tracheal Combitube is a side-by-side melding of a classic endotracheal tube with an esophageal obturator airway. After blind insertion, this device provides the ability to oxygenate and ventilate a patient. Success is attained whether the tube is placed into the esophagus (as it is 90-95% of the time) or into the trachea.[25,26,27] A pharyngeal "anchoring" balloon effectively secures the device in the airway.

Success rates in adequately oxygenating and ventilating patients with the Combitube are 99%.[25,26,27] This device should not be used in children under age 16, in patients with a history of tracheal or upper airway abnormalities, and in patients with an intact gag reflex. Complications of using this device include dental, oral, and esophageal trauma and aspiration.

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