Virtual Disaster Medicine

Training Center (VDMTC)

Module 12

The American Society of Anesthesiologists' Management

of the Difficult Airway Algorithm and Explanation-Analysis of the Algorithm

Problems with the ASA Algorithm and Likely Future Directions

APPROPRIATE OPTIONS FOR THE CANNOT-INTUBATE-CANNOT-VENTILATE SITUATION

Since 1992, most anesthesiologists in the United States have become very familiar with the LMA³⁵ and the Combitube³⁰ and have found that both work well in elective and emergency situations.^9,30,35  Although the algorithm does not dictate the order of preference of these devices in the CICV situation, the anesthesiologist must take the following considerations into account: (1) the anesthesiologist’s own experience and level of comfort in the use of these methods, (2) the availability of these devices, (3) the type of airway obstruction (upper versus lower), and (4) the benefits and risks involved.  Although the LMA-Classic is easily inserted, even by inexperienced personnel,⁴⁶ it does not provide an airtight seal around the larynx or protect the trachea from aspiration.  Although there is an increased complexity of insertion with the LMA-ProSeal, it forms a better seal^{14-16,18,22,37,41} than the LMA-Classic and provides improved protection against aspiration.^17,26,27,36  Also, when properly positioned, the Combitube allows ventilation with a higher seal pressure than the LMA-Classic, protects against regurgitation,⁴ and allows further attempts⁵² at intubation while the esophageal cuff protects the airway.  The Combitube has been successfully used in difficult intubation^3,4 and CICV situations,^12,25,38,51 including failure with an LMA.⁴³

The decision to use the Combitube depends on availability, experience, and the clinical situation.³³  However, it must be remembered that both the LMA and the Combitube are supraglottic ventilatory devices and that is their inherent weakness.  Thus, they cannot solve a truly glottic (e.g., spasm, massive edema, tumor, abscess) or subglottic problem.³⁰  If a truly glottic or subglottic problem exists, the only solution will be to get the ventilatory mechanism below the level of the lesion (e.g., ET, TTJV, rigid ventilating bronchoscope, surgical airway).  One of the algorithms inherent weaknesses is that it does not discriminate between the obstructed and the unobstructed airway in its guidelines.

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