Difficult airway (D.A) has long been one of the major goals in the evaluation process of every patient that needs airway management. Assessing the likelihood a patient will likely be difficult to ventilate, intubate, be difficult for supraglottic airway placement or potentially a difficult surgical airway are actually the first steps recommended by the ASA DA Algorithm.[1] The word prediction is derived from the latin pre “before”, and dicere “to say” and as important as this might be, actually is one of the hardest tasks of the whole issue of airway management. The literature has plenty of references in which a set criteria and/or methods are used to attempt to establish if on clinical grounds or by other tests a patient might p o s e d i f fi c u l t i e s i f a i r w a y instrumentation is needed.[2-19] In order to be of value these tests or methods have to be simple, objective, reproducible, and must have little or no inter-observer variation. Having said this, as it turns out none of the current available methods have the sufficient sensitivity and/or specificity, and unfortunately we sometimes still to this date rely on our experience, our instincts and sometimes luck, and the definition if the patient was easy or not can only be made after the airway instrumentation has taken place; (in the worst case scenario we find out if our “prediction” was correct or not after failure to secure the airway or after difficulties are encountered). In order to continue this discussion, we need then to define the statistical definitions of our prediction methods in terms of sensi t iv i ty (probability of a positive test among patients with a D.A), specificity (probability of a negative test among patients without a D.A), positive predictive value (PPV) the probability of a D.A among patients with a positive test. Some of the most commonly used methods are: 1-Mallampati score: Perhaps the most p o p u l a r m e t h o d u s e d b y anesthesiologists and ER physicians, was described originally in 1985 and subsequently modified in 1987 by Samsoon;[10, 20] it is a classification system used to predict the ease of larynx exposure on direct laryngoscopy (DL) based on the degree of visibility of oropharyngeal structures and the ratio of the size of the tongue to the oro-pharynx with the patient and examiner facing each other and not phonating;[21] the higher the score the lower the chances of having adequate laryngeal exposure, and therefore greater chance of difficulty with intubation. Originally as described, it had a very high sensitivity and greater than 90% PPV, however, in retrospect the original description may turned out to be considerable less accurate: the AIRWAY ROTATION JANUARY 2009
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