Roth D, Pace NL, Lee A, et al.(2018). Airway physical examination tests for detection of difficult airway management in apparently normal adult patients. Cochrane Database Syst Rev5:CD008874
The airway is a crucial component in the management of unconscious, anaesthetised or sedated patients.Insufficient ventilation or difficult intubation are detriments to health and difficult to predict, even in patients without anatomical pathologies or abnormalities of the upper airways.
Difficulty in airway management is defined by the presence of one of these criteria: difficult mask ventilation, difficult direct laryngoscopy, difficult tube insertion or failure of tracheal intubation.
Several quick bedside tests exist and can be used to identify high risk for difficult airways.
What is the most appropriate clinical screening test to predict difficult airway in adults without obvious airway abnormalities?
For difficult direct laryngoscopy, the upper lip bite test has the highest sensitivity (percentage of correctly identified difficult airways) compared to other tests (67%). Wilson’s scores and the modified Mallampati test have the highest specificities (percentage of correctly classified patients without difficult airways)(95% and 80%, respectively).
For difficult intubation, the modified Mallampati test has the highest sensitivity, significantly higher than the mouth opening and thyromental distance tests (P<0.001). Unfortunately, there was not enough information to compare it to the upper lip bite test. The mouth opening test has a significantly higher specificitycompared to other tests (P<0.001).
For difficult mask ventilation and failed intubation, the data are not sufficient to make quality comparisons.
All screening tests have low sensitivity and high variability. So, the high frequency of false negatives can lead to catastrophic situations, especially when inducing anaesthesia.
The methodological quality of the selected studies is considered high in terms of applicability and moderate in terms of risk of bias. The high and unexplained heterogeneity among studies hinders performing an analysis focused on test combinations.
The screening tests reviewed in this study appear to have moderate effectiveness in hospital situations. No analyses of these tests are present in the emergency or pre-hospital situations, where the rate of difficult airway is much higher compared to be in-hospital.
Bataillon de Marins Pompiers de Marseille, groupement santé,
Centre Hospitalo-Universitaire de TOURS
Marmara University School of Medicine