Prediction of failed facemask ventilation: new scoring system for difficult airway.

BACKGROUND

We previously have shown that there was a strong correlation between failed facemask ventilation, failed ventilation through a supraglottic airway, and difficult tracheal intubation. The primary aim of this study was to evaluate whether or not an established method to predict difficult ventilation through a supraglottic airway was also useful for predicting failed facemask ventilation.

METHODS

This was a single-center, retrospective observational study. We studied 28,081 anesthetized patients in whom ventilation through a facemask, and supraglottic airway was attempted as the initial technique during induction of anesthesia, between May 2011 and March 2016. For each patient, the score which had been validated to be useful for predicting difficult ventilation through a supraglottic airway was calculated. The score ranged between 0 and 7 points, and we defined a low risk when the score was 0-3, and a high risk when the score was 4-7. To measure and compare the predictive accuracy of the score, we generated a receiver operating characteristic curve and compared the area under the curve (AUC).

RESULTS

The incidence of failed facemask ventilation was significantly higher in patients with high-risk predictive score than in patients with low-risk predictive score [0.38% vs 0.056%, odds ratio 6.8 (95% CI 2.6-18.1, p value = 0.002)], and the sensitivity of the score was 25%, while the specificity was 95%, with a negative predictive value of 99%. The AUC of the score was 0.71 (95% CI 0.58-0.83).

CONCLUSIONS

The predictive score for difficult ventilation through a supraglottic airway is also useful to predict failed facemask ventilation.