Prospective development and validation of an objective classification for difficult facemask ventilation: the MASCAN...

Difficult facemask ventilation is an entity that lacks a robust definition, leading to inconsistent identification in clinical practice and research. The aim of this study was to develop and validate an objective classification and numeric score for difficult facemask ventilation.

Four hundred patients who required tracheal intubation for ear, nose and throat or maxillofacial surgery participated in this prospective single centre study. After induction of anaesthesia, facemask ventilation was attempted using pressure-controlled mechanical ventilation. The primary outcome was difficult facemask ventilation documented as an alert in the patient health records. An independent observer assessed for potential indicators of difficult facemask ventilation: two-handed grip; oral airway use; jaw thrust; senior consultant anaesthetist taking over; conversion to manual rescue ventilation; peripheral oxygen saturation drop; tidal volume; and leak fraction.

Difficult facemask ventilation occurred in 43 (10.8%) patients. Five eligible indicators were selected by cross-validated least absolute shrinkage selector operator regression and used to develop a multivariable logistic regression model (MASCAN model) and score (MASCAN score). These indicators were: two-handed grip; oral airway use; jaw thrust; tidal volume ≤ 2 ml.kg^-1; and peripheral oxygen saturation drop ≥ 10%. The area under the receiver operating characteristic curve was 0.96 (95%CI 0.93-0.98) for the MASCAN model and 0.94 (95%CI 0.91-0.98) for the MASCAN score.

The MASCAN score is an objective, data-driven classification for difficult facemask ventilation with clearly defined thresholds that may improve airway documentation and inform future airway management.