Difficult mask ventilation: Predictor
Difficult mask ventilation (DMV), defined as: “the inability of an unassisted anesthesiologist to maintain SpO2 >92%” is an uncommon but important scenario. Incidence of DMV in various studies has ranged from around 0.5 - 5%, with the largest review reporting an incidence of around 1%. Unfortunately DMV is difficult to predict, with one study reporting that only 17% of people found to have DMV had been predicted to have DMV. Importantly, patients who are difficult to mask ventilate have up to a fourfold higher incidence of being a difficult intubation that those who were easy to mask. Predictors of difficult mask ventilation include the following:
Patients with 3 risk factors had a 20 fold greater incidence of DMV (around 5%) than those with 0 risk factors (incidence 0.25%).