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:
- Age > 55
- BMI > 26
- Presence of a beard
- Lack of teeth
- History of snoring
- Retrognathia
- Mallampati score of 3 or 4
- Male gender
Patients with 3 risk factors had a 20 fold greater incidence of DMV (around 5%) than those with 0 risk factors (incidence 0.25%).
References
- Kheterpal, S et al. Incidence and Predictors of Difficult and Impossible Mask Ventilation. Anesthesiology 2006; 105: 885-891. PubMed Link
- Langeron, O et al. Prediction of difficult mask ventilation. Anesthesiology 2000; 92:1229–36. PubMed Link
Other References
- Keys to the Cart: February 13, 2017; A 5-minute video review of ABA Keywords Link
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