Prevalence and risk factors of difficult mask ventilation: A systematic review and meta-analysis.

Study Objective: This meta-analysis aimed at identifying the risk factors for and their strengths in predicting difficult mask ventilation (MV) through a systematic approach.

Design: Meta-analysis of observational studies.

Setting: Operating room.

Intervention: Airway- or patient-related risk factors for difficult MV reported in over 20% of eligible studies identified through literature review.

Patients: Adults receiving anesthetic induction with requirement of MV.

Measurements: Databases including EMBASE, MEDLINE, Google Scholar, and Cochrane Library were searched from inception to July 2022. The primary outcomes were the identification of commonly reported risk factors for MV and a comparison of their strengths in difficult MV prediction, while the secondary outcomes were the prevalence of difficult MV in the general population and those with obesity.

Main Results: Meta-analysis of 20 observational studies involving 335,846 patients identified 13 risk factors with predictive strengths (all p < 0.05): neck radiation (OR = 5.0, five studies, n = 277,843), increased neck circumference (OR = 4.04, 11 studies, n = 247,871), obstructive sleep apnea (OSA) (OR = 3.61, 12 studies, n = 331,255), presence of beard (OR = 3.35, 12 studies, n = 295,443), snoring (OR = 3.06, 14 studies, n = 296,105), obesity (OR = 2.99, 11 studies, n = 278,297), male gender (OR = 2.76, 16 studies, n = 320,512), Mallampati score III-IV (OR = 2.36, 17 studies, n = 335,016), limited mouth opening (OR = 2.18, six studies, n = 291,795), edentulous (OR = 2.12, 11 studies, n = 249,821), short thyroid-mental distance (OR = 2.12, six studies, n = 328,311), old age (OR = 2, 11 studies, n = 278,750), and limited neck movement (OR = 1.98, nine studies, n = 155,101). The prevalence of difficult MV was 6.1% (16 studies, n = 334,694) and 14.4% (four studies, n = 1152) in the general population and those with obesity, respectively.

Conclusions: Our results demonstrated the strengths of 13 most common risk factors for predicting difficult MV, which may serve as an evidence-based reference for clinicians to incorporate into their daily practice.