title: Difficult mask ventilation in obese patients: analysis of predictive factors.
abstract: BACKGROUND
  This study aimed to determine the accuracy of commonly used preoperative difficult airway indices as predictors of difficult mask ventilation (DMV) in obese patients (BMI >30 kg/m2).
  
  
  METHODS
  In 309 consecutive obese patients undergoing general surgery, the modified Mallampati test, patient's Height/Thyromental distance ratio, Inter-Incisor Distance, Protruding Mandible (PM), history of Obstructive Sleep Apnea and Neck Circumference (NC) were recorded preoperatively. DMV was defined as Grade 3 mask ventilation (MV) by the Han's scale (MV inadequate, unstable or requiring two practitioners). Data are shown as means±SD or number and proportions. Independent DMV predictors were identified by multivariate analysis. The discriminating capacity of the model (ROC curve area) and adjusted weights for the risk factors (odds ratios) were also determined.
  
  
  RESULTS
  BMI averaged 42.5±8.3 kg/m2. DMV was reported in 27 out of 309 patients (8.8%; 95%CI 5.6-11.9%). The multivariate analysis retained NC (OR 1.17; P<0.0001), limited PM (1.99; P=0.046) and Mallampati test (OR 2.12; P=0.009) as risk predictors for DMV. Male gender was also included in the final model (OR 1.87; P=0.06) as biologically important variable albeit the borderline statistical significance. The model yielded a good discriminating capacity (ROC curve 0.85). The four parameters were used to create an unweighted prediction score (ROC curve 0.84) with >2 associated factors as the best discriminating point for DMV.
  
  
  CONCLUSIONS
  Obese patients show increased incidence of DMV with respect to the undifferentiated surgical population. Limited PM, Mallampati test and NC are important DMV predictors.
authors.affiliation: Department of Anesthesia, IRCCS Multimedica, Sesto San Giovanni, Milan, Italy - albino.leoni@gmail.com.
authors.forename: A
authors.initials: A
authors.lastname: Leoni
authors.forename: S
authors.initials: S
authors.lastname: Arlati
authors.forename: D
authors.initials: D
authors.lastname: Ghisi
authors.forename: M
authors.initials: M
authors.lastname: Verwej
authors.forename: D
authors.initials: D
authors.lastname: Lugani
authors.forename: P
authors.initials: P
authors.lastname: Ghisi
authors.forename: G
authors.initials: G
authors.lastname: Cappelleri
authors.forename: V
authors.initials: V
authors.lastname: Cedrati
authors.forename: A
authors.initials: A
authors.lastname: El Tantawi Ali Alsheraei
authors.forename: M
authors.initials: M
authors.lastname: Pocar
authors.forename: V
authors.initials: V
authors.lastname: Ceriani
authors.forename: G
authors.initials: G
authors.lastname: Aldegheri
mesh_terms: D000328:Adult; D000368:Aged; D058109:Airway Management / Q000295:instrumentation / Q000379:methods*; D005260:Female; D006801:Humans; D017214:Laryngeal Masks; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000150:complications* / Q000503:physiopathology; D012121:Respiration, Artificial / Q000379:methods*; D012307:Risk Factors