title: Difficult mask ventilation in general surgical population: observation of risk factors and predictors.
abstract: BACKGROUND
  There are few predictors of difficult mask ventilation and a simple, objective, predictive system to identify patients at risk of difficult mask ventilation does not currently exist. We present a retrospective - subgroup analysis aimed at identifying predictive factors for difficult mask ventilation (DMV) in patients undergoing pre-operative airway assessment before elective surgery at a major teaching hospital.
  
  
  METHODS
  Data for this retrospective analysis were derived from a database of airway assessments, management plans, and outcomes that were collected prospectively from August 2008 to May 2010 at a Level 1 academic trauma center. Patients were stratified into two groups based on the difficulty of mask ventilation and the cohorts were analyzed using univariate analysis and stepwise selection method.
  
  
  RESULTS
  A total of 1399 pre-operative assessments were completed with documentation stating that mask ventilation was attempted. Of those 1399, 124 (8.9%) patients were found to be difficult to mask ventilate. A comparison of patients with and without difficult mask ventilation identified seven risk factors for DMV: age, body mass index (BMI), neck circumference, history of difficult intubation, presence of facial hair, perceived short neck and obstructive sleep apnea. Although seven risk factors were identified, no individual subject had more than four risk factors.
  
  
  CONCLUSIONS
  The results of this study confirm that in a real world clinical setting, the incidence of DMV is not negligible and suggest the use of a simple bedside predictive score to improve the accuracy of DMV prediction, thereby improving patient safety. Further prospective studies to validate this score would be useful.
authors.affiliation: Department of Anesthesiology, University of Texas Medical School at Houston, Houston, 77030, USA.
authors.forename: Davide
authors.initials: D
authors.lastname: Cattano
authors.affiliation: Department of Anesthesiology, University of Texas Medical School at Houston, Houston, 77030, USA.
authors.forename: Peter V
authors.initials: PV
authors.lastname: Killoran
authors.affiliation: Division of Clinical and Translational Sciences, , Department of Internal Medicine, University of Texas Medical School at Houston, Houston, 77030, USA.
authors.forename: Chunyan
authors.initials: C
authors.lastname: Cai
authors.affiliation: Department of Anesthesiology, University of Texas Medical School at Houston, Houston, 77030, USA.
authors.forename: Anastasia D
authors.initials: AD
authors.lastname: Katsiampoura
authors.affiliation: Emergency Department, Anesthesia and Intensive Care Section, "GB Morgagni - L Pierantoni" Hospital, Forli, 47121, Italy.
authors.forename: Ruggero M
authors.initials: RM
authors.lastname: Corso
authors.affiliation: Department of Anesthesiology, University of Texas Medical School at Houston, Houston, 77030, USA.
authors.forename: Carin A
authors.initials: CA
authors.lastname: Hagberg