title: Mallampati class, obesity, and a novel airway trajectory measurement to predict difficult laryngoscopy.
abstract: OBJECTIVE
  To determine whether Mallampati class correlates with Cormack-Lehane grade in obese adults, and investigate a novel airway trajectory measurement (ATM) to anticipate difficult laryngoscopy.
  
  
  METHODS
  Retrospective cohort plus a pilot study.
  
  
  METHODS
  One hundred eighty-four nonobese and 160 obese adults underwent laryngoscopy. Spearman correlations, gamma coefficients (G), and Kendall's τ investigated body mass index (BMI):Mallampati, BMI: Cormack-Lehane, and Mallampati:Cormack-Lehane. A z test compared the two groups. Twenty-six volunteers had neck x-rays taken in the sniffing position to examine trajectories to the larynges (ATM).
  
  
  RESULTS
  Positive predictive value of high Mallampati for difficult laryngoscopy was 8.57%. BMI did not correlate with Mallampati (r = 0.055 [nonobese], r = -0.056 [obese]) or Cormack-Lehane [r = -0.014 [nonobese], r = -0.022 [obese]). Among nonobese adults, gamma coefficients for BMI:Mallampati was 0.039 (P = .63), for BMI:Cormack-Lehane was 0.02 (P = .85), and for Mallampati:Cormack-Lehane was 0.43 (P = .004). Among obese adults, gamma coefficients for BMI:Mallampati was -0.127 (P = .16), for BMI:Cormack-Lehane was 0.014 (P = .88), and for Mallampati:Cormack-Lehane was 0.365 (P = .01). Kendall's τ were comparable to gamma coefficients in all analyses. When comparing gamma coefficients for Mallampati:Cormack-Lehane among the nonobese and obese, z = 0.04 (P = .98). In the ATM study, only Mallampati and upper lip bite test had a significant relationship (G = 1.00, P < .001).
  
  
  CONCLUSIONS
  Mallampati correlates poorly with Cormack-Lehane, regardless of BMI. Pilot data suggest that ATM is feasible.
authors.affiliation: Department of Otolaryngology-Head & Neck Surgery, University of Washington Valley Medical Center, Renton, Washington.
authors.forename: Scott L
authors.initials: SL
authors.lastname: Lee
authors.forename: Clint
authors.initials: C
authors.lastname: Hosford
authors.forename: Quyen T
authors.initials: QT
authors.lastname: Lee
authors.forename: Steve M
authors.initials: SM
authors.lastname: Parnes
authors.forename: Stanley M
authors.initials: SM
authors.lastname: Shapshay
mesh_terms: D000328:Adult; D000768:Anesthesia, General; D015992:Body Mass Index; D015331:Cohort Studies; D004825:Epiglottis / Q000473:pathology*; D005260:Female; D005931:Glottis / Q000473:pathology*; D006801:Humans; D007442:Intubation, Intratracheal / Q000009:adverse effects / Q000145:classification* / Q000379:methods*; D007828:Laryngoscopy / Q000009:adverse effects / Q000145:classification* / Q000379:methods*; D008297:Male; D009765:Obesity / Q000150:complications*; D010865:Pilot Projects; D012189:Retrospective Studies; D013223:Statistics as Topic
keywords: Cormack-Lehane; Mallampati; Obesity; airway trajectory measurement; difficult laryngoscopy