title: Neck circumference to thyromental distance ratio: a new predictor of difficult intubation in obese patients.
abstract: BACKGROUND
  This study was performed to assess whether intubation is more difficult in obese patients and to assess the ability of a new index: the ratio of the neck circumference to thyromental distance (NC/TM), to predict difficult intubation in obese patients.
  
  
  METHODS
  The incidence of difficult tracheal intubation in 123 obese (BMI≥27.5 kg m(-2)) and 125 non-obese patients was compared. Difficult intubation was determined using the intubation difficulty scale (IDS≥5). The NC/TM ratio was calculated and its ability to predict difficult intubation in obese patients was compared with that of established predictors including high BMI, the Mallampati score, the Wilson score, NC, width of mouth opening, sternomental distance, TM, and a previous history of difficult intubation.
  
  
  RESULTS
  Difficult intubation was more frequent in obese patients than in non-obese patients (13.8% vs 4.8%; P=0.016). Multivariate analysis revealed that the Mallampati score, the Wilson score, and NC/TM independently predicted difficult intubation in obese patients. Among these three indices, NC/TM showed the highest sensitivity and a negative predictive value, and largest area under the curve on an ROC curve.
  
  
  CONCLUSIONS
  Difficult intubation was more common in obese patients and the NC/TM was a better method for predicting difficult intubation than other established indices.
authors.affiliation: Department of Anaesthesia and Pain Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, 50, Ilwon-Dong, Kangnam-Gu, Seoul 135-710, Republic of Korea.
authors.forename: W H
authors.initials: WH
authors.lastname: Kim
authors.forename: H J
authors.initials: HJ
authors.lastname: Ahn
authors.forename: C J
authors.initials: CJ
authors.lastname: Lee
authors.forename: B S
authors.initials: BS
authors.lastname: Shin
authors.forename: J S
authors.initials: JS
authors.lastname: Ko
authors.forename: S J
authors.initials: SJ
authors.lastname: Choi
authors.forename: S A
authors.initials: SA
authors.lastname: Ryu
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000768:Anesthesia, General; D000886:Anthropometry / Q000379:methods; D002680:Chin / Q000473:pathology; D004812:Epidemiologic Methods; D005260:Female; D006801:Humans; D007442:Intubation, Intratracheal / Q000379:methods*; D007828:Laryngoscopy; D008297:Male; D008371:Manubrium / Q000473:pathology; D008875:Middle Aged; D009333:Neck / Q000473:pathology*; D009765:Obesity / Q000150:complications / Q000473:pathology*; D011379:Prognosis; D018570:Risk Assessment / Q000379:methods; D055815:Young Adult