title: Predictors of difficult intubation defined by the intubation difficulty scale (IDS): predictive value of 7 airway assessment factors.
abstract: BACKGROUND
  The intubation difficulty scale (IDS) has been used as a validated difficulty score to define difficult intubation (DI). The purpose of this study is to identify airway assessment factors and total airway score (TAS) for predicting DI defined by the IDS.
  
  
  METHODS
  There were 305 ASA physical status 1-2 patients, aged 19-70 years, who underwent elective surgery with endotracheal intubation. During the pre-anesthetic visit, we evaluated patients by 7 preoperative airway assessment factors, including the following: Mallampati classification, thyromental distance, head & neck movement, body mass index (BMI), buck teeth, inter-incisor gap, and upper lip bite test (ULBT). After endotracheal intubation, patients were divided into 2 groups based on their IDS score estimated with 7 variables: normal (IDS < 5) and DI (IDS ≥ 5) groups. The incidence of TAS (> 6) and high score of each airway assessment factor was compared in two groups: odds ratio, confidence interval (CI) of 95%, with a significant P value ≤ 0.05.
  
  
  RESULTS
  The odds ratio of TAS (> 6), ULBT (class III), head & neck movement (< 90°), inter-incisor gap (< 4 cm), BMI (≥ 25 kg/m(2)) and Mallampati classification (≥ class III) were respectively 13.57 (95% CI = 2.99-61.54, P < 0.05), 12.48 (95% CI = 2.50-62.21, P < 0.05), 3.11 (95% CI = 0.87-11.13), 2.32 (95% CI = 0.75-7.19), 2.22 (95% CI = 0.81-6.06), and 1.22 (95% CI = 0.38-3.89).
  
  
  CONCLUSIONS
  We suggest that TAS (> 6) and ULBT (class III) are the most useful factors predicting DI.
authors.affiliation: Department of Anesthesiology and Pain Medicine, Kosin University College of Medicine, Busan, Korea.
authors.forename: Suk-Hwan
authors.initials: SH
authors.lastname: Seo
authors.forename: Jeong-Gil
authors.initials: JG
authors.lastname: Lee
authors.forename: Soo-Bong
authors.initials: SB
authors.lastname: Yu
authors.forename: Doo-Sik
authors.initials: DS
authors.lastname: Kim
authors.forename: Sie-Jeong
authors.initials: SJ
authors.lastname: Ryu
authors.forename: Kyung-Han
authors.initials: KH
authors.lastname: Kim
keywords: Anesthesia; Evaluation studies; Intubation