title: Chest anteroposterior diameter affects difficulty of laryngoscopy for non-morbidly obese patients.
abstract: OBJECTIVE
  This prospective, observational study was performed to examine the hypothesis that if conventional 7-cm head elevation is applied, laryngoscopy is more difficult for patients with anteroposterior chest diameter (chest AP diameter) outside the average range (≥17.7 or ≤14.7 cm).
  
  
  METHODS
  Chest AP diameter at the sternal notch were measured preoperatively. All patients were placed on a surgical bed with an incompressible 7-cm pillow. During laryngoscopy, the laryngeal view was graded by use of the Cormack-Lehane classification. Difficult visualization of the larynx (DVL) was defined as a grade 3 or 4 view.
  
  
  RESULTS
  DVL was observed for 49 patients (18.2 %). Differences between measured chest AP diameter for each patient and the calculated median value were used for statistical analysis. In univariate analysis, the difference between chest AP diameter and the median value was significantly related to DVL. Logistic regression analysis confirmed that the difference between chest AP diameter and the median value was an independent predictor of DVL (odds ratio, 3.900; 95 % confidence interval, 2.371-6.415; p < 0.001). Receiver operating characteristic curve analysis showed that this test with a test threshold of 1.5 cm had reasonable diagnostic accuracy (area under the curve of 0.748).
  
  
  CONCLUSIONS
  When using a standard pillow size of 7 cm, chest AP diameter above or below the average range (≥17.7 or ≤14.7 cm) was a strong predictor of DVL for apparently normal-sized patients. In such cases, modification of pillow height should be considered.
authors: Department of Anesthesiology and Pain Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, 50 Irwon-Dong, Gangnam-Gu, Seoul, 135-710, Republic of Korea.
authors: Ji-Won
authors: JW
authors: Choi
authors: Jie-Ae
authors: JA
authors: Kim
authors: Hae-Kyoung
authors: HK
authors: Kim
authors: Min-Seok
authors: MS
authors: Oh
authors: Duk-Kyung
authors: DK
authors: Kim
mesh_terms: D049628:Body Size; D005260:Female; D006801:Humans; D007442:Intubation, Intratracheal / Q000379:methods; D007828:Laryngoscopy / Q000379:methods*; D007830:Larynx / Q000033:anatomy & histology; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D009017:Morbidity; D009765:Obesity / Q000503:physiopathology*; D011187:Posture; D011446:Prospective Studies; D013909:Thorax / Q000033:anatomy & histology