title: Predicting Optimal Insertion Depth of a Left-sided Double-Lumen Endobronchial Tube.
abstract: OBJECTIVE
  Appropriate placement of the double-lumen endobronchial tube (DLT) is essential for one-lung ventilation. Several formulae based on body height (BH) have been used for estimating the optimal insertion depth of a left-sided DLT. In this study, the authors examined the following 5 formulae for accuracy of prediction: 0.11×BH+10.53 (cm) from Brodsky et al(1); 0.15×BH+3.96 (cm) from Bahk and Oh(2); 0.148×BH+3.8 (cm) from Chow et al;(3) 0.1×BH+12.5 (cm) from Takita et al(4); and 0.1977×BH - 4.2423 (cm) (authors' formula).
  
  
  METHODS
  Single-center, retrospective, observational study.
  
  
  METHODS
  University hospital.
  
  
  METHODS
  Anesthetic records of patients older than 20 years who received one-lung ventilation using a left-sided DLT were included.
  
  
  METHODS
  The patients' sex, age, body weight, BH, and the final correct insertion depth of the left-sided DLT after fiberscope verification were recorded. Linear regression and correlation were used to analyze the data.
  
  
  RESULTS
  One hundred seventy anesthetic records were analyzed. The insertion depth was distributed normally in 4 groups with different BH intervals. The correlations between the correct insertion depth and all the lengths calculated using each formula were significant (p<0.001), with a similar high coefficient of determination (r = 0.809). The regression line derived from the authors' formula-0.1977×BH - 4.2423 (cm)-showed the most accuracy in predicting the correct insertion depth.
  
  
  CONCLUSIONS
  The height-based formula of 170 - 29.5 - 5 - 1 (the insertion depth is 29.5 cm for patients who are 170 cm tall, and the insertion length is increased or decreased by 1 cm for every 5 cm increase or decrease in BH) modified by the equation of 0.1977×BH - 4.2423 is a useful tool to predict the optimal insertion depth in initially blind left-sided DLT insertion.
authors.affiliation: Department of Anesthesiology, Tri-Service General Hospital and National Defense Medical Center, Taipei, Taiwan.
authors.forename: Wei-Lin
authors.initials: WL
authors.lastname: Lin
authors.affiliation: Department of Anesthesiology, Tri-Service General Hospital and National Defense Medical Center, Taipei, Taiwan. Electronic address: cherng1018@yahoo.com.tw.
authors.forename: Chen-Hwan
authors.initials: CH
authors.lastname: Cherng
mesh_terms: D000328:Adult; D004867:Equipment Design; D005260:Female; D006801:Humans; D007442:Intubation, Intratracheal / Q000295:instrumentation* / Q000379:methods*; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D055815:Young Adult
keywords: double-lumen endobronchial tube; insertion depth; one lung ventilation; thoracic anaesthesia