title: Accuracy of a new body length-based formula for predicting tracheal tube size in Chinese children.
abstract: BACKGROUND
  Variations in body weight and length (height) in children in the same age group have increased. Traditional age-based formulas often fail to predict the correct endotracheal tube (ETT) size. In our previous study, we devised a new length-based formula as follows: ETT internal diameter (ID) (mm) = 2 + (body length in cm/30). The current study was undertaken to assess the accuracy of this formula in Chinese children.
  
  
  METHODS
  The ETT size was selected according to this length-based formula for 336 children who required tracheal intubation during general anesthesia. Incidences of tube change were recorded. Statistical analysis was performed using the chi-square test for differences in accuracy between age groups and body length groups.
  
  
  RESULTS
  The length-based formula predicted a suitable ETT size in 277 (82.4%) of 336 subjects. There were 59 (17.6%) reintubations. Only 5 (1.49%) patients needed two tube changes when the correct ETT size was 1 mm larger or smaller than predicted. There were no statistically significant differences between age groups or length groups.
  
  
  CONCLUSIONS
  The length-based formula ID (mm) = 2 + body length in cm/30 has high accuracy in predicting the appropriate ETT size in Chinese children.
authors.affiliation: Department of Anesthesiology, Chang Gung Memorial Hospital, Taipei, Taoyuan, Taiwan ROC.
authors.forename: Ming-Hung
authors.initials: MH
authors.lastname: Shih
authors.forename: Chin-Yang
authors.initials: CY
authors.lastname: Chung
authors.forename: Bai-Chuan
authors.initials: BC
authors.lastname: Su
authors.forename: Chao-Tsen
authors.initials: CT
authors.lastname: Hung
authors.forename: Shu-Yam
authors.initials: SY
authors.lastname: Wong
authors.forename: Teresa Kit-Man
authors.initials: TK
authors.lastname: Wong
mesh_terms: D044466:Asian People; D001827:Body Height; D002648:Child; D002675:Child, Preschool; D004867:Equipment Design; D005260:Female; D006801:Humans; D007223:Infant; D007442:Intubation, Intratracheal / Q000295:instrumentation*; D008297:Male