title: A comparison of three methods for estimating appropriate tracheal tube depth in children.
abstract: BACKGROUND
  Estimating appropriate tracheal tube (TT) depth following tracheal intubation in infants and children presents a challenge to anesthesia practitioners. We evaluated three methods commonly used by anesthesiologists to determine which one most reliably results in appropriate positioning.
  
  
  METHODS
  After IRB approval, 60 infants and children scheduled for fluoroscopic procedures requiring general anesthesia were enrolled. Patients were randomly assigned to one of three groups: (1) deliberate mainstem intubation with subsequent withdrawal of the TT 2 cm above the carina ('mainstem' method); (2) alignment of the double black line marker near the TT tip at the vocal cords ('marker' method); or (3) placement of the TT at a depth determined by the formula: TT depth (cm) = 3 x TT size (mmID) ('formula' method). TT tip position was determined to be 'appropriate' if located between the sternoclavicular junction (SCJ) and 0.5 cm above the carina as determined by fluoroscopy. Risk ratios were calculated, and data were analysed by the chi-square test accepting statistical significance at P < 0.05.
  
  
  RESULTS
  The mainstem method was associated with the highest rate of appropriate TT placement (73%) compared with both the marker method (53%, P = 0.03, RR = 1.56) and the formula method (42%, P = 0.006, RR = 2.016). There was no difference between the marker and formula methods overall (P = 0.2, RR = 1.27). Analysis of age-stratified data demonstrated higher success with the marker method compared with the formula method for patients 3-12 months (P = 0.0056, RR = 4.0).
  
  
  CONCLUSIONS
  Deliberate mainstem intubation most reliably results in appropriate TT depth in infants and children.
authors.affiliation: Department of Anesthesia, University of California at San Diego School of Medicine, San Diego, CA 92103, USA. ermariano@ucsd.edu
authors.forename: Edward R
authors.initials: ER
authors.lastname: Mariano
authors.forename: Chandra
authors.initials: C
authors.lastname: Ramamoorthy
authors.forename: Larry F
authors.initials: LF
authors.lastname: Chu
authors.forename: Michael
authors.initials: M
authors.lastname: Chen
authors.forename: Gregory B
authors.initials: GB
authors.lastname: Hammer
mesh_terms: D000768:Anesthesia, General; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D007223:Infant; D007442:Intubation, Intratracheal / Q000379:methods*; D008297:Male