title: The effect of tracheal tube size on air leak around the cuffs.
abstract: BACKGROUND
  This randomized single-blinded, cross-over study was done to evaluate the influence of the size of tracheal tubes on air leaks around the cuffs.
  
  
  METHODS
  In a benchtop model, the number of longitudinal folds on the cuffs was evaluated for different sizes of tracheal tubes. In an anesthetized patient study, thirty patients scheduled for elective surgery under general anesthesia were included. After induction of anesthesia, the trachea was intubated with two sizes of tracheal tubes in a random sequence: in men, internal diameter of 7.5 mm and 8.0 mm; in women, internal diameter of 7.0 mm and 7.5 mm. After tracheal intubation with each tube, air leak pressures were evaluated at intracuff pressures of 20, 25 and 30 cmH(2)O by auscultation. To calculate the tracheal tube resistance (R), an inspiratory pause of 20% was applied and the resulting peak airway pressure (P(peak)), plateau pressure (P(pl)) and mean expiratory tidal volume (Flow) were inserted in the formula R = (P(peak) - P(pl))/Flow.
  
  
  RESULTS
  More longitudinal folds of the tracheal tube cuffs occurred in larger sized tubes compared to the smaller ones in a benchtop model. Air leakage was significantly less for the smaller tracheal tubes than for the larger ones for each gender at intracuff pressures of 20, 25 and 30 cmH(2)O. Tracheal tube resistances were not significantly altered by the size of tracheal tube.
  
  
  CONCLUSIONS
  The use of a smaller tracheal tube within an acceptable size can reduce air leakage around the cuff without significantly changing the tracheal tube resistance.
authors.affiliation: Department of Anesthesiology and Pain Medicine, Seoul National University Bundang Hospital, Seongnam, Korea.
authors.forename: Jin-Young
authors.initials: JY
authors.lastname: Hwang
authors.forename: Sang-Hyun
authors.initials: SH
authors.lastname: Park
authors.forename: Sung-Hee
authors.initials: SH
authors.lastname: Han
authors.forename: Seong-Joo
authors.initials: SJ
authors.lastname: Park
authors.forename: Soo-Kyung
authors.initials: SK
authors.lastname: Park
authors.forename: Jin-Hee
authors.initials: JH
authors.lastname: Kim