title: Flow resistances of disposable double-lumen, single-lumen, and Univent tubes.
abstract: OBJECTIVE
  To compare the airflow resistances of modern double-lumen, single-lumen, and Univent (Fuji Systems Corp; Tokyo, Japan) tubes.
  
  
  METHODS
  A laboratory bench study.
  
  
  METHODS
  A university hospital laboratory.
  
  
  METHODS
  Pressure differentials (Pd) were measured across study tubes at 10 L/min airflow (V) increments from 0 to 60 L/min in a tracheal model. Coefficients of resistance k1 (linear) and k2 (nonlinear) were calculated for each tube by the method of least squares using the Rohrer equation Pd/V = k1 + k2V. Data were assessed by analysis of variance (ANOVA) for the effects of tube design, circumference, and manufacturer on k1 and k2.
  
  
  RESULTS
  Calculated combined mean k1 and k2 were significantly lower for single-lumen tubes compared with double-lumen or Univent tubes. There were no significant differences for k1 values between double-lumen or Univent tubes. The values for k2 were significantly lower for double-lumen tubes compared with Univent tubes. The k2 values were significantly lower for Rusch (Duluth, GA) or Sheridan (Argyle, NY) double-lumen tubes compared with Mallinckrodt (St Louis, MO) double-lumen tubes. This difference was because of the Y-connectors of the Mallinckrodt tubes.
  
  
  CONCLUSIONS
  Flow resistances of modern disposable double-lumen tubes are lower than commonly perceived. In most clinical situations, there will be no decrease in flow resistance when a Rusch or Sheridan double-lumen tube is replaced by a single-lumen tube.
authors.affiliation: Department of Anaesthesia, The Toronto Hospital, University of Toronto, Ontario, Canada.
authors.forename: P D
authors.initials: PD
authors.lastname: Slinger
authors.forename: L
authors.initials: L
authors.lastname: Lesiuk
mesh_terms: D000403:Airway Resistance; D004209:Disposable Equipment; D004867:Equipment Design; D007442:Intubation, Intratracheal / Q000295:instrumentation*; D008962:Models, Theoretical