FLOW RESISTANCES OF DISPOSABLE DOUBLE-LUMEN, SINGLE-LUMEN, AND UNIVENT TUBES

Objective: To compare the airflow resistances of modern double-lumen, single-lumen, and Univent (Fuji Systems Corp; Tokyo, Japan) tubes. Des ign: A laboratory bench study. Setting: A university hospital laborato ry. Measurements: Pressure differentials (Pd) were measured across stu dy tubes at 10 L/min airflow ((V) over circle) increments from 0 to 60 L/min in a tracheal model. Coefficients of resistance k(1) (linear) a nd k(2) (nonlinear) were calculated for each tube by the method of lea st squares using the Rohrer equation Pd/(V) over dot = k(1) + k(2)(V) over dot. Data were assessed by analysis of variance (ANOVA) for the e ffects of tube design, circumference, and manufacturer on k(1) and k(2 ). Main Results: Calculated combined mean k(1) and k(2) were significa ntly lower for single-lumen tubes compared with double-lumen or Univen t tubes. There were no significant differences for k(1) values between double-lumen or Univent tubes. The Values for k(2) were significantly lower for double-lumen tubes compared with Univent tubes. The k(2) va lues were significantly lower for Rusch (Duluth, GA) or Sheridan (Argy le, NY) double-lumen tubes compared with Mallinckrodt (St Louis, MO) d ouble-lumen tubes. This difference was because of the Y-connectors of the Mallinckrodt tubes. Conclusions: Flow resistances of modern dispos able double-lumen tubes are lower than commonly perceived. In most cli nical situations, there will be no decrease in flow resistance when a Rusch or Sheridan double-lumen tube is replaced by a single-lumen tube . Copyright a 1998 by W.B. Saunders Company.