Original Article

An In Vitro Comparison of Micro Air Passage in the Venous Reservoir Bag

PSICOR, Inc.; University of Colorado Health Science Center, Denver, CO

^* Direct communications to: Charles M. Tyndal, Jr., PSICOR, Inc., 810 East Grand River, Brighton, MI 48116

Abstract

The increasing use of membrane oxygenators and collapsable venous reservoir bags (VRB) imposes a concern not associated with bubble oxygenators: Venous line air. Since no defoamer is present, a VRB must rely on flow characteristics or a barrier to remove air from the venous return. The purpose of this study is to determine the air removal efficiency of seven commercially available VRBs.

Seven VRBs with clear crystaloid solution were tested for microbubble passage using an ultrasonic bubble detector at the outlet. At 5 LPM flow, 50cc of air was injected into a stopcock in the venous line. Microbubble counts were taken in six trials of each bag, and divided into three size ranges: 10–50µ, 50–100µ, and >100µ. The means and standard deviations are presented below.

There were significant differences (p<.001) between the bags in all three microbubble size ranges. Although the two best VRBs, BMR1900 and Shiley1500 had similar counts, their design is remarkably dissimilar. The BMR1900 contains a 200µ heparin coated screen and is the only VRB utilizing a barrier in the blood path.