Laboratory Evaluation of the Pressure Flow Characteristics of Venous Cannulas During Vacuum-Assisted Venous Drainage

Abstract

Vacuum-assisted venous drainage (VAVD) is frequently used to increase venous return through smaller venous cannula and reduced venous line size. The purpose of this study is to determine the maximal flow rates achieved through various venous cannula with varying amounts of negative pressure applied during VAVD. The first test circuit consisted of 25 different venous cannulae connected to 3/8 inner diameter tubing on the positive side of a centrifugal pump. Flows through the cannula were measured at a line pressure of 20, 40, 60, and 80 mmHg. The second circuit consisted of the test cannula connected to 3/8-in inner diameter tubing, a hard-shell venous reservoir, and flow probe placed on the venous line. Using a vacuum regulator and venous line pressure monitor, flow rates were measured through each cannula at −20, −40, −60, and −80 mmHg of vacuum. The results show a mean correlation of 0.989 between the two methods of flow measurement (p < .001). Mean flow rates were established at 40 and 80 mmHg using both methods. For each 40 mmHg increase using vacuum, blood flow was increased by 42.08 ± 0.09%. These data have been incorporated into a chart to allow the perfusionist to identify the negative pressure necessary to achieve venous return when using specific venous cannula during VAVD.