Comparison of Flow Differences among Venous Cannulas

Abstract

The efficiency of four methods of venous drainage during cardiopulmonary bypass was evaluated. Superior vena caval (SVC), inferior vena caval (IVC), right atrial (RA), and right ventricular (RV) pressures as well as RV blood flow were measured for cannulation with a single USCI 40F atrial cannula, a single Sarns 51F cavoatrial cannula, and double USCI 32F caval cannulas with and without caval tourniquets. Measurements for all cannulas were recorded in conditioned dogs during nor-mothermic cardiopulmonary bypass with the heart beating, with the heart fibrillated, and with the apex of the heart elevated in the circumflex position. Venous drainage using double caval cannulas with caval snares provided maximum decompression of the venous system (SVC pressure, − 3 ± 1.52 mm Hg [standard deviation]; IVC pressure, −1.67 ± 2.67 mm Hg to 0.4 ± 2.09 mm Hg). However, decompression of the right side of the heart with this method was the poorest (RA pressure, 5 ± 1.46 mm Hg to 9.60 ± 2.78 mm Hg; RV pressure, 5.67 ± 0.82 mm Hg to 12.5 ± 1.51 mm Hg; RV vent flow, 96 ± 4 ml/min to 370 ± 50 ml/min). The caval cannulas without tapes provided similar venous decompression but with better right-heart decompression (RA pressure, −0.71 ± 1.95 mm Hg to 0.60 ± 2.51 mm Hg; RV pressure, 2.13 ± 2.23 mm Hg to 11.6 ± 0.89 mm Hg; RV vent flow, 29 ± 5 ml/min to 75 ± 4.5 ml/min). The USCI 40F atrial cannula provided less efficient decompression of the inferior vena cava (IVC pressure, 4.33 ± 1.96 mm Hg to 7.17 ± 3.46 mm Hg). The Sarns 51F cavoatrial cannula had the most efficient right-heart decompression (RA pressure, −11.6 ± 2.19 mm Hg to −4.1 ± 1.7 mm Hg; RV pressure, −2.5 ± 1.57 mm Hg to 4.6 ± 1.2 mm Hg; RV vent flow, 0 ± 7 ml/min to 26 ± 9 ml/min). Placing the heart in the circumflex position adversely affected right heart decompression in all techniques except single cannulation with the 51F cavoatrial cannula. Likewise, venous decompression was affected adversely in all techniques except double cannulation with caval snares. With the single 40F atrial cannula, SVC and IVC pressures were both elevated. Only the SVC pressure was affected when the cavoatrial cannula was used.