In vitro comparison of cavoatrial (dual stage) cannulae for use during cardiopulmonary bypass

An in vitro normothermic, human blood test circuit was constructed to test four cavoatrial (dual stage) cannulae, their right atrial baskets and IVC tips for venous return flow versus siphon drainage gradient. Simulated patient CVP and ECC oxygenator/venous reservoir inlet resistance were held constant at 10 mmHg and 15 mmHg respectively as siphon gradient was varied from 0 centimetres (cm) to -40 cm of blood. At the same siphon gradients between -10 and -40 cm, the Research Medical, Inc. (RMI) VV 3651 L, its right atrial (RA) basket, and IVC tip yielded significantly greater flows than the Sarns Inc. 12340, CR Bard, Inc. 1969, and the RMI VV 3651 B cannula, except the RMI VV 3651 B RA basket was equivalent to the VV 3651 L basket. The 12340 and 1969 baskets were equivalent. The 1969 IVC tip was superior to the 12340 tip. The mechanism for CPB venous collapse and flutter, its treatment, and the importance of monitoring myocardial temperature, as well as assuring great vein and cardiac decompression during cavoatrial cannulation and aortic cross clamping are outlined.