Pulmonary shunting during venovenous bypass.

Abstract

Using mongrel dogs, an experimental study was performed to investigate Qs/Qt during v-v bypass with or without oxygenation. During bypass, the systemic circulation was maintained under constant conditions, while bypass flow rate, SVO2 and PVCO2 varied independently. The results were as follows: 1) In dogs undergoing v-v bypass without oxygenation, Qs/ Qt and A-aDO2 increased markedly in proportion to bypass flow in animals receiving blood infusion into the right ventricle, but a remarkable increase was not seen in animals receiving blood infusion into the right atrium. The pulmonary artery waveform appeared to influence Qs/Qt. 2) A significant positive correlation was found between QS/Qt and SVO2. A-aDO2 showed no correlation to SVO2. 3) The Qs/Qt showed no remarkable changes despite significant changes in PVCO2 (from 22 to 96mmHg). 4) With regard to Qs/Qt and SVO2, it may be proper to perform v-v bypass at a flow rate of 30ml/Kg/min with blood infusion into the right atrium.