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.
SUMMAREffects of pulsatile venous flow upon the microcirculation were investigated in conditions with different venous pressures by using regional perfusion in dog's hind legs. In animals with venous pressure of -18 cm H2O (collapsed stage), venous pulsation brought about a significant increase in mean oxygen consumption ratio and suppressed a rise of mean resistance ratio significantly.In animals with venous pressure of +2cm H2O (normal venous pressure stage), the venous pulsation was effective in a rise of mean oxygen consumption ratio but was not effective in suppression of mean resistance ratio. In animals with venous pressure of +10cm H2O (congestive stage), no effect of venous pulsation was recognized.We suppose that the intermittent elevation of venous pressure by venous pulsation is effective for opening some capillaries in animals with venous pressure below +2cm H2O.
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