Abstract
Summary
Respiratory fluctuations in ventricular outflows were measured in unanesthetized dogs by simultaneously recording aortic and pulmonary artery flows and intrathoracic pressure. The respective stroke volumes were computed and the beat by beat values were plotted over a series of respiratory cycles. The data showed that in the early postoperative period there was an imbalance between the ventricular outflows during normal breathing. This imbalance was characterized by an increase in right ventricular stroke output and a decrease in left ventricular stroke output during inspiration with a reversal during expiration, that is, they were out of phase. However, this temporal imbalance diminished with recovery from the surgical procedure, so that by the fifth postoperative day the right and left ventricular stroke outputs were essentially in phase. Therefore, our data indicate that the principle of restoration to correct a temporal imbalance between the two ventricular outflows with normal spontaneous breathing is of minor importance.
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