Nonpulsatile mode of blood flow required for cardiopulmonary bypass and total body perfusion.

Higher morbidity and mortality rates are seen after the use of cardiopulmonary bypass in infants and elderly patients. Clinical procedures acceptable for adult patients may not be acceptable for them. Infants require more effective tissue gas exchange or tissue perfusion because of their active metabolic status. On the other hand, vascular systems of elderly patients are more rigid and do not have enough reserve capacity for nonpulsatile perfusion compared to young adults. More effective tissue perfusion is needed for them during cardiopulmonary bypass. Traditionally, we utilize a nonphysiological, nonpulsatile pump and perfuse the patients with bypass flows below their resting cardiac outputs (70-80%). In our experience, in general, it is necessary to have approximately 20% higher cardiac output in cases where we use a nonpulsatile mode of total body perfusion compared with a pulsatile mode of perfusion. In addition, higher bypass flow is expected to be required for infants because of their higher metabolic rate and for elderly patients because of their more rigid vascular structure.