1450 PRESERVATION OF BRAIN BLOOD FLOW AUTOREGULATION AND OXYGEN DELIVERY DURING HEMORRHAGE AND DOPAMINE INFUSION

Abstract

Although sick infants who may suffer brain injury are treated with many drugs (e.g., dopamine) which affect the systemic circulation, their effects on the cerebral circulation are not well understood. To study the effect of hemorrhagic hypotension and dopamine infusion on the cerebral circulation, we measured aortic pressure (MAP), hematocrit (Hct) and calculated brain oxygen delivery (BOD) in 9 lambs that were < 1 wk old during a control period (CON); hemorrhage of 25cc/kg (HEM); dopamine [5μg/kg/min] (DOPA 5); dopamine [20μg/kg/min](DOPA 20). Cardiac output (CO) and brain blood flow(BBF) were measured using microspheres.Summary of results: X±sx, * different than control, p<0.05Despite a fall in aortic pressure, hematocrit and cardiac output during hemorrhage, brain blood flow and oxygen delivery were preserved. During dopamine infusion aortic pressure and cardiac output returned to baseline and brain blood flow and oxygen delivery remained unchanged. We conclude that brain oxygen delivery and autoregulation of blood flow in the newborn lamb are not impaired by this degree of hemorrhage or dopamine infusion.