Cerebral Blood Flow and Oxygen Metabolism during Selective Cerebral Perfusion

(Department of Cardiovascular Surgery, Fukushima Medical College at Fukushima, Fukushima, Japan)

Seiichi Ando
The purpose of this study was to evaluate the pathologic physiology of the brain during selective cerebral perfusion (SCP) during surgery for aortic dissection and aortic arch aneurysm. To evaluate the differences in cerebral blood flow and cerebral oxygen metabolism during SCP and normal cardiopulmonary bypass (CPB), we compared 10 patients undergoing selective cerebral purfusion (SCP group) with 20 patients undergoing normal cardiopulmonary bypass surgery (CPB group). In this study, the middle cerebral arterial blood flow velocity (MCAV) was continuously measured in both groups with a Labodop DP-100 trans cranial doppler velocimeter (TCD) during operation to measure the changes in cerebral blood flow. The tympanitic membrane temperature, the bladder temperature, the temporal arterial pressure, the internal jugular venous pressure and the arterial blood hemoglobin concentration were measured every 20 min to evaluate the cerebral blood flow conditions. Further more the oxygen partial pressure (PaO2), the carbon dioxide partial pressure (PaCO2) and the oxygen saturation were also measured in arterial and internal jugular venous blood to evaluate the cerebral oxygen metabolism. The cerebral oxygen extraction rate (COER), and the cerebral metabolic rate for oxygen (CMRO2) were calculated. The cerebral perfusion pressure and the brain temperature in the SCP group were lower than those of the CPB group, while PaCO2 in the SCP group was higher than that of the CPB group during SCP. In spite of the low cerebral perfusion pressure and the decrease in cerebral metabolism in the SCP group, mean MCAV remained at levels similar to those of the CPB group during SCP. This suggests that the high PaCO2 level may be a significant factor in the increased cerebral blood flow during SCP. In conclusion, MCAV in the SCP group was maintained by the high PaCO2 levels during SCP, causing COER and CMRO2 levels to be much the same as in the CPB group.
@Jpn. J. Cardiovasc. Surg. 29: 245-253 (2000)