Cerebral blood flow velocity monitoring in patients during cardiac surgery with hypothermic VS. normothermic CPB

Abstract

Introduction It is clear that neurological complications occur due to imbalance of oxygen delivery and brain needs. Neurological outcomes in patients (pts) after cardiac surgery may be associated with impaired cerebral blood flow (CBF) during cardiopulmonary bypass (CPB)¹. Aim of study was to compare the pattern of CBF and neurological outcomes in patients underwent cardiac surgery with normothermic and hypothermic CPB modes. Methods After the local Ethic Committee approval, we studied 97 patients underwent cardiac surgery with CPB. In 75 pts (group 1) we used moderate hypothermic 28.2±0.3°C and in 22 pts (group 2) – normothermic 36.5±0.2°C perfusion. Cerebral blood flow velocity (CBFV) was measured in the middle cerebral artery using transcranial Doppler sonography continiously during anaesthesia and surgery. Statistics was performed at 8 selected stages (1-stable anaesthesia, 2-before CPB, 3-start CPB, 4-stable CPB, 5-aorta unclamp, 6-stop CPB, 7-aorta decanulation, 8-end of surgery). Cognitive function estimated by 5 computerized psychometric tests (21 parameters) 2 days before operation and 2 weeks after surgery. Results We observed significantly higher CBFV in pts operated with normothermic mode of CPB starting with stable CPB to the end of surgery (stages 4-8) in comparison to pts operated with hypothermic perfusion (figure). Impairment of psychometric tests performing in pts with normothermic CPB was significantly higher than in pts operated with moderate hypothermia: 31.64±12.2% (18.1-54.5%) vs 27.95±10.18% (7.01-52.6%). Discussion Excessive cerebral perfusion in pts operated with normothermic mode of CPB may cause increasing quantity of microemboli to CBF and contribute higher rate of cognitive impairments² ³. Hypothermic mode of CPB is more preferable for cerebral protection in patients underwent cardiac surgery with CPB.