Effects of induced hypotension and hyperventilation on cerebral arteriovenous oxygen saturation and lactate
Yu Yingqun;Xu Jianguo;Duan Manlin(Department of Anesthesiology,Jinling Hospital Nanjing,210002)
The effect of induced hypotension by enfluane combined with hyperventilation on cerebral metabolism and cerebral blood flow during elective craniotomy for supratentorial tumor resection are studied in thirty patients with signs of intracranial hypertension. After the dura was opened,the hypotension was induced by increasing enfluane concentrations to 1.1～1.5MAC to achieve an intraarterial pressure of 10±0.67 kPa for one hour.The arterial carbon dioxide pressure(PaCO2) was maintained between 4.13～4.30 kPa during the anesthesia.Arterial and jugular venous blood samples were obtained simultaneously for determination of blood gases,oxygen saturation, hemoglobin,and lactate concentration,The measurements were made before anesthesia induction,after endotracheal intubation,after dural opening,after one hour of induced hypotension,and at the end of operation.In fourteen patients,the craniotomy lasted for more than three hours,then at the third hour, the arterial and jugular venous blood samples were drawn. The arterial oxygen saturation(SaO2)was always greater than 97% and remained constant throughout the study.Baseline jugular venous saturation(SjvO2)was 70.8%±5.83%,and increased significantly after endotracheal intubation,but didn't change during surgery.The initial difference between the arterial and jugular venous blood lactate concentration(AVDL)was-0.13±0.28mmol/L.During surgery,the AVDL tended to decrease,however,an increased AVDL might still be present in several cases with cerebral ischelmia,while arterial lactate concentration was increased.The results suggest that the SjvO2 and AVDL monitoring,which can't replay each other,may be of clinical value during neurosurgical operation with hyperventilation and induced hypotension by enfluane.