title: Cerebral blood flow, cerebral metabolic rate of oxygen and relative CO2-reactivity during craniotomy for supratentorial cerebral tumours in halothane anaesthesia. A dose-response study.
abstract: Fourteen patients were studied during craniotomy for small supratentorial cerebral tumours. Cerebral blood flow (CBF) and cerebral metabolic rate of oxygen (CMRO2) were measured twice by a modification of the Kety-Schmidt technique using 133Xe intravenously. Anaesthesia was induced with thiopental 4-6 mg kg-1, fentanyl and pancuronium, and maintained with an inspiratory halothane concentration of 0.45% in nitrous oxide 67% at a moderate hypocapnic level. In one group of patients (n = 7) the inspiratory halothane concentration was maintained at 0.45% throughout anaesthesia. About 1 h after induction of anaesthesia CBF and CMRO2 averaged 35 +/- 2 ml 100 g-1 min-1 and 2.7 +/- 0.3 ml O2 100 g-1 min-1 (mean +/- s.c. mean), respectively. During repeat studies 1 h later CBF and CMRO2 did not change. In another group of patients (n = 7) an increase in halothane concentration from 0.45% to 0.90% was associated with a significant decrease in CMRO2 from 2.3 +/- 0.1 to 2.0 +/- 0.1 ml O2 100 g-1 min-1. The CO2-reactivity measured after the second flow measurement was preserved. It is concluded that halothane in this study induces a dose-dependent decrease in cerebral metabolism, an increase in CBF while CO2-reactivity is maintained.
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000758:Anesthesia; D001794:Blood Pressure; D001921:Brain / Q000378:metabolism*; D002245:Carbon Dioxide / Q000097:blood; D002528:Cerebellar Neoplasms / Q000601:surgery*; D002560:Cerebrovascular Circulation; D003399:Craniotomy; D004305:Dose-Response Relationship, Drug; D006221:Halothane; D006801:Humans; D008875:Middle Aged; D010100:Oxygen / Q000097:blood; D010101:Oxygen Consumption
chemical_list: D002245:Carbon Dioxide; D010100:Oxygen; D006221:Halothane