Background: Different anesthetic agents have different effects on cerebrovascular physiology. However, the importance of these differences in neuroanesthetic practice are unclear. In an effort to determine whether important clinical differences are present, the authors compared three anesthetic techniques in 121 adults undergoing elective surgical removal of a supratentorial, intracranial mass lesion.
Methods: Patients were assigned randomly to one of three groups. In group 1 (n = 40), anesthesia was induced with propofol and maintained with fentanyl (approximately 10 micrograms/kg load, 2-3 micrograms.kg-1.h-1 infusion) and propofol (50-300 micrograms.kg-1.min-1). In group 2 (n = 40), anesthesia was induced with thiopental and maintained with isoflurane and nitrous oxide. Up to 2 micrograms/kg fentanyl was given after replacement of the bone flap. In group 3 (n = 41), anesthesia was induced with thiopental and maintained with fentanyl (approximately 10 micrograms/kg load, 2-3 micrograms.kg-1.h-1 infusion), nitrous oxide, and low-dose isoflurane, if required. Blood pressure, heart rate, expired gas concentrations, and ventilatory parameters were recorded automatically in all patients. Epidural intracranial pressure (ICP) was measured via the first burr hole, brain swelling was rated at the time of dural opening, and emergence was monitored closely. Preoperative computed tomography or magnetic resonance imaging scans were evaluated, and pre- and postoperative neurologic exams were performed by a neurosurgeon unaware of group assignments. Total hospital stay (days) and total hospital cost (exclusive of physician charges) also were reviewed.
Results: During induction, higher heart rates were seen in isoflurane/nitrous oxide patients, whereas mean arterial pressure was approximately 10 mmHg less during the maintenance phase (compared with both other groups). Otherwise, there were few intergroup hemodynamic differences. While there were no clinically important intergroup differences in mean ICP (+/- SD)-group 1, ICP = 12 +/- 7 mmHg; group 2, 15 +/- 12 mmHg; group 3, ICP = 11 +/- 8 mmHg-more isoflurane/nitrous oxide patients (nine, group 2) had an ICP > or = 24 mmHg than in the other groups (two each). Emergence was, overall, more rapid with fentanyl/nitrous oxide. For example, the median time until the patient could be awakened by quiet verbal command, e.g., "Open your eye," was 5 min, versus 10 min in the other groups. There were no relationships between ICP and any measurement of emergence (e.g., time to response to commands). Seven of 41 (17%) fentanyl/nitrous oxide patients vomited in the early postoperative period, compared with only 1 of 40 (2.5%) of those given propofol/fentanyl and 2 of 40 (5%) receiving isoflurane/nitrous oxide (P = 0.03). There were no differences in the incidence of new postoperative deficits, total hospital stay, or cost.
Conclusions: Although there are modest differences among the three tested anesthetics, short-term outcome was not affected. These results indicate that, despite their respective cerebrovascular effects, all of the anesthetic regimens used were acceptable in these patients undergoing elective surgery.