The equivalence of anesthetic regimens with respect to plasma glucose elevation during cerebrovascular surgery

Hyperglycemia, even if mild, is known to aggravate neuronal damage from cerebral ischemia. In order better to define the influence of currently used anesthetic techniques on plasma glucose levels during cerebrovascular surgery, we examined serial plasma glucose values during 43 carotid endarterectomies (CEA) and 19 intracranial arteriovenous malformation (AVM) resections. CEA patients (aged 67.6 +/- 1.4 years and weighing 76.4 +/- 2.3 kg, mean +/- SEM) received N2O in O2 and either isoflurane (ISO) (n = 14), halothane (n = 8), fentanyl (n = 10), or sufentanil (n = 11). Plasma glucose was compared at 1.12 +/- 0.05 h (stage 1), 2.08 +/- 0.07 h (stage 2), and 3.12 +/- 0.1 h (stage 3) after induction of anesthesia. AVM patients received ISO and N2O in O2. Plasma glucose was compared 2.32 +/- 0.14 h (stage 1) and 6.25 +/- 0.34 h (stage 2) after induction of anesthesia (surgical stage). Glucose was determined by the hexokinase method. In the CEA cases, progressively elevated plasma glucose levels were associated with successive surgical stage (114 +/- 6, 122 +/- 6, and 138 +/- 6 mg/dl). The seven CEA patients that carried the diagnosis of diabetes mellitus tended to have higher glucose levels but they did not differ significantly from nondiabetic patients. The AVM patients (aged 35.7 +/- 2.3 years and weighing 71.1 +/- 2.9 kg) were all nondiabetic. They were significantly younger than the CEA patients and each received dexamethasone intraoperatively. In these patients, there was a significant effect (p <0.04) of surgical stage to increase plasma glucose (115 +/- 10 vs. 126 +/- 10 mg/dl). For CEA, the anesthetic techniques examined do not differ significantly in their influence on plasma glucose levels, but all techniques were associated with a gradual increase in plasma glucose levels intraoperatively, even in nondiabetic patients. Compared to the group of younger AVM patients, glucose elevation was more pronounced in the elderly CEA patients. We conclude that intraoperative monitoring of plasma glucose may be useful in elderly patients during prolonged neurovascular procedures.