Effects of hyperventilation on the balance of cerebral oxygen supply and consumption during craniotomy / 中华麻醉学杂志

ABSTRACT

Objective To assess the effects of hyperventilation on the balance of cerebral oxygen supply and consumption during craniotomy Methods Twenty ASA Ⅰ Ⅱ patients with supratentorial tumor undergoing elective craniotomy were studied Anesthesia was induced with fentanyl 2 4 ?g/kg and propofol 1 2mg/kg I V and tracheal intubation was facilitated with succinylcholine 1 5 2 0mg/kg I V After tracheal intubation the patients were mechanically ventilated Anesthesia was maintained with isoflurane with or without nitrous oxide and intermittent intravenous bolus of vecuroinum The patients were randomly divided into two groups in group Ⅰ anesthesia was maintained with 1 5% isoflurane alone (ISO group, n=10); in group Ⅱ with 0 8% isoflurane and 60% 65% N 2O(ISO N 2O group, n=10) Demographic data including age, sex and weight were not significantly different between the two groups In group Ⅰ there were 6 male and 4 female, the mean age was (40 1?9 7) years and weight (64 5?7 3)kg whereas in group Ⅱ there were 5 male and 5 female, mean age was(43 6?8 4)years and mean body weight (62 7?6 5)kg After the opening of dura mechanical ventilation was regulated to maintain PaCO 2 at 4 7 6 0kPa(normal ventilation), 0 9) Arterial and venous blood lactate was within normal range but had a tendency to increase Conclusions Severe hyperventilation influences the balance of cerebral oxygen supply and consumption significantly during either isoflurane or isoflurane N 2O anesthesia at equal MAC, particularly in ISO N 2O group Severe hyperventilation should not be used during anesthesia for brain surgery