Influence of Sufentanil on Cerebral Metabolism and Circulation in the Rat

Abstract

The authors examined the effects of large i.v. doses of sufentanil (5-160 .mu.g/kg) on cerebral blood flow (CBF) and cerebral metabolic rate for oxygen (CMRO2) in rats. CBF and CMRO2 were measured by a modified Kety-Schmidt technique using 133Xe washout. Progressive decreases in CBF and CMRO2 occurred in animals receiving sufentanil. The maximum decrease was 53% and 40% for CBF and CMRO2 respectively, at a dose of 80 .mu.g/kg. The values for CBF and CMRO2 in this group were 105 .+-. 10 ml .cntdot. g-1 .cntdot. min-1 (mean .+-. SEM [SE of mean]) and 6.5 .+-. 0.5 ml .cntdot. 100 g-1 .cntdot. min-1, respectively, compared with 226 .+-. 28 ml .cntdot. g-1 .cntdot. min-1 and 10.9 .+-. 1 ml .cntdot. 100 g-1 .cntdot. min-1 in the control group, which received N2O 70% in O2. Larger doses of sufentanil did not cause further significant changes in CBF and CMRO2. Sharp waves appeared on the EEG of all the animals following sufentanil injection; some animals had EEG changes develop consistent with seizure activity. This seizure-like activity appeared to consist of a single episode of short duration in the groups receiving 5, 10 and 20 .mu.g/kg sufentanil. The incidence and frequency of seizure activity increased in the groups receiving higher doses of sufentanil, although the duration of seizures was still short. Sufentanil evidently causes a significant decrease in CBF and CMR02 similar to that previously reported for fentanyl. High doses of sufentanil may cause frequent seizure-like patterns appearing on EEG.