[Influence of intrathecal morphine and buprenorphine on EEG and their analgesic effect].

This study was performed on fifty patients undergoing gynecological operations of lower abdomen. Their mean age and body weight were 43 +/- 5yrs and 55 +/- 8kg (mean +/- SD) respectively. All patients were given spinal anesthesia for surgery. Patients were divided into four groups of ten patients at random as follows: Group I (control) received 7.5mg of dibucaine only, Group II received 7.5mg of dibucaine with 0.05mg of buprenorphine (B), Group III received 7.5mg of dibucaine with 0.25mg of morphine (M), Group IV was the same as G-III but received 0.2mg of naloxone after operation. We observed EEG during operation and assessed intrathecal B and M for postoperative analgesic effect and side effects. EEG finding was as follows. In G-I, alpha and beta waves appeared dominantly during operation. In G-II, G-III and G-IV, EEG showed specific beta wave which is characterized with low voltage and rapid activity. This specific EEG change emerged at 10 minutes after the intrathecal injection of M in G-III and G-IV, and at 60 minutes after the intrathecal injection of B in G-II. This finding showed that intrathecal M with less lipid solubility reached more rapidly to CSF in the fourth ventricle than intrathecal B. The result suggests that the earlier respiratory depression may be caused by large doses of intrathecal M. Postoperative analgesic effect was recognized remarkably in G-II, G-III and G-IV (P less than 0.01). The duration for pain relief was 6 hrs in G-II and 12 hrs in G-III and G-IV.(ABSTRACT TRUNCATED AT 250 WORDS)