Epidural administered buprenorphine in the perioperative period

Purpose

To study the effect of epidural buprenorphine on minimum alveolar concentration (MAC) of volatile anaesthetics, duration of analgesia and respiratory function in the perioperative period.

Methods

One hundred and twenty patients, ASA I–II undergoing gynaecological surgery were randomly divided into three studies. The forty patients in each study were randomly divided into four groups depending on the dosage; Group I (control), Group II (80 μg · kg^?1 morphine), Group III (4 μg · kg^?1 buprenorphine), Group IV (8 μg · kg^?1 buprenorphine). The MAC of halothane was measured following epidural administration of the agents in each group. The duration of analgesia was assessed by the first request for pentazocine. Postoperative analgesic effects were assessed by the total dosage of pentazocine required for the 48 hr after surgery. Respiratory rate (RR), minute volume (MV), and PaCO₂ were measured during surgery and the postoperative period. The MAC of halothane was reduced in Group IV (P < 0.01). The duration of analgesia was 10.0 ± 5.1 hr (Mean ± SE) in Group 1, 37.7 ± 4.7 hr in Group II, 27.1 ± 7.1 hr in Group III, and 44.4 ± 4.1 hr in Group IV. Total dosage of pentazocine was lower in Group IV (P < 0.05) than in the other groups. The decrease of RR, MV and the increase of PaCO₂ were observed within 60 min in Group III and IV dose dependently.

Conclusion

Epidural buprenorphine administered in a dose of 4 or 8 μg · kg^?1 provides postoperative analgesia that is no less effective than that of morphine.