Effects of intraoperative low dose ketamine on remifentanil-induced hyperalgesia in gynecologic surgery with sevoflurane anesthesia.
BACKGROUND
Remifentanil is useful during general anesthesia because of its rapid onset and short acting time. However, some studies report that due to opioid-induced hyperalgesia (OIH) and tolerance, remifentanil also increases early postoperative pain. The occurrence of OIH and opioid-induced tolerance is mainly thought to be due to central sensitization by the activation of NMDA receptors. Therefore, we investigated the effects of continuous infusion of ketamine, an NMDA receptor antagonist, on postoperative pain and the quantity of opioids used.


METHODS
40 patients scheduled to undergo laparoscopic gynecologic surgery were randomly allocated into two groups. Anesthesia was equally maintained with sevoflurane and 4 ng/ml of remifentanil in all patients. Ketamine (0.3 mg/kg) was injected and followed with a continuous dosage of 3 µl/kg/min in the ketamine group (n = 20) while the control group was injected and infused with an equal amount of normal saline. We compared postoperative VAS up to 7 hours and morphine demand through PCA.


RESULTS
Postoperative VAS and morphine demand was significantly lower in the ketamine group 2 and 3 hours after surgery, respectively.


CONCLUSIONS
When general anesthesia is maintained with sevoflurane and remifentanil in patients undergoing laparoscopic gynecologic surgery, continuous infusion of low dose ketamine decreased early postoperative pain and the quantity of opioids used.
Department of Anesthesiology and Pain Medicine, College of Medicine, Chungnam National University, Deajeon, Korea.
Boo Hwi
BH
Hong
Wang Yong
WY
Lee
Yoon Hee
YH
Kim
Seok Hwa
SH
Yoon
Won Hyung
WH
Lee