Intravenous morphine after gynecological surgery : pain relief, endocrine and immune respone

Sammanfattning: Background: We need more efficient methods to alleviate postoperative pain and reduce endocrine / immune stress response. Subjects and methods: Patient controlled analgesia (PCA) with iv morphine was evaluated with respect to pain relief and endocrine / immune response to surgical trauma in 130 patients undergoing gynecological surgery. Anesthetic regimens included general anesthesia, epidural anesthesia, epidural morphine and combinations of these methods. Results: Large individual differences in iv morphine consumption were found. In the early hours after abdominal gynecological surgery in general anesthesia high doses of iv morphine increased side effects without improving pain relief. Infiltration of bupivacaine or morphine in the wound did not improve pain relief although bupivacaine reduced morphine consumption. Epidural anesthesia with addition of epidural morphine provided superior pain relief and reduced the need for iv morphine. The risk of side effects demands prolonged postoperative supervision. We found no correlation between pain scores and morphine concentrations or morphine consumption. The explanation may be inadequate effects of iv opioids on the visceral component in pain after hysterectomy. A concomitant increase in adrenal C21 (cortisol, 17a-hydroxy-progesterone) and Cl9 steroids (dehydroepiandrosterone, 4-androstene-3, 17-dione) was observed during surgery and in the early postoperative hours, reflecting increased ACTH stimulation. During the later postoperative phase C21 steroid levels remained elevated while Clg steroid levels decreased, indicating a redistribution of intraadrenal steroid flux from androgens towards glucocorticoids, probably in order to maintain an adequate prolonged cortisol secretion. The endocrine response was alleviated by epidural morphine and to a lesser extent by large doses of iv morphine. Infiltration of bupivacaine or morphine into the edge of the wound did not improve pain relief or modify the surgical trauma response. The immune response measured as plasma IL-6 was influenced by the magnitude of the trauma and reduced by epidural anesthesia and by large doses of iv morphine. Conclusions: The method of anesthesia is important to postoperative pain and stress. In the early hours after gynecological surgery iv morphine provides inadequate pain relief. Epidural anesthesia together with epidural morphine is superior with respect to pain relief and alleviation of endocrine / immune response. The adrenocortical trauma response follows a biphasic pattern. Postoperative use of PCA with iv morphine can not compensate for the differences in peroperative anesthetic technique with respect to postoperative pain and trauma response. Key words: Anaesthesia: general, epidural. Postoperative pain: PCA, morphine, bupivacaine. Hormones: adrenocortical steroids, estrogens. Immune response: Interleukin-6.