Safety and Efficacy of Low-Dose Intrathecal Morphine for Laparoscopic Hysterectomy: A Randomized,Controlled Pilot Study

Abstract

Abstract

Objective:

The primary objective of this research was to assess the efficacy of intrathecally administered low-dose morphine and bupivacaine as analgesic modalities for patients undergoing total laparoscopic hysterectomy (TLH) under general anesthesia and the effects of these agents on perioperative humoral stress markers.

Design:

Prospective, randomized, double-blind controlled study.

Materials and Methods:

Forty-seven American Society of Anesthesiologists I–II female patients scheduled for elective TLH under general anesthesia were randomized into 3 groups. Patients in Group B (n = 15, bupivacaine-only) received a subarachnoid block (SAB) with 5 mg of bupivacaine; patients in Group M (n = 16, morphine) received a SAB with 5 mg of bupivacaine and 200 μg of morphine. Patients in Group C (n = 16, control) received skin infiltration with a local anesthetic alone. Blood samples for testing levels of plasma cortisol, growth hormone (GH), insulin, and adrenocorticotropic hormone (ACTH) were taken at 8 am on the day prior to surgery, 30 minutes after initiation of pneumoperitoneum, and 1 hour after end of surgery. Visual analogue score (VAS) testing was performed every 2 hours for 8 hours and again at 24 hours. In patients who had pain (VAS >3), although having patient controlled analgesia, a 25 μg of an intravenous bolus of fentanyl was repeated until the patient was pain-free. Total postoperative fentanyl consumption and complications, such as postoperative nausea and vomiting (PONV), pruritus, and respiratory depression were compared among the groups.

Results:

Patients in Groups C and B had significantly greater pain at rest and on movement in the postoperative period, compared to patients in Group M. Patients in Group M required significantly lower doses of fentanyl (175 μg) than patients in Group B (350 μg) and Group C (425 μg) during 24 hours of observation (p = 0.0001). There was a significantly lower rise in ACTH, cortisol, and GH, and maintenance of insulin levels in the intraoperative and postoperative samples in group M, compared to Group C. The incidence of PONV and pruritus was high in Group M, compared to Groups B and C, but this was not statistically significant (Fisher's exact test: 0.45 and 0.33, respectively). No patients in Group M had respiratory depression.

Conclusions:

Preinduction administration of low-dose intrathecal morphine resulted in better postoperative analgesia up to 24 hours, leading to a significant reduction of parenteral opioid consumption during the perioperative period without a significant increase in side-effects. Intrathecal morphine also resulted in a significant decrease in surgical stress, compared to what occurred in the control group. (J GYNECOL SURG 34:77)