Comparison of 75 and 150 μg doses of intrathecal morphine for postoperative analgesia after transurethral resection of the prostate under spinal anesthesia.

Objective: The administration of single dose intrathecal (IT) morphine with local anesthetics during spinal anesthesia produces an effective postoperative analgesia. In this study, we evaluated the efficacy and safety of two different doses of IT morphine with bupivacaine for postoperative analgesia after transurethral resection of prostate (TURP).

Study Design: Prospective, randomized study.

Setting: Urology Department.

Patients, Participants: Sixty patients who were scheduled to undergo TURP with spinal anesthesia.

Methods: Patients were allocated to receive IT morphine (75 μg) with bupivacaine heavy (group I) and IT morphine (150 μg) with bupivacaine heavy (group II). Postoperative pain was evaluated by Visual Analogous Scale during 24 hours. The need for rescue analgesia, adverse effects and patient satisfaction were recorded.

Results: Groups were comparable with respect to demographic data. VAS scores were similarly low in both groups. However, the request for analgesia was significantly higher in group I (27 percent) than group II (7 percent; p = 0.04). The incidence of postoperative nausea was similarly low in both groups. No patients reported pruritis in group I where as six patients (20 percent) reported mild pruritis not necessitating treatment in group II (p = 0.036) Patients satisfaction was similarly high in both the groups.

Conclusions: IT morphine 150 μg reduced the need for rescue analgesia compared to IT morphine 75 μg in patients undergoing TURP under spinal anesthesia. As the incidence of pruritis was low with no treatment, IT morphine 150 μg may be a suitable dose for postoperative analgesia for patients undergoing TURP under spinal anesthesia.