BACKGROUND: We sought to investigate the effect of morphine and fentanyl on shivering when used adjunctively with bupivacaine during spinal anesthesia in patients undergoing varicose vein surgery on an outpatient basis.

MATERIAL AND METHODS: The study included a total of 90 patients, aged 25–45 years, ASA I–II, scheduled to undergo endovenous laser ablation under spinal anesthesia for lower extremity venous insufficiency/varicose vein disease. Patients were randomly allocated into 3 groups: Group M (morphine group) received 5 mg 0.5% hyperbaric bupivacaine + 0.1 mg morphine, Group F (fentanyl group) received 5 mg 0.5% hyperbaric bupivacaine + 25 µg fentanyl, and Group C (control group) received 5 mg 0.5% hyperbaric bupivacaine + physiologic saline. The level of sensory blockade was assessed with pin-prick test and the level of motor blockade was assessed with Bromage scale at 5-min intervals. Shivering grade and time to first postoperative analgesic requirement was recorded.

RESULTS: Level and time of sensory block showed a slight but insignificant increase in the Morphine Group and Fentanyl Group. Time of postoperative analgesic requirement was significantly longer in patients who received morphine (p<0.05). Shivering was significantly less common in patients who received morphine and fentanyl than in patients who are in the Control Group (p<0.02).

CONCLUSIONS: Morphine or fentanyl may be used as adjunctives to spinal anesthesia to prevent shivering in patients undergoing venous surgery.

Keywords: Ablation Techniques - methods, Analgesics, Opioid - administration & dosage, Anesthesia, Spinal - methods, Anesthetics, Local - administration & dosage, Bupivacaine - administration & dosage, Double-Blind Method, Fentanyl - administration & dosage, Morphine - administration & dosage, Pain Measurement, Pain, Postoperative, Shivering - drug effects, Varicose Veins - surgery