Opioid delivered by PCA (patient-controlled analgesia) is effective at relieving pain after surgery, but it is associated with side effects, such as nausea, vomiting, pruritus, respiratory depression, and urinary retention. The purpose of this study was to compare fentanyl-related side effects and the quality of analgesia when naloxone or ondansetron was added to IV PCA regimen.

Ninety patients undergoing lumbar laminectomy were enrolled in this study. General anesthesia was maintained with 50% N₂O and enflurane. In the recovery room patients received a 1 µg/kg bolus of fentanyl, and addition normal saline 2 ml (group C), ondansetron 4 mg (group O), or naloxone 0.04 mg (group N). Simultaneously intravenous fentanyl PCA with normal saline (group C), ondansetron 4 mg (group O), or naloxone 0.36 mg (group N) was commenced. Pain scores and side effects were assessed on postoperative days (PODs) 0, 1, and 2 using a VAS (visual analogue scale).

The incidences of vomiting in the groups C, O, and N were 13.2%, 13.2%, and 3.3%, respectively. The VAS scores for nausea on PODs 0 and 1 in group N were significantly lower than in group C. The VAS scores for sedation on POD 0 in group N was lower than in group C, and on POD 2 lower than in group O. No differences in the VAS for pain and urinary retention were observed between the three groups.

Low-dose naloxone with IV fentanyl PCA is effective at reducing opioid-related nausea and sedation without attenuating the quality of analgesia.