Objective: This is a prospective, randomised, double blind trial to assess the effectiveness of intrathecal fentanyl in the relief of post-operative pain in patients undergoing lumbar spine surgery.

Method: 60 patients were recruited. All received our standard analgesic regime with morphine PCA via a syringe driver. They were electronically randomised to two groups – one received 15 micrograms of fentanyl intathecally; the other had nothing. The fentanyl was administered by the operating surgeon under direct vision at the end of the procedure.

All patients were monitored in recovery for two hours. Visual Analogue Scale (VAS) pain scores were assessed at 2, 4, 24 and 48 hours post-op. The time to first bolus delivery of PCA was recorded as was the total amount of morphine PCA used. Both patient and assessor were blinded.

Results: The patients randomised to receive fentanyl showed a significant decrease in their mean VAS pain scores for the first 24 hours. Their time to first bolus of PCA was significantly increased. They also used 40% less morphine PCA (p< 0.05 in all cases). None of the patients suffered respiratory compromise requiring treatment and they all left recovery after 2 hours to be nursed on the general ward.

Conclusion: Intrathecal fentanyl is effective at reducing post-operative pain and PCA morphine use after lumbar spinal surgery. We support its use over morphine because of the reduced incidence of respiratory complications and the ability to nurse patients on a general ward.