A placebo-controlled trial of midazolam as an adjunct to morphine patient-controlled analgesia after spinal surgery

Study ObjectiveTo investigate the potential benefit of postoperatively providing a patient-controlled anxiolytic agent, midazolam, in addition to morphine.DesignA double-blinded, placebo-controlled trial of patient-controlled midazolam.SettingA Community hospital.Participants29 patients undergoing elective spinal surgery.InterventionsPostoperatively, via two separate patient-controlled pumps, the treatment group received morphine and midazolam, and the control group received morphine and saline solution.MeasurementsRepeated measures using numerical rating scales of the primary outcomes of pain and anxiety were obtained every two hours postoperatively. Amount of morphine and midazolam/placebo administered was assessed, as were other secondary outcomes.Main ResultsAnxiety level in the treatment group declined more rapidly over the 24 hours after surgery than in the control group. The treatment group used less morphine than the control. Preoperative positive affect was the only significant psychological predictor of postoperative outcomes.ConclusionsPatients who received both midazolam and morphine experienced a more rapid decline in anxiety and used less opioid medication than those receiving morphine alone.