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

Abstract Study Objective To investigate the potential benefit of postoperatively providing a patient-controlled anxiolytic agent, midazolam, in addition to morphine. Design A double-blinded, placebo-controlled trial of patient-controlled midazolam. Setting A Community hospital. Participants 29 patients undergoing elective spinal surgery. Interventions Postoperatively, via two separate patient-controlled pumps, the treatment group received morphine and midazolam, and the control group received morphine and saline solution. Measurements Repeated 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 Results Anxiety 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. Conclusions Patients who received both midazolam and morphine experienced a more rapid decline in anxiety and used less opioid medication than those receiving morphine alone.