The Effect of Intraoperative Diphenhydramine/Morphine on Acute Pain and Opioid Consumption after Spine Surgery

Background: One of the most common problems after spine surgery is very severe pain that usually affects outcome of patients after surgery and duration of hospital stay. Acute postoperative pain has several mechanisms, and multimodal analgesia by different mechanism of action will help control to it. In this study, we intend to investigate the effect of intravenous diphenhydramine injection during induction of anesthesia and morphine before incision on the control of acute pain in postoperative laminectomy. Methods: 130 patients scheduled for spine surgeries were assigned to receive a single pre induction dose of diphenhydramine 0.4mg/kg IV (D group) and morphine 0.15mg/kg before incision in addition acetaminophen 1gr IV at the end of surgery and just morphine 0.15mg/kg and acetaminophen 1gr IV (C group) in a randomized, double-blind trial. Postoperative pain, analgesic requirements in recovery and 24 hr after surgery were assessed. Results: The mean pain intensity in recovery was lower in the diphenhydramine group than in the control group (MD, 2.13; 95% confidence interval (CI), 1.72–2.53; P < .0001) and the need for analgesia was much lower in the diphenhydramine group than in the control group. P < 0.001. The severity of pain and the need for analgesics in the diphenhydramine group had a significant decrease in the ward compared to the control group. Conclusion: Prophylactic diphenhydramine 0.4 mg/kg at induction of general anesthesia in combination with morphin0.15mg/kg before incision and acetaminophen1gr at the end of surgery reduced the postoperative severity of acute pain and opioids requirement in the early postoperative period after spine surgeries.