Effect of adding Ketamine to the morphine in patients addicted to opioid post orthopedic operation pain

Post-operative pain reduction is one of the problems in the patients with preoperative narcotic dependency. Morphine is the most common drugs to control postoperative pain. Due to resistance to morphine and its side effects in addict patients, using of adjuvant drugs such as ketamine has increased. The aim of this study was to evaluate the effect of adding ketamine to morphine in patients addicted to opioid with post orthopedic operation pain.
In a double blind clinical trial, 60 patients undergoing orthopedic operation with history of opioid consumption were randomly divided in 2 groups. Post operation, the first group received morphine 20 mg and the second group received morphine 20 mg ketamine 100 mg via IV patient-controlled analgesia (IPCA). The pain score as visual analogue scale (VAS), sedation score, and nausea and vomiting were evaluated at 1, 6, 12 and 24 hours post operation. SPSS v.20 was used for data analysis.
Results showed that dose of morphine consumption in morphine group was significantly increased compared to the morphine ketamine group (p 0.001). In addition, only at 12 hours after surgery the mean of pain score in the morphine group was significantly reduced compared to the second group (p = 0.02). The mean of sedation score at 1 (p 0.001), 6 (p = 0.002), 12 (p = 0.001) and 24 (p 0.001) hours after surgery in the morphine group was increased compared to the other group. At 1 hour, the mean of nausea and vomiting scores in the morphine group was significantly reduced compared to the morphine ketamine group (p = 0.024).
Addition of ketamine to morphine in the patients with history of opioid consumption reduced using of the morphine. But had no effect on pain and sedation score reduction.