Effect of adding Ketamin to the combination of Morphine and Midazolam in opioid tolerant patients on post operative pain

Aims and Uncontrolled postoperative pain may increase patients’ mortality and morbidity. One way to control postoperative pain is by using narcotics with patient controlled intravenous analgesia (PCIA) method. Some investigators try to use many drugs in combination with narcotics in order to come over the side effects and tolerance to them in special groups of patients. We tried to compare different doses of Ketamine in combination with Morphine and Midazolam as PCIA for control of postoperative pain in patients with history of opioid addiction. In a double blind clinical trial, 120 patients undergoing lower limb orthopedic surgery with history of opioid consumption, were randomized to receive PCIA of Morphine 20 mg + Midazolam 10mg± Ketamine 50 or 100 mg daily, for 48h after surgery. Pain scores as VAS and sedative level as Ramsay scale and other possible side effects such as nausea and vomiting, and any rescue doses of analgesics were evaluated at 2, 6,24,36,48 hours after initiation of PCIA. Considering pain acuity, groups with PCIA containing Ketamine in addition to Morphine and Midazolam, showed significant decrease in pain score. However, there was no difference in sedation score between the groups. There was a significant decrease in the number of rescue doses of analgesics in groups with PCIA containing Ketamine compared with the other group. There was no difference in any evaluation between the groups with PCIA containing 50 mg or 100mg Ketamine. A better control of pain was achieved in opioid addict patients with the addition of Ketamin either 50 or 100 mg to PCIA pump compared to the control group with PCIA containing Midazolam and Morphine.