POST-OPERATIVE ANALGESIA IN PATIENTS UNDERGOING MAJOR SURGERIES: EFFECT OF ADDING IV KETAMINE TO MORPHINE IN PRESENCE OF MORPHINE RESISTANT PAIN

CORRESPONDING AUTHOR:
Dr. Arti Rajkumar,
Department of Anaesthesia,
Christian Medical College,
Ludhiana.
Email: arti.rajkumar@gmail.com

ABSTRACT: Peri-operative management of opioid resistant pain is major clinical problem especially in the immediate postoperative period. The role of NMDA receptor in the processing of nociceptive input has lead naturally to renewed clinical interest in NMDA receptor antagonist such as ketamine. This paper reviews the use and efficacy of adding low dose ketamine to morphine in management of acute post-operative pain in patients who perceive pain in spite of large consumption of morphine and added advantages of decreasing opioid consumption and there by resulting in minimizing dose related side effects. We conducted a randomized double blind study on 120 patients undergoing major abdominal surgery. All patients were kept in PACU post operatively and were given basal analgesia with IV morphine till maximum of 100µg /kg within 30 min period, but if patient still complained of pain (≥6 of 10 on VAS) with an acceptable cognition state (≥ 15 in the MMSE) and who rated themselves not sedated (≥ 5 of 10 on VAS) were taken as resistant to morphine and were enrolled in one of the two treatment groups. The MS group received 3 boluses of 30 µg/kg of morphine plus saline whereas MK group received 3 boluses of 15 µg of morphine plus 250 µg/kg of ketamine. The total dose of morphine required by MK patients (0.42±0.12 mg/kg) was significantly less than MS patients (1.21± 0.43mg/kg). (P<0.0001). The quality of analgesia was in favor of MK group even in terms of rescue analgesia as amount of diclofenac required was double in MS patients than in MK patients. (186.84 ± 37.83 vs. 83.57 ±30.28, P= 0.0001). The VAS score at rest and ambulation was significantly less in MK group as compared to MS group at 180 minutes (P<0.001). The 10 minute level of wakefulness (1-10 VAS) in the MS group (6.88 ± 1.09) was significantly (P < 0.0001) less than MK group (8.28 ± 0.43). Postoperative nausea and vomiting was seen in 68.37% of MS patients as compared to only 8.30% of MK patients (P= 0.0001). No hemodynamic ill effects or psychosomatic effects were seen in MK group. We concluded that the postoperative administration of concomitant small doses of MK provided rapid and sustained improvement in pain control in major abdominal surgeries.

KEYWORDS: Analgesia, Post-operative, Morphine, Ketamine.