Efficacy of dexmedetomidine in reducing postoperative morphine consumption in patients undergoing total abdominal hysterectomy

Mazlilah ABDUL MALEK ¹, Nurlia YAHYA ¹, Rufinah TEO ¹, Vanitha SIVANASER ², Shereen TANG Suet Ping ¹, Raha ABDUL RAHMAN ¹, Norsidah ABDUL MANAP ¹

¹ Department of Anaesthesiology & Intensive Care, Universiti Kebangsaan Malaysia Medical Centre, Kuala Lumpur, and ² Department of Anaesthesia & Intensive Care, Hospital Kuala Lumpur, Malaysia

ABSTRACT

Introduction: Dexmedetomidine is an alpha-2-adrenergic receptor agonist and neither has respiratory depressant effect nor addictive potential. These favourable properties are useful following major surgical procedures that are associated with significant morbidity caused by pain. This prospective, randomised, double-blinded placebo controlled study was conducted in patients undergoing total abdominal hysterectomy to determine the efficacy of two different doses of intraoperative dexmedetomidine infusions in reducing the amount of morphine consumption during the first 24 hour postoperative period. Materials and Methods: Sixty ASA I or II patients aged between 35 to 60 years were randomised into three groups to receive intraoperative infusions of dexmedetomidine 0.3 µg/kg/hr (Group A), dexmedetomidine 0.5 µg/kg/hr (Group B) or normal saline as placebo (Group C) without any loading dose, immediately after induction of anaesthesia. Haemodynamic parameters (heart rate and mean arterial pressure) were recorded prior to induction of anaesthesia and at 15 minute intervals intraoperatively. Patients were given patient-controlled analgesia with morphine after surgery and morphine consumption was recorded at 6, 12 and 24 hours postoperatively. Results: Group A and B showed a significant reduction in morphine consumption, compared to Group C and a higher percentage of reduction was noted in Group B as compared to Group A. Group B showed a significant 33% reduction at the 24 hour postoperative period. Mean heart rates were significantly lower in both Group A and B however none of the patients required any rescue drugs. There were no significant differences observed in MAP in all three groups. No side effects were reported. Conclusion: Intraoperative dexmedetomidine infusion of 0.5 µg/kg/hr significantly reduces postoperative morphine consumption when compared to 0.3 µg/kg/hr without causing significant haemodynamic instability and side effects. 

Keywords: Dexmedetomidine, morphine, total abdominal hysterectomy, drug adverse effect 

Correspondence author: Rufinah TEO,  Department of Anaesthesiology and Intensive Care, Universiti Kebangsaan Malaysia Medical Centre, Jalan Yaacob Latif, Bandar Tun Razak, Cheras, 56000, Kuala Lumpur, Malaysia. Tel: +60124280835 E-mail: finah77@yahoo.com

Brunei Int Med J. 2016; 12 (3): 97-103