Double-blind randomized controlled trial for co-administration of N-methyl D-aspartate receptor antagonists with intravenous patient controlled morphine for postoperative pain management

ABSTRACT

This double-blind randomized controlled trial evaluated the efficacy of co-administration of two N-methyl D-aspartate [NMDA] receptor antagonists magnesium sulphate and ketamine hydrochloride with i.v. morphine patient controlled analgesia [IVPCA], as regard the improved analgesic efficacy and lower pain scores compared with morphine patient- controlled analgesia alone after elective thoracotomies. Seventy-five patients were all randomized allocated to receive, by patient controlled i.v. analgesia either morphine 0.4 mg/ml alone [group I], 0.4 morphine mg/ml with magnesium sulphate 30 mg/ml [group II], or morphine 0.4 mg/ml with ketamine hydrochloride 1 mg/ml [group III]. Postoperative analgesia was started when verbal rating scale was >/= 2. Patients were first given a standardized loading dose [0.05 mg/kg[-1]] of the study solution. They were then allowed to use bolus doses of this solution [0.0125 mg/kg[-1] with lockout interval 20 min without time limit or background infusion]. Pain scores, sedation, discomfort, cumulative morphine consumption and adverse effects were recorded up to 24 h after the start of patient-controlled analgesia. The level of discomfort, level of sedation and verbal rating scores decreased significantly with time in all groups [P<0.05]. Both verbal rating and discomfort scores were significantly lower in groups II and III at 15, 30 and 60 min compared with group I [P< 0.001]. Cumulative morphine consumption after 12 and 24 h was significantly higher in group I [median 29 and 50 mg, respectively] compared with group II [22 and 43 mg] and group III [23 and 44 mg]. In conclusions, the combination of NMDA receptor antagonists [magnesium sulphate or ketamine hydrochloride] and morphine delivered via IVPCA is safe and effective means of providing immediate postoperative analgesia, and significant lower morphine consumption with less side effects than morphine alone