Intraperitoneal dextromethorphan and levo-bupivacaine mixture for reduction of postoperative visceral hyperalgesia and cytokine production in patients undergoing laparoscopic cholecystectomy

ABSTRACT

To assess the efficacy and safety of intraperitoneal administration of a dextromethorphan-levo-bupivacaine mixture in different volumes and doses on hemodynamics, postoperative pain intensity and types, opioid consumption and cytokine levels in patients undergoing elective laparoscopic cholecystectomy. Seventy-five patients ASA grade I and II undergoing laparoscopic cholecystectomy under general anaesthesia were studied. The patients were allocated into one of three groups according to dose and volume of intraperitoneally administered mixture Large volume and dose of dextromethorphan and levo-bupivacaine 0.125% mixture [120ml with 90mg of dextromethorphan], small volume and dose of dextromethorphan and levo-bupivacaine 0.125% mixture [60ml with 45mg of dextromethorphan] and control group in which levo-bupivacaine 0.125% 60ml was administered. Intravenous patient controlled analgesia [I.V. PCA] with morphine was initiated and maintained for 24 hours. Pain was assessed for 24 hours by visual analogue scale. Stress response to surgery was evaluated by cytokine levels including tumour necrosis factor alpha [TNF-alpha] and interleukin-l beta [IL-1 beta]. Side effects, sedation level and morphine consumption were also recorded. Demographic data were similar. Pain intensity [intra-abdominal and shoulder pains] was lower in large volume and dose of dextromethorphan-levo-bupivacaine mixture [LDL] group when compared to other two groups. The addition of dextromethorphan to levo-bupivacaine in large volume and dose of dextromethorphan-levo-bupivacaine mixture [LDL] and small volume and dose of dextromethorphan-levo-bupivacaine mixture [SDL] groups resulted in better control of pain than intraperitoneal levo-bupivacaine [control group] alone. Shoulder pain was better controlled than intra-abdominal pain. Postoperative morphine consumption by I.V-PCA was less in LDL group with decreased number of repeated requests. TNF-alpha and IL-1 beta levels were significantly less in LDL and SDL groups up to 24 hours postoperatively when compared to control group with no significant changes at 12 hours to preoperative levels indicating decreased stress response to surgery. The use of intraperitoneal large volume and dose of dextromethorphan [90mg] in 120ml of levo-bupivacaine 0.125% resulted in better postoperative control of pain intensity, opioid consumption and cytokine release in response to surgical stress when compared to either small volume and dose of dextromethorphan [45mg] in 60ml of levo-bupivacaine mixture or levo-bupivacaine 60ml alone