Tramadol and postoperative shivering in patients undergoing open and laparoscopic cholecystectomy under general anaesthesia

Background: For many years, shivering after anaesthesia has been recognised, and is one consequence of perioperative hypothermia. Shivering affects a number of physiological parameters. The aim of the study was to evaluate the severity of hypothermia after open and laparoscopic cholecystectomy, and to determine the efficacy of injection tramadol hydrochloride (HCl) in preventing postanaesthetic shivering. Method: Eighty American Society of Anesthesiologists (ASA) Grade I and II patients scheduled to undergo either laparoscopic cholecystectomy, (Group A, n = 40) or open cholecystectomy (Group B, n = 40), were included in this randomised prospective study. Patients were further allocated randomly to two groups, to receive either tramadol 1 mg/kg (treatment group, Group A1 and B1, n = 40, 20 patients in each group), or the equivalent volume of normal saline (control group, Group A2 and B2, n = 40, 20 patients in each group), at the time of wound closure. Results: Fall in temperature was significantly more in the laparoscopic cholecystectomy group (0.70oC and 0.81oC), than in the open cholecystectomy group (0.32oC and 0.275oC). The incidence of postanaesthetic shivering was comparable in the treatment groups (A1 and B1), but was significantly higher in the control groups (A2 and B2). Incidence of sedation was not significantly different between treatment and control groups. Conclusion: Tramadol significantly reduced the incidence and severity of shivering, following open and laparoscopic cholecystectomy operations.