Tramadol in the treatment of postanesthetic shivering

Background: As an inhibitor of the reuptake of serotonin and norepinephrine in the spinal cord, the mechanism of action of tramadol resembles that of nefopam, which has been used in the treatment of postanesthetic shivering. Methods: In a randomized, placebo-controlled, double-blind study, we assessed the effects of tramadol (0.5 mg . kg(-1), 1 mg . kg(-1) and 2 mg . kg(-1) i.v.) or normal saline on shivering after a standardized general anesthesia in 40 adult patients, ASA physical status I or II (group 1), and in 64 adult patients regardless of the foregoing general anesthesia and ASA physical status (group 2). Results: Tramadol 1 mg . kg(-1) or more abolished shivering completely 5 min after treatment in all patients of groups 1 and 2. In group 1, the three dosages of tramadol were not statistically different in lowering the severity and prevalence of postanesthetic shivering. Tramadol 0.5 mg . kg(-1) was significantly slower than tramadol 1 or 2 mg . kg(-1) in tempering the severity as well as lowering the prevalence of postanesthetic shivering in group 2. Conclusion: Tramadol's distinct features in the treatment of shivering reside in its high safety profile and weak sedative properties, particularly in patients with poor cardiorespiratory reserve, in outpatients and on recurrence of shivering. (C) Acta Anaesthesiologica Scandinavica 41 (1997).