Intravenous tramadol for post-operative pain--comparison of intermittent dose regimens with and without maintenance infusion.

Abstract

Thirty-five ASA Grade I-II females received tramadol 150 mg intravenously followed randomly and double-blind by an infusion of either tramadol 15 mg h-1 (Group I) or saline (Group II) and tramadol 100 mg bolus on demand for the treatment of post-operative pain. Patients in Group I required 60% less tramadol on demand (P less than 0.01) and had better pain relief after operation (P less than 0.05) than those in the group given saline. Total tramadol consumption, however, was about 30% higher in Group I (P less than 0.05) and was associated with an increased incidence of minor side-effects. In both groups median serum tramadol concentrations peaked at 15 and 60 min and decreased after the second peak steadily (P less than 0.001). Tramadol failed to relieve pain within 2 h after the beginning of treatment in 6% (Group I) and 20% (Group II) of the patients. It is suggested that use of an i.v. maintenance tramadol infusion in addition to on-demand i.v. tramadol boluses is a safe and recommended mode of post-operative intravenous pain therapy.