[Control of postoperative pain in heart surgery. Comparison of analgesics].

BACKGROUND: Evaluation of the efficacy of three analgesic drugs (tramadol, ketorolac, and morphine) for the control of postoperative pain in cardiac surgery. DESIGN: prospective randomized study. SETTING: University Hospital, Postoperative intensive care unit. PARTICIPANTS AND INTERVENTION: sixty patients, who underwent cardiac surgery, were studied. They were randomly allocated in four groups, treated with a different postoperative analgesic therapy: A) tramadol in continuous infusion; B) ketorolac in continuous infusion; C) tramadol, in repeated boluses; D) morphine, in repeated boluses. MEASUREMENTS: the analgesic efficacy of each drug and administration protocol was evaluated by hemodynamic stability, arterial blood gases analysis, Visual Analogue Scale (VAS), resting and after cough, the VAS derivatives PID and SPID, the concentration of plasma epinephrine and norepinephrine, at eight postoperative times. Adverse effects were also registered. RESULTS: Only tramadol, in continuous i.v. infusion, achieves the required analgesic effect, significantly decreasing both VAS scores, at the end of the administration of the drug. This treatment reduced epinephrine plasma levels in the first postoperative day, when the residual analgesic effect of surgical anesthesia can be considered disappeared. CONCLUSIONS: Tramadol in continuous infusion (dose 12 mg/h) proved to be effective for the control of postoperative pain after cardiac surgery. The proposed dose represents a good compromise between analgesic efficacy and interference with the vital functions of operated patients.