[Metamizol versus propacetamol: comparative study of the hemodynamic and antipyretic effects in critically ill...

To compare the antipyretic and hemodynamic effects of metamizol and propacetamol in critically ill patients with fever.

A prospective randomized trial enrolling 60 patients admitted to our postoperative intensive care unit with fever > 38 degrees C. Patients were assigned to group M to receive intravenous doses of 2 g of metamizol or group P to receive 2 g of propacetamol. Measures were central temperature (Ta), systolic (SBP), diastolic (DBP) and mean (MBP) blood pressures, mean pulmonary artery pressure, central venous pressure, pulmonary capillary pressure, pulmonary and systemic vascular resistance index, and mixed venous saturation. All measures were taken at four times: baseline and 30, 60 and 120 minutes after infusion of the medication. Patients whose SBP fell below 90 mm Hg were withdrawn from the study.

Patient characteristics and baseline hemodynamics and Ta were similar in the two groups. We observed a significant decrease in temperature in both groups, the maximum decrease occurring 120 minutes after administration of the antipyretic (0.5 degree C and 0.6 degree in the metamizol and propacetamol groups, respectively). SBP, DBP, MBP, and the vascular resistance index decreased from baseline values in both groups 30, 60 and 120 minutes after dosing. Thirteen percent of the patients in group M and 6.67% in group P were withdrawn from the study because of hypotension. We observed no statistically significant differences between the groups in Ta or hemodynamic variables at any of the four moments of measurement.

Both metamizol and propacetamol are effective antipyretics at the doses tested. However, both have adverse hemodynamic side effects that may be poorly tolerated by critically patients.