Propranolol decreases cardiac work in a dose-dependent manner in severely burned children
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BACKGROUND: Severe burn is followed by profound cardiac stress. Propranolol, a nonselective β(1,) β(2)-receptor antagonist, decreases cardiac stress, but little is known about the dose necessary to cause optimal effect. Thus, the aim of this study was to determine in a large, prospective, randomized, controlled trial the dose of propranolol that would decrease heart rate ≥15% of admission heart rate and improve cardiac function. Four-hundred six patients with burns >30% total body surface area were enrolled and randomized to receive standard care (controls; n = 235) or standard care plus propranolol (n = 171). METHODS: Dose-response and drug kinetics of propranolol were performed. Heart rate and mean arterial pressure (MAP) were measured continuously. Cardiac output (CO), cardiac index, stroke volume, rate-pressure product, and cardiac work (CW) were determined at regular intervals. Statistical analysis was performed using analysis of variance with Tukey and Bonferroni corrections and the Student t test when applicable. Significance was accepted at P < .05. RESULTS: Propranolol given initially at 1 mg/kg per day decreased heart rate by 15% compared with control patients, but was increased to 4 mg/kg per day within the first 10 days to sustain treatment benefits (P < .05). Propranolol decreased CO, rate-pressure product, and CW without deleterious effects on MAP. The effective plasma drug concentrations were achieved in 30 minutes, and the half-life was 4 hours. CONCLUSION: The data suggest that propranolol is an efficacious modulator of the postburn cardiac response when given at a dose of 4 mg/kg per day, and decreases and sustains heart rate 15% below admission heart rate.
