To determine if the cardiovascular effects of excessive catecholamines could be selectively blocked in severely burned patients without adversely affecting protein or fat kinetics.
Prospective cohort study.
A large tertiary care referral center in Galveston, Tex.
Sixteen patients with greater than 40% body surface area burns.
Patients were randomly selected to receive propranolol hydrochloride, a nonselective β1- and β2-blocker, or metoprolol tartrate, a selective β1-blocker.
Main Outcome Measures:
Heart rate; rate-pressure product; rate of appearance of urea, glucose, and leucine; and leucine oxidation were measured before and after selective or nonselective β-adrenergic blockade.
Propranolol and metoprolol caused a significant decrease in heart rate, from a mean (±SD) of 143 ± 15 to 115±11 and from 147±17 to 120±9 beats per minute, respectively, during the 5-day study period. Neither the rate of appearance of urea nor the rate of urea production were significantly altered by propranolol or metoprolol therapy. Only propranolol produced a significant decrease (P<.05) in the rate of appearance of glycerol, from a mean (±SD) of 5.54±0.62 to 3.07±0.7 μmol/kg per minute. The rate of appearance of leucine, used as an index of total body protein catabolism, was not significantly altered by either β-blocker.
Selective β1-adrenergic blockade did not reduce lipolysis; however, a β1- and β2-adrenergic blockade significantly reduced lipolysis. Thus, the increased lipolysis, characteristic of severely burned patients, is caused by stimulation of the β2-adrenergic receptors for catecholamines.(Arch Surg. 1994;129:1301-1305)