Effects of propranolol on resting metabolic rate after severe head injury

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Abstract
Postabsorptive resting metabolic rate (RMR), measured by indirect calorimetry, and the effect of iv propranolol administration were studied in 12 nonseptic patients with severe head injury by means of indirect calorimetry. Before propranolol RMR was moderately increased (126 ± 10.47% of predicted values) whereas urinary excretion of catecholamines was markedly elevated (p < .01 vs. normal values). RMR was significantly correlated with both resting heart rate (HR) (r = .72, p < .01) and 24-h urinary N excretion (r = .85, p < .001). The administration of iv propranolol (0.1 mg/kg) produced a rapid decrease in HR (-10 ± 4%, p < .001) and in RMR (-6.1 ± 23%, p < .001). Further administration of propranolol produced no additional reduction in either HR or RMR. We conclude that severely head-injured patients are moderately hypermetabolic in resting and postabsorptive conditions, and that acute iv propranolol administration induces a reduction of about one quarter of the resting hypermetabolism. (Crit Care Med 1989: 17:328)