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The effect of central nervous system narcosis on the sympathetic response to stress

1976; Elsevier BV; Volume: 20; Issue: 4 Linguagem: Inglês

10.1016/0022-4804(76)90019-6

1095-8673

James W. Taylor, Edwin W. Hander, ROBERT W. SKREEN, Douglas W. Wilmore,

Injury Epidemiology and Prevention

Heat production at the end of three hours of cold exposure (14°C) in normal men was significantly lower during He-O2 inhalation when compared with room air (43.8 ± 3.2 kcal/m2hr vs 58.8 ± 5.5, P < 0.05) as was core temperature (36.5 ± 0.1 vs 36.7 ± 0.1, P < 0.02). No effects on metabolism were noted in eight thermal neutral nonstressed studies (metabolic rate 37.8 ± 1.5 vs 35.2 ± 3.0, air vs He-O2). In six studies in normals, metabolism was unchanged following epinephrine infusion while breathing He-O2 (47.2 ± 2.0 vs 48.3 ± 0.9), suggesting helium dampens CNS sympathetic outflow but does not act as a peripheral blocking agent. Four burn patients (mean burn size 47% total body surface) were studied while breathing He-O2 for two hours, two (mean burn size 38%) while breathing argon-O2, and five (mean burn size 74%) following intravenous morphine administration. Hypermetabolism did not decrease with inhalation of the inert gases in the burn patient. However, morphine administration (0.38 mg/kg/hr) signficantly decreased oxygen consumption (77.4 ± 5.9 vs 55.0 ± 3.7), pulse rate (115 ± 4 beats/min vs 104 ± 5), core temperature (38.2 ± 0.1°C vs 37.3 ± 0.1), and minute ventilation (21.5 ± 2.5 liter/min. vs. 12.0 ± 1.0) while blood pressure and blood gases remained unchanged. The CNS response to injury or cold exposure may be dampened by central narcosis. The effect produced varies with the extent of stress, and some agents that modify mild stress in normal men exert no detectable effects on the hypermetabolic response to injury.