Partial and "complete" adrenergic blockade in posthemorrhagic shock

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Abstract
Blood loss was induced in unanesthetized dogs and sheep using the hydrostatic bottle technique. Non-medicated, metaraminol-, Arfonad-, phenoxybenzamine-, propranolol-, and phenozybenzamine + propranolol-medicated animals were used. Reinfusion of the shed blood restored the circulation to control level yet a few hours later half of the nonmedicated animals, all metaraminol-and Arfonad-medicated animals, and three-fourths of the phenoxybenzamine-medicated animals relapsed into irreversible shock and died. Propranolol treatment also failed to affect survival rate but markedly reduced acidosis. Simultaneous administration of phenoxybenzamine + propranolol prevented metabolic acidosis and produced a marked im -provement in survival rate. It is concluded that in shock, metabolic acidosis is secondary to endogenous catecholamine secretion and that "complete" (as opposed to partial) adrenergic blockade considerably improves tolerance to hypotension.