Circulatory shock
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We compared the use of hypertonic salt solution (300 mEq Na/liter) with Ringer's lactate as an initial resuscitation fluid for the treatment of hemorrhagic shock. We monitored vascular pressures and cardiac output as well as microvascular function using chronic lymph fistulae in the lung and soft tissues to reflect transvascular fluid and protein flux. Seven unanesthetized sheep were bled to an aortic pressure of 50 mm Hg (2 hours) on two occasions 4-5 days apart, and were resuscitated initially with either lactated Ringer's (LR) or hypertonic saline (HS) to restore left atrial pressure to baseline. ⋯ The initial pulmonary hypertension seen with LR was eliminated with HS. Lymph flow in lung and soft tissue increased to a comparable degree in both groups, the increase being explained by the degree of plasma hypoproteinemia which was present. We conclude that HS increases cardiac output with less net fluid, decreases pulmonary vascular resistance, and does not result in more edema formation when compared with lactated Ringer's as an initial fluid for treatment of hemorrhagic shock.
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There is controversy concerning the efficacy of ATP-MgCl2 in improving survival following hemorrhagic shock. To resolve this issue, the effect of ATP-MgCl2 infusion on survival following shock was reinvestigated. Rats were bled to and maintained at a mean arterial blood pressure of 40 mmHg for 90 min. ⋯ Survival was measured in one group of animals, and in another group of animals reticuloendothelial (RE) function was determined with 131I gelatinized test lipid emulsion in search of the mechanism of the beneficial effect of ATP-MgCl2 following hemorrhagic shock. The results indicate that survival was significantly improved if the animals were treated with ATP-MgCl2 following hemorrhagic shock. In addition, RE function, which was markedly depressed following hemorrhagic shock, was significantly improved by ATP-MgCl2 treatment, indicating that the beneficial effect of ATP-MgCl2 for hemorrhagic shock could be through the improvement of RE function.