Circulatory shock
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We examined the specific effects of 7.5% hypertonic saline (HTS) on myocardial performance and regional blood flow and compared the efficacies of HTS and lactated Ringer's solution (LR) for hypovolemic resuscitation. Studies were performed in anesthetized dogs subjected to rapid hemorrhage to decrease mean arterial pressure by 50% over 60 min. The animals were resuscitated with either HTS (n = 8) at 5 ml/kg or LR (n = 7) at a dose required for equivalent restoration of cardiac output. ⋯ Hemorrhage decreased blood flow to various organs by 50% to 70% of baseline. Except for better improvement in splenic and hepatic perfusion with HTS, similar restoration of blood flow to the heart, muscle, skin, kidney, and jejunum was observed at 10 min after resuscitation with either fluid. In this animal model of rapid and severe hemorrhagic shock, HTS given at approximately one-sixth the volume of LR was equally effective in providing temporary restoration of hemodynamic function.(ABSTRACT TRUNCATED AT 250 WORDS)
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The present work is a continuation of studies concerned with mathematical modelling and simulation of microvascular fluid and protein exchange following burn injuries [Bert et al.: Circulatory Shock 28: 199-219, 1989: Bowen et al.: Circulatory Shock 28: 221-233, 1989]. The model has been extended to include the effects of different types of fluid resuscitation on the circulatory and microvascular exchange systems. The model and a statistical fitting procedure were used to find the ranges of fitting parameter values that best describe the changes in interstitial fluid volume and protein mass as well as transcapillary protein extravasation for three sets of experiments (no resuscitation, resuscitation with Ringer's or resuscitation with plasma). Typical changes in mass exchange related parameters postburn that resulted in simulation predictions which were a good fit to the experimental data include: an increase in the large pore pathway for protein of 100 times in the injured skin and 5 times in non-injured skin and skeletal muscle, an increase in fluid filtration coefficients in injured skin of 10 times and an instantaneous decrease of 50% in the area available for exchange in injured skin at the time of the burn.
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Extracorporeal membrane oxygenation (ECMO) can provide total cardiopulmonary support via extrathoracic vascular cannulation. We evaluated the effects of ECMO in gram-negative septic shock in immature piglets subjected to fecal-Escherichia coli peritonitis. Group I, SEPSIS CONTROL (n = 10), had an intraperitoneal injection of E. coli but did not receive ECMO. ⋯ Conventional ventilatory therapy was unsuccessful in each. Systemic arterial blood pressure was significantly higher in ECMO CONTROL animals (P less than 0.01) as were leukocyte counts (P less than 0.01). In this model of gram-negative septic shock, ECMO did provide cardiopulmonary support but did not improve mortality.
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Monophosphoryl lipid A (MPL) is a nontoxic derivative of lipid A. In this study, the induction of tolerance by MPL to the hemodynamic effects of lethal endotoxemia was tested. Ten Sprague-Dawley rats were received either Salmonella minnesota MPL 0.5 mg/100 g intravenously (i.v.) or equivalent volume of diluent (control) i.v. on day zero. ⋯ Arterial lactate was 2.6 +/- 0.3 mmol/liter in controls and 1.3 +/- 0.2 mmol/liter in MPL animals at 6 hr (P less than 0.05). The controls died 7.5 +/- 1.3 hr after LPS administration, whereas all the MPL-pretreated animals survived. These data indicate that MPL induces tolerance to the acute hemodynamic effects of LPS and enhances survival from lethal endotoxemia.