RESUMO OBJETIVO Soluções hipertônicas e hiperoncóticas podem reduzir as necessidades de fluidos e o edema tissular, melhorar a perfusão e reduzir a incidência de paraplegia associada com pinçamento aórtico com reperfusão subsequente. Foram avaliados os potenciais benefícios de uma solução de hipertônica de acetato de sódio mais dextrana sobre a reperfusão pós isquêmica. Avaliamos o fluxo sanguíneo e a capacidade antioxidante do plasma, a medula espinal e o músculo esquelético acima e abaixo da oclusão aórtica, bem como o fígado, rim e pâncreas. MÉTODO A aorta de porcos anestesiados (n = 5-6/grupo ) foi ocluída ao nível de T9 durante 30 min; os animais receberam 4 ml/kg acetato de Sódio + dextrana (HAD) ou 8,4% de NaHCO3 ( Controle ). Os porcos foram sacrificados 1h mais tarde. RESULTADOS Ao reduzir-se o fluxo de sangue a zero na medula espinal e músculo distal, observou-se duplicação do fluxo espinal e aumento de 6 vezes no músculo proximal. Durante a reperfusão, o fluxo de sangue em todas as regiões voltaram aos níveis basais, sem diferenças estatísticas entre HAD e Controles. A taxa de peroxidação lipídica no plasma foi menor em HAD que nos controles. O músculo distal apresentou níveis de glutationa 41% mais baixa e atividades significativamente mais baixas dos enzimas antioxidantes glutationa-peroxidase e redutase, catalase, superóxido dismutase em comparação com o músculo proximal. A medula espinal distal exibiu níveis 2,5 vezes mais elevados de malondialdeído e 50% maior de atividade catalase comparados com medula espinal proximal. Para qualquer tecido, diferenças significativas na capacidade antioxidante ou evidência de peroxidação lipídica favoreceram o grupo HAD em comparação com os controles. CONCLUSÃO HAD apresentou vantagens discretas sobre o bicarbonato em relação ao fluxo de sangue e status antioxidante de medula espinal e muscular após este período de oclusão aórtica seguida de reperfusão.

BACKGROUND Hypertonic/hyperoncotic fluids may reduce overall fluid requirements and tissue edema, improve perfusion and reduce the incidence of paraplegia associated with aortic cross-clamping and subsequent reperfusion. OBJECTIVE We evaluated potential benefits of a hypertonic saline acetate solution on reperfusion injury following ischemia. We examined blood flow and plasma antioxidant status, spinal cord and skeletal muscle above and below the cross-clamp, as well as in the liver and the kidney. METHOD The aorta of anesthetized swine (n=5-6/group) was cross-clamped at the level of T9 for 30 min; animals were infused with 4 ml/kg of hypertonic acetate dextran (HAD) or 8.4% NaHCO3 (Control). Pigs were euthanatized 1h later. RESULTS As blood flow fell to zero in lower spinal cord and muscle, it doubled in the upper cord and increased 6-fold in upper muscle. Upon reperfusion, blood flow in all regions returned to baseline levels, with no statistical differences between HAD and Controls. Lipid peroxidation in plasma was lower in HAD than Controls. Lower muscle had 41% lower glutathione levels and significantly lower activities of the antioxidant enzymes glutathione peroxidase and reductase, catalase, superoxide dismutase versus upper muscle. The lower spinal cord had 2.5 fold higher malondialdehyde levels and 50% higher catalase activity than upper spinal cord. Within a tissue, any significant differences in antioxidant status or evidence of lipid peroxidation favored HAD over Control. CONCLUSION HAD offered only minor advantages over NaHCO3 with respect to blood flow and antioxidant status of spinal cord and muscle following this period of aortic cross-clamping and reperfusion.

The objectives of this review are to assess the current state of hypertonic saline as a prehospital resuscitation fluid in hypotensive trauma patients, particularly after the 3 major Resuscitation Outcomes Consortium trauma trials in the US and Canada were halted due to futility. Hemorrhage and traumatic brain injury are the leading causes of death in both military and civilian populations. Prehospital fluid resuscitation remains controversial in civilian trauma, but small-volume resuscitation with hypertonic fluids is of utility in military scenarios with prolonged or delayed evacuation times. A large body of pre-clinical and clinical literature has accumulated over the past 30 years on the hemodynamic and, most recently, the anti-inflammatory properties of hypertonic saline, alone or with dextran-70. This review assesses the current state of hypertonic fluid resuscitation in the aftermath of the failed Resuscitation Outcomes Consortium trials.

INTRODUCTION: Investigation of resuscitation fluids in our swine hemorrhage model revealed moderate to severe chronic pneumonia in five swine at necropsy. Our veterinary staff suggested that we perform a retrospective analysis of prospectively collected data from these animals. We compared the data to that of ten healthy swine to determine the physiologic consequences of the added stress on our hemorrhage/resuscitation model. METHODS: Anesthetized, immature female swine (40 ± 5 kg) were instrumented for determining arterial and venous pressures, cardiac output and urine production. A controlled hemorrhage of 20 ml/kg over 4 min 40 sec was followed at 30 min by a second hemorrhage of 8 ml/kg and resuscitation with 1.5 ml/kg/min of LR solutions to achieve and maintain systolic blood pressure at 80 ± 5 mmHg for 3.5 hrs. Chemistries and arterial and venous blood gasses were determined from periodic blood samples along with hemodynamic variables. RESULTS: There were significant decreases in survival, urine output, cardiac output and oxygen delivery at 60 min and O2 consumption at 120 min in the pneumonia group compared to the non-pneumonia group. There were no differences in other metabolic or hemodynamic data between the groups. CONCLUSION: Although pneumonia had little influence on pulmonary gas exchange, it influenced cardiac output, urine output and survival compared to healthy swine, suggesting a decrease in the physiologic reserve. These data may be relevant to patients with subclinical infection who are stressed by hemorrhage and may explain in part why some similarly injured patients require more resuscitation efforts than others.