Shock : molecular, cellular, and systemic pathobiological aspects and therapeutic approaches : the official journal the Shock Society, the European Shock Society, the Brazilian Shock Society, the International Federation of Shock Societies
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Microvascular responses to blood volume restitution using red blood cells (RBCs) with modified hemoglobin (Hb) oxygen affinity were studied in the hamster window chamber model during resuscitation from hemorrhagic shock. Allosteric effectors inositol hexaphosphate and 5-hydroxymethyl-2-furfural were introduced into the RBCs by electroporation to decrease and increase Hb-oxygen affinity. In vitro P50s (partial pressure of oxygen at 50% Hb saturation) were modified to 10 and 50 mmHg (normal P50, 32 mmHg). ⋯ There was no significant difference in oxygen extraction. Oxygen extraction ratio (oxygen extraction/oxygen delivery) x 100 was significantly higher in HP50 than in LP50. These results suggest that lowering blood P50 in resuscitation provides improved microvascular function in comparison with higher P50.
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Monitoring of central venous oxygen saturation (ScvO2) is considered comparable with mixed venous oxygen saturation (SvO2) in the initial resuscitation phase of septic shock. Our aim was to assess their agreement in septic shock in the intensive care unit setting and the effect of a potential difference in a computed parameter, namely, oxygen consumption (VO2). In addition, we sought for a central venous to pulmonary artery (PA) lactate gradient. ⋯ Thus, our data suggest that ScvO2 and SvO2 are not equivalent in intensive care unit patients with septic shock. Additionally, the substitution of ScvO2 for SvO2 in the calculation of VO2 produces unacceptably large errors. Finally, the decrease in lactate between RA and PA may support the hypothesis that the mixing of RA and coronary sinus blood is at least partially responsible for the difference between ScvO2 and SvO2.
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Respiratory rate (RR) is a basic vital sign, measured and monitored throughout a wide spectrum of health care settings, although RR is historically difficult to measure in a reliable fashion. We explore an automated method that computes RR only during intervals of clean, regular, and consistent respiration and investigate its diagnostic use in a retrospective analysis of prehospital trauma casualties. At least 5 s of basic vital signs, including heart rate, RR, and systolic, diastolic, and mean arterial blood pressures, were continuously collected from 326 spontaneously breathing trauma casualties during helicopter transport to a level I trauma center. "Reliable" RR data were identified retrospectively using automated algorithms. ⋯ For identifying casualties subsequently diagnosed with a major hemorrhagic injury and requiring blood transfusion, standard RR yields an AUC of 0.60 (0.49-0.70), whereas reliable RR yields 0.77 (0.67-0.85), P < 0.001. Reliable RR, as determined by an automated algorithm, is a useful parameter for the diagnosis of respiratory pathology and major hemorrhage in a trauma population. It may be a useful input to a wide variety of clinical scores and automated decision-support algorithms.
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The importance of postoperative procalcitonin (PCT) measurements for outcome prediction is currently controversial. Conflicting results have been obtained for patients after polytrauma, sepsis, peritonitis, or cardiac surgery and may result from incomplete adjustment for important confounders or from nonlinear PCT effects. We retrospectively analyzed the association of PCT concentration with postoperative mortality, morbidity, and length of stay in an unselected series of 220 consecutive patients who required postoperative intensive care unit therapy or surveillance. ⋯ At mortality analysis, the predictive power of PCT was superior to that of Acute Physiology and Chronic Health Evaluation II score and of IL-6 (optimal cutoff point, 1.44 ng/mL; sensitivity, 80.8%; specificity, 80.4%). The use of PCT was comparable to that of other prognostic markers when combined mortality/morbidity were examined. Our results suggest that PCT may deserve further testing as a prognostic tool in unselected, critically ill, surgical patients.
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The purpose of the study was to investigate microcirculation and vascular reactivity during experimental endotoxemia and endotoxin tolerance in humans by comparing different methods of approach. Endotoxin tolerance was induced in nine healthy volunteers by intravenous injection of 2 ng . kg(-1) . d(-1) LPS for 5 consecutive days. Microcirculation and vascular reactivity were monitored before and after LPS administrations on days 1 and 5 by near-infrared spectroscopy, sidestream dark-field imaging, and forearm blood flow by venous occlusion strain-gauge plethysmography during local intra-arterial infusion of endothelial-dependent vasodilator acetylcholine (0.5, 2, and 8 microg . min(-1) . dL(-1)). ⋯ Sidestream dark-field imaging showed 33% (IQR, 14%-40%) and 30% (IQR, 10%-33%) diminished flow in medium and large microvessels, respectively, 2 h after LPS administration on day 1 (P = 0.07 and 0.04, respectively), which was absent on day 5 (P = 0.47 for both vessels). Forearm blood flow measurements showed an attenuation of acetylcholine-induced vasodilatory response, with 67% (IQR, 45%-72%) 4 h after the first LPS administration (P = 0.01), but not when tolerance was present on day 5 (P = 0.61). Human endotoxemia results in endothelial dysfunction that can be adequately detected with different methods and was restored with development of LPS tolerance.