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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This prospective study was aimed to test the hypothesis that tissue hemoglobin oxygen saturation (StO₂) measured noninvasively using near-infrared spectroscopy is a reliable indicator of global oxygen delivery (DO₂) measured invasively using a pulmonary artery catheter (PAC) in patients with septic shock. The study setting was a 26-bed medical-surgical intensive care unit at a university hospital. Subjects were adult patients in septic shock who required PAC hemodynamic monitoring for resuscitation. ⋯ A StO₂ cutoff value of 75% predicted iDO₂ below 450, with a sensitivity of 0.9 and a specificity of 0.9. In patients in septic shock and normalized MAP, low StO₂ reflects extremely low iDO₂. Steady-state StO₂ does not correlate with moderately low iDO₂, indicating poor sensitivity of StO₂ to rule out hypoperfusion.
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Oxidative stress, a situation with increased reactive oxygen species production and/or decreased antioxidant defense mechanisms, is evident in the pathogenesis of sepsis. Peroxiredoxin 4 (Prx4) is a hydrogen peroxide degrading peroxidase recently found circulating in blood of septic patients and potentially reflecting an antioxidant system in imbalance. We studied Prx4 serum levels of 79 consecutively enrolled medical intensive care unit patients. ⋯ In this study, elevated serum levels of the antioxidant Prx4 were associated with an increased disease severity and adverse outcome of critically ill patients with sepsis. Peroxiredoxin 4 may therefore be a helpful new biomarker for diagnosing, monitoring, and risk assessing these patients. The pathophysiological mechanisms behind the observed increase remain to be elucidated.
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Midkine, a multifunctional cytokine, in patients with severe sepsis and septic shock: a pilot study.
The objective of the study was to evaluate whether severe sepsis and septic shock are related to alterations in midkine concentrations, to identify disease-related factors associated with these alterations, and to initially appraise whether midkine might serve as a biomarker in sepsis. Prospective observational cross-sectional study with 5-day follow-up. Circulating midkine was measured (enzyme-linked immunosorbent assay) in 38 septic (13 with severe sepsis, 25 with septic shock), 82 active inflammatory bowel disease (IBD) (26 with systemic inflammatory response syndrome [SIRS]) patients, and 87 healthy subjects. ⋯ In conclusion, sepsis and septic shock are associated with midkine elevation, substantially more pronounced than in inflammation, even systemic, revealing a new potential mediator of deregulation of neutrophil migration. Sepsis-related global hypoxia seems to contribute to midkine elevation. Our results substantiate further research on possible midkine application as a sepsis biomarker: in differentiating SIRS from sepsis and identifying gram-positive sepsis and septic patients at risk of CVI and shock.
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Nitric oxide-mediated activation of large conductance calcium-activated potassium (BK) channels is considered an important underlying mechanism of sepsis-induced hypotension. Indeed, the nonselective K-channel inhibitor, tetraethylammonium chloride (TEA), has been proposed as a potential treatment to raise blood pressure in septic shock by virtue of its ability to inhibit BK channels. As experimental evidence has so far relied on pharmacological inhibition, we examined the effects of channel deletion using BKα subunit knockout (α, Slo) mice in two mouse models of polymicrobial sepsis, namely, intraperitoneal fecal slurry and cecal ligation and puncture. ⋯ However, following cecal ligation and puncture, a significantly reduced survival was seen in both BKα mice and (high-dose) TEA-treated WT mice compared with untreated WT animals. In conclusion, the BK channel does not appear to be integral to sepsis-induced hypotension but does affect survival through other mechanisms. The pressor effect of TEA may be related to effects on other potassium channels.
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Sepsis develops as a result of the host response to infection, and its mortality rate in ICU remains high. Severe inflammation usually causes overproductions of proinflammatory cytokines, i.e., TNF-α and reactive oxygen species, which lead to mitochondrial damage and energetic depletion. Autophagy is a survival mechanism for eukaryote to recycle intracellular nutrients and maintain energy homeostasis. ⋯ The tissue localization of autophagy was identified by immunohistochemistry and transmission electron microscopy. Our results showed that (a) increase in LC3-II level in liver tissue occurs at 3 h, peaks at 6 h, and then surprisingly declines quickly until 18 h after CLP (CLP18h); (b) significant hepatic dysfunction was observed at CLP18h; (c) ratio of LC3 aggregation is significantly higher in hepatocytes than in Kupffer cells, and (d) loss of Atg7, an essential gene for autophagosome formation, exaggerates the TNF-α-induced cell death, depletion of ATP, and decrease of albumin production in hepatocytes. These results indicate that autophagy occurs transiently in hepatocytes at early stage, and the decline in autophagy at late stage may contribute to the functional failure in liver during polymicrobial sepsis.