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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Efforts to improve survival from sepsis are focusing increasingly on intervention during the earliest stages of this disease. The importance of derangements in microvascular flow in patients with established sepsis is well recognized. However, little data are available to describe microvascular changes in early sepsis. ⋯ Sepsis results in derangements of microvascular flow, which can be identified in the early stages of this disease. These abnormalities are more marked in the most severely ill patients. Further research is required to fully characterize the effects of sepsis on microvascular function.
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Dysfunction of hepatic microcirculation during inflammatory stress conditions is associated with overexpression of caveolin 1 (Cav-1) in sinusoidal endothelial cells. Because Cav-1 binds and inhibits eNOS, it was suggested that Cav-1 overexpression inhibits endothelin 1 (ET-1)-mediated eNOS activation after endotoxemia in the liver; however, a causal link between stress-mediated suppression of eNOS and Cav-1 overexpression has not been fully established. We hypothesize that genetic knockout of Cav-1 reverses the LPS-suppressed ET-1-mediated eNOS activation. ⋯ The reversal of LPS inhibition resulted in an increase in ET-1-induced eNOS translocation to the plasma membrane and an augmentation of NO production in the perinuclear region and plasma membrane of Cav-1 KO LSECs. These results showed that genetic knockout of Cav-1 increased basal eNOS activity and at least partially restored ET-1-mediated eNOS translocation and NO production in LSECs after LPS treatment. In conclusion, Cav-1 overexpression is a requirement for decreased eNOS activity in LSECs after endotoxemia.
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Increased catecholamine (CA) levels after severe burn are associated with stress, inflammation, hypermetabolism, and impaired immune function. The CA secretion profiles in burned patients are not well described. Mechanisms, duration, and extent of CA surge are unknown. ⋯ There were differences over time in survivors versus nonsurvivors, with CA levels significantly higher in nonsurvivors at two time points. Inflammatory cytokines show a similar profile during the study period. Our study gives clinicians a useful insight into the extent and magnitude of CA elevation to better design treatment strategies.
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Randomized Controlled Trial
Efficacy and safety of dopamine versus norepinephrine in the management of septic shock.
The optimum septic shock vasopressor support strategy is currently debated. This study was performed to evaluate the efficacy and safety of norepinephrine (NE) and dopamine (DA) as the initial vasopressor in septic shock patients who were managed with a specific treatment protocol. A prospective, randomized, open-label, clinical trial was used in a medical intensive care unit comparing DA with NE as the initial vasopressor in fluid-resuscitated 252 adult patients with septic shock. ⋯ In this protocol-directed vasopressor support strategy for septic shock, DA and NE were equally effective as initial agents as judged by 28-day mortality rates. However, there were significantly more cardiac arrhythmias with DA treatment. Patients receiving DA should be monitored for the development of cardiac arrhythmias (NCT00604019).
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Relationship of basal heart rate variability to in vivo cytokine responses after endotoxin exposure.
Autonomic inputs from the sympathetic and parasympathetic nervous systems, as measured by heart rate variability (HRV), have been reported to correlate to the severity injury and responses to infectious challenge among critically ill patients. In addition, parasympathetic/vagal activity has been shown experimentally to exert anti-inflammatory effects via attenuation of splanchnic tissue TNF-alpha production. We sought to define the influence of gender on HRV responses to in vivo endotoxin challenge in healthy humans and to determine if baseline HRV parameters correlated with endotoxin-mediated circulating cytokine responses. ⋯ We found that gender, body mass index, or resting heart rate did not significantly alter the HRV response after endotoxin exposure. Using entropy analysis, we observed that females had significantly higher entropy values at 24 h after endotoxin exposure. Using a serially sampling protocol for cytokine determination, we found a significant correlation of several baseline HRV parameters (percentage of interval differences of successive interbeat intervals more than 50 ms, r = 0.42, P < 0.05; high-frequency variability, r = 0.4, P < 0.05; and low-frequency/high-frequency ratio, r = -0.43, P < 0.05) on TNF-alpha release after endotoxin exposure.