Critical care : the official journal of the Critical Care Forum
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Sepsis is a complex syndrome that develops when the initial, appropriate host response to an infection becomes amplified, and is then dysregulated. Among other factors, the innate immune system is of central importance to the early containment of infection. Death from infection is strongly heritable in human populations. ⋯ The rationale for studying gene SNPs in critical illnesses seeks to identify potential markers of susceptibility, severity, and clinical outcome; seeks to identify potential markers for responders and non-responders in clinical trials, and seeks to identify targets for therapeutic intervention. In this review, we focus on the current state of association studies of those genes governing the powerful bacterial infection-induced inflammation and provide guidelines for future studies describing disease associations with genetic variations based on current recommendations. We envision a time in the near future when genotyping will be include in the standard evaluation of critically ill patients and will help to prioritize a therapeutic option.
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The organs of the hepatosplanchnic system are considered to play a key role in the development of multiorgan failure during septic shock. Impaired oxygenation of the intestinal mucosa can lead to disruption of the intestinal barrier, which may promote a vicious cycle of inflammatory response, increased oxygen demand and inadequate oxygen supply. ⋯ These therapies may have beneficial or detrimental effects not only on systemic haemodynamics but also on splanchnic haemodynamics, at both the macrocirculatory and microcirculatory levels. This clinical review focuses on the splanchnic haemodynamic and metabolic effects of standard therapies used in patients with septic shock, as well as on the recently described nonconventional therapies such as vasopressin, prostacyclin and N-acetyl cysteine.
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Mechanical ventilation can cause and perpetuate lung injury if alveolar overdistension, cyclic collapse, and reopening of alveolar units occur. The use of low tidal volume and limited airway pressure has improved survival in patients with acute lung injury or acute respiratory distress syndrome. The use of recruitment maneuvers has been proposed as an adjunct to mechanical ventilation to re-expand collapsed lung tissue. ⋯ However, it is unclear whether recruitment maneuvers are useful when patients with acute lung injury or acute respiratory distress syndrome are ventilated with high positive end-expiratory pressure, and in the presence of lung fibrosis or a stiff chest wall. Moreover, it is unclear whether the use of high airway pressures during recruitment maneuvers can cause bacterial translocation. This article reviews the intrinsic mechanisms of mechanical stress, the controversy regarding clinical use of recruitment maneuvers, and the interactions between lung infection and application of high intrathoracic pressures.
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Acid-base disorders are common in critically ill patients. Metabolic acid-base disorders are particularly common in patients who require acute renal replacement therapy. In these patients, metabolic acidosis is common and multifactorial in origin. ⋯ The nature and extent of these acid-base changes is governed by the intensity of plasma water exchange/dialysis and by the 'buffer' content of the replacement fluid/dialysate, with different effects depending on whether lactate, acetate, citrate, or bicarbonate is used. These effects can be achieved in any patient irrespective of whether they have acute renal failure, because of the overwhelming effect of plasma water exchange on nonvolatile acid balance. Critical care physicians must understand the nature, origin, and magnitude of alterations in acid-base status seen with acute renal failure and during continuous hemofiltration if they wish to provide their patients with safe and effective care.
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The use of glucocorticoids (corticotherapy) in severe sepsis is one of the main controversial issues in critical care medicine. These agents were commonly used to treat sepsis until the end of the 1980s, when several randomized trials casted serious doubt on any benefit from high-dose glucocorticoids. ⋯ The concepts of adrenal insufficiency and peripheral glucocorticoid resistance are developed, and the main experimental and clinical data that support the use of low-dose glucocorticoids in septic shock are discussed. Finally, we propose a decision tree for diagnosis of adrenal insufficiency and institution of cortisol replacement therapy.