Critical care : the official journal of the Critical Care Forum
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Review Historical Article
Bench-to-bedside review: a brief history of clinical acid-base.
The history of assessing the acid-base equilibrium and associated disorders is intertwined with the evolution of the definition of an acid. In the 1950s clinical chemists combined the Henderson-Hasselbalch equation and the Bronsted-Lowry definition of an acid to produce the current bicarbonate ion-centred approach to metabolic acid-base disorders. ⋯ This approach, using the strong ion difference (particularly the sodium chloride difference) and the concentration of weak acids (particularly albumin), pushes bicarbonate into a minor role as an acid-base indicator rather than as an important mechanism. The Stewart approach may offer new insights into acid-base disorders and therapies.
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This review describes current knowledge on the mechanisms that underlie glucocorticoid insufficiency in sepsis and the molecular action of glucocorticoids. In patients with severe sepsis, numerous factors predispose to glucocorticoid insufficiency, including drugs, coagulation disorders and inflammatory mediators. These factors may compromise the hypothalamic-pituitary axis (i.e. secondary adrenal insufficiency) or the adrenal glands (i.e. primary adrenal failure), or may impair glucocorticoid access to target cells (i.e. peripheral tissue resistance). ⋯ The molecular action of glucocorticoids results in genomic and nongenomic effects. Direct and indirect transcriptional and post-transcriptional effects related to the cytosolic glucocorticoid receptor account for the genomic effects. Nongenomic effects are probably subsequent to cytosolic interaction between the glucocorticoid receptor and proteins, or to interaction between glucocorticoids and specific membrane binding sites.
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Of brain-injured patients admitted to intensive care units, a significant number acquires nosocomial infections. Increased susceptibility to infectious agents could, at least partly, be due to transient immunodepression triggered by brain damage. ⋯ Activation of the hypothalamo-pituitary-adrenal axis and the sympathetic nervous system plays a crucial role in brain-mediated immunodepression. In this review we discuss the role of immunodepression in the development of nosocomial infections and clinical trials on immunomodulation in brain-injured patients with hospital-acquired infections.
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Severe sepsis is a dreaded consequence of infection and necessitates intensive care treatment. Severe sepsis has a profound impact on mortality and on hospital costs, but recent incidence data from The Netherlands are not available. The purpose of the present study was to determine the prevalence and incidence of severe sepsis occurring during the first 24 hours of admission in Dutch intensive care units (ICUs). ⋯ The annual number of admissions for severe sepsis in Dutch ICUs was calculated at 8643 +/- 929 cases/year, which is 0.054% of the population, 0.61% of hospital admissions and 11% of ICU admissions.
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Three new articles in Critical Care add to an expanding body of information on the epidemiology of severe sepsis. Although there have been a range of approaches to estimate the incidence of severe sepsis, most studies report severe sepsis in about 10 +/- 4% of ICU patients with a population incidence of 1 +/- 0.5 cases per 1000. Importantly, the availability of ICU services may well determine the number of treated cases of severe sepsis, and it seems clear that these studies are reporting the treated incidence, not the incidence, of severe sepsis. In the future, we must focus on whether all severe sepsis should be treated, and, consequently, what level of ICU services is optimal.