Critical care : the official journal of the Critical Care Forum
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Bland-Altman analysis is used for assessing agreement between two measurements of the same clinical variable. In the field of cardiac output monitoring, its results, in terms of bias and limits of agreement, are often difficult to interpret, leading clinicians to use a cutoff of 30% in the percentage error in order to decide whether a new technique may be considered a good alternative. This percentage error of +/- 30% arises from the assumption that the commonly used reference technique, intermittent thermodilution, has a precision of +/- 20% or less. ⋯ In a worked example in this paper, we discuss the limitations of this approach, in particular in regard to the situation in which the reference technique may be either more or less precise than would normally be expected. This can lead to inappropriate conclusions being drawn from data acquired in validation studies of new monitoring technologies. We conclude that it is not acceptable to present comparison studies quoting percentage error as an acceptability criteria without reporting the precision of the reference technique.
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Randomized Controlled Trial
The effect of exogenous glucagon-like peptide-1 on the glycaemic response to small intestinal nutrient in the critically ill: a randomised double-blind placebo-controlled cross over study.
Hyperglycaemia occurs frequently in the critically ill, affects outcome adversely, and is exacerbated by enteral feeding. Furthermore, treatment with insulin in this group is frequently complicated by hypoglycaemia. In healthy patients and those with type 2 diabetes, exogenous glucagon-like peptide-1 (GLP-1) decreases blood glucose by suppressing glucagon, stimulating insulin and slowing gastric emptying. Because the former effects are glucose-dependent, the use of GLP-1 is not associated with hypoglycaemia. The objective of this study was to establish if exogenous GLP-1 attenuates the glycaemic response to enteral nutrition in patients with critical illness induced hyperglycaemia. ⋯ Acute, exogenous GLP-1 infusion markedly attenuates the glycaemic response to enteral nutrition in the critically ill. These observations suggest that GLP-1 and/or its analogues have the potential to manage hyperglycaemia in the critically ill.
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Comparative Study
Comparison of three methods of extravascular lung water volume measurement in patients after cardiac surgery.
Measurement of extravascular lung water (EVLW) by using the lithium-thermal (Li-thermal) and single-thermal indicator dilution methods was compared with the indocyanine green-thermal (ICG-thermal) method in humans. ⋯ The principal finding of this study was that the prototype Li-thermal method did not provide reliable measurements of EVLW volume when compared with the ICG-thermal reference technique. Although minimal bias was associated with the single-thermal method, limits of agreement were approximately 45% of the normal value of EVLW volume. The Li-thermal method performed very poorly because of the overestimation of mean indicator transit time by using an external lithium ion electrode. These findings suggest that the assessment of lung water content by lithium-indicator dilution is not sufficiently reliable for clinical use in individual patients.
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Randomized Controlled Trial
Hemostasis during low molecular weight heparin anticoagulation for continuous venovenous hemofiltration: a randomized cross-over trial comparing two hemofiltration rates.
Renal insufficiency increases the half-life of low molecular weight heparins (LMWHs). Whether continuous venovenous hemofiltration (CVVH) removes LMWHs is unsettled. We studied hemostasis during nadroparin anticoagulation for CVVH, and explored the implication of the endogenous thrombin potential (ETP). ⋯ We found no accumulation and no removal of LMWH activity during CVVH. However, we found that early circuit clotting was associated with more severe organ failure, prior systemic thrombin generation with consumptive coagulopathy, heparin resistance and elevated extracorporeal thrombin generation. ETP integrates these complex effects on the capacity to form thrombin.
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In the previous issue of Critical Care, Blanco and colleagues contributed to a growing body of literature on the international epidemiology of severe sepsis. Taken together, these studies confirm that the sepsis incidence is high, that the development of organ dysfunction is a major determinant of mortality and that the occurrence of organ dysfunction is influenced by chronic comorbid medical conditions. ⋯ Identifying factors that contribute to the development of organ dysfunction in sepsis will lead to the development of new treatment modalities that will reduce mortality. Future studies must therefore focus on the impact of new treatment modalities for preventing progression to multiple organ dysfunction syndrome and consequent mortality in sepsis.