Critical care : the official journal of the Critical Care Forum
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Editorial Comment
Respiratory variation in inferior vena cava diameter: surrogate of central venous pressure or parameter of fluid responsiveness? Let the physiology reply.
In the previous issue of Critical Care, Muller and colleagues investigated whether respiratory variation in inferior vena cava diameter (ΔIVC) could be a useful predictor of fluid responsiveness in spontaneously breathing patients. The study concludes that accuracy was not very good and therefore that this parameter should be used with caution in these patients. There is still confusion about the meaning of IVC respiratory variations, whether the patient is spontaneously breathing or mechanically ventilated. In this brief commentary, we try to summarize as clearly as possible the significance of IVC variation in different clinical settings.
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Observational Study
Whole blood impedance aggregometry as a biomarker for the diagnosis and prognosis of severe sepsis.
Sepsis leads to an activation of the immune system and hemostatis. However, studies on platelet aggregation in severe sepsis using impedance aggregometry have not been performed and the diagnostic and prognostic capabilities are unknown. In the present study we hypothesized that impedance aggregometry findings might serve as a biomarker for the diagnosis and prognosis of severe sepsis. ⋯ In severe sepsis, impedance aggregometry allows better prediction of diagnosis and survival than conventional biomarkers and platelet count.
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The need for a reliable neurological evaluation in severely brain-injured patients conflicts with sedation, which is routinely administered. Helbok and colleagues prospectively evaluated in a small cohort of 20 sedated severely brain-injured patients the effects of a wakeup test on intracranial pressure (ICP), brain tissue oxygen tension and brain metabolism. The test has been considered potentially risky on 34% of the study days. ⋯ In this cohort, the information gained with the wake-up test has been negligible. Given the current little knowledge about the benefits of interruption of continuous sedation in brain-injured patients, it is extremely important to adopt multiple monitoring modalities in neurocritical care in order to escape wake-up tests in those patients who will potentially be harmed by this procedure. Once the clinical condition will improve, sedation needs to be tapered and suspended as soon as possible.
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New ways of approaching sedation and analgesia are being considered in our endeavour to improve our management of the ventilated patient. Long-term psychological problems are not insignificant and before we can assume benefit or harm of any new approach we must not delude ourselves by using sampling methods that can miss those patients most at risk.