Critical care : the official journal of the Critical Care Forum
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Comparative Study
Effects of thoraco-pelvic supports during prone position in patients with acute lung injury/acute respiratory distress syndrome: a physiological study.
This study sought to assess whether the use of thoraco-pelvic supports during prone positioning in patients with acute lung injury/acute respiratory distress syndrome (ALI/ARDS) improves, deteriorates or leaves unmodified gas exchange, hemodynamics and respiratory mechanics. ⋯ The application of thoraco-pelvic supports decreases chest wall compliance, increases pleural pressure and slightly deteriorates hemodynamics without any advantage in gas exchange. Consequently, we stopped their use in clinical practice.
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Early changes of CD4-positive lymphocytes and NK cells in patients with severe Gram-negative sepsis.
Our aim was to define early changes of lymphocytes and of NK cells in severe sepsis and to correlate them with serum levels of soluble triggering receptor expressed on myeloid cells-1 (sTREM-1). ⋯ Early severe sepsis is characterized by CD4-lymphopenia and increased NK cells, providing a survival benefit for the septic patient at percentages >20%. The survival benefit resulting from elevated NK cells might be connected to elevated serum levels of sTREM-1.
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Measurements of central venous oxygen saturation (ScvO2) have been successfully used to guide haemodynamic therapy in critical care. The efficacy of this approach in the treatment of severe sepsis and septic shock has stimulated interest in the use of ScvO2 to guide management in patients undergoing major surgery. The physiological basis of ScvO2 measurement is complex. ⋯ Second, there is some uncertainty as to which interventions are the most effective for achieving the desired value of ScvO2 or how long this value should be maintained. The study by The Collaborative Study Group on Perioperative ScvO2 Monitoring published in this edition of Critical Care may help provide answers to some of these questions. Our understanding of ScvO2 measurement remains limited, however, and the routine use of peri-operative ScvO2-guided goal-directed therapy cannot be recommended until a large randomised trial has confirmed the value of this approach.
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Predicting fluid responsiveness has become a topic of major interest. Measurements of intravascular pressures and volumes often fail to predict the response to fluids, even though very low values are usually associated with a positive response to fluids. ⋯ PLR induces an abrupt increase in preload due to autotransfusion of blood contained in capacitance veins of the legs, which leads to an increase in cardiac output in preload-dependent patients. This commentary discusses some of the technical issues related to this test.
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The complex biology of critical illness not only reflects the initial insult that brought the patient to the intensive care unit but also, and perhaps even more importantly, it reflects the consequences of the many clinical interventions initiated to support life during a time of lethal organ system insufficiency. The latter may amplify or modify the response to the former and are eminently amenable to modulation by changes in practice. ⋯ In the preceding issue of Critical Care, O'Mahony and colleagues reported on an animal model in which sequential insults--low-dose endotoxin followed by mechanical ventilation--induce much greater remote organ injury than either insult alone. Although animal models are poor surrogates for clinical illness, studies such as these provide valuable platforms for probing the complex interactions between insult and therapy that give rise to the intricate biology of critical illness.