Critical care : the official journal of the Critical Care Forum
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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.
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During 2005 Critical Care published several original papers dealing with resource management. Emphasis was placed on sepsis, especially the coagulation cascade, prognosis and resuscitation. The papers highlighted important aspects of the pathophysiology of coagulation and inflammation in sepsis, as well as dealing with the proper use of newly developed compounds. ⋯ Resuscitation received great attention, dealing with the effects of fluid infusion in hemodynamics and the lung. The information obtained can be used to address unknown effects of established therapies, to enlighten current clinical discussion on controversial topics, and to introduce novel medical resources and strategies. Future clinical work will rely heavily on these preclinical and laboratory data.
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Further work on the use of albumin in the intensive care unit is discussed. The interesting pilot study by Dubois and colleagues examines the potential benefits for albumin supplementation in the hypoalbuminaemic critically ill patient. Maintaining the fluid theme, we discuss recent work on factors influencing post-intensive care unit blood transfusion as well as another study on erythropoietin. Finally, a large multicentred trial comparing continuous venovenous haemofiltration with intermittent haemodialysis is outlined, the results of which pose more questions than answers.