Best practice & research. Clinical anaesthesiology
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Best Pract Res Clin Anaesthesiol · Jun 2007
TRALI--definition, mechanisms, incidence and clinical relevance.
Transfusion-related acute lung injury (TRALI) is defined as new acute lung injury (ALI) that occurs during or within six hours of transfusion, not explained by another ALl risk factor. Transfusion of part of one unit of any blood product can cause TRALI. The mechanism may include factors in unit(s) of blood, such as antibody and biologic response modifiers. ⋯ Management is similar to that for ALI and is predominantly supportive. When TRALI is suspected, Blood banks should be notified to quarantine other components from the same donation. No special blood product is required for subsequent transfusion of a patient who has developed TRALI.
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In clinical practice, the decision to transfuse is linked to the hope of increasing oxygen transport (TO2) to tissues. Physiologic transfusion triggers should progressively replace arbitrary hemoglobin-based transfusion triggers. These 'physiologic' transfusion triggers can be based on signs and symptoms of impaired global oxygenation (lactate, venous O2 saturation [SvO2]) or, even better, of regional tissue oxygenation (electrocardiographic ST-segment, electroencephalographic P300 latency). The SvO2 or its surrogate, the central venous 02 saturation (ScvO2), is a clinical tool which integrates the relationship between whole-body O2 uptake and TO2, and as such can be proposed as a simple physiologic transfusion trigger.
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Performing a surgical procedure on a patient undergoing anti-platelet therapy raises a dilemma: is it safer to withdraw the drugs and reduce the haemorrhagic risk, or to maintain them and reduce the risk of myocardial ischaemic events? Based on recent clinical data, this review concludes that the risk of coronary thrombosis on anti-platelet drugs withdrawal is much higher than the risk of surgical bleeding when maintaining them. In secondary prevention, aspirin is a lifelong therapy and should never be stopped. Clopidogrel is mandatory as long as the coronary stents are not fully endothelialized, which takes 6-24 weeks depending on the technique used, but might be required for a longer period.
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Best Pract Res Clin Anaesthesiol · Jun 2007
ReviewAllogeneic red blood cell transfusion: physiology of oxygen transport.
Allogeneic red blood cell (RBC) transfusions have been shown to be associated with considerable risks. While their efficiency in many clinical situations has not been proven, the number of studies finding adverse outcomes in terms of morbidity (e.g. postoperative infections) and mortality continues to rise. ⋯ Only a thorough knowledge of the physiology and pathophysiology of oxygen transport can be a solid base for meaningful transfusion decisions. Therefore, the goal of this article is to review the basics of oxygen transport and normovolaemic anaemia.
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The majority of intensive care unit (ICU) patients will receive a blood transfusion at some point during the course of their ICU stay, generally in an attempt to increase oxygen delivery and hence tissue oxygenation. The efficacy of red blood cell (RBC) transfusion can be evaluated through its effects on patient mortality or morbidity, or more simply by its effects on tissue oxygenation. ⋯ The true challenge lies in determining which patients will benefit from transfusion and those in whom it may be safe to delay or withhold transfusion. In this article, several key factors influencing the systemic and regional efficacy of blood transfusion will be reviewed.