Haemoglobin/red cells. Hb can be measured in laboratory and point-of-care testing. It is highly accurate. Whilst Hb is an important component of oxygen delivery, there is mounting evidence that the advantage of increasing Hb is offset by the harm and cost of transfusing blood from donors. Several landmark trials have reinforced this point. It is generally accepted that 70g/dl should be the transfusion trigger in most critically ill patients. Transfusion should be avoided out-of-hours, although this is surprisingly difficult to do, due to the tempo of workflow, where decisions to transfuse tend to occur in the day, leading to delivery of transfusion at night. Evidence suggests that fresh blood is not superior to stored blood. Attempts to develop artificial haemoglobins have been unsuccessful. 

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Factor Xa levels - a method of tracking anticoagulation that is thought to provide a better laboratory marker than more historical measures such as PT and APTR. 

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TEG - Thromboelastography provides rapid point-of-care testing of whole blood clotting. It has multiple advantages over more standard laboratory blood tests in that it provides a rapid evaluation of the ability of whole blood to clot. There is minimal lead-time, and the test can be used to guide resuscitation with blood products and adjuvant therapies designed to augment or prevent blood clotting. The test is also easy to understand and does not test individual components of blood clotting. 

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There are several key parameters.

r time: represents the time from the start of the test to initial fibrin formation. 15-23 mins normal blood; 5-7 minutes kaolin activated. 

k-time - represents the time to develop effective clot after r time. 20mm amplitude. 5-10 mins whole blood; 1-3 mins kaolin activated

alpha angle - measures speed of fibrin build-up

max amplitude - measures clot strength - platelet function Normal range 47-58mm (fibrin clot is 80% platelets and 20% fibrinogen