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In a typical set of rules, a platelet donor must weigh at least 50 kg (110 lb) and have a platelet count of at least 150 x 10 9 /L (150,000 platelets per mm³). [2] One unit has greater than 3×10 11 platelets. Therefore, it takes 2 liters of blood having a platelet count of 150,000/mm³ to produce one unit of platelets.
For example, in patients undergoing surgery, a level below 50×10 9 /L is associated with abnormal surgical bleeding, and regional anaesthetic procedures such as epidurals are avoided for levels below 80×10 9 /L. [68] Platelets may also be transfused when the platelet count is normal but the platelets are dysfunctional, such as when an ...
Higher platelet transfusion thresholds have been used in premature neonates, but this has been based on limited evidence. [19] There is now evidence that using a high platelet count threshold (50 x 10 9 /L) increases the risk of death or bleeding compared to a lower platelet count threshold (25 x 10 9 /L) in premature neonates. [20]
For apheresis platelet donation the donor's pre platelet count should be above 150 x 10^9/L. For apheresis plasma donation, the donor's total protein level should be greater than 60 g/L. For double red cell apheresis, donors of either gender require a minimum hemoglobin level of 14.0 g/dl.
Platelet plug formation: The adhered platelets aggregate and form a temporary plug to stop bleeding. This process is often called "primary hemostasis". [19] Coagulation cascade: It is a series of enzymatic reactions that lead to the formation of a stable blood clot. The endothelial cells release substances like tissue factor, which triggers the ...
Originally, platelets were stored in the donor’s own plasma. Nowadays, many blood banks have switched to using platelet additive solution to store platelets. Typically, when platelets are isolated from whole blood, not all plasma is removed, as platelets need to be in a certain volume of plasma in order to have a clear separation from other ...
Clot retraction is dependent on the release of multiple coagulation factors from platelets trapped in the fibrin mesh of the clot. Thus, failure to retract can be a sign of thrombocytopenia or a rare condition called thrombasthenia. Blood clot prevention can be of use before this condition develops.
The platelet plug, also known as the hemostatic plug or platelet thrombus, is an aggregation of platelets formed during early stages of hemostasis in response to one or more injuries to blood vessel walls. After platelets are recruited and begin to accumulate around the breakage, their “sticky” nature allows them to adhere to each other.