Miscellaneous Articles

Platelet infusion filter or not?

Michael Storm CRNA, MNA
Collected data July 2010

Alan D. Michelson: Platelet 2nd ed.p.45

Quick Platelet overview

Platelets, or thrombocytes, are small, irregularly-shaped non-nuclear cell fragments (i.e. cells that do not have a nucleus containing DNA). These structures are round or oval, flattened, disk-shaped. They are typically 2-5 µm in diameter, but some large platelets can be up to 7 µm in diameter. They are very thin, only 0.5 µm thick. They are formed by cleaving off fragments from the megakaryocytes in the bone marrow, a process regulated by the hormone thrombopoietin. The average lifespan of a platelet is 5 to 10 days. A normal platelet count is 150-400,000 µL.

Platelets play a fundamental role in hemostasis. The platelets circulate in an inactivated form in the blood and are primarily found hugging the walls of the blood vessels (due to their lightweight the flow in the vessels will force the platelets towards the outside). When encountering a damaged part of the vessel they become exposed to the endothelial underlying extracellular matrix (ECM) including collagen, von Willebrand factor (vWF) and other glycoprotein’s. This will activate the platelets and they undergo a transformation characterized by three major phases: adhesion, activation, and aggregation.

Miller: Miller’s Anesthesia 7th ed.p.2292-3

Platelet transfusion should normally be reserved for clinically coagulopathic patients with a documented low serum level (<50,000 per high-power field). When the patient is in shock, however, and blood loss is likely to be substantial, platelets should be empirically administered in proportion to RBCs and plasma (1 : 1 : 1). Transfused platelets have a very short serum half-life and should be administered only to patients with active coagulopathic bleeding. Platelets should not be administered through filters, warmers, or rapid infusion systems because they will bond to the inner surfaces of these devices, thereby reducing the quantity of platelets actually reaching the circulation.

Barash: Clinical Anesthesia 6th ed.p.385

Platelets should be delivered through the standard 170-micron blood set filter. A micropore filter should not be used.

Charles J. Coté et al: A practice of anesthesia for infants and children 4th ed.p.199

Platelets should be filtered only by large-pore filters (>150 µm) or leukocyte-reduction filters (if indicated); micropore filters may absorb large numbers of platelets and therefore diminish the effectiveness of a platelet transfusion.