Clinical perspectives of platelet transfusions: defining the optimal dose.

To halt bleeding in patients with severe thrombocytopenia due to bone marrow failure, it is desirable to achieve a post-transfusion blood platelet count of 40 x 10(9)/L by platelet transfusions. Based on calculations of corrected count increments, each 1 x 10(11) platelets transfused will increase the blood platelet count approximately 10 x 10(9)/L per each square meter of patient body surface area. Thus, the post-transfusion blood platelet count will be approximately 20 x 10(9)/L following transfusion of 3 x 10(11) platelets to a 5 foot, 8 inch patient weighing 170 pounds (2.0 m2), who is bleeding because of a pre-transfusion platelet count of 5 x 10(9)/L. The post-transfusion platelet count likely will be even lower in sick patients (sepsis, amphotericin B plus antibiotic therapy, splenomegaly, graft-vs.-host disease, etc.) or if platelets are lost from the unit by leukofiltration before transfusion. Although a dose of 3 x 10(11) platelets is acceptable, in a regulatory sense for product quality, it is inadequate to control bleeding in most thrombocytopenic adult patients. Adjusting dose for body size, bleeding patients with pre-transfusion blood platelet of < 10 x 10(9)/L and weighing > 120 pounds should receive approximately 6 x 10(11) platelets, those weighing 30 to 120 pounds should receive 3 x 10(11) platelets, and infants weighing < 30 pounds (15 kg) should receive 5-10 ml/kg of platelet concentrate.