Complications of massive transfusion
Hemostasis may already be abnormal due to the underlying condition. During massive transfusion of red cells, platelet numbers fall as few functioning platelets exist in whole blood that has been stored for more than 48 h. Factors V and VIII are reduced after storage for a few days, and remaining levels may be diluted if large volumes of intravenous crystalloid or colloid are given. In addition, DIC may be provoked by release of thromboplastin-like material from platelets, white cells, and red cells broken down during storage of red cells and because of partial activation of coagulation factors. The extent of hemostatic derangement varies widely and is not predictable according to the volume of red cells transfused. Therefore prophylactic replacement formulas (e.g. platelets and fresh frozen plasma after every eight units of red cells) are not recommended. It is preferable to monitor hemostasis and use fresh frozen plasma when abnormalities of the coagulation system exist. Cryoprecipitate is indicated in DIC when the fibrinogen level is below 0.8 g/l. Thrombocytopenia below 50 * 10 9/l contributes to microvascular bleeding from mucosal surfaces (e.g. mouth, gastrointestinal tract, epistaxis), wounds, and puncture sites. A standard adult dose of platelets is usually 6 to 8 units of platelets (individually or pooled) which gives approximately 1 unit of platelets per 10 kg body weight. One unit of platelets contains at least 0.55 * 10 9 platelets in 50 ml of plasma. The patient's platelet count may be monitored to guide further requirements if bleeding continues.