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Haemostasis and component treatment7. Haemostasis and component treatmentStored blood undergoes progressive losses of coagulation factors mainly of F V & F VIII. Platelet function is also quickly lost after storage.If plasma reduced red cells or red cells optimal additive solution are transfused, coagulation factors will be reduced. Infusion of crystalloids and colloids will further cause dilution of coagulation factors and platelets. Role of components Component therapy is indicated where bleeding is due to deficient haemostasis rather than from major vessel injuries. Platelet concentrates To achieve platelet count above 40 x 10^9/1, 1 unit of platelet concentrate/10kg of body weight is given for patients with continuous non-surgical bleeding. FFP and cryoprecipaitate FFP provides a broad spectrum replacement correction of coagulation abnormalities. 12 ml!kg body weight of FFP administered is usually sufficient but in case of continued bleeding with DIC, a more vigorous and specific treatment protocol in the form of cryoprecipitate (1-1.5 packs!10 kg) is advisable. Cryoprecipitate given in addition to FF1’ will also correct the deficiencies of fibrinogen and factor VIII. Oxygen affinity changes Massive rapid transfusion of high oxygen affinity aged stored blood can seriously affect tissue oxygenation. This coupled with increased cardiopulmonary overload is dangerous for critically ill patients. It is reasonable therefore to use faily fresh blood (less than 1 week old especialily where arteriosclerotic vascular disease is a problem. Electrolyte changes Hypocaicaemia Citrate in the anticoagulant fluid binds ionized caLcium and lowers plasma Ca+ + levels. In healthy individuals due to very rapid citrate metabolism by the liver, hypocalcaemia is not a major problem. However, in neonates and hypothermic patients, hypocalcaemia may occur causing arrthemias, transistent tetany and disturbance in coagulation. If ECO changes suggest hypocalcaemia, 5 ml of 10% calcium gluconate (proportionally less for children and neonates) should be given at 5 minutes intervals Intravenously until ECG changes revents to normal. Hyperkalaemia Storage increases K+ content of plasma to reach over> 30 mg/I. in the presence of hypothermia, acidosis and hypocalcemia a high K-concentration is potentially dangerous and causes impaired myocardial function and eventually cardiac arrest. Avoidance of hypothemia is the best measure for prevention of effects due to hyperkalemia and hypocalcaemia. Acid Base disturbance Although stored blood has a reduced pH, acidosis in recipients of massive transfusion is rare as metabolism of citrate produces an alkalosis. Arterial pH should be monitored during massive transfusion and when pH falls below 7.2, it should be corrected by perfusion of sodium bicarbonate along with I/V fluids. Hypothermia Rapid transfusion results in unwanted cooling of the body. Blood warmers should be used for rates of infusion exceeding 1 unit/lO minute in aduls and proportionately less for children. Hypothermia slows citrate metabolism, potentiates the harmful cardiac effects of hyperkalemia and hypocalcaemia and reduces oxygen release from haempglobin. Adult respiratory distress syndrome (ARDS) Adult respiratory distress syndrome is a major complication of massive blood transfusion. It is a consequence of several factors, but delay of inadequate resuscitation, sepsis, adverse drug reactions, etc. play a role in its casuation. Under or over transfusion should be avoided. Microaggregate filters should be used and plasma oncotic pressure should be maintained above 20 mm of Hg.
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Preservation Storage Transportation of Blood / 7. Haemostasis and component treatment
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