1994 American Society of Anesthesiologists Task Force
-- benefits include improved O2 carrying capacity, tissue oxygenation, and decreased bleeding
-- costs, limit risks and adverse reactions
-- 18 - 54% transfusions are inappropriate
-- $ 150 per PRBC
-- risks; Hep C 3/10,000 Hep B 1/200,000 HIV 1/450,000
ŸCMV most commonly transmitted viral agent ( subclinical except in immunosuppressed )
Ÿparasites, bacteria are rare 1/1,000,000
Ÿnonhemolytic transfusion reaction 1 - 5 % ( fever, chills, urticaria )
Ÿhemolytic reactions 1/33,000 , fatal in 1/500,000
Ÿ ( hypoT,tachycardia, hemoglobinuria, microvascular bleeding)
Ÿimmunosupression ( some studies suggest that patients with colorectal, breast, prostate, and certain other cancers may experiance earlier recurrence and lower survival rates if association; higher rates of post-operative infection )
Ÿalloimmunization
-- risk of O neg blood very small
Red Cell Transfusions
-- objective; improvement of inadequate oxygen delivery and the minimization of adverse outcomes as a result of this
-- less than 2% of oxygen delivered to tissues is in dissolved oxygen
-- 70 ml/kg x 70 kg = 4.9 L
-- 1 PRBC = 1g/L or 3% HCT
-- PRBC HCT = 70 - 80 %
-- PRBC contains less protein antigens, K+, and cellular debris, less infusion of calcium chelating agent, less potential for a transfusion reaction
1) rarely indicated with Hgb > 10, almost always when
2) risk of complications from inadequate O2 delivery determine need for transfusion if Hgb 6 - 10
3) the use of a single Hgb trigger for all patients, and other approaches that fail to consider all important physiologic and surgical factors affecting oxygenation are not recommended
-- ¯DO2 may lead to ischemic effects of heart and brain
-- separate effects of anemia (¯DO2 ) from effects of hypovolemia/hemorrhage
Ÿclass 1 ( 0 - 15 % ) - mild tachycardia and vasoconstriction
Ÿclass 2 ( 15 - 30 % ) - tachycardia and ¯ pulse pressure, anxiety, restlessness
Ÿclass 3 ( 30 - 40 % ) - marked tachycardia, tachypnea, hypotension, AMS
Ÿall of the above can usually be treated with crystalloid therapy
Ÿclass 4 ( > 40 % ) - life threatening, needs blood
-- lower limit of human tolerance to acute normovolemic anemia has not been established, it is believed DO2 adequate in most instances at 7 g/dL ( 18 - 25 % )
-- heart produces lactic acid at 15 - 20 %, Hgb of 6, no heart failure until hcy
Platelet Transfusions
-- whole blood and PRBC contain no functioning PLT after 48 hours
1) prophylactic PLT transfusions are rarely indicated in surgical patients with PLT > 100,00 and are usually indicated in the bleeding patient when the count is less than 50,000. If the PLT count is between 50 - 100,000, the need for PLT transfusions should be based on the risk of bleeding
2) vaginal deliveries and operations associated with insignificant bloodloss may be undertaken if yhe PLT
3) PLT indicated with normal counts if known or suspected PLT dysfn or microvascular bleeding
4) prophylactic PLT transfusions are ineffective and rarely indicated when thrombocytopenia is due to increased PLT destruction
-- the dose of PLT transfusion should increase the PLT count by 50,000, therefore one PLT per 10 Kg
FFP
-- indicated to restore clinically depleted clotting factors, not as volume expander
-- defrosting takes 20-30 minutes and each unit should be administered over 15 - 20 minutes to minimize inactivation of labile clotting factors
1) urgent reversal of Warfarin therapy
2) correction of known coagulation deficiencies for which specific concentrates are not available
3) for the correction of microvascular bleeding in the presence of an elevated PT ot PTT > 1.5
4) for correction of microvascular bleeding secondary to coagulation factor deficiency in patients transfused with more than one blood volume and when the Pt and PTT cannot be obtained in a timely fashion. A dilutional coagulopathy is generally believed to require at least a replacement of an entire blood volume. When this occurs, only about a third of the original clotting factors remain.
-- 4-6 units of PLT, one unit of single-donor apheresis PLT and one unit of whole blood provide a quantity of coagulation factors similar to those in one unit of FFP
-- recommended dose is 10 - 15 ml/kg ( 200 ml/unit ). The dose advised for the reversal of warfarin is half the dose
Cryoprecipitate
1) patients with von Willebrands disease unresponsive to DDAVP, bleeding patients with vWD
2) bleeding patients with fibrinogen levels below 80 - 100 mg/dL
Patrick Melanson, MD, FRCPC