A review of transfusion risks and optimal management of perioperative bleeding with cardiac surgery

Abstract

A pproximately 10 to 14 million red blood cell (RBC) units 1 and 1.5 million platelet (PLT) transfusions (approx. 85%, single-donor plateletpheresis products; the remainder, pools of six whole-blood-donor PLT concentrates) are administered in the United States each year. Transfusion-related adverse (20% of transfusions) and serious adverse (0.5%) events were estimated by Walker in the 1980s. 2 More recently, serious adverse events have been estimated to occur in 0.1 percent of RBCs and 0.04 percent of PLT transfusions. With early estimates, transfusion-associated adverse events were thought to lead to a short-term (i.e., not including disease transmission-related deaths) mortality of 1 to 1.2 per 100,000 patients, or approximately 35 transfusion-related deaths per year in the United States. With more recent estimates, long-term or total mortality (i.e., including disease transmission-related deaths) is probably higher due to unrecognized or unreported transfusion-related deaths. 1,3 Perioperative signs and symptoms (e.g., fever, hypotension, tachycardia, hypoxemia, microvascular bleeding, hemoglobinuria, low urine output) can accompany any of several serious transfusion-related complications such as acute hemolytic transfusion reactions (HTRs), bacterial contamination, anaphylaxis, transfusion-related acute lung injury (TRALI), or other events (e.g. hyperkalemia, fluid overload, air embolus). Current risks associated with blood and blood component transfusion can be characterized as immune-mediated versus non-immunemediated, hemolytic versus nonhemolytic, or acute versus delayed transfusion reactions, as well as bloodborne disease transmission. Another approach would involve subdividing transfusion risks into those that are the leading causes of mortality versus those that are uncommon causes of transfusion-related mortality. The leading causes of transfusion-related mortalityReports to the US Food and Drug Administration (FDA) 4 and quoted mathematical estimates 1 of transfusionrelated mortality indicate that the leading causes of transfusion-related mortality are (in decreasing order): TRALI, bacterial or viral contamination of blood and blood components, and transfusion of ABO-mismatched blood. Transfusion-associated respiratory distress can be related to one of the following (in order of decreasing frequency): fluid overload (also called transfusion-associated circulatory overload or TACO), allergic reactions, or TRALI. Although the exact incidence of circulatory overload related to transfusion is unknown (e.g., 1 in every 200-10,000 units), 5 it is more likely in older patients with a history of congestive heart failure. Reported estimates of the frequency of TRALI range from 1:400 to 1:50,000 units transfused (i.e., involving plasma, PLTs, or RBCs). 6 This extremely wide estimated range reflects the difficulties in clinical recognition of TRALI with resultant underreporting. Both one-hit (white blood cell [WBC] antibodies) and two-hit mechanisms have been proposed as the etiology of TRALI. Indeed, as TRALI ...

Acute Kidney Injury After Cardiac Surgery

“…Surgical reexploration is also inextricably linked to both anemia and RBC transfusion, because the principal reason for reexploration after cardiac surgery is coagulopathy (which is exacerbated by anemia), which leads to excessive blood loss (and massive RBC transfusion). 43 …”

“…40 Anemia impairs hemostasis because normal platelet function is dependent on the presence of an adequate (but as yet undetermined) hemoglobin concentration. 41,42 In cardiac surgery, during which patients are already at increased risk for bleeding due to CPB-related hemostatic defects, 43 the added burden of anemia-induced platelet dysfunction may lead to excessive bleeding, which in turn may necessitate multiple RBC transfusions and reexploration, both of which are associated with AKI.…”

The rationale for platelet transfusion during cardiopulmonary bypass: an observational study

“…Concurrent with the results of our and other observational studies, physicians identified bleeding as the most important factor in influencing their decision to transfuse platelets, which coincides with the belief that microvascular bleeding is thought to be predominantly secondary to platelet dysfunction 2,16 and consistent with recommendations regarding when to transfuse platelets. 17 This finding supports the need for point-of-care tests to identify whether bleeding is mainly secondary to thrombocytopathy, particularly as physicians identified the *P = 0.0099 when compared with 101-150 9 10 9 L -1 preoperative platelet count; **P \ 0.0001 when compared with no platelet transfusion.…”

“…2 Thus, platelets are often transfused pre-emptively for bleeding, as clear indications for platelet transfusion have not been determined and the use of point-of-care testing to guide transfusion of hemostatic products is neither well established nor widely available.…”

Allogeneic leukocytes in cardiac surgery: Good or bad?

“…Observational studies observed that RBC transfusion was the most consistent factor associated with mortality and morbidity [28,29]; however, these were retrospective studies and therefore provide no proof of the causal effect of allogeneic RBC transfusion on postoperative morbidity and mortality after cardiac surgery, in which many factors influence outcome; to date, this association is not fully understand. Compared to other unexpected adverse transfusion effects, the clinical effects of leukocyte-mediated TRIM on mortality following cardiac surgery are more well-known [30]; therefore, the role of TRIM in cardiac surgery requires further study in order to increase our understanding of the effects of allogeneic leukocytes on postoperative complications and outcome. As allogeneic leukocytes are the most important factor associated with the clinical effects of TRIM, RCTs investigating their role followed.…”