IMPORTANCE More than 100 million units of blood are collected worldwide each year, yet the indication for red blood cell (RBC) transfusion and the optimal length of RBC storage prior to transfusion are uncertain.OBJECTIVE To provide recommendations for the target hemoglobin level for RBC transfusion among hospitalized adult patients who are hemodynamically stable and the length of time RBCs should be stored prior to transfusion.EVIDENCE REVIEW Reference librarians conducted a literature search for randomized clinical trials (RCTs) evaluating hemoglobin thresholds for RBC transfusion (1950( -May 2016 and RBC storage duration (1948( -May 2016 without language restrictions. The results were summarized using the Grading of Recommendations Assessment, Development and Evaluation method. For RBC transfusion thresholds, 31 RCTs included 12 587 participants and compared restrictive thresholds (transfusion not indicated until the hemoglobin level is 7-8 g/dL) with liberal thresholds (transfusion not indicated until the hemoglobin level is 9-10 g/dL). The summary estimates across trials demonstrated that restrictive RBC transfusion thresholds were not associated with higher rates of adverse clinical outcomes, including 30-day mortality, myocardial infarction, cerebrovascular accident, rebleeding, pneumonia, or thromboembolism. For RBC storage duration, 13 RCTs included 5515 participants randomly allocated to receive fresher blood or standard-issue blood. These RCTs demonstrated that fresher blood did not improve clinical outcomes.FINDINGS It is good practice to consider the hemoglobin level, the overall clinical context, patient preferences, and alternative therapies when making transfusion decisions regarding an individual patient. Recommendation 1: a restrictive RBC transfusion threshold in which the transfusion is not indicated until the hemoglobin level is 7 g/dL is recommended for hospitalized adult patients who are hemodynamically stable, including critically ill patients, rather than when the hemoglobin level is 10 g/dL (strong recommendation, moderate quality evidence). A restrictive RBC transfusion threshold of 8 g/dL is recommended for patients undergoing orthopedic surgery, cardiac surgery, and those with preexisting cardiovascular disease (strong recommendation, moderate quality evidence). The restrictive transfusion threshold of 7 g/dL is likely comparable with 8 g/dL, but RCT evidence is not available for all patient categories. These recommendations do not apply to patients with acute coronary syndrome, severe thrombocytopenia (patients treated for hematological or oncological reasons who are at risk of bleeding), and chronic transfusion-dependent anemia (not recommended due to insufficient evidence). Recommendation 2: patients, including neonates, should receive RBC units selected at any point within their licensed dating period (standard issue) rather than limiting patients to transfusion of only fresh (storage length: <10 days) RBC units (strong recommendation, moderate quality evidence). CONCLUSIONS AND R...
RBC antibodies arising from transplanted organs and directed against recipient RBCs represent a well-established immunohematologic complication of solid organ transplantation. In ABO-unmatched organs, the frequency and severity of graft antibodies and hemolysis generally increase with the size (lymphoid content) of the organ, from kidney to liver to heart-lung transplants. In the cases reviewed here, the frequency of hemolysis increased in cyclosporine-treated kidney transplant recipients and O-to-A liver transplant recipients and decreased in group AB liver transplant recipients and kidney transplant recipients receiving azathioprine or low-dose postoperative graft irradiation. Available data cannot otherwise distinguish which cyclosporine-treated recipients of ABO-unmatched kidneys and livers (30-40% of total) will develop graft antibody. There has been no conclusive effect to date of the age, race, or gender of the donor or the recipient, of cadaver versus living kidney donors, or of patients' A2 or secretor status. In a few cases of living-donor kidney grafts, the donor was the patient's mother or wife who had been exposed to the recipient's RBC antigens via pregnancy. The ABO antibodies are typically IgG, appear 7 to 10 days after transplantation, and last for about a month. If immediate-spin crossmatching is done routinely, DATs are recommended in compatibility testing after ABO-unmatched transplants. Changes in the immunosuppressive regimen, such as a change from cyclosporine therapy, have not affected the duration of these antibodies. Most patients require only transfusions for this self-limited process, but six cases of hemolysis-induced acute renal failure have been reported, and one death was attributed to complications of hemolysis. RBC or plasma exchange has been performed in a few fulminant cases. RBCs of the donor's blood type are given when antibody appears. Some workers recommend such transfusion as prophylaxis at the time of surgery, although in liver transplants, the plasma accompanying a large amount of group O RBCs given perioperatively might be problematic. In several other centers, ABO-unmatched liver transplants have equivalent overall graft survivals, but the Pittsburgh adult patients with hemolysis have had reduced early graft survival. In the cases reviewed here, nine IgG Rh antibodies from kidney grafts directed against recipient RBCs have been observed, usually beginning 2 to 3 weeks after a cyclosporine-treated transplant, lasting for 2 to 6 months after operation, and causing mild hemolysis. One case represented a primary immune response from a previously unsensitized donor.(ABSTRACT TRUNCATED AT 400 WORDS)
Despite extended RBC typing, alloimmunization may still occur due to RBC variants that are not detected on routine screening and transfusions at institutions where extended RBC typing is not done. Extended RBC typing should be the standard of care for patients with SCD. Prospective genotyping may reduce allosensitization to rare variants not detected on routine screening.
The increasing success of liver transplantation in recent years has provided an experimental model to study and document the hepatic synthesis of many plasma proteins. 1-5 The normal hepatobiliary tract has not been regarded as a major source of antibody,6 , 7 aside from the enteric IgA secreted from plasma into the biliary tree. 8 Liver transplantation affords the opportunity to study the production of antibody to red cells. Recipient ABO incompatibility to the donor (a mismatched transplant, e.g., a group A liver transplanted into a group B recipient), although not absolutely contraindicated in liver transplantation, is avoided when possible. However, ABO-unmatched transplants (defined as a group O liver transplanted into a non-group O recipient or a group A or B liver to an AB recipient) are used frequently. We report the short-term occurrence of anti-recipient ABO antibody after eight unmatched transplants. In five cases there was evidence of hemolysis. No such antibodies have been seen in over 180 ABO-matched transplants at our center. These antibodies were most probably produced by donor lymphocytes transplanted in or with the livers. METHODS Serologic studies were performed according to standard methods. 9 Serum isohemagglutinins were tested without intubation, after 37°C incubation for 30 minutes, and with broad-spectrum antiglobulin reagents. Six patients with ABO-unmatched liver transplants and confirmed anti-recipient antibody production were studied prospectively. Blood samples were drawn at least weekly for direct and indirect antiglobulin testing, crossmatching, and elutions. The hematocrit, serum bilirubin, clinical status, and transfusions were closely monitored. Two other confirmed cases (in Patients 5 and 7) were found on review of all ABO-unmatched liver transplantations performed at our center. Confirmed cases of isohemagglutinin production were defined as those in which passive transfer of antibody could be ruled out-i.e., either no unmatched plasma-containing blood products were given at surgery (five cases) or, if they were, immediate postoperative specimens were negative for antibody (Patients 1A, 1B, and 6)-and there was serologic or clinical confirmation of the antibody's presence by repeat testing or signs of hemolysis. Cases were designated as possible if the antibody was first detected after the second postoperative day but the above criteria were not met in full. Liver transplantation was performed according to established techniques, including cyclosporine immunosuppression. 10,11 Little or no plasma was transferred in the grafts because the livers were copiously perfused with preservative solution and then, just before anastomosis, with saline. 12 Our transfusion practices have been described elsewhere.
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