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In a trial involving more than 2400 critically ill patients, 90-day mortality was similar among patients receiving blood donated on average 6 days earlier and those receiving blood donated 22 days earlier. The age of the transfused blood did not influence outcomes. Blood transfusions are administered frequently and may have unintended consequences in critically ill patients. 1 – 4 Current regulations permit the storage of red cells for up to 42 days, but prolonged storage has been associated with changes that may render red cells ineffective as oxygen carriers and that lead to the accumulation of substances that have untoward biologic effects. 5 – 8 A systematic review of 18 observational studies involving a total of 409,840 patients and three randomized, controlled trials involving a total of 126 patients suggested that the transfusion of older red cells, as compared with newer red cells, was associated with . . .

Red-cell transfusions are a cornerstone of critical care practice, 1 but there are divergent views on the risks of anemia and the benefits of transfusion in this setting. One important concern is that anemia may not be well tolerated by critically ill patients. 2 , 3 Indeed, two recent studies suggested that anemia increases the risk of death after surgery in patients with cardiac disease 2 and in critically ill patients. 3 Red-cell transfusions are used to augment the delivery of oxygen in the hope of avoiding the deleterious effects of oxygen debt. 4 This view prompted the routine use of transfusion in patients with hemoglobin . . .

In this clinical trial involving patients undergoing high-risk cardiac surgery, aprotinin was somewhat more effective than either aminocaproic acid or tranexamic acid in reducing massive perioperative bleeding but at the expense of a higher rate of death, mainly from cardiac causes. Aprotinin cannot be recommended to control blood loss in this clinical setting. In patients undergoing high-risk cardiac surgery, aprotinin was somewhat more effective than either aminocaproic acid or tranexamic acid in reducing massive perioperative bleeding but at the expense of a higher rate of death, mainly from cardiac causes. Every year an estimated 1 million to 1.25 million patients worldwide undergo cardiac surgery, including high-risk procedures such as repeat coronary-artery bypass grafting (CABG), valve replacements, and combined procedures. 1 High-risk procedures present an increased risk of death, massive bleeding, renal failure, and thrombotic complications, as compared with first-time isolated CABG. 2 – 4 Three antifibrinolytic agents have been used in cardiac surgery to minimize bleeding and reduce the need for transfusion: aprotinin, a naturally occurring serine protease inhibitor, and two lysine analogues, tranexamic acid and aminocaproic acid. 5 In clinical trials, all three drugs have been shown to be effective in reducing the . . .

Correcting the decrease in oxygen delivery from anemia using allogeneic RBC transfusions has been hypothesized to help with increased oxygen demands during weaning from mechanical ventilation. However, it is also possible that transfusions hinder the process because RBCs may not be able to adequately increase oxygen delivery. In this study, we determined whether a liberal RBC transfusion strategy improved outcomes related to mechanical ventilation. Seven hundred thirteen patientsreceiving mechanical ventilation, representing a subgroup of patients from a larger trial, were randomized to either a restrictive transfusion strategy, receiving allogeneic RBC transfusions at a hemoglobin concentration of 7.0 g/dL (and maintained between 7.0 g/dLand to 9.0 g/dL), or to a liberal transfusion strategy, receiving RBCsat 10.0 g/dL (and maintained between 10.0 g/dL and 12.0 g/dL). The larger trial was designed to evaluate transfusion practice rather than weaning per se. Baseline characteristics in the restrictive-strategy group (n = 357) and the liberal-strategy group (n = 356) were comparable. The average durations of mechanical ventilation were 8.3 ± 8.1 days and8.3 ± 8.1 days (95% confidence interval [CI] around difference,−0.79 to 1.68; p = 0.48), while ventilator-free days were17.5 ± 10.9 days and 16.1 ± 11.4 days (95% CI around difference,−3.07 to 0.21; p = 0.09) in the restrictive-strategy group vs the liberal-strategy group, respectively. Eighty-two percent of the patients in the restrictive-strategy group were considered successfully weaned and extubated for at least 24 h, compared to 78% for theliberal-strategy group (p = 0.19). The relative risk (RR) of extubation success in the restrictive-strategy group compared to theliberal-strategy group, adjusted for the confounding effects of age, APACHE (acute physiology and chronic health evaluation) II score, and comorbid illness, was 1.07 (95% CI, 0.96 to 1.26; p = 0.43). Theadjusted RR of extubation success associated with restrictive transfusion in the 219 patients who received mechanical ventilation for >7 days was 1.1 (95% CI, 0.84 to 1.45; p = 0.47). In this study, there was no evidence that aliberal RBC transfusion strategy decreased the duration of mechanical ventilation in a heterogeneous population of critically illpatients.

An emerging agent can threaten the safety of the blood supply. Drs. Morris Blajchman and Eleftherios Vamvakas write that the risk of transfusion-transmitted infection is not static, as new agents continue to emerge and old ones change their properties and epidemiologic patterns. In 2002, as mosquitoes carried West Nile virus across the United States, infecting 4200 people, 23 confirmed cases of transfusion-transmitted infection and 7 related deaths were reported. 1 This was a dramatic demonstration that an emerging agent can threaten the safety of the blood supply. Because the virus's incubation period is usually 3 to 15 days and transmission by transfusion stood out against the background of a mosquito-borne epidemic, these transmissions were recognized quickly, nucleic acid–amplification technology was adapted for the detection of the virus, and the Food and Drug Administration (FDA) and Health Canada mandated the screening of donated blood . . .

Problem Intravenous immunoglobulin (IVIG) has been used to suppress autoimmune and inflammatory disorders by a variety of mechanisms. Recently, the CD200 tolerance-promoting signal has been found to play a role in IVIG suppression of blood natural killer (NK) cells. Further, different types of IVIG have been reported to differ in this activity, and that has been related to efficacy (and inefficacy) of treatment of women with pregnancy failure. CD200 acts by binding to CD200 receptors (C200R). The objective of this study was to determine if CD200-dependent NK suppression by IVIG involved direct binding of IVIG-associated CD200 molecules to CD200R on NK cells. Method of study Peripheral Blood Lymphocytes isolated from human blood were used as a source of NK cells to lyse Cr 51 -labelled K562 target cells in vitro in 18 and 4 h assays, and three different types of IVIG were tested for suppressive activity in the presence or absence of specific monoclonal anti-huCD200. In some experiments, CD56 + NK cells were purified using anti-CD56 magnetic beads. Western blotting of IVIG using a specific anti-huCD200 antibody was done. Enzyme-Linked ImmunoSorbent Assays were used to measure cytokine production in NK assays. Results Different IVIGs showed significant differences in potency in suppressing NK cytolytic activity in vitro (mg/ml for 60% suppression, Gammagard 4.1, Gamunex 14.1, Gamimmune 20.2). For CD200-dependent suppression, Gammagard was twice as potent as Gamimmune, but equivalent to Gamunex. The presence of suppression in 4 hour assays indicated stimulation of cytokine synthesis was unlikely to explain CD200-dependent suppression. Purification of NK cells led to loss of the CD200-dependent component. Western blotting confirmed that material reactive with anti-CD200 antibody was present in Immunoglobulin G (IgG) preparations, and at a lower level in human serum that contains IgG. Conclusions IVIGs are not all equipotent in suppressing NK cell cytolytic activity. CD200 associated with IVIG is an important component of suppression. CD200-dependent suppression appears to be mediated by a non-NK population that then acts on NK cells by direct contact rather than indirectly through release of immunosuppressive cytokines.

In a trial involving nearly 1100 patients undergoing cardiac surgery, there were no significant differences in outcomes among patients receiving transfusions of red cells stored for 10 days or less as compared with outcomes in those receiving red cells stored for 21 days or more. The objective of red-cell transfusion is to increase oxygen delivery and improve clinical outcomes. However, in the United States, storage systems are licensed for up to 42 days on the basis of the estimated in vivo recovery of transfused red cells rather than on the basis of the clinical effectiveness of the transfusion. 1 During storage, red cells undergo numerous changes. 2 , 3 Some laboratory data suggest that red cells stored for longer periods may not traverse the microcirculation or deliver oxygen as effectively as those stored for shorter periods. 4 , 5 Several observational studies have assessed the association between the duration of . . .