Duration of red blood cell storage and survival of transfused patients (CME)

BACKGROUND: Disquieting reports of increased complication and death rates after transfusions of red blood cells (RBCs) stored for more than 14 days prompted us to perform an observational retrospective cohort study of mortality in relation to storage time. STUDY DESIGN AND METHODS: We conducted a cohort study utilizing data on all recipients of at least one RBC transfusion in Sweden and Denmark between 1995 and 2002, as recorded in the Scandinavian Donations and Transfusions (SCANDAT) database. Relative risks of death in relation to storage time were estimated using Cox regression, adjusted for several possible confounding factors. RESULTS: After various exclusions, 404,959 transfusion episodes remained for analysis. The 7‐day risk of death was similar in all exposure groups, but a tendency for a higher risk emerged among recipients of blood stored for 30 to 42 days (hazard ratio, 1.05; 95% confidence interval [CI], 0.97‐1.12), compared to recipients of blood stored for 10 to 19 days. With 2‐year follow‐up, this excess remained at the same level (hazard ratio, 1.05; 95% CI, 1.02‐1.08). No dose‐response pattern was revealed and no differential effect was seen when the analyses were restricted to recipients of leukoreduced units only. CONCLUSION: Although a small excess mortality was noted in recipients of the oldest RBCs, the risk pattern was more consistent with weak confounding than with an effect of the momentary exposure to stored RBCs. It seems, thus, that any excess mortality conferred by older RBCs in the combined Swedish and Danish transfusion recipient population is likely less than 5%, which is considerably smaller than in the hitherto largest investigation.     

Safety and effects of two red blood cell transfusion strategies in pediatric cardiac surgery patients: a randomized controlled trial

Objective

To investigate the safety and effects of a restrictive red blood cell (RBC) transfusion strategy in pediatric cardiac surgery patients.

Design

Randomized controlled trial.

Setting

Pediatric ICU in an academic tertiary care center, Leiden University Medical Center, Leiden, The Netherlands.

Patients

One hundred seven patients with non-cyanotic congenital heart defects between 6 weeks and 6 years of age. One hundred three patients underwent corrective surgery on cardiopulmonary bypass.

Interventions

Prior to surgery patients were randomly assigned to one of two groups with specific RBC transfusion thresholds: Hb 10.8 g/dl (6.8 mmol/l) and Hb 8.0 g/dl (5.0 mmol/l).

Measurements

Length of stay in hospital (primary outcome), length of stay in PICU, duration of ventilation (secondary outcome), incidence of adverse events and complications related to randomization (intention to treat analysis).

Results

In the restrictive transfusion group, mean volume of transfused RBC was 186 (±70) ml per patient and in the liberal transfusion group 258 (±87) ml per patient, (95 % CI 40.6–104.6), p < 0.001. Length of hospital stay was shorter in patients with a restrictive RBC transfusion strategy: median 8 (IQR 7–11) vs. 9 (IQR 7–14) days, p = 0.047. All other outcome measures and incidence of adverse effects were equal in both RBC transfusion groups. Cost of blood products for the liberal transfusion group was 438.35 (±203.39) vs. 316.27 (±189.96) euros (95 % CI 46.61–197.51) per patient in the restrictive transfusion group, p = 0.002.

Conclusions

For patients with a non-cyanotic congenital heart defect undergoing elective cardiac surgery, a restrictive RBC transfusion policy (threshold of Hb 8.0 g/dl) during the entire perioperative period is safe, leads to a shorter hospital stay and is less expensive.     

Duration of red blood cells storage and outcome in critically ill patients

Purpose

There is conflicting evidence on the effect of red blood cells (RBC) storage duration and clinical outcomes. We aimed to investigate the association between RBC storage duration and clinical outcomes in patients admitted to the intensive care unit (ICU).

Materials and Methods

We retrospectively (2001-2011) studied adults admitted to the ICUs of 2 hospitals who received RBC. Using the mean, maximum and minimum age of RBC units transfused, we evaluated the association between RBC storage duration and mortality. We also analyzed the association between mean age of RBC units and length of stay (LOS) in survivors. We performed sensitivity analyses in patients who only received RBC in ICU and who only received leukodepleted RBC.

Results

We studied 8416 patients who received a median of 4 (interquartile range, 2-7) RBC units. After multivariate analysis, age of RBC was not independently associated with mortality, including in the subgroup analyses. Furthermore, there was no clinically relevant relationship between mean RBC age and LOS.

Conclusions

RBC storage duration was not associated with increased mortality nor ICU and hospital LOS. These results support the view that the effect of RBC storage duration on outcomes in critically ill patients is uncertain.     

The clinical utility of an index of global oxygenation for guiding red blood cell transfusion in cardiac surgery

BACKGROUND: This observational study explored the potential utility of oxygen extraction ratio (O₂ER) as an adjunct to the hemoglobin (Hb) concentration for guiding red blood cell (RBC) transfusion decisions after cardiac surgery with cardiopulmonary bypass (CPB).
STUDY DESIGN AND METHODS: Hb and O₂ER measures were obtained before as well as 15 and 120 minutes after RBC transfusion episodes (defined as 1-2 RBC units given in succession after CPB, within 24 hr of surgery). Changes related to RBC transfusions among patients with normal (≤30%) and elevated (>30%) pretransfusion O₂ERs were analyzed.
RESULTS: Of the 176 patients enrolled, 74 received RBC transfusions. Of these, 50 had data available for 62 transfusion episodes. Pretransfusion episode O₂ER values were elevated in 27 cases and normal in 35 (56%) cases. Among those who received transfusion for low Hb concentration, 43 percent (27/62) had normal pretransfusion O₂ER values. While the posttransfusion O₂ER values did not change in patients with normal pretransfusion O₂ER values, they did decrease in patients with elevated pretransfusion O₂ER values (% change [±SD] at 15 and 120 min after transfusion was −5.2 ± 7.8 and −3.8 ± 8.0%, respectively; p < 0.05).
CONCLUSION: If a normal O₂ER in anemic patients with no evidence of organ dysfunction indicates adequate tissue oxygen delivery, then our findings suggest that incorporating O₂ER into the transfusion decision will substantially reduce postcardiac surgery RBC transfusions by allowing us to safely avoid transfusing this group of patients. Future studies are needed to assess the validity of this conclusion.     

Risks of packed red blood cell transfusion in patients undergoing cardiac surgery

Packed red blood cell (PRBC) transfusion is common in patients undergoing cardiac surgery. Evidence has accumulated demonstrating that such patients can tolerate relatively low hemoglobins, and an extensive body of literature has developed demonstrating that patients undergoing such surgery who receive PRBC are at risk for several adverse outcomes including increased mortality, atrial fibrillation, and more postoperative infections, as well as numerous other complications. The PubMed database was searched for the English language literature on the topic of PRBC transfusion and outcomes in patients undergoing cardiac surgery, as well as alternatives to this intervention. Data were reviewed to assess the impact of transfusion in patients undergoing cardiac surgery on mortality, cardiac, infectious, and pulmonary, as well as a variety of miscellaneous complications. Patients receiving PRBC were consistently identified as being at higher risk for complications in all categories. The limited prospective data were consistent with the retrospective data, which comprised most of the literature. The preponderance of the literature suggests that patients undergoing cardiac surgery can tolerate lower hemoglobin/hematocrit values than traditionally appreciated. Most published data also indicate that PRBC transfusion should be reserved for patients with an identifiable clinical/physiologic indication fir this intervention, consistent with recent specialty society guidelines.     

Postoperative red blood cell transfusion and morbid outcome in uncomplicated cardiac surgery patients

Objective  

To evaluate postoperative red blood cell (RBC) transfusion and its association with postoperative cardiac events and multiorgan morbidity in uncomplicated cardiac surgery patients.     

Buffering and dilution in red blood cell storage

BACKGROUND: Red blood cell (RBC) storage solutions work in a narrow pH range between 7.2 and 6.4. While keeping RBC within that pH range, ATP production can be increased by buffering or dilution. STUDY DESIGN AND METHODS: In the first study, 12 units of packed CP2D RBCs were pooled in groups of four, re-aliquoted, and added to one of four additive solutions (ASs): AS-3, 110 mL; EAS-61, 170 mL; EAS-78, 170 mL; or EAS-81, 110 mL. EAS-78 and -81 contain bicarbonate. Units were sampled approximately weekly for 10 weeks for biochemical measures. In the second study, 12 volunteers donated RBCs for measures of (51)Cr in vivo recovery after 6 or 8 weeks of storage in EAS-81. RESULTS: RBCs stored in the higher-volume or buffered ASs had higher RBC ATP concentrations. The combination had an additive effect. Hemolysis was reduced in dilute ASs and less so with buffering. RBCs stored for 8 weeks (n=6) in EAS-81 exhibited 87+/- 2 percent 24-hour (51)Cr in vivo recovery and 0.4+/- 0.2 percent hemolysis. CONCLUSIONS: It is possible to store RBCs for 8 weeks in buffered conventional volume ASs. Combining buffering and increased AS volume improves stored RBC characteristics further.     

Variability and predictability of large-volume red blood cell transfusion in cardiac surgery: a multicenter study

BACKGROUND: In cardiac surgery, excessive blood loss requiring large-volume red blood cell (RBC) transfusion is a common occurrence that is associated with significant morbidity and mortality. The objectives of this study were to measure the interinstitution variation and predictability of large-volume RBC transfusion. STUDY DESIGN AND METHODS: Data were retrospectively collected on 3500 consecutive cardiac surgical patients at seven Canadian hospitals during 2004. The crude and risk-adjusted institutional odds ratios (ORs) for large-volume (>or=5 U) RBC transfusion were calculated with logistic regression. The predictive accuracy of an existing prediction rule for large-volume RBC transfusion was calculated for each institution. RESULTS: Large-volume RBC transfusion occurred in 538 (15%) patients. When compared to the reference hospital (median crude rate), the institutional unadjusted and adjusted ORs for large-volume RBC transfusion ranged from 0.29 to 1.26 and 0.14 to 1.15, respectively (p<0.0001 for interinstitution variation). The variation was lower, but still considerable, for excessive blood loss, defined as at least 5-U RBC transfusion or reexploration; the ORs ranged from 0.42 to 1.22 (p<0.0001). The prediction rule performed well at most sites; its pooled positive predictive value for excessive blood loss was 71 percent (range, 63%-89%), and its negative predictive value was 90 percent (range, 87%-93%). CONCLUSIONS: There is marked interinstitution variation in large-volume RBC transfusion in cardiac surgery that is not explained by patient- or surgery-related factors. Despite this variation, patients at high or low risk for large-volume RBC transfusion can be accurately identified by a prediction rule composed of readily available clinical variables.     

Clinical implications of red blood cell and platelet storage lesions: an overview.

Both red blood cells and platelets undergo lesions upon storage which affect their function and possibly their clinical outcome. Some of these lesions are reversible, others not. Improved additive solutions and leukocyte depletion can delay the appearance of storage lesions. In addition, cellular apoptosis leads to numerous mitochondrial and surface changes during storage which have the potential to induce immune suppression by tuning down the innate immune system. This overview highlights some laboratory and clinical aspects of red cell and platelet storage lesions.     

Relationship between red cell storage duration and outcomes in adults receiving red cell transfusions: a systematic review

Introduction

The duration of red blood cell (RBC) storage before transfusion may alter RBC function and supernatant and, therefore, influence the incidence of complications or even mortality.

Methods

A MEDLINE search from 1983 to December 2012 was performed to identify studies reporting age of transfused RBCs and mortality or morbidity in adult patients.

Results

Fifty-five studies were identified; most were single-center (93%) and retrospective (64%), with only a few, small randomized studies (eight studies, 14.5%). The numbers of subjects included ranged from eight to 364,037. Morbidity outcomes included hospital and intensive care unit (ICU) length of stay (LOS), infections, multiple organ failure, microcirculatory alterations, cancer recurrence, thrombosis, bleeding, vasospasm after subarachnoid hemorrhage, and cognitive dysfunction. Overall, half of the studies showed no deleterious effects of aged compared to fresh blood on any endpoint. Eleven of twenty-two (50%) studies reported no increased mortality, three of nine (33%) showed no increased LOS with older RBCs and eight of twelve (66%) studies showed no increased risks of organ failure. Ten of eighteen (55%) studies showed increased infections with transfusion of older RBCs. The considerable heterogeneity among studies and numerous methodological flaws precluded a formal meta-analysis.

Conclusions

In this systematic review, we could find no definitive argument to support the superiority of fresh over older RBCs for transfusion.     

Relationships among haemoglobin level, packed red cell transfusion and clinical outcomes in patients after cardiac surgery

Objective  To identify associations among haemoglobin (Hb) concentrations, blood transfusions, and clinical outcomes in patients after cardiac surgery, especially in those who undergo valve replacement or bypass surgery. Design  Prospective observational trial. Setting  Surgical intensive care unit in a tertiary-level university hospital. Patients  1216 Consecutive patients. Measurements  Haemoglobin at admission and 6, 12, 24, and 48 h later, and then, every 24 h while patients remained in the intensive care unit (ICU); number of transfusions and clinical events. Results  Patients were divided into quartiles according to minimal haemoglobin, the first and second of which (Hb <8.10 and <8.91 g/dL, respectively) differed significantly (P < 0.001) from the other two quartiles in terms of more organ failure, longer ICU stay, and higher mortality. We found associations between being transfused ≥4 packed red cells (PRCs) and a worse clinical outcome and higher mortality. The associated mortality rate was higher for patients who underwent bypass surgery when they had Hb ≤8.9 g/dL and for those who underwent valve replacement when they had Hb >8.9 g/dL and were transfused ≥4 PRCs. Conclusions  Low haemoglobin concentrations and transfusions in patients undergoing cardiac surgery are associated with increased morbidity and mortality. Also, anemia and transfusions are associated with poor outcome. Therefore, intra- and postoperative bleeding seem to be a risk factor in patients undergoing cardiac surgery.     

不同保存期全血制备洗涤红细胞的超微结构变化

目的 探讨不同保存期的全血制备洗涤红细胞前后电镜下红细胞形态的变化。方法 采集CPD—A抗凝全血。实验分Ⅰ～Ⅵ组，分别于4℃保存7、10、15、20、25、30d。于制备前取全血1滴，5％戊二醛固定，经2000r／min离心10min后，分出血浆，取样检测血红蛋白。余下的红细胞再加等量生理盐水，1500r／min离心5min，连续2次，取样为制备后测定组。结果 组Ⅰ和组Ⅱ制备前后红细胞成双面凹的圆盘结构，细胞均匀混悬。组Ⅲ制备前红细胞形态正常，制备后少数红细胞出现聚集状、球形或边缘不整齐，并有棘形红细胞出现。组Ⅳ、组Ⅴ、组Ⅵ于制备前血浆微红；制备后，球形红细胞、棘形红细胞、中问漏孔的红细胞增加。结论 制备洗涤红细胞的最佳时间应在4℃保存10d内的全血，保存15d以后的全血制备洗涤红细胞形态发生异常变化，出现棘形红细胞，囊泡化后的红细胞易溶血，红细胞寿命缩短，影响洗涤红细胞的质量。