The age of red blood cells is associated with bacterial infections in critically ill trauma patients. Blood Transfus. 2012;10:290-295. [PMID: 22395349 DOI: 10.2450/2012.0068-11]

The Red-cell Transfusion Strategy Dilemma in Critically Ill Patients in ICU: Is Restrictive or Liberal the Answer?

Background

The primary therapeutic approach for promptly increasing haemoglobin concentration is red blood cell transfusion. However, the risk associated with RBC transfusion and the overall accessibility exhibit significant variation.

Objective

This meta-analysis evaluates the comparison and outcome of restrictive and liberal transfusion strategies in intensive care unit.

Methods

A comprehensive search was carried out on various databases, including CENTRAL, PubMed, MEDLINE, and ScienceDirect for randomized control clinical trials evaluating the comparison of clinical outcomes of restrictive and liberal transfusion strategies in critically ill patients. The primary outcomes measure was mortality, which included ICU mortality and hospital mortality. In addition, data were pooled using random-effect models and heterogeneity was evaluated through I2 statistics.

Results

Out of 15 eligible RCTs obtained, involving 12,439 patients. The result demonstrated no significant difference of restrictive red-cell transfusion strategy over liberal red-cell transfusion strategy in reducing mortality outcomes with a pooled effect size (relative risk [RR] 0.92; 95% confidence interval [CI] 0.78 - 1.08; I2 = 0%, indicating minimal to no difference. Similarly, analyses of secondary outcomes identified no significant differences in several clinical results.

Conclusion

This present meta-analysis provides evidence that restrictive red-cell transfusion strategy doesn't significantly difference in overall mortality and several secondary clinical results of critically ill patients in ICU compared to liberal red-cell transfusion strategy. Otherwise, restrictive transfusion strategy lowered RBC transfusion requirements, and was expected to be more cost-effective.

MiR-33a-5p in stored red blood cells regulates genes of innate immune response and promotes inflammation

BACKGROUND AND OBJECTIVES

Blood transfusion is a common therapeutic procedure in hospitalized patients. Red blood cell (RBC) units undergo various biochemical and morphological changes during storage (storage lesion). miRNAs have been studied intensively regarding cellular metabolic processes, but the effect of miRNAs on blood storage is not well defined.

MATERIALS AND METHODS

We performed bioinformatics analysis on the public data set of miRNA expression of RBC based on R language, and performed the Kyoto encyclopedia of genes and genomes (KEGG) enrichment analysis on the target genes of differentially expressed miRNA. The expression of miRNA differential genes in blood samples stored at different times was verified by qRT-PCR. Next, we used ELISA and qRT-PCR to verify the expression of IL-1β, IL-6, IL-12 and TNF-α in blood at day 1 and day 42. In addition, in vitro, we transfected macrophages with overexpressed miRNA, and the effects of overexpressed miRNA on macrophage polarization and the release of inflammatory factors were verified by flow cytometry and qRT-PCR and ELISA.

RESULTS

This study combined bioinformatics analysis and experiments to discover the differentially expressed miRNAs in long-term stored blood. The results showed that compared to fresh blood samples, the inflammatory factors were significantly doubled by ELISA, as well as the higher mRNA expression at 42 day. Experimentally verified that miR-33a-5p promoted the M1 type macrophage polarization and increased the release of related inflammatory factors through PPARα/ACC2/AMPK/CPT-1a axis regulation.

CONCLUSIONS

This study elucidates a potential mechanism of inflammatory factor accumulation in long-term stored blood, providing a theoretical basis and a potential target to prevent transfusion-related adverse reactions.

Red blood cell transfusion-related dynamics of extracellular vesicles in intensive care patients: a prospective subanalysis

Extracellular vesicles (EVs) accumulate during packed red blood cell (PRBC) storage. To date, the involvement of EVs in transfusion-related immunomodulation (TRIM) has not been prospectively evaluated in intensive care unit (ICU) patients. This was a prospective subanalysis of a recent observational feasibility study in postoperative ICU patients after: (1) open aortic surgery (Aorta), (2) bilateral lung transplantation (LuTx), and (3) other types of surgery (Comparison). Patient plasma was collected three times each before and after leukoreduced PRBC transfusion at 30-min intervals. The total number of EVs and EVs derived from erythrocytes (EryEVs), total platelets (total PEVs), activated platelets, granulocytes (GEVs), monocytes, and myeloid cells in PRBC samples and patient plasma were analyzed by flow cytometry. Statistical analysis was performed by Spearman's correlation test, linear mixed models and pairwise comparisons by Wilcoxon matched-pairs test. Twenty-three patients (Aorta n = 5, LuTx n = 9, Comparison n = 9) were included in the final analysis. All EV subgroups analyzed were detectable in all PRBCs samples (n = 23), but concentrations did not correlate with storage time. Moreover, all EVs analyzed were detectable in all plasma samples (n = 138), and EV counts were consistent before transfusion. Concentrations of total EVs, EryEVs, total PEVs, and GEVs increased after transfusion compared with baseline in the entire cohort but not in specific study groups. Furthermore, the change in plasma EV counts (total EVs and EryEVs) after transfusion correlated with PRBC storage time in the entire cohort. Extracellular vesicles were detectable in all PRBC and plasma samples. Individual EV subtypes increased after transfusion in the entire cohort, and in part correlated with storage duration. Future clinical studies to investigate the role of EVs in TRIM are warranted and should anticipate a larger sample size.Trial registration: Clinicaltrials.gov: NCT03782623.

Red blood cell transfusion-related eicosanoid profiles in intensive care patients—A prospective, observational feasibility study

Introduction: Eicosanoids are bioactive lipids present in packed red blood cells (PRBCs), and might play a role in transfusion-related immunomodulation (TRIM). We tested the feasibility of analyzing eicosanoid profiles in PRBC supernatant and in plasma samples of postoperative intensive care unit (ICU) patients transfused with one unit of PRBCs.

Methods: We conducted a prospective, observational feasibility study enrolling postoperative ICU patients: 1) patients treated with acetylsalicylic acid following abdominal aortic surgery (Aorta); 2) patients on immunosuppressants after bilateral lung transplantation (LuTx); and 3) patients undergoing other types of major surgery (Comparison). Abundances of arachidonic acid (AA) and seven pre-defined eicosanoids were assessed by liquid chromatography and tandem mass spectrometry. PRBC supernatant was sampled directly from the unit immediately prior to transfusion. Spearman’s correlations between eicosanoid abundance in PRBCs and storage duration were assessed. Patient plasma was collected at 30-min intervals: Three times each before and after transfusion. To investigate temporal changes in eicosanoid abundances, we fitted linear mixed models.

Results: Of 128 patients screened, 21 were included in the final analysis (Aorta n = 4, LuTx n = 8, Comparison n = 9). In total, 21 PRBC and 125 plasma samples were analyzed. Except for 20-hydroxyeicosatetraenoic acid (HETE), all analyzed eicosanoids were detectable in PRBCs, and their abundance positively correlated with storage duration of PRBCs. While 5-HETE, 12-HETE/8-HETE, 15-HETE, 20-HETE, and AA were detectable in virtually all plasma samples, 9-HETE and 11-HETE were detectable in only 57% and 23% of plasma samples, respectively.

Conclusions: Recruitment of ICU patients into this transfusion study was challenging but feasible. Eicosanoid abundances increased in PRBC supernatants during storage. In plasma of ICU patients, eicosanoid abundances were ubiquitously detectable and showed limited fluctuations over time prior to transfusion. Taken together, larger clinical studies seem warranted and feasible to further investigate the role of PRBC-derived eicosanoids in TRIM.

MicroRNAs as Quality Assessment Tool in Stored Packed Red Blood Cell in Blood Banks

Micro-ribonucleic acids are control gene expression in cells. They represent the changed cellular states that occur can be employed as biomarkers. Red blood cells alter biochemically and morphologically while they are being stored, which could be detrimental to transfusion. The effect of storage on the erythrocyte transcriptome is not mostly investigated. Because adult erythrocytes lack a nucleus, it has long been assumed that they lack deoxyribonucleic acid and ribonucleic acid. On the other hand, erythrocytes contain a diverse range of ribonucleic acids, of which micro-ribonucleic acids are key component. Changes in this micro-ribonucleic acid protect cells from death and adenine triphosphate depletion, and they are linked to specific storage lesions. As a result, changes in micro-ribonucleic acid in stored erythrocytes may be used as a marker to assess the quality and safety of stored erythrocytes. Therefore, this review ams to review the role of microRNA in stored packed red blood cells as quality indicator. Google Scholar, PubMed, Scopus, and Z-libraries are used for searching articles and books. The article included in this paper was written in the English language and had the full article. During long storage of RBCs, miR-16-2-3p, miR-1260a, miR-1260b, miR-4443, miR-4695-3p, miR-5100, let-7b, miR-16, miRNA-1246, MiR-31-5p, miR-203a, miR-654-3p, miR-769-3p, miR-4454, miR-451a and miR-125b- 5p are up regulated. However, miR-96, miR-150, miR-196a, miR-197, miR-381 and miR-1245a are down regulated after long storage of RBCs. The changes of this microRNAs are linked to red blood cell lesions. Therefore, micro-ribonucleic acids are the potential quality indicator in stored packed red blood cells in the blood bank. Particularly, micro-ribonucleic acid-96 is the most suitable biomarker for monitoring red blood cell quality in stored packed red blood units.

Erythrocyte Storage Lesion Improvements Mediated by Naringin Screened from Vegetable/Fruit Juice Using Cell Extract and HPLC-MS

In blood banking, storage at 4°C for weeks is known to cause damages to erythrocytes, called storage lesions that may later cause transfusion-related adverse events. In previous experiments, we found that vegetable/fruit juices can effectively reduce the storage lesion. Currently, we attempt to analyze the potential bioactive components and test whether the compounds can improve the storage lesions of erythrocytes. Equal portions in wet weight of 20 fresh vegetables and fruits were blended with phosphate buffered solution (PBS), and clear solutions were produced as additive to the packed erythrocytes from consented blood donors at 1 : 10 ratio (ml : gram). The blood samples were stored for 35 days at 4°C, and the supernatants were performed high liquid chromatography-mass spectrometry (HPLC-MS) analysis at 0 days, 14 days, and 35 days. The blood bags supplemented with identified bioactive components were stored in a refrigerator for 35 days, and the morphology, complete blood count (CBC), phosphatidylserine (PS) extroversion, hemolysis, and reactive oxygen species (ROS) levels were measured at the end of storage. Five potential bioactive components from vegetable/fruit juices contributed to the improvements of storage lesion. One of the compounds was unequivocally identified as naringin, and two were tentatively assigned as vitexin 6″-O-malonyl 2″-O-xyloside and luteolin 7-(6″-malonyl neohesperidoside). Naringin alleviated the storage lesion of red blood cells (RBCs) by reducing ROS levels and living cell extraction with HPLC-MS is a simple, reliable, and effective method for screening potential bioactive components.

The accumulation of exosome-associated microRNA-1246 and microRNA-150-3p in human red blood cell suspensions

Background

Transfusion-related immunomodulation (TRIM) can be caused by exosomes, in which case, microRNAs (miRNAs) are one critical factor impacting exosome behavior. This study aims to investigate and analyze the expression profiles of exosomal miRNA in red blood cell (RBC) suspensions during storage and to identify potential TRIM-related miRNAs as well as their potential functions.

Methods

A total of 25 packs of RBC suspensions were randomly collected. Exosome were extracted by ultracentrifugation and then identified and characterized by nanoparticle tracking analysis (NTA), transmission electron microscopy (TEM) and western blot (WB). Exosomal miRNA profiles were acquired using gene chips in five packs on week 1 and week 5. The expression data were compared from the two time points identifying accumulated miRNAs with statistical significance and their predicted targeting genes were analyzed. Based on the gene chip results, quantitative reverse transcription-polymerase chain reactions (qRT-PCR) were performed to verify miRNA accumulation in the rest 20 packs sampling on week 1, 3 and 5.

Results

Gene chip analysis revealed that most exosomal miRNAs were enriched as the storage period progressed. Compared to samples from week 1, week 5 samples exhibited a total of 539 differential miRNA expressions, among which, 159 were statistically significant (P < 0.05) and 148 (93.08%) were accumulated. In the bioinformatics functional analysis, significant immunoregulatory annotations related to the thyroid hormone, mitogen-activated protein kinase (MAPK), focal adhesion and RAS signaling pathways were identified. The top 17 differential expression miRNAs were validated by qRT-PCR. The results confirmed that all the 17 miRNAs were accumulated with increasing storage time. In particular, miRNA-1246 and miRNA-150-3p were the most enriched strands by more than 150-folds in the 5-week storage period.

Conclusions

As storage progressed, numerous exosomal miRNAs accumulated in the RBC suspensions, which are informatically connected to multiple immuno-signaling pathways. MiRNA-1246 and miRNA-150-3p may be essential mediators impacting the immunoregulation functions of exosomes in RBC suspensions, considering their significant accumulating scales. Further research should therefore focus on the relationship between these miRNAs and TRIM.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12967-021-02887-2.

Impact of stored red cells on clinical outcome in critically ill

BACKGROUND

The use and benefit of fresh blood and leuco-reduced blood for critically ill patients has been inconclusive. In this study we have tried to observe the same, in patients admitted to intensive care unit.

STUDY DESIGN AND METHODS

Prospective study was done to observe the effect of transfusion in critically ill patients in a tertiary care hospital. Clinical condition in cases and controls was assessed with the help of Simplified Acute Physiology Score II scoring tool. Clinical outcome among patients who received blood was compared using two cutoffs, 14 and 21 days of shelf life to delineate fresh from old blood. Length of hospital stay, length of stay in ICU, number of days on ventilator and number of hospital acquired infections were used as the surrogate markers for morbidity.

RESULTS

Of the 558 critically ill patients admitted during the study period, 427 received (cases) while 131 did not receive the transfusion (controls). Mean SAPS II scores of cases and controls were comparable. We observed a significantly higher rate of mortality among patients who received RBC units over 21 days. However morbidity parameters were affected even when the cutoff of 14 days is considered. Buffy-coat reduced blood did not influence the outcome in the study group.

CONCLUSION

Critically ill patients may be prioritized for receiving fresher units of packed red cells preferably less than 21 days old. Transfusion is an independent risk factor for morbidity. Hence the risk to benefit ratio should be carefully assessed for every red cell transfusion in critically ill patients.

Towards patient-specific management of trauma hemorrhage: the effect of resuscitation therapy on parameters of thromboelastometry

Essentials The response of thromboelastometry (ROTEM) parameters to therapy is unknown. We prospectively recruited hemorrhaging trauma patients in six level-1 trauma centres in Europe. Blood products and pro-coagulants prevent further derangement of ROTEM results. ROTEM algorithms can be used to treat and monitor trauma induced coagulopathy. SUMMARY: Background Rotational thromboelastometry (ROTEM) can detect trauma-induced coagulopathy (TIC) and is used in transfusion algorithms. The response of ROTEM to transfusion therapy is unknown. Objectives To determine the response of ROTEM profiles to therapy in bleeding trauma patients. Patients/Methods A prospective multicenter study in bleeding trauma patients (receiving ≥ 4 red blood cell [RBC] units) was performed. Blood was drawn in the emergency department, after administration of 4, 8 and 12 RBC units and 24 h post-injury. The response of ROTEM to plasma, platelets (PLTs), tranexamic acid (TXA) and fibrinogen products was evaluated in the whole cohort as well as in the subgroup of patients with ROTEM values indicative of TIC. Results Three hundred and nine bleeding and shocked patients were included. A mean dose of 3.8 g of fibrinogen increased FIBTEM CA5 by 5.2 mm (IQR: 4.1-6.3 mm). TXA administration decreased lysis by 5.4% (4.3-6.5%). PLT transfusion prevented further derangement of parameters of clot formation. The effect of PLTs on EXTEM ca5 values was more pronounced in patients with a ROTEM value indicative of TIC than in the whole cohort. Plasma transfusion decreased EXTEM clotting time by 3.1 s (- 10 s to 3.9 s) in the whole cohort and by 10.6 s (- 45 s to 24 s) in the subgroup of patients with a ROTEM value indicative of TIC. Conclusion The effects of therapy on ROTEM values were small, but prevented further derangement of test results. In patients with ROTEM values indicative of TIC, the efficacy of PLTs and plasma in correcting deranged ROTEM parameters is possibly more robust.

Red blood cell storage lesion: causes and potential clinical consequences

Red blood cells (RBCs) are a specialised organ that enabled the evolution of multicellular organisms by supplying a sufficient quantity of oxygen to cells that cannot obtain oxygen directly from ambient air via diffusion, thereby fueling oxidative phosphorylation for highly efficient energy production. RBCs have evolved to optimally serve this purpose by packing high concentrations of haemoglobin in their cytosol and shedding nuclei and other organelles. During their circulatory lifetimes in humans of approximately 120 days, RBCs are poised to transport oxygen by metabolic/redox enzymes until they accumulate damage and are promptly removed by the reticuloendothelial system. These elaborate evolutionary adaptions, however, are no longer effective when RBCs are removed from the circulation and stored hypothermically in blood banks, where they develop storage-induced damages ("storage lesions") that accumulate over the shelf life of stored RBCs. This review attempts to provide a comprehensive view of the literature on the subject of RBC storage lesions and their purported clinical consequences by incorporating the recent exponential growth in available data obtained from "omics" technologies in addition to that published in more traditional literature. To summarise this vast amount of information, the subject is organised in figures with four panels: i) root causes; ii) RBC storage lesions; iii) physiological effects; and iv) reported outcomes. The driving forces for the development of the storage lesions can be roughly classified into two root causes: i) metabolite accumulation/depletion, the target of various interventions (additive solutions) developed since the inception of blood banking; and ii) oxidative damages, which have been reported for decades but not addressed systemically until recently. Downstream physiological consequences of these storage lesions, derived mainly by in vitro studies, are described, and further potential links to clinical consequences are discussed. Interventions to postpone the onset and mitigate the extent of the storage lesion development are briefly reviewed. In addition, we briefly discuss the results from recent randomised controlled trials on the age of stored blood and clinical outcomes of transfusion.

Platelet storage duration and its clinical and transfusion outcomes: a systematic review

Background

Platelets (PLTs) are usually stored for up to 5 days prior to transfusion, although in some blood services the storage period is extended to 7 days. During storage, changes occur in both PLT and storage medium, which may lead to PLT activation and dysfunction. The clinical significance of these changes remains uncertain.

Methods

We performed a systematic review to assess the association between PLT storage time and clinical or transfusion outcomes in patients receiving allogeneic PLT transfusion. We searched studies published in English between January 2000 and July 2017 identified from MEDLINE, Embase, PubMed and the Cochrane Libraries.

Results

Of the 18 studies identified, five included 4719 critically ill patients (trauma, post-cardiac surgery and a heterogeneous population of critically ill patients) and 13 included 8569 haematology patients. The five studies in critically ill patients were retrospective and did not find any association between PLT storage time when PLTs were stored for up to 5 days and mortality. There was also no association between older PLTs and sepsis in the two largest studies (n = 4008 patients). Of the 13 studies in haematology patients, seven analysed prolonged storage time up to 6.5 or 7 days. Administration of fresh PLTs (less than 2 or 3 days) was associated with a significant increase in corrected count increment (CCI) compared to older PLTs in seven of the eight studies analysing this outcome. One single centre retrospective study found an increase in bleeding events in patients receiving older PLTs.

Conclusions

PLT storage time does not appear to be associated with clinical outcomes, including bleeding, sepsis or mortality, in critically ill patients or haematology patients. The freshest PLTs (less than 3 days) were associated with a better CCI, although there was no impact on bleeding events, questioning the clinical significance of this association. However, there is an absence of evidence to draw definitive conclusions, especially in critically ill patients.

Electronic supplementary material

The online version of this article (10.1186/s13054-018-2114-x) contains supplementary material, which is available to authorized users.

Measurement of Intraoperative Blood Loss in Pediatric Orthopaedic Patients: Evaluation of a New Method

Introduction:

Our goal was to validate a new method of intraoperative blood loss measurement in pediatric patients who undergo orthopaedic surgery.

Methods:

We prospectively collected surgical sponges from 55 patients who underwent pediatric posterior spinal fusion, single-event multilevel surgery, or hip reconstruction for measurement of intraoperative blood loss. We enrolled patients if expected estimated blood loss (EBL) was >200 mL. The methods used for blood loss assessment included the Triton sponge scanning system, visual method, gravimetric method, and measured assay (reference) method.

Results:

The Triton system calculation of cumulative EBL per patient against the reference method yielded a strong positive linear correlation (R² = 0.88). A weaker correlation was noted between the gravimetric method and reference EBL (R² = 0.49). The Triton system had a low bias and narrow limits of agreement relative to the reference method (49 mL; 95% CI, 30 to 68). The gravimetric method had a higher bias and wider limits of agreement (101 mL; 95% CI, 67 to 135). The comparison of visual total EBL against the reference method yielded a notable discrepancy.

Discussion:

Estimated blood loss measured using the Triton system correlated better with the reference method than with the gravimetric method. The visual estimation method was found to be inaccurate. Intraoperative use of the Triton system is convenient and precise for monitoring intraoperative blood loss.

The Non-Hemostatic Aspects of Transfused Platelets

Platelets transfusion is a safe process, but during or after the process, the recipient may experience an adverse reaction and occasionally a serious adverse reaction (SAR). In this review, we focus on the inflammatory potential of platelet components (PCs) and their involvement in SARs. Recent evidence has highlighted a central role for platelets in the host inflammatory and immune responses. Blood platelets are involved in inflammation and various other aspects of innate immunity through the release of a plethora of immunomodulatory cytokines, chemokines, and associated molecules, collectively termed biological response modifiers that behave like ligands for endothelial and leukocyte receptors and for platelets themselves. The involvement of PCs in SARs—particularly on a critically ill patient’s context—could be related, at least in part, to the inflammatory functions of platelets, acquired during storage lesions. Moreover, we focus on causal link between platelet activation and immune-mediated disorders (transfusion-associated immunomodulation, platelets, polyanions, and bacterial defense and alloimmunization). This is linked to the platelets’ propensity to be activated even in the absence of deliberate stimuli and to the occurrence of time-dependent storage lesions.

Supernatants and lipids from stored red blood cells activate pulmonary microvascular endothelium through the BLT2 receptor and protein kinase C activation

BACKGROUND

Although transfusion is a lifesaving intervention, it may be associated with significant morbidity in injured patients. We hypothesize that stored red blood cells (RBCs) induce proinflammatory activation of human pulmonary microvascular endothelial cells (HMVECs) resulting in neutrophil (PMN) adhesion and predisposition to acute lung injury (ALI).

STUDY DESIGN AND METHODS

Ten units of RBCs were collected; 50% (by weight) were leukoreduced (LR-RBCs) and the remainder was unmodified and stored in additive solution-5 (AS-5). An additional 10 units of RBCs were collected, leukoreduced, and stored in AS-3. HMVECs were incubated with [10%-40%]_FINAL of the supernatants on Day (D)1 to D42 of storage, lipid extracts, and purified lipids. Endothelial surface expression of intercellular adhesion molecule-1 (ICAM-1), interleukin (IL)-8 release, and PMN adhesion to HMVECs were measured. HMVEC signaling via the BLT2 receptor was evaluated. Supernatants and lipids were also employed as the first event in a two-event model of ALI.

RESULTS

The supernatants [10%-40%]_FINAL from D21 LR-RBCs and D42 RBCs and LR-RBCs and the lipids from D42 stored in AS-5 induced increased ICAM-1 surface expression on endothelium, IL-8 release, and PMN adhesion. In addition, the supernatants [20%-40%]_FINAL from D21 and D42 RBCs in AS-5 also increased endothelial surface expression of ICAM-1. D42 supernatants and lipids also caused coprecipitation of β-arrestin-1 with BLT2, protein kinase C (PKC)β_I , and PKCδ and served as the first event in a two-event rodent model of ALI.

CONCLUSION

Lipids that accumulate during RBC storage activate endothelium and predispose to ALI, which may explain some of the adverse events associated with the transfusion of critically injured patients.

Use of propensity score methods to address adverse events associated with the storage time of blood in an obstetric population: a comparison of methods

Background

A recent topic of interest in the blood transfusion literature is the existence of adverse effects of transfusing red cells towards the end of their storage life. This interest has been sparked by conflicting results in observational studies, however a number of methodological difficulties with these studies have been noted. One potential strategy to address these difficulties is the use of propensity scores, of which there are a number of possible methods. This study aims to compare the traditional methods for binary exposures with more recently developed generalised propensity score methods.

Methods

Data were obtained from probabilistically linked hospital, births and blood bank databases for all women giving birth from 23 weeks gestation in New South Wales, Australia, between July 2006 and December 2010 with complete information on the birth admission and blood issued. Analysis was restricted to women who received 1–4 units of red cells. Three different propensity score methods (for binary, ordinal and continuous exposures) were compared, using each of four different approaches to estimating the effect (matching, stratifying, weighting and adjusting by the propensity score). Each method was used to determine the effect of blood storage time on rates of severe morbidity and readmission or transfer.

Results

Data were available for 2990 deliveries to women receiving 1–4 units of red cells. The rate of severe maternal morbidity was 3.7 %, and of readmission or transfer was 14.4 %. There was no association between blood storage time and rates of severe morbidity or readmission irrespective of the approach used. There was no single optimal propensity score method; the approaches differed in their ease of implementation and interpretation.

Conclusions

Within an obstetric population, there was no evidence of an increase in adverse events following transfusion of older blood. Propensity score methods provide a useful tool for addressing the question of adverse events with increasing storage time of blood, as these methods avoid many of the pitfalls of previous studies. In particular, generalised propensity scores can be used in situations where the exposure is not binary.

Transfusion of platelets, but not of red blood cells, is independently associated with nosocomial infections in the critically ill

BACKGROUND

Red blood cell (RBC) transfusion has been associated with nosocomial infection in the critically ill patients. However, this association may be confounded by length of stay, as prolonged intensive care unit (ICU stay) increases both risk of infection and risk of transfusion. Also, it is not known whether specific blood products have differential risks.

METHODS

In this prospective multicentre cohort study, the risk of bacterial infections associated with transfusion products in critically ill (ICU) patients was determined in an integrated statistical model, using Cox proportional hazard analysis to account for attrition bias. In all acutely admitted patients with a length of stay of >48 h between 1 January 2011 and 31 December 2012, the occurrence of nosocomial infections in the ICU was prospectively monitored using CDC criteria.

RESULTS

Of 3502 screened patients, 476 (13.6 %) developed a nosocomial infection. These patients had higher APACHE IV scores, had longer ICU length of stay and were more frequently transfused compared to patients without an infection. Logistic regression showed that RBC transfusion was a risk factor for infection [odds ratio (OR) 1.98, 95 % confidence interval (CI) 1.54-2.55, p < 0.001], as well the number of RBC units transfused (OR 1.04, 95 % CI 1.03-1.06, p < 0.001). However, these associations disappeared in the Cox proportional hazard analysis. In contrast, we found an association between plasma transfusion and infection [hazard ratio (HR) 1.36, 95 % CI 1.10-1.69, p = 0.004] and between platelet transfusion and infection (HR 1.46, 95 % CI 1.18-1.81, p < 0.001). However, only platelet transfusion was associated with infection independently from other transfusion products (HR 1.40, 95 % CI 1.03-1.90, p = 0.03).

CONCLUSIONS

In critically ill patients, transfusion of platelets, but not of RBCs and plasma, is an independent risk factor for acquiring a nosocomial infection.

Impact of the age of stored blood on trauma patient mortality: a systematic review

BACKGROUND

The impact of the age of stored red blood cells on mortality in patients sustaining traumatic injuries requiring transfusion of blood products is unknown. The objective of this systematic review was to identify and describe the available literature on the use of older versus newer blood in trauma patient populations.

METHODS

We searched PubMed, Embase, Lilac and the Cochrane Database for published studies comparing the transfusion of newer versus older red blood cells in adult patients sustaining traumatic injuries. Studies included for review reported on trauma patients receiving transfusions of packed red blood cells, identified the age of stored blood that was transfused and reported patient mortality as an end point. We extracted data using a standardized form and assessed study quality using the Newcastle-Ottawa Scale.

RESULTS

Seven studies were identified (6780 patients) from 3936 initial search results. Four studies reported that transfusion of older blood was independently associated with increased mortality in trauma patients, while 3 studies did not observe any increase in patient mortality with the use of older versus newer blood. Three studies associated the transfusion of older blood with adverse patient outcomes, including longer stay in the intensive care unit, complicated sepsis, pneumonia and renal dysfunction. Studies varied considerably in design, volumes of blood transfused and definitions applied for old and new blood..

CONCLUSION

The impact of the age of stored packed red blood cells on mortality in trauma patients is inconclusive. Future investigations are warranted.

Transfusion related morbidity in premature babies: Possible mechanisms and implications for practice

Many premature babies, especially those with a low birth weight are given multiple transfusions during their first few weeks of life. The major serious complications of prematurity include bronchopulmonary dysplasia, with lesser incidences of retinopathy of prematurity, intraventricular haemorrhage, and necrotising enterocolitis. Many studies have shown correlations between the receipt of blood transfusions and the development of these conditions, but little is known of the underlying pathophysiology of this relationship. Recent studies are beginning to provide some answers. This review examines recent findings with regard to the influence of preparation and storage of paediatric packed red blood cell units on heme, iron, and oxidative status of the units and relates these to the ability of the premature baby to deal with these changes following the receipt of blood transfusions. Paediatric packed red blood cell units are a potential source of heme, redox active iron and free radicals, and this increases with storage age. Haemolysis of transfused red blood cells may add further iron and cell free haemoglobin to the recipient baby. Premature babies, particularly those with low birth weight and gestational age appear to have little reserve to cope with any additional iron, heme and/or oxidative load. The consequences of these events are discussed with regard to their contribution to the major complications of prematurity and a novel hypothesis regarding transfusion-related morbidity in premature babies is presented. The review concludes with a discussion of potential means of limiting transfusion related iron/heme and oxidative load through the preparation and storage of packed red blood cell units and through modifications in clinical practice.

Adverse effects of hemorrhagic shock resuscitation with stored blood are ameliorated by inhaled nitric oxide in lambs*

OBJECTIVES

Transfusion of stored RBCs is associated with increased morbidity and mortality in trauma patients. Plasma hemoglobin scavenges nitric oxide, which can cause vasoconstriction, induce inflammation, and activate platelets. We hypothesized that transfusion of RBCs stored for prolonged periods would induce adverse effects (pulmonary vasoconstriction, tissue injury, inflammation, and platelet activation) in lambs subjected to severe hemorrhagic shock and that concurrent inhalation of nitric oxide would prevent these adverse effects.

DESIGN

Animal study.

SETTING

Research laboratory at the Massachusetts General Hospital, Boston, MA.

SUBJECTS

Seventeen awake Polypay-breed lambs.

INTERVENTIONS

Lambs were subjected to 2 hours of hemorrhagic shock by acutely withdrawing 50% of their blood volume. Lambs were resuscitated with autologous RBCs stored for 2 hours or less (fresh) or 39 ± 2 (mean ± SD) days (stored). Stored RBCs were administered with or without breathing nitric oxide (80 ppm) during resuscitation and for 21 hours thereafter.

MEASUREMENTS AND MAIN RESULTS

We measured hemodynamic and oxygenation variables, markers of tissue injury and inflammation, plasma hemoglobin concentrations, and platelet activation. Peak pulmonary arterial pressure was higher after resuscitation with stored than with fresh RBCs (24 ± 4 vs 14 ± 2 mm Hg, p < 0.001) and correlated with peak plasma hemoglobin concentrations (R = 0.56, p = 0.003). At 21 hours after resuscitation, pulmonary myeloperoxidase activity was higher in lambs resuscitated with stored than with fresh RBCs (11 ± 2 vs 4 ± 1 U/g, p = 0.007). Furthermore, transfusion of stored RBCs increased plasma markers of tissue injury and sensitized platelets to adenosine diphosphate activation. Breathing nitric oxide prevented the pulmonary hypertension and attenuated the pulmonary myeloperoxidase activity, as well as tissue injury and sensitization of platelets to adenosine diphosphate.

CONCLUSIONS

Our data suggest that resuscitation of lambs from hemorrhagic shock with autologous stored RBCs induces pulmonary hypertension and inflammation, which can be ameliorated by breathing nitric oxide.

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.

Age of red blood cells and transfusion in critically ill patients

Red blood cells (RBC) storage facilitates the supply of RBC to meet the clinical demand for transfusion and to avoid wastage. However, RBC storage is associated with adverse changes in erythrocytes and their preservation medium. These changes are responsible for functional alterations and for the accumulation of potentially injurious bioreactive substances. They also may have clinically harmful effects especially in critically ill patients. The clinical consequences of storage lesions, however, remain a matter of persistent controversy. Multiple retrospective, observational, and single-center studies have reported heterogeneous and conflicting findings about the effect of blood storage duration on morbidity and/or mortality in trauma, cardiac surgery, and intensive care unit patients. Describing the details of this controversy, this review not only summarizes the current literature but also highlights the equipoise that currently exists with regard to the use of short versus current standard (extended) storage duration red cells in critically ill patients and supports the need for large, randomized, controlled trials evaluating the clinical impact of transfusing fresh (short duration of storage) versus older (extended duration of storage) red cells in critically ill patients.