Current issues relating to the transfusion of stored red blood cells

Leukoreduction of red blood cell units decreases dysregulatory micro RNAs during routine storage: An observational study with In-silico analysis

BACKGROUND

Red Blood cells (RBCs) bring about harmful consequences during storage. MicroRNA (miRNA) dysregulation in stored RBCs could represent potential biomarkers of storage lesions. Although leukoreduction prevents damage to RBCs, it is uncertain whether leukoreduction of RBCs would impact the dysregulation of miRNAs during storage. This study evaluated the potential role of miRNAs for any alteration of leukoreduced (LR) and non-leukoreduced (NLR) RBCs till 21 days of storage.

STUDY DESIGN AND METHODS

In this prospective study, thirty male volunteers' blood was equally divided into leukoreduced RBCs (LR) and NLR RBC (NLR) bags and stored till Day 21 at 4-60c. Selected miRNAs were quantified on Days 0 and 21. Further, bioinformatic tools were used to analyze the selected miRNAs and their predicted target genes (mRNAs) and identify the miRNA-mRNA regulatory relationships.

RESULTS

A significantly higher fold change values of three miRNAs (miR-96-5p, miR-197-3p, miR-769-3p) were observed in NLR RBCs (p < .05). A significantly higher (p < .05) expression levels of miR-150-5p and miR-197-3p were observed in NLR RBCs till 21 days of storage. Further, the correlation with mRNA quantification confirmed the regulatory role of these miRNAs upon functional pathway enrichment analysis.

DISCUSSION

A higher level of dysregulation of miRNAs was observed in NLR RBCs. Validation from In-Silico analysis suggested the regulatory role of miRNAs in cell apoptosis, senescence, and RBC-related signaling pathways. This indicated that stored LR RBCs would likely have better in vivo survival and function following transfusion. However, an in vivo study of miRNA in RBCs is warranted for conclusive evidence.

Safety and efficacy of human polymerized hemoglobin on guinea pig resuscitation from hemorrhagic shock

For the past thirty years, hemoglobin-based oxygen carriers (HBOCs) have been under development as a red blood cell substitute. Side-effects such as vasoconstriction, oxidative injury, and cardiac toxicity have prevented clinical approval of HBOCs. Recently, high molecular weight (MW) polymerized human hemoglobin (PolyhHb) has shown positive results in rats. Studies have demonstrated that high MW PolyhHb increased O₂ delivery, with minimal effects on blood pressure, without vasoconstriction, and devoid of toxicity. In this study, we used guinea pigs to evaluate the efficacy and safety of high MW PolyhHb, since like humans guinea pigs cannot produce endogenous ascorbic acid, which limits the capacity of both species to deal with oxidative stress. Hence, this study evaluated the efficacy and safety of resuscitation from severe hemorrhagic shock with high MW PolyhHb, fresh blood, and blood stored for 2 weeks. Animals were randomly assigned to each experimental group, and hemorrhage was induced by the withdrawal of 40% of the blood volume (BV, estimated as 7.5% of body weight) from the carotid artery catheter. Hypovolemic shock was maintained for 50 min. Resuscitation was implemented by infusing 25% of the animal's BV with the different treatments. Hemodynamics, blood gases, total hemoglobin, and lactate were not different before hemorrhage and during shock between groups. The hematocrit was lower for the PolyhHb group compared to the fresh and stored blood groups after resuscitation. Resuscitation with stored blood had lower blood pressure compared to fresh blood at 2 h. There was no difference in mean arterial pressure between groups at 24 h. Resuscitation with PolyhHb was not different from fresh blood for most parameters. Resuscitation with PolyhHb did not show any remarkable change in liver injury, inflammation, or cardiac damage. Resuscitation with stored blood showed changes in liver function and inflammation, but no kidney injury or systemic inflammation. Resuscitation with stored blood after 24 h displayed sympathetic hyper-activation and signs of cardiac injury. These results suggest that PolyhHb is an effective resuscitation alternative to blood. The decreased toxicities in terms of cardiac injury markers, vital organ function, and inflammation following PolyhHb resuscitation in guinea pigs indicate a favorable safety profile. These results are promising and support future studies with this new generation of PolyhHb as alternative to blood when blood is unavailable.

A deep 96-well plate RBC storage platform for high-throughput screening of novel storage solutions

Background: Red blood cell (RBC) storage solutions, also known as additive solutions (ASs), first developed in the 1970s, enable extended storage of RBCs. Unfortunately, the advancements in this field have been limited, due to labor intensive and time-consuming serial in vitro and in vivo testing, coupled with very high commercialization hurdles. This study examines the utility of deep 96-well plates for preliminary screenings of novel ASs through comparison of RBC storage with the standard PVC bags in terms of hemolysis and ATP levels, under both normoxic (N) and hypoxic/hypocapnic (H) storage conditions. The necessity for the presence of DEHP, normally provided by PVC bags, is also examined. Materials and methods: A pool of 2 ABO compatible RBC units was split between a bag and a plate. Each plate well contained either 1, 2 or 0 PVC strips cut from standard storage bags to supply DEHP. The H bags and plates were processed in an anaerobic glovebox and stored in O2 barrier bags. Hemolysis and ATP were measured bi-weekly using standard methods. Results: Final ATP and hemolysis values for the plate-stored RBCs were comparable to the typical values observed for 6-week storage of leukoreduced AS-3 RBCs in PVC bags under both N and H conditions. Hemolysis was below FDA and EU benchmarks of 1% and 0.8%, respectively, and excluding DEHP from plates during storage, resulted in an inconsequential increase when compared to bag samples. Discussion: In combination with high-throughput metabolomics workflow, this platform provides a highly efficient preliminary screening platform to accelerate the initial testing and consequent development of novel RBC ASs.

Red Blood Cell Transfusions and Risk of Postoperative Venous Thromboembolism

INTRODUCTION

Postoperative venous thromboembolism (VTE) is a major risk for orthopaedic surgery and associated with notable morbidity and mortality. Knowing a patient's risk for VTE may help guide the choice of perioperative VTE prophylaxis. Recently, red blood cells (RBCs) have been implicated for their role in pathologic thrombosis. Therefore, we examine the association between perioperative RBC transfusion and postoperative VTE after orthopaedic surgery.

METHODS

A retrospective cohort study was done by conducting a secondary analysis of data obtained from the 2016 American College of Surgeons National Surgical Quality Improvement Program database. Our population consisted of 234,608 adults who underwent orthopaedic surgery. The exposure was whether patients received a perioperative RBC transfusion. The primary outcome was postoperative VTE within 30 days of surgery that warranted therapeutic intervention, which was subsequently split into symptomatic deep vein thrombosis (DVT) and pulmonary embolism (PE). Odds ratios (ORs) were estimated using a multivariate logistic regression model.

RESULTS

At baseline, 1,952 patients (0.83%) had postoperative VTE (DVT in 1,299 [0.55%], PE in 801 [0.34%], and both DVT and PE in 148 [0.06%]). Seven hundred ninety-five patients (0.3%) received preoperative RBC transfusions only, 11,587 patients (4.9%) received postoperative RBC transfusions only, and 848 patients (0.4%) received both preoperative and postoperative RBC transfusions. Postoperative RBC transfusion was associated with higher odds of VTE (adjusted OR [aOR], 1.47; 95% confidence interval [CI], 1.19-1.81), DVT (aOR, 1.40; 95% CI, 1.09-1.79), PE (aOR, 1.59; 95% CI, 1.14-2.22), and 30-day mortality (aOR, 1.21; 95% CI, 1.01-1.45) independent of various presumed risk factors. When creating subgroups within orthopaedics by Current Procedural Terminology codes, postoperative transfusions in spine (aOR, 2.03; 95% CI, 1.13-3.67) and trauma (aOR, 1.40; 95% CI, 1.06-1.86) were associated with higher odds of postoperative VTE.

CONCLUSION

Our results suggest that postoperative RBC transfusion may be associated with an increased risk of postoperative VTE, both symptomatic DVT and life-threatening PE, independent of confounders. Additional prospective validation in cohort studies is necessary to confirm these findings. In addition, careful perioperative planning for patients deemed to be at high risk of requiring blood transfusion may reduce these postoperative complications in orthopaedic patients.

LEVEL OF EVIDENCE

III.

Pro-Con Debate: Viscoelastic Hemostatic Assays Should Replace Fixed Ratio Massive Transfusion Protocols in Trauma

Major trauma patients at risk of traumatic coagulopathy are commonly treated with early clotting factor replacement to maintain hemostasis and prevent microvascular bleeding. In the United States, trauma transfusions are often dosed by empiric, low-ratio massive transfusion protocols, which pair plasma and platelets in some ratio relative to the red cells, such as the "1:1:1" combination of 1 units of red cells, 1 unit of plasma, and 1 donor's worth of pooled platelets. Empiric transfusion increases the rate of overtransfusion when unnecessary blood products are administered based on a formula and not on at patient's hemostatic profile. Viscoelastic hemostatic assays (VHAs) are point-of-care hemostatic assays that provided detailed information about abnormal clotting pathways. VHAs are used at many centers to better target hemostatic therapies in trauma. This Pro/Con section will address whether VHA guidance should replace empiric fixed ratio protocols in major trauma.

The effect of position and frequency of mixing on canine packed red blood cell units during storage

OBJECTIVE

Hemolysis is an indicator of storage lesion that occurs in stored packed red blood cells (pRBCs) over time. Intermittent mixing of red blood cells in the additive solutions may be beneficial but may also result in iatrogenic injury. Position of units in storage may also affect the quality of the pRBCs. This prospective study was designed to evaluate hemolytic effect of mixing frequency and storage position on canine pRBCs over a period of 28 days.

DESIGN

Prospective in vitro study SETTING: Private practice referral hospital with an internal blood bank ANIMALS: Thirty-two healthy prescreened dogs enrolled in a volunteer blood banking program INTERVENTIONS: None MEASUREMENTS AND MAIN RESULTS: A total of 160 samples were evaluated. Forty canine pRBC units were split into 4 daughter bags and stored in varying positions with different mixing frequencies. Samples were stored upright and mixed daily, upright and mixed weekly, horizontally and mixed daily, or horizontally and mixed weekly for a period of 28 days. At days 0, 7, 14, and 28, samples from the units were analyzed to calculate percent hemolysis. No differences were found in any hemolytic indicators investigated (total hemoglobin, free plasma hemoglobin, and packed cell volume) until day 28 in all test groups. Canine pRBCs stored upright and mixed weekly or stored horizontally and mixed weekly resulted in less hemolysis and free plasma hemoglobin when compared to units stored horizontally and mixed daily only at day 28.

CONCLUSIONS

Statistically significant hemolysis was not evident amongst canine pRBC groups less than 28 days old suggesting that positioning and mixing frequency was irrelevant until day 28. Beyond 28 days despite the presence of hemolysis, no definitive recommendation could be made with respect to best practice for storage position or mixing frequency of stored canine pRBCs.

Measuring potassium level in packed red blood cells before using: Word of caution for congenital cardiac surgery

BACKGROUND AND AIM OF THE STUDY

Transfusion-associated hyperpotassemia is a serious complication of packed red blood cell (PRBC) transfusion after congenital cardiac surgery. Our study aimed to identify risk factors and potential preventive measures of transfusion-associated hyperpotassemia in neonates and infants after congenital cardiac surgery.

METHODS

Pediatric patients who underwent congenital cardiac surgery and need transfusion were enrolled in this prospective study. The potassium concentration of PRBC was checked from the sample taken from the segment. The volume of transfusion, age of PRBC, potassium concentration of unit were recorded. The estimated increment of potassium level in patients after PRBC transfusion was calculated.

RESULTS

Seventy-four individual patients, 95 distinct transfusions, 112 blood products were evaluated. The mean age of the blood unit was 3.8 ± 1.4 days. The mean potassium concentration in the PRBCs was 9.9 ± 2.4 mmol/L. A weak correlation was observed between the potassium value of the PRBC and the age of PRBC (p = 0.049, r = 0.2, y = 0.24 × x + -0.68). There was a weak correlation between the potassium value of PRBCs and the age of the unit (p < 0.001, r = 0.37, y = 2.8 × x + -3.6).

CONCLUSIONS

Before transfusion, even PRBC is fresh, measuring the potassium level of PRBC and the potassium that will be given to the pediatric patient with transfusion can prevent transfusion-related hyperpotassemia and related complications. Otherwise, high potassium levels, which may be overlooked despite being fresh, may cause serious complications, even cardiac arrest, especially in neonates and infants.

An Evaluation of Morphological Changes and Deformability of Suspended Red Blood Cells Prepared Using Whole Blood with Different Hemoglobin Levels of Tibetans

Background

The hypoxic environment stimulates the human body to increase the levels of hemoglobin (HGB) and hematocrit and the number of red blood cells. Such enhancements have individual differences, leading to a wide range of HGB in Tibetans' whole blood (WB).

Study Design

WB of male Tibetans was divided into 3 groups according to different HGB (i.e., A: >120 but ≤185 g/L, B: >185 but ≤210 g/L, and C: >210 g/L). Suspended red blood cells (SRBC) processed by collected WB and stored in standard conditions were examined aseptically on days 1, 14, 21, and 35 after storage. The routine biochemical indexes, deformability, cell morphology, and membrane proteins were tested.

Results

Mean corpuscular volume, adenosine triphosphate, pH, and deformability were not different in group A vs. those in storage (p > 0.05). The increased rate of irreversible morphology of red blood cells was different among the 3 groups, but there was no difference in the percentage of red blood cells with an irreversible morphology after 35 days of storage. Group C performed better in terms of osmotic fragility and showed a lower rigid index than group A. Furthermore, SDS-PAGE revealed similar cross-linking degrees of cell membrane protein but the band 3 protein of group C seemed to experience weaker clustering than that of group A as detected by Western Blot analysis after 35 days of storage.

Conclusions

There was no difference in deformability or morphological changes in the 3 groups over the 35 days of storage. High HGB levels of plateau SRBC did not accelerate the RBC change from a biconcave disc into a spherical shape and it did not cause a reduction in deformability during 35 days of preservation in bank conditions.

Do We Store Packed Red Blood Cells under "Quasi-Diabetic" Conditions?

Red blood cell (RBC) transfusion is one of the most common therapeutic procedures in modern medicine. Although frequently lifesaving, it often has deleterious side effects. RBC quality is one of the critical factors for transfusion efficacy and safety. The role of various factors in the cells’ ability to maintain their functionality during storage is widely discussed in professional literature. Thus, the extra- and intracellular factors inducing an accelerated RBC aging need to be identified and therapeutically modified. Despite the extensively studied in vivo effect of chronic hyperglycemia on RBC hemodynamic and metabolic properties, as well as on their lifespan, only limited attention has been directed at the high sugar concentration in RBCs storage media, a possible cause of damage to red blood cells. This mini-review aims to compare the biophysical and biochemical changes observed in the red blood cells during cold storage and in patients with non-insulin-dependent diabetes mellitus (NIDDM). Given the well-described corresponding RBC alterations in NIDDM and during cold storage, we may regard the stored (especially long-stored) RBCs as “quasi-diabetic”. Keeping in mind that these RBC modifications may be crucial for the initial steps of microvascular pathogenesis, suitable preventive care for the transfused patients should be considered. We hope that our hypothesis will stimulate targeted experimental research to establish a relationship between a high sugar concentration in a storage medium and a deterioration in cells’ functional properties during storage.

Evaluation of cellular changes in blood stored for transfusion at Bungoma County Referral Hospital, Kenya

Introduction

during the storage of transfusion blood, it may undergo a series of cellular changes that in speculation could be the reason behind the risk of using prolonged stored blood. It's important therefore to monitor the cellular changes that may reduce its survival and function. The objective was to assess the cellular changes in whole blood stored for transfusion at Bungoma county referral hospital.

Methods

a single center, prospective and observational study design involving 20 randomly selected donor blood units in citrate phosphate dextrose adenine (CPDA-1) anticoagulant was employed, cellular changes were evaluated for 35 days. The changes were tested using the Celtac F Haematology analyzer. Statistical Analysis of variance was employed in the descriptive statistics. All the investigation was executed using statistical package for social sciences (SPSS V.23). Results were regarded as significant at P<0.05. Results were presented in tables and charts.

Results

at the end of the 35 days blood storage at blood bank conditions, WBC, RBC, platelets counts and MCHC decreased significantly (P<0.0001, =0.0182, <0.0001, =0.0035). The MCV, HCT and MCH increased significantly (P <0.0001, =0.0003, =0.0115) while HGB had insignificant variance (P =0.4185).

Conclusion

platelets, WBC, RBC counts, and indices are significantly altered in stored blood especially when stored over two weeks based on most of the cellular components analyzed in this study. The study, therefore, recommends the utilization of fresh blood to avoid the adverse outcome of cellular changes of reserved blood.

Is fresh, leucodepleted, whole blood transfusion superior to blood component transfusion in pediatric patients undergoing spinal deformity surgeries? A prospective, randomized study analyzing postoperative serological parameters and clinical recovery

Purpose

To compare the effectiveness of fresh whole blood (FWB) and blood component transfusion in improving clinical outcome and serological parameters in the early postoperative period following spinal deformity surgery.

Methods

Patients undergoing major spinal deformity surgeries involving ≥ 6 levels of fusion and expected blood loss ≥ 750 ml between September 2017 and August 2018 were included in the study. The patients were randomized into two groups: FWBG and CG, receiving fresh whole blood and component transfusions, respectively.

Results

A total of 65 patients with spinal deformities of different etiologies were included. The mean age was 14.0 and 14.9 years in FWB and CG, respectively. All other preoperative parameters were comparable. The mean fusion levels and surgical time were 11.1 and 221.20 min in FWB, as compared with 10.70 and 208.74minutes in CG, respectively. Intraoperative blood losses were 929 ml (FWBG) and 847 ml(CG), and the mean volumes of transfusion were 1.90 (FWBG) and 1.65 units (CG). FWBG was significantly superior to CG in the following clinical and laboratory parameters: duration of oxygen dependence [36.43 (FWBG) vs. 43.45 h (CG); P = 0.0256], mean arterial pH [7.442 (FWBG) vs. 7.394 (CG); p < 0.001], interleukin-6 [30.04 (FWBG) vs. 35.10 (CG); p < 0.019], mean duration of HDU stay [40.6 hours (FWBG) vs 46.51 hours (CG); p = 0.0234] and postoperative facial puffiness [7/30 in FWBG vs. 18/35 (CG) (P < 0.02)].

Conclusion

FWB transfusion can potentially improve the immediate postoperative outcome in patients undergoing major spinal deformity surgeries by reducing the duration of intensive care unit stay and oxygen dependence. The other potential benefits of this practice, based on our study, include a reduced inflammatory response (reduced lactate and IL-6) and postoperative facial puffiness. However, further large-scale validation studies in future are necessary to precisely determine the role of FWB in spine surgeries.

Level of evidence II

Diagnostic: individual cross-sectional studies with the consistently applied reference standard and blinding.

Microfluidic capillary networks are more sensitive than ektacytometry to the decline of red blood cell deformability induced by storage

Ektacytometry has been the primary method for evaluating deformability of red blood cells (RBCs) in both research and clinical settings. This study was designed to test the hypothesis that the flow of RBCs through a network of microfluidic capillaries could provide a more sensitive assessment of the progressive impairment of RBC deformability during hypothermic storage than ektacytometry. RBC units (n = 9) were split in half, with one half stored under standard (normoxic) conditions and the other half stored hypoxically, for up to 6 weeks. RBC deformability was measured weekly using two microfluidic devices, an artificial microvascular network (AMVN) and a multiplexed microcapillary network (MMCN), and two commercially available ektacytometers (RheoScan-D and LORRCA). By week 6, the elongation indexes measured with RheoScan-D and LORRCA decreased by 5.8–7.1% (5.4–6.9% for hypoxic storage). Over the same storage duration, the AMVN perfusion rate declined by 27.5% (24.5% for hypoxic) and the MMCN perfusion rate declined by 49.0% (42.4% for hypoxic). Unlike ektacytometry, both AMVN and MMCN measurements showed statistically significant differences between the two conditions after 1 week of storage. RBC morphology deteriorated continuously with the fraction of irreversibly-damaged (spherical) cells increasing significantly faster for normoxic than for hypoxic storage. Consequently, the number of MMCN capillary plugging events and the time MMCN capillaries spent plugged was consistently lower for hypoxic than for normoxic storage. These data suggest that capillary networks are significantly more sensitive to both the overall storage-induced decline of RBC deformability, and to the differences between the two storage conditions, than ektacytometry.

Transfusion-Associated Hyperkalemic Cardiac Arrest in Neonatal, Infant, and Pediatric Patients

Red blood cell (RBC) transfusions are a life-saving intervention, with nearly 14 million RBC units transfused in the United States each year. However, the safety and efficacy of this procedure can be influenced by variations in the collection, processing, and administration of RBCs. Procedures or manipulations that increase potassium (K⁺) levels in stored blood products can also predispose patients to hyperkalemia and transfusion-associated hyperkalemic cardiac arrest (TAHCA). In this mini review, we aimed to provide a brief overview of blood storage, the red cell storage lesion, and variables that increase extracellular [K⁺]. We also summarize cases of TAHCA and identify potential mitigation strategies. Hyperkalemia and cardiac arrhythmias can occur in pediatric patients when RBCs are transfused quickly, delivered directly to the heart without time for electrolyte equilibration, or accumulate extracellular K⁺ due to storage time or irradiation. Advances in blood banking have improved the availability and quality of RBCs, yet, some patient populations are sensitive to transfusion-associated hyperkalemia. Future research studies should further investigate potential mitigation strategies to reduce the risk of TAHCA, which may include using fresh RBCs, reducing storage time after irradiation, transfusing at slower rates, implementing manipulations that wash or remove excess extracellular K⁺, and implementing restrictive transfusion strategies.

Association Between Preoperative Blood Transfusion and Postoperative Venous Thromboembolism: Review Meta-Analysis

BACKGROUND

Several studies have shown that preoperative blood transfusion is associated with postoperative venous thromboembolism (VTE). In this study, a meta-analysis was performed to explore the relationship between preoperative blood transfusion and postoperative VTE.

METHODS

Published articles were identified through a comprehensive review of PubMed and EMBASE. Data from studies reporting relative risks, odds ratios, or hazard ratios comparing the risk of postoperative VTE among participants who had preoperative blood transfusion versus those without preoperative blood transfusion were analyzed. A random-effect model was used to calculate pooled odds ratios and 95% confident intervals (CIs).

RESULTS

Eight studies, which included 3,504,778 participants, aligned with our inclusion criteria and were included in the meta-analysis. Pooled analysis showed an association between preoperative blood transfusion and postoperative VTE, with an odds ratio of 2.95 (95% CI: 1.65-5.30; I² = 89.1%). In subgroup analyses, the positive association between preoperative blood transfusion and postoperative VTE was still exist in studies with confounders adjustment. Sensitivity analysis by one-study-removed analysis confirmed the robustness of our results.

CONCLUSIONS

Our study indicated that preoperative blood transfusion was associated with higher odds of postoperative VTE. Further large-scale prospective cohort studies are needed to investigate the causality between preoperative blood transfusion and postoperative VTE.

Comparison of UV spectrometry and fluorometry-based methods for quantification of cell-free DNA in red cell components

BACKGROUND:

Stress and shear force applied on blood components during processing and storage may induce cellular damage leading to release of cell-free DNA (cfDNA). In this study, we have compared ultraviolet (UV) spectrophotometry with UV-induced fluorescence for the quantification of cfDNA in red cell supernatant.

MATERIALS AND METHODS:

cfDNA was extracted from 200 μL sample of supernatants from 99 packed red blood cells using QIAamp DNA Blood Mini Kit (Qiagen, Germany). Quantification of cfDNA was done using two different methods: one based on spectrophotometry (NanoDrop 2000c, ThermoFisher Scientific, USA) and another based on fluorometry (Qubit 2.0, Life Technologies, ThermoFisher Scientific, USA). Interassay variability of both the methods was estimated using serial dilutions of standard with known DNA concentration.

RESULTS:

DNA quantification by both the methods was close to actual amount of known standard in dilutions with higher concentration of DNA (21.68 to 2.71 ng/μl). While at higher dilutions, quantification by NanoDrop was neither precise nor accurate. Median cfDNA concentration in the study units was found to be 1.60 ng/μl (25^th–75^th percentile range: 1.10–2.10) by UV spectrophotometry (NanoDrop) compared to 0.080 ng/μl (25^th–75^th percentile range: 0.050–0.130) by fluorometry (Qubit).

CONCLUSION:

Due to high interassay variability between the two methods and the better precision and accuracy of Qubit, it is recommended that fluorometry-based method be used for the quantification of cfDNA in blood components.

Biochemical profile changes in stored donor blood for transfusion

OBJECTIVES

This study's aim was to find out that how various biochemical parameters of donor blood are affected during storage.

METHODS

This cross-sectional study was conducted in hematology Unit of Rehman Medical Institute, Peshawar and Fatimid Foundation, Peshawar Khyber Pakhtunkhwa, over a period of six months from June 2018 to November 2018. This study includes 300 healthy volunteer donors. Analysis of stored blood was done at 0, 3, 7, 14- and 21-days interval. Data were recorded and analyzed in SPSS v 20. A p value of less than 0.05 was taken as significant.

RESULTS

Three hundred healthy volunteer donors were included in the study in which 63% were male and 37% were females. Mean age was 26.54±7.3 years with age range from 23-46 years. Out of 300 donors 15.33% were O+, 35.33%, 9.66% B+, 8.33% A+, 7.66% AB+, 7.66% O-, 7% A- and 9% B-. Significant. Changes were observed in serum potassium, LDH, pH, serum chloride, serum sodium and AST levels. (p:<0.001). however, storage did not affect rest of the parameters.

CONCLUSION

This study reveals that during storage certain changes occur in haematological and biochemical parameters which ultimately may put patients at risk.

Association of Perioperative Red Blood Cell Transfusions With Venous Thromboembolism in a North American Registry

Importance

Increasing evidence supports the role of red blood cells (RBCs) in physiological hemostasis and pathologic thrombosis. Red blood cells are commonly transfused in the perioperative period; however, their association with postoperative thrombotic events remains unclear.

Objective

To examine the association between perioperative RBC transfusions and postoperative venous thromboembolism (VTE) within 30 days of surgery.

Design, Setting, and Participants

This analysis used prospectively collected registry data from the American College of Surgery National Surgical Quality Improvement Program (ACS-NSQIP) database, a validated registry of 525 teaching and nonteaching hospitals in North America. Participants included patients in the ACS-NSQIP registry who underwent a surgical procedure from January 1 through December 31, 2014. Data were analyzed from July 1, 2016, through March 15, 2018.

Main Outcomes and Measures

Risk-adjusted odds ratios (aORs) were estimated using multivariable logistic regression. The primary outcome was the development of postoperative VTE (deep venous thrombosis [DVT] and pulmonary embolism [PE]) within 30 days of surgery that warranted therapeutic intervention; DVT and PE were also examined separately as secondary outcomes. Subgroup analyses were performed by surgical subtypes. Propensity score matching was performed for sensitivity analyses.

Results

Of 750 937 patients (56.8% women; median age, 58 years; interquartile range, 44-69 years), 47 410 (6.3%) received at least 1 perioperative RBC transfusion. Postoperative VTE occurred in 6309 patients (0.8%) (DVT in 4336 [0.6%]; PE in 2514 [0.3%]; both DVT and PE in 541 [0.1%]). Perioperative RBC transfusion was associated with higher odds of VTE (aOR, 2.1; 95% CI, 2.0-2.3), DVT (aOR, 2.2; 95% CI, 2.1-2.4), and PE (aOR, 1.9; 95% CI, 1.7-2.1), independent of various putative risk factors. A significant dose-response effect was observed with increased odds of VTE as the number of intraoperative and/or postoperative RBC transfusion events increased (aOR, 2.1 [95% CI, 2.0-2.3] for 1 event; 3.1 [95% CI, 1.7-5.7] for 2 events; and 4.5 [95% CI, 1.0-19.4] for ≥3 events vs no intraoperative or postoperative RBC transfusion; P < .001 for trend). In subgroup analyses, the association between any perioperative RBC transfusion and postoperative VTE remained statistically significant across all surgical subspecialties analyzed. The association between any perioperative RBC transfusion and the development of postoperative VTE also remained robust after 1:1 propensity score matching (47 142 matched pairs; matched OR, 1.9; 95% CI, 1.8-2.1).

Conclusions and Relevance

The results of this study suggest that perioperative RBC transfusions may be significantly associated with the development of new or progressive postoperative VTE, independent of several putative confounders. These findings, if validated, should reinforce the importance of rigorous perioperative management of blood transfusion practices.

Association of perioperative red blood cell transfusion with postoperative venous thromboembolism in pediatric patients: A propensity score matched analysis

OBJECTIVE

To examine the association between perioperative red blood cell (RBC) transfusion and postoperative venous thromboembolism (VTE) in pediatric surgical patients.

METHODS

Retrospective cohort study using the National Surgical Quality Improvement Project Pediatric, a validated registry of 118 United States children's hospitals. Patients under 19 years of age undergoing a surgical procedure between 2012 and 2017 were included, with the main exposure being RBC transfusion in the perioperative period (48 hours prior to operation to 72 hours after operation). The primary 30-day outcome of interest was a postoperative VTE requiring therapy. Risk-adjusted odds ratios (aOR) were calculated using multiple logistic regression. Subgroup analyses were performed across multiple surgical specialties. Sensitivity analyses were performed after (a) imputation for missing variables and (b) propensity score matching.

RESULTS

During the study years, 482 867 pediatric patients (56.7% male; median age, 6 years [interquartile range, 1-12 years]) underwent an operation. Of these, 30 879 (6.4%) received at least one perioperative RBC transfusion. Postoperative VTE requiring therapy occurred in 618 patients (0.13%). After adjustment for multiple risk factors, perioperative RBC transfusion was associated with an increased risk of VTE (aOR 2.4; 95% CI, 1.9-3.0). The increased VTE risk persisted after imputation of missing demographic and clinical data as well as after 1:1 propensity score matching (29 811 matched pairs, aOR 2.2; 95% CI, 1.7-2.8).

CONCLUSIONS

Perioperative RBC transfusion is associated with an increased, albeit still very low, risk of postoperative VTE in pediatric patients. Patients receiving blood in the perioperative period may benefit from additional monitoring or VTE prophylaxis.

Improved flowing behaviour and gas exchange of stored red blood cells by a compound porous structure

Storage lesions in red blood cells (RBCs) hinder efficient circulation and tissue oxygenation. The absence of flow mechanics and gas exchange may contribute to this problem. To test if in vitro compensation of flow mechanics and gas exchange helps RBC recovery, three-dimensional polydimethylsiloxane (PDMS) porous structures were fabricated with a sugar mould, simulating lung alveoli. RBC suspensions were passed through the porous structure cyclically, simulating in vivo blood circulation. Acid-base indices, partial gas pressures, ions, glucose and RBC indices were analyzed. An atomic force microscope was used to investigate local mechanical properties of intact RBCs. RBCs suspensions that passed through the porous structures had a higher pH and oxygen partial pressure, and a lower potassium concentration and carbon dioxide partial pressure. Meantime they had better biochemical properties relative to static samples, namely, they exhibited a more homogenous distribution of Young's Modulus. RBCs that passed through a PDMS porous structure were healthier than static ones, giving hints to prevent RBC storage lesions.

Feasibility of photoacoustic imaging for the non-invasive quality management of stored blood bags

BACKGROUND AND OBJECTIVES

During the in vitro storage of red blood cells (RBCs), unfavourable changes (storage lesions) cause a rapid consumption of intracellular diphosphoglycerate. The latter deregulates the oxygen-haemoglobin binding potential, subsequently increasing oxygen saturation (SO₂ ) and membrane degradation, transforming RBCs from biconcave discs to rigid spherical bodies (spheroechinocytes). Current laboratory techniques invasively extract RBC samples to assess the quality of red cell concentrate (RCC) units. Optical technologies could provide a means of assessing quality non-invasively.

MATERIALS AND METHODS

A photoacoustic (PA) imaging technique was developed for acquiring the SO₂ of blood bags non-invasively. Seven RCC units were monitored every 3-5 days until expiry (6 weeks). Measurements were validated against a conventional blood gas analyzer (BGA). Using an image flow cytometry assay, morphological profile trends were compared against the SO₂ trends during blood bag storage.

RESULTS

A strong correlation (r²  ≥ 0·95) was found when comparing temporal data between PA and BGA SO₂ measurements. Inter-sample PA variability was found to be similar to that produced by BGA (±0·8%). A strong correlation was found to exist between the temporal changes in SO₂ and relative spheroechinocyte population (0·79 ≤ r²  ≤ 0·97).

CONCLUSION

This study suggests that PA imaging can non-invasively track the SO₂ of stored RBCs non-invasively. By longitudinally monitoring the change in SO₂ , it is possible to infer the effects of the storage lesion on RBC morphology. This non-invasive monitoring technique allows for the assessment of blood bags, without compromising sterility pre-transfusion.

Hypoxic storage of erythrocytes slows down storage lesions and prolongs shelf-life

Conventional storage conditions of erythrocytes cause storage lesions. We propose that hypoxic storage conditions, involving removal of oxygen and replacement with helium, the changes in stored erythrocytes under hypoxic condition were observed and assessed. Erythrocytes were divided into two equal parts, then stored in conventional and hypoxic conditions, separately. Blood gas analysis, hemorheology, and hemolysis were performed once a week. Energy metabolism and membrane damage were monitored by enzyme-linked immunosorbent assay. Phosphatidylserine exposure was measured by flow cytometry. P₅₀ was measured and the oxygen dissociation curve (ODC) plotted accordingly. Erythrocyte morphology was observed microscopically. In the 9th week of storage, the hemolysis of the hypoxia group was 0.7%; lower (p < .05) than that of the control group and still below the threshold of quality requirements. The dissolved oxygen and pO₂ were only 1/4 of that in the control group (p < .01); the adenosine triphosphate, glucose, and lactic acid levels were decreased (p < .05), while the 2,3-diphosphoglycerate levels were increased relative to that in the control group (p < .01). There were no statistically significant differences in membrane damage, deformability, and aggregation between the two groups. In addition, the ODC of the two groups was shifted to the left but this difference was not statistically different. Basically similar to the effect of completely anaerobic conditions. Erythrocytes stored under hypoxic conditions could maintain a relatively stable state with a significant decrease in hemolysis, reduction of storage lesions, and an increase in shelf-life.

Extracellular Vesicles in Red Blood Cell Concentrates: An Overview

Red blood cell (RBC) concentrates may be stored for up to 42 days before transfusion to a patient. During storage extracellular vesicles (EVs) develop and can be detected in significant amounts in RBC concentrates. The concentration of EVs is affected by component preparation methods, storage solutions, and inter-donor variation. Laboratory investigations have focused on the effect of EVs on in vitro assays of thrombin generation and immune responses. Assays for EVs in RBC concentrates are not standardized. The aims of this review are to describe the factors that determine the presence of erythrocyte-EVs in RBC concentrates, the current techniques used to characterize them, and the potential role of EV analysis as a quality control maker for RBC storage.

Single cell analysis of aged RBCs: quantitative analysis of the aged cells and byproducts

This study initially focused on characterizing the aging process of red blood cells by correlating the loss of hemoglobin and the translocation of phosphatidylserine (PS) in expired human red blood cells, hRBCs. Five pre-storage, leukoreduced hRBC units in AS-5 solution were stored between 1 and 6 °C for 42 days. Aliquots from each of these units were stained with Annexin-V FLUOS, which binds to externalized PS, and the hemoglobin within the cells was placed in a methemoglobin state with sodium nitrite, metHb. These aliquots were subsequently sorted into four sub-populations, ranging from no PS expression to high PS expression using a BD FACS ARIAIII. Each of these sub-fractions were introduced into the cell tracking velocimetry apparatus which measured both the magnetically-induced and the gravity-induced velocity. Subsequently, the samples were removed from the cell tracking velocimetry instrument and characterized using the Multisizer 4e Coulter Counter. From the magnetically-induced velocity, the amount of hemoglobin, in pg Hb per cell can be determined, and using an average value of the density of RBCs, the size can be determined. For the PS negative sub-fraction of RBCs, the size of the RBC was as expected but the average hemoglobin, Hb, content was below the threshold which defines anemia. In contrast, unexpected results were observed with the various levels of expression of PS. First, virtually all of the PS expressing cells were significantly smaller, on the order of 1 micron, than a normal RBC after 42 days of storage; yet the density of these small cells/microvesicles was such that they had settling velocities similar to normal-sized RBCs. Further, while the total amount of Hb per small cell/microvesicle was only approximately 25% of the full-sized RBCs, the volume of these small cells/microvesicles is only 1/200 of the PS negative RBCs. This suggests that these PS expressing cells are shrunken RBCs, or shrunken microvesicles from RBCs that concentrated the Hb internally. These results suggest not only a relationship between the loss of hemoglobin and the amount of PS exposed on the cellular outer wall, but also a mechanism by which these aged RBCs break down. It is not known at this time whether this is an artifact of storage or similar mechanisms occur in circulation within the human body.

Stored red blood cells enhance in vivo migration of dendritic cells by promoting reactive oxygen species-induced cytoskeletal rearrangement

BACKGROUND

A complex array of physicochemical changes occurs in red blood cells (RBCs) during storage, leading to enhanced posttransfusion clearance. Dendritic cells (DCs) play crucial roles in the engulfment of aged RBCs; however, it is unclear how stored RBCs (sRBCs) modulate their responses to inflammatory stimuli and DC migration ability.

STUDY DESIGN AND METHODS

In this study, we examined whether sRBCs affect the migration ability of DCs and elucidated the detailed mechanisms mediating this process. Murine RBCs were incubated with marrow DCs after removing the storage supernatant. The effects of sRBCs on cytokine secretion from DCs, surface marker expression, and homing ability were examined.

RESULTS

More sRBCs were internalized by DCs than fresh RBCs (fRBCs), and RBC accumulation significantly promoted the expression of allostimulatory molecules and the secretion of Th1-type cytokines in the presence of lipopolysaccharide (LPS). In particular, the lymphoid-tissue homing ability of transfused DCs treated with sRBCs (sRBC-DCs) was also significantly greater than that of fRBCs. Up regulation of CCR7 and improved organization of the cytoskeleton were observed in sRBC-DCs, and blocking Rho/Rho-associated protein kinase (ROCK), PI3K/Akt, and NF-κB pathways greatly hindered cytoskeletal rearrangement. Moreover, high levels of reactive oxygen species (ROS) were detected in sRBC-DCs, and treatment with N-acetylcysteine simultaneously decreased the lymph node-homing ability of DCs and phosphorylation of RhoA, ROCK1, and cortactin.

CONCLUSIONS

sRBCs initiated differential immune responses compared to fRBCs, and the presence of LPS augmented this phenomenon. Up regulation of CCR7 and ROS production promotes cytoskeletal reorganization and contributes to the increased homing of sRBCs-DCs.

Inhaled nitric oxide

Nitric oxide (NO) is a gas that induces relaxation of smooth muscle cells in the vasculature. Because NO reacts with oxyhaemoglobin with high affinity, the gas is rapidly scavenged by oxyhaemoglobin in red blood cells and the vasodilating effects of inhaled NO are limited to ventilated regions in the lung. NO therefore has the unique ability to induce pulmonary vasodilatation specifically in the portions of the lung with adequate ventilation, thereby improving oxygenation of blood and decreasing intrapulmonary right to left shunting. Inhaled NO is used to treat a spectrum of cardiopulmonary conditions, including pulmonary hypertension in children and adults. However, the widespread use of inhaled NO is limited by logistical and financial barriers. We have designed, developed and tested a simple and economic NO generation device, which uses pulsed electrical discharges in air to produce therapeutic levels of NO that can be used for inhalation therapy. LINKED ARTICLES: This article is part of a themed section on Nitric Oxide 20 Years from the 1998 Nobel Prize. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v176.2/issuetoc.

Transfusion of red blood cells stored for shorter versus longer duration for all conditions

BACKGROUND

Red blood cell (RBC) transfusion is a common treatment for anaemia in many conditions. The safety and efficacy of transfusing RBC units that have been stored for different durations before a transfusion is a current concern. The duration of storage for a RBC unit can be up to 42 days. If evidence from randomised controlled trials (RCT) were to indicate that clinical outcomes are affected by storage duration, the implications for inventory management and clinical practice would be significant.

OBJECTIVES

To assess the effects of using red blood cells (RBCs) stored for a shorter versus a longer duration, or versus RBCs stored for standard practice duration, in people requiring a RBC transfusion.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, Embase, CINAHL, PubMed (for epublications), LILACS, Transfusion Evidence Library, Web of Science CPCI-S and four international clinical trial registries on 20 November 2017.

SELECTION CRITERIA

We included RCTs that compared transfusion of RBCs of shorter versus longer storage duration, or versus standard practice storage duration.

DATA COLLECTION AND ANALYSIS

We used standard Cochrane methods.

MAIN RESULTS

We included 22 trials (42,835 participants) in this review.The GRADE quality of evidence ranged from very low to moderate for our primary outcome of in-hospital and short-term mortality reported at different time points.Transfusion of RBCs of shorter versus longer storage duration Eleven trials (2249 participants) compared transfusion of RBCs of shorter versus longer storage duration. Two trials enrolled low birth weight neonates, two enrolled children with severe anaemia secondary to malaria or sickle cell disease, and eight enrolled adults across a range of clinical settings (intensive care, cardiac surgery, major elective surgery, hospitalised in-patients, haematology outpatients). We judged only two trials to be at low risk of bias across all domains; most trials had an unclear risk for multiple domains.Transfusion of RBCs of shorter versus longer storage duration probably leads to little or no difference in mortality at seven-day follow-up (risk ratio (RR) 1.42, 95% confidence interval (CI) 0.66 to 3.06; 1 trial, 3098 participants; moderate quality evidence) or 30-day follow-up (RR 0.85, 95%CI 0.50 to 1.45; 2 trials, 1121 participants; moderate quality evidence) in adults undergoing major elective cardiac or non-cardiac surgery.For neonates, no studies reported on the primary outcome of in-hospital or short-term mortality. At 40 weeks gestational age, the effect of RBCs of shorter versus longer storage duration on the risk of death was uncertain, as the quality of evidence is very low (RR 0.90, 95% CI 0.41 to 1.85; 1 trial, 52 participants).The effect of RBCs of shorter versus longer storage duration on the risk of death in children with severe anaemia was also uncertain within 24 hours of transfusion (RR 1.50, 95% CI 0.43 to 5.25; 2 trials, 364 participants; very low quality evidence), or at 30-day follow-up (RR 1.40, 95% CI 0.45 to 4.31; 1 trial, 290 participants; low quality evidence).Only one trial, in children with severe anaemia (290 participants), reported adverse transfusion reactions. Only one child in each arm experienced an adverse reaction within 24 hours of transfusion.Transfusion of RBCs of shorter versus standard practice storage duration Eleven trials (40,588 participants) compared transfusion of RBCs of shorter versus standard practice storage duration. Three trials enrolled critically ill term neonates; two of these enrolled very low birth weight neonates. There were no trials in children. Eight trials enrolled critically ill and non-critically ill adults, with most being hospitalised. We judged four trials to be at low risk of bias across all domains with the others having an unclear risk of bias across multiple domains.Transfusion of RBCs of shorter versus standard practice storage duration probably leads to little or no difference in adult in-hospital mortality (RR 1.05, 95% CI 0.97 to 1.14; 4 trials, 25,704 participants; moderate quality evidence), ICU mortality (RR 1.06, 95% CI 0.98 to 1.15; 3 trials, 13,066 participants; moderate quality evidence), or 30-day mortality (RR 1.04, 95% CI 0.96 to 1.13; 4 trials, 7510 participants;moderate quality evidence).Two of the three trials that enrolled neonates reported that there were no adverse transfusion reactions. One trial reported an isolated case of cytomegalovirus infection in participants assigned to the standard practice storage duration group. Two trials in critically ill adults reported data on transfusion reactions: one observed no difference in acute transfusion reactions between arms (RR 0.67, 95% CI 0.19 to 2.36, 2413 participants), but the other observed more febrile nonhaemolytic reactions in the shorter storage duration arm (RR 1.48, 95% CI 1.13 to 1.95, 4919 participants).Trial sequential analysis showed that we may now have sufficient evidence to reject a 5% relative risk increase or decrease of death within 30 days when transfusing RBCs of shorter versus longer storage duration across all patient groups.

AUTHORS' CONCLUSIONS

The effect of storage duration on clinically important outcomes has now been investigated in large, high quality RCTs, predominantly in adults. There appears to be no evidence of an effect on mortality that is related to length of storage of transfused RBCs. However, the quality of evidence in neonates and children is low. The current practice in blood banks of using the oldest available RBCs can be continued safely. Additional RCTs are not required, but research using alternative study designs, should focus on particular subgroups (e.g. those requiring multiple RBC units) and on factors affecting RBC quality.

The Age of BLood Evaluation (ABLE) randomised controlled trial: description of the UK-funded arm of the international trial, the UK cost-utility analysis and secondary analyses exploring factors associated with health-related quality of life and health-care costs during the 12-month follow-up

BACKGROUND

At present, red blood cells (RBCs) are stored for up to 42 days prior to transfusion. The relative effectiveness and safety of different RBC storage times prior to transfusion is uncertain.

OBJECTIVE

To assess the clinical effectiveness and cost-effectiveness of transfusing fresher RBCs (stored for ≤ 7 days) compared with current standard-aged RBCs in critically ill patients requiring blood transfusions.

DESIGN

The international Age of BLood Evaluation (ABLE) trial was a multicentre, randomised, blinded trial undertaken in Canada, the UK, the Netherlands and France. The UK trial was funded to contribute patients to the international trial and undertake a UK-specific health economic evaluation.

SETTING

Twenty intensive care units (ICUs) in the UK, as part of 64 international centres.

PARTICIPANTS

Critically ill patients aged ≥ 18 years (≥ 16 years in Scotland) expected to require mechanical ventilation for ≥ 48 hours and requiring a first RBC transfusion during the first 7 days in the ICU.

INTERVENTIONS

All decisions to transfuse RBCs were made by clinicians. One patient group received exclusively fresh RBCs stored for ≤ 7 days whenever transfusion was required from randomisation until hospital discharge. The other group received standard-issue RBCs throughout their hospital stay.

MAIN OUTCOME MEASURES

The primary outcome was 90-day mortality. Secondary outcomes included development of organ dysfunction, new thrombosis, infections and transfusion reactions. The primary economic evaluation was a cost-utility analysis.

RESULTS

The international trial took place between March 2009 and October 2014 (UK recruitment took place between January 2012 and October 2014). In total, 1211 patients were assigned to receive fresh blood and 1219 patients to receive standard-aged blood. RBCs were stored for a mean of 6.1 days [standard deviation (SD) ± 4.9 days] in the group allocated to receive fresh blood and 22.0 days (SD ± 8.4 days) in the group allocated to receive standard-aged blood. Patients received a mean of 4.3 RBC units (SD ± 5.2 RBC units) and 4.3 RBC units (SD ± 5.5 RBC units) in the groups receiving fresh blood and standard-aged blood, respectively. At 90 days, 37.0% of patients in the group allocated to receive fresh blood and 35.3% of patients in the group allocated to receive standard-aged blood had died {absolute risk difference 1.7% [95% confidence interval (CI) -2.1% to 5.5%]}. There were no between-group differences in any secondary outcomes. The UK cohort comprised 359 patients randomised and followed up for 12 months for the cost-utility analysis. UK patients had similar characteristics and outcomes to the international cohort. Mean total costs per patient were £32,346 (95% CI £29,306 to £35,385) in the group allocated to receive fresh blood and £33,353 (95% CI £29,729 to £36,978) in the group allocated to receive standard-aged blood. Approximately 85% of the total costs were incurred during the index hospital admission. There were no significant cost differences between the two groups [mean incremental costs for those receiving fresh vs. standard-aged blood: -£231 (95% CI -£4876 to £4415)], nor were there significant differences in outcomes (mean difference in quality-adjusted life-years -0.010, 95% CI -0.078 to 0.057).

LIMITATIONS

Adverse effects from the exclusive use of older RBCs compared with standard or fresh RBCs cannot be excluded.

CONCLUSIONS

The use of RBCs aged ≤ 7 days confers no clinical or economic benefit in critically ill patients compared with standard-aged RBCs.

FUTURE WORK

Future studies should address the safety of RBCs near the end of the current permitted storage age.

TRIAL REGISTRATION

Current Controlled Trials ISRCTN44878718.

FUNDING

This project was funded by the National Institute for Health Research (NIHR) Health Technology Assessment programme and will be published in full in Health Technology Assessment; Vol. 21, No. 62. See the NIHR Journals Library website for further project information. The international ABLE trial was also supported by peer-reviewed grants from the Canadian Institutes of Health Research (177453), Fonds de Recherche du Québec - Santé (24460), the French Ministry of Health Programme Hospitalier de Recherche Clinique (12.07, 2011) and by funding from Établissement Français du Sang and Sanquin Blood Supply.

Blood transfusion strategies for acute upper gastrointestinal bleeding: are we back where we started?

Blood transfusion practices for acute upper gastrointestinal hemorrhage have changed over time. Restrictive strategies, which gave way to more liberal approaches for the greater part of the 20^th century, have again gained traction as emerging research suggests restricting transfusion is associated with similar, or possibly better outcomes in UGI bleeding. In a large, retrospective cohort study from an integrated health care system in Taiwan, Chen, et al., report the association between early blood transfusion and clinical outcomes in patients presenting to the emergency department with UGI bleeding, and these findings are discussed in the context of current knowledge and practice.

A microfluidic platform to study the effects of vascular architecture and oxygen gradients on sickle blood flow

Our goal was to develop a model of the microvasculature that would allow us to quantify changes in the rheology of sickle blood as it traverses the varying vessel sizes and oxygen tensions in the microcirculation. We designed and implemented a microfluidic model of the microcirculation that comprises a branching microvascular network and physiologic oxygen gradients. We used computational modeling to determine the parameters necessary to generate stable, linear gradients in our devices. Sickle blood from six unique patients was perfused through the microvascular network and subjected to varying oxygen gradients while we observed and quantified blood flow. We found that all sickle blood samples fully occluded the microvascular network when deoxygenated, and we observed that sickle blood could cause vaso-occlusions under physiologic oxygen gradients during the microvascular transit time. The number of occlusions observed under five unique oxygen gradients varied among the patient samples, but we generally observed that the number of occlusions decreased with increasing inlet oxygen tension. The model system we have developed is a valuable tool to address fundamental questions about where in the circulation sickle-cell vaso-occlusions are most likely to occur and to test new therapies.

Mechanisms of red blood cell transfusion-related immunomodulation

Red blood cell (RBC) transfusion is common in critically ill, postsurgical, and posttrauma patients in whom both systemic inflammation and immune suppression are associated with adverse outcomes. RBC products contain a multitude of immunomodulatory mediators that interact with and alter immune cell function. These interactions can lead to both proinflammatory and immunosuppressive effects. Defining clinical outcomes related to immunomodulatory effects of RBCs in transfused patients remains a challenge, likely due to complex interactions between individual blood product characteristics and patient-specific risk factors. Unpacking these complexities requires an in-depth understanding of the mechanisms of immunomodulatory effects of RBC products. In this review, we outline and classify potential mediators of RBC transfusion-related immunomodulation and provide suggestions for future research directions.

Rat red blood cell storage lesions in various additive solutions

BACKGROUND

Small rodent models are routinely used to evaluate the safety and efficacy of blood transfusions. Limited comprehensive literature exists about effect of different storage solutions in rat red blood cells (RBCs) characteristics. RBCs undergo time dependent biochemical and biophysical changes during storage known as hypothermic storage lesions (HSLs).

OBJECTIVE

This study evaluates the effects of RBC additive solutions (AS) during storage of rat RBCs.

METHODS

Blood was leukoreduced and stored as per manufacturer instructions at 4°C up to 42-days. Three solutions, CPDA-1; AS-1; and AS-7 (SOLX), were evaluated. Biochemical parameters measured included extracellular K+, pH, hemolysis, 2,3-diphosphoglycerate (2,3-DPG), oxygen affinity, ATP, and lactate. Mechanical properties measured included RBC deformability, elongation index (EI), RBC membrane shear elastic modulus (SEM), mean corpuscular volume (MCV), viscosity, and aggregability.

RESULTS

There were no differences in biochemical or mechanical parameters at baseline or after one week of storage. However, after two weeks, AS-7 preserved biochemical and mechanical properties as compared to CPDA-1 and AS-1. Changes were observed to be significant after 14-days of storage. AS-7 prevented extracellular K+ increase, reduced acidosis, showed lower hemolysis, preserved ATP and 2,3-DPG levels (consequently oxygen affinity), and reduced lactate. AS-7, when compared to CPDA-1 and AS-1, prevented the reduction in RBC deformability and was found to preserve the EI at multiple shear stresses, the membrane SEM, the aggregability and viscosity.

DISCUSSION

Rat RBCs stored with AS-7 presented reduced changes in biochemical and mechanical parameters, when compared with rat RBCs stored in CPDA-1 and AS-1, after as early as two weeks of storage.

Raman spectroscopy of stored red blood cell concentrate within sealed transfusion blood bags

Spectral information relevant to the quality of stored blood can be obtained in situ through sealed blood transfusion bags using a commercially available instrument.

Blood Quality Diagnostic Device Detects Storage Differences Between Donors

In 2013, nearly 15 million units of banked blood were transfused in the United States of America alone. Blood shortages are expected to increase globally. Donated blood is not equal due to differences in quality and deterioration rate. There are no methods to detect time-dependent biochemical and biophysical changes of red blood cells (RBCs) or the deterioration rate of donated RBCs. Nine randomly selected RBC units collected by the San Diego Blood Bank were examined for interdonor variability over six weeks of storage. In vitro RBC quality was assessed weekly by conventional biochemical tests including free Hb, K+, ATP, P50, 2,3 DPG, lactate, and pH. Deformability was measured via cell filtration. Briefly, the RBC suspension (10% Hct), was forced through a 5.0-μm pore membrane (106 mm2) at various flow rates. No interdonor variability in biochemical or mechanical parameters was observed at baseline. Interdonor variability in biochemical properties (free Hb, K+, ATP, P50, 2,3 DPG, lactate, and pH) was observed after 14 days of storage. However, significant differences from baseline in RBC mechanical properties (i.e., filterability) were observed as early as 7 days into storage at the lowest flow rates and after 28 days of storage at all flow rates. There was a net decrease in filterability over time for all donors, but the rate at which filterability decreased (i.e., deterioration rates) was different when comparing individual donors. Changes in all biochemical parameters were significant different between donors. These data suggest that filterability is more sensitive to changes in blood quality than conventional biochemical parameters.

Erythrocyte-Derived Microparticles Activate Pulmonary Endothelial Cells in a Murine Model of Transfusion

Erythrocyte-derived microparticles (MPs) are sub-micrometer, biologically active vesicles shed by red blood cells as part of the biochemical changes that occur during storage. We hypothesized that MPs from stored red blood cells would activate endothelial cells. MPs from aged murine packed red blood cells (pRBCs) were isolated and used to treat confluent layers of cultured endothelial cells. Endothelial expression of leukocyte adhesion molecules, endothelial-leukocyte adhesion molecule-1 (ELAM-1) and intercellular adhesion molecule-1(ICAM-1), and inflammatory mediator, interleukin-6 (IL-6), was evaluated at 0.5, 6, 12, and 24 h of treatment. Healthy C57BL/6 mice were transfused with a MP suspension and lung sections were analyzed for adhesion molecules and sequestered interstitial leukocytes. Increased levels of ELAM-1 and ICAM-1 were found on cultured endothelial cells 6 h after MP stimulation (6.91 vs. 4.07 relative fluorescent intensity [RFI], P < 0.01, and 5.85 vs. 3.55 RFI, P = 0.01, respectively). IL-6 in cell culture supernatants was increased after 12 h of MP stimulation compared with controls (1.24 vs. 0.73 ng/mL, P = 0.03). In vivo experiments demonstrated that MP injection increased ELAM-1 and ICAM-1 expression at 1 h (18.56 vs. 7.08 RFI, P < 0.01, and 23.66 vs. 6.87 RFI, P < 0.01, respectively) and caused increased density of pulmonary interstitial leukocytes by 4 h of treatment (69.25 vs. 29.25 cells/high powered field, P < 0.01). This series of experiments supports our hypothesis that erythrocyte-derived MPs are able to activate pulmonary endothelium, leading to the pulmonary sequestration of leukocytes following the transfusion of stored pRBCs.

Femtogram Resolution of Iron Content on a Per Cell Basis: Ex Vivo Storage of Human Red Blood Cells Leads to Loss of Hemoglobin

The magnetic characteristics of hemoglobin (Hb) changes with the binding of dioxygen (O2) to the heme prosthetic groups of the globin chains: from paramagnetic ferrous Hb to diamagnetic ferrous oxyhemoglobin (oxyHb) with reversibly bound O2, or paramagnetic ferric methemoglobin (metHb). When multiplied over the number of Hb molecules in a red blood cell (RBC), the effect is detectable through motion analysis of RBCs in a high magnetic field and gradient. This motion is referred to as magnetophoretic mobility, which can be conveniently expressed as a fraction of the cell sedimentation velocity. In this Article, using a previously developed and reported instrument, cell tracking velocimetry (CTV), we are able to detect difference in Hb concentration in two RBC populations to a resolution of 1 × 107 Hb molecules per cell (4 × 107 atoms of Fe per cell or 4-5 femtograms of Fe). Similar resolution achieved with inductively coupled plasma-mass spectrometry requires on the order of 105-106 cells and provides an average, whereas CTV provides a measurement for each cell. CTV analysis revealed that RBCs lose, on average, 17% of their Hb after 42 days of storage, the maximum FDA-approved length of time for the cold storage of RBCs in additive solution. This difference in Hb concentration was the result of routine RBC storage; clinical implications are discussed.

Duration of red blood cell storage and inflammatory marker generation

Red blood cell (RBC) transfusion is a life-saving treatment for several pathologies. RBCs for transfusion are stored refrigerated in a preservative solution, which extends their shelf-life for up to 42 days. During storage, the RBCs endure abundant physicochemical changes, named RBC storage lesions, which affect the overall quality standard, the functional integrity and in vivo survival of the transfused RBCs. Some of the changes occurring in the early stages of the storage period (for approximately two weeks) are reversible but become irreversible later on as the storage is extended. In this review, we aim to decipher the duration of RBC storage and inflammatory marker generation. This phenomenon is included as one of the causes of transfusion-related immunomodulation (TRIM), an emerging concept developed to potentially elucidate numerous clinical observations that suggest that RBC transfusion is associated with increased inflammatory events or effects with clinical consequence.

Prolonging the shelf life of Lumbricus terrestris erythrocruorin for use as a novel blood substitute

Limitations associated with the storage of red blood cells have motivated the development of novel blood substitutes that are able to withstand long-term storage at elevated temperatures. The hemoglobin of the earthworm Lumbricus terrestris (LtEc) is an attractive blood substitute candidate, since it is resistant to oxidation and aggregation during storage. Several factors were investigated to optimize the thermal and oxidative stability of LtEc during storage, including pH, antioxidant supplements, and deoxygenation. A strategy for the reduction of fully oxidized LtEc with antioxidants was also developed. Overall, LtEc was shown to have the highest thermal stability in Ringer's Modified Lactate solution with 10 mM HEPES at pH 7.0. Deoxygenation of the LtEc was also shown to significantly reduce oxidation of the ferrous heme iron (e.g., %Fe²⁺after 7 d at 37 °C = 75.7%). However, even in cases where oxidation does occur, the addition of 1.8 mM ascorbic acid (AA) was found to reduce 98.3% of the oxidized LtEc (37 μM heme). Most importantly, the oxygen transport properties of LtEc were unaffected by storage at high temperatures or oxidation followed by reduction with AA. These results show that LtEc can be stored at high temperatures (37 °C) without any significant loss of function.

Older red cell units are associated with an increased incidence of infection in chronically transfused adults with sickle cell disease

BACKGROUND

In adults with sickle cell disease (SCD), the effects of the red cell storage lesion are not well defined. The objectives of this study were to: (1) describe the distribution of storage ages provided to adults with SCD, and (2) evaluate clinical outcomes associated with storage age.

PATIENTS AND METHODS

We performed a retrospective cohort study of adults with SCD managed with prophylactic simple transfusion regimens. Units were universally pre-storage leukocyte reduced and CEK-matched. Age of the unit was 42 days minus the difference between the expiration and transfusion dates. A mixed effects model, which accounts for a subject's contribution to repeated transfusion encounters, was used to investigate the association between storage age and the incidence of hospital encounters for infection and pain crises prior to the next red cell transfusion.

RESULTS

Over the study interval, twenty-eight steady-state adults with SCD received 627 units via simple transfusion over 281 outpatient encounters. Overall median unit storage age was 22 days (range: 2-42 days). Receipt of older units was associated with an increased incidence of emergency department or hospital admission for infection prior to the next transfusion (p=0.04). There was no association between unit storage age and admission for pain (p=0.4).

DISCUSSION

In a cohort of chronically transfused adults with SCD, we provide evidence that receipt of older units is associated with a higher rate of admission for infection. Prospective studies will need to validate these data and explore potential mechanisms by which these older units promote infection.

The impact of red blood cell storage duration on tissue oxygenation in cardiac surgery

OBJECTIVE

Although storage alters red blood cells, several recent, randomized trials found no differences in clinical outcomes between patients transfused with red blood cells stored for shorter versus longer periods of time. The objective of this study was to see whether storage impairs the in vivo ability of erythrocytes to traverse the microcirculation and deliver oxygen at the tissue level.

METHODS

A subset of subjects from a clinical trial of cardiac surgery patients randomized to receive transfusions of red blood cells stored ≤10 days or ≥21 days were assessed for thenar eminence and cerebral tissue hemoglobin oxygen saturation (S_tO₂) via the use of near-infrared spectroscopy and sublingual microvascular blood flow via side-stream darkfield videomicroscopy.

RESULTS

Among 55 subjects, there was little change in the primary endpoint (thenar eminence S_tO₂ from before to after transfusion of one unit) and the change was similar in the 2 groups: +1.7% (95% confidence interval, -0.3, 3.8) for shorter-storage and +0.8% (95% confidence interval, -1.1, 2.9) for longer-storage; P = .61). Similarly, no significant differences were observed for cerebral S_tO₂ or sublingual microvascular blood flow. These parameters also were not different from preoperatively to 1 day postoperatively, reflecting the absence of a cumulative effect of all red blood cell units transfused during this period.

CONCLUSIONS

There were no differences in thenar eminence or cerebral S_tO₂, or sublingual microcirculatory blood flow, in cardiac surgery patients transfused with red blood cells stored ≤10 days or ≥21 days. These results are consistent with the clinical outcomes in the parent study, which also did not differ, indicating that storage may not impair oxygen delivery by red blood cells in this setting.

Multiphoton excited hemoglobin fluorescence and third harmonic generation for non-invasive microscopy of stored blood

Red blood cells (RBC) in two-photon excited fluorescence (TPEF) microscopy usually appear as dark disks because of their low fluorescent signal. Here we use 15fs 800nm pulses for TPEF, 45fs 1060nm pulses for three-photon excited fluorescence, and third harmonic generation (THG) imaging. We find sufficient fluorescent signal that we attribute to hemoglobin fluorescence after comparing time and wavelength resolved spectra of other expected RBC endogenous fluorophores: NADH, FAD, biliverdin, and bilirubin. We find that both TPEF and THG microscopy can be used to examine erythrocyte morphology non-invasively without breaching a blood storage bag.