Mortality increases after massive exchange transfusion with older stored blood in canines with experimental pneumonia

Navigating Hemolysis and the Renal Implications of Hemoglobin Toxicity in Cardiac Surgery

Cardiopulmonary bypass–induced hemolysis is linked to acute kidney injury in cardiac surgery. Emerging therapies targeting cell-free hemoglobin, like haptoglobin, nitric oxide, and antioxidants, show promise in reducing kidney injury, highlighting the need for further research.

Cardiac Magnetic Resonance Studies in a Large Animal Model That Simulates the Cardiac Abnormalities of Human Septic Shock

BACKGROUND

Septic shock is associated with increases in end-diastolic volume (EDV) and decreases in ejection fraction that reverse within 10 days. Nonsurvivors do not develop EDV increases. The mechanism is unknown.

METHODS AND RESULTS

Purpose-bred beagles (n=33) were randomized to receive intrabronchial Staphylococcus aureus or saline. Over 96 hours, cardiac magnetic resonance imaging and echocardiograms were performed. Tissue was obtained at 66 hours. From 0 to 96 hours after bacterial challenge, septic animals versus controls had significantly increased left ventricular wall edema (6%) and wall thinning with loss of mass (15%). On histology, the major finding was nonocclusive microvascular injury with edema in myocytes, the interstitium, and endothelial cells. Edema was associated with significant worsening of biventricular ejection fractions, ventricular-arterial coupling, and circumferential strain. Early during sepsis, (0-24 hours), the EDV decreased; significantly more in nonsurvivors (ie, greater diastolic dysfunction). From 24 to 48 hours, septic animals' biventricular chamber sizes increased; in survivors significantly greater than baseline and nonsurvivors, whose EDVs were not different from baseline. Preload, afterload, or heart rate differences did not explain these differential changes.

CONCLUSIONS

The cardiac dysfunction of sepsis is associated with wall edema. In nonsurvivors, at 0 to 24 hours, sepsis induces a more severe diastolic dysfunction, further decreasing chamber size. The loss of left ventricular mass with wall thinning in septic survivors may, in part, explain the EDV increases from 24 to 48 hours because of a potentially reparative process removing damaged wall tissue. Septic cardiomyopathy is most consistent with a nonocclusive microvascular injury resulting in edema causing reversible systolic and diastolic dysfunction with more severe diastolic dysfunction being associated with a decreased EDV and death.

In a Canine Model of Septic Shock, Cardiomyopathy Occurs Independent of Catecholamine Surges and Cardiac Microvascular Ischemia

BACKGROUND

High levels of catecholamines are cardiotoxic and associated with stress-induced cardiomyopathies. Using a septic shock model that reproduces the reversible cardiomyopathy seen over 10 days associated with human septic shock, we investigated the effects of catecholamines on microcirculatory perfusion and cardiac dysfunction.

METHODS AND RESULTS

Purpose-bred beagles received intrabronchial Staphylococcus aureus (n=30) or saline (n=6). The septic animals were than randomized to epinephrine (1 μg/kg per minute, n=15) or saline (n=15) infusions from 4 to 44 hours. Serial cardiac magnetic resonance imaging, catecholamine levels, and troponins were collected over 92 hours. Serial adenosine-stress perfusion cardiac magnetic resonance imaging was performed on septic animals randomized to receive saline (n=8 out of 15) or epinephrine (n=8 out of 15). High-dose sedation was given to suppress endogenous catecholamine release. Despite catecholamine levels largely remaining within the normal range throughout, by 48 hours, septic animals receiving saline versus nonseptic animals still developed significant worsening of left ventricular ejection fraction, circumferential strain, and ventricular-aortic coupling. In septic animals that received epinephrine versus saline infusions, plasma epinephrine levels increased 800-fold, but epinephrine produced no significant further worsening of left ventricular ejection fraction, circumferential strain, or ventricular-aortic coupling. Septic animals receiving saline had a significant increase in microcirculatory reserve without troponin elevations. Septic animals receiving epinephrine had decreased edema, blunted microcirculatory perfusion, and elevated troponin levels that persisted for hours after the epinephrine infusion stopped.

CONCLUSIONS

Cardiac dysfunction during sepsis is not primarily due to elevated endogenous or exogenous catecholamines nor due to decreased microvascular perfusion-induced ischemia. However, epinephrine itself has potentially harmful long-lasting ischemic effects during sepsis including impaired cardiac microvascular perfusion that persists after stopping the infusion.

Cardiac Magnetic Resonance Studies in a Large Animal Model that Simulates the Cardiac Abnormalities of Human Septic Shock

Background

Septic shock, in humans and in our well-established animal model, is associated with increases in biventricular end diastolic volume (EDV) and decreases in ejection fraction (EF). These abnormalities occur over 2 days and reverse within 10 days. Septic non-survivors do not develop an increase in EDV. The mechanism for this cardiac dysfunction and EDV differences is unknown.

Methods

Purpose-bred beagles randomized to receive intrabronchial Staphylococcus aureus (n=27) or saline (n=6) were provided standard ICU care including sedation, mechanical ventilation, and fluid resuscitation to a pulmonary arterial occlusion pressure of over 10mmHg. No catecholamines were administered. Over 96h, cardiac magnetic resonance imaging, echocardiograms, and invasive hemodynamics were serially performed, and laboratory data was collected. Tissue was obtained at 66h from six septic animals.

Results

From 0-96h after bacterial challenge, septic animals vs. controls had significantly increased left ventricular wall edema (6%) and wall thinning with loss of mass (15%) which was more pronounced at 48h in non-survivors than survivors. On histology, edema was located predominantly in myocytes, the interstitium, and endothelial cells. Edema was associated with significantly worse biventricular function (lower EFs), ventricular-arterial coupling, and circumferential strain. In septic animals, from 0-24h, the EDV decreased from baseline and, despite cardiac filling pressures being similar, decreased significantly more in non-survivors. From 24-48h, all septic animals had increases in biventricular chamber sizes. Survivors biventricular EDVs were significantly greater than baseline and in non-survivors, where biventricular EDVs were not different from baseline. Preload, afterload, or HR differences did not explain these differential serial changes in chamber size.

Conclusion

Systolic and diastolic cardiac dysfunction during sepsis is associated with ventricular wall edema. Rather than differences in preload, afterload, or heart rate, structural alterations to the ventricular wall best account for the volume changes associated with outcome during sepsis. In non-survivors, from 0-24h, sepsis induces a more severe diastolic dysfunction, further decreasing chamber size. The loss of left ventricular mass with wall thinning in septic survivors may, in part explain, the EDV increases from 24-48h. However, these changes continued and even accelerated into the recovery phase consistent with a reparative process rather than ongoing injury.

Cell-Free Hemoglobin in the Pathophysiology of Trauma: A Scoping Review

OBJECTIVES

Cell-free hemoglobin (CFH) is a potent mediator of endothelial dysfunction, organ injury, coagulopathy, and immunomodulation in hemolysis. These mechanisms have been demonstrated in patients with sepsis, hemoglobinopathies, and those receiving transfusions. However, less is known about the role of CFH in the pathophysiology of trauma, despite the release of equivalent levels of free hemoglobin.

DATA SOURCES

Ovid MEDLINE, Embase, Web of Science Core Collection, and BIOSIS Previews were searched up to January 21, 2023, using key terms related to free hemoglobin and trauma.

DATA EXTRACTION

Two independent reviewers selected studies focused on hemolysis in trauma patients, hemoglobin breakdown products, hemoglobin-mediated injury in trauma, transfusion, sepsis, or therapeutics.

DATA SYNTHESIS

Data from the selected studies and their references were synthesized into a narrative review.

CONCLUSIONS

Free hemoglobin likely plays a role in endothelial dysfunction, organ injury, coagulopathy, and immune dysfunction in polytrauma. This is a compelling area of investigation as multiple existing therapeutics effectively block these pathways.

Assessment of stored red blood cells through lab-on-a-chip technologies for precision transfusion medicine

Transfusion of red blood cells (RBCs) is one of the most valuable and widespread treatments in modern medicine. Lifesaving RBC transfusions are facilitated by the cold storage of RBC units in blood banks worldwide. Currently, RBC storage and subsequent transfusion practices are performed using simplistic workflows. More specifically, most blood banks follow the "first-in-first-out" principle to avoid wastage, whereas most healthcare providers prefer the "last-in-first-out" approach simply favoring chronologically younger RBCs. Neither approach addresses recent advances through -omics showing that stored RBC quality is highly variable depending on donor-, time-, and processing-specific factors. Thus, it is time to rethink our workflows in transfusion medicine taking advantage of novel technologies to perform RBC quality assessment. We imagine a future where lab-on-a-chip technologies utilize novel predictive markers of RBC quality identified by -omics and machine learning to usher in a new era of safer and precise transfusion medicine.

Clinical efficacy of intraoperative Cell Saver autologous blood salvage in emergency surgery for massive hemothorax

The objective of this study was to investigate the efficacy of intraoperative Cell Saver blood salvage during emergency surgery for massive hemothorax on minimizing perioperative allogeneic red blood cell (RBC) transfusion. Fourteen consecutive patients of massive hemothorax with more than 800 cc of intrathoracic bleeding estimated by chest X-ray and/or chest computed tomography (CT) scan at presentation between 2009 and 2021 were retrospectively reviewed. Intraoperative Cell Saver blood salvage was performed in 11 patients (Cell Saver group) with a median volume of 820 cc (range, 421-1700 cc). The amount of perioperative allogeneic RBC transfusion in the Cell Saver group (median, 4 units) was significantly smaller than that in the non-Cell Saver group (median, 10 units) (P = 0.009). The volume of Cell Saver autologous transfusion in 6 patients without preoperative chest tube drainage (median, 1114 cc) was significantly larger than that in 5 patients who had preoperative drainage (median, 660 cc) (P = 0.0173). In conclusion, the utilization of intraoperative blood salvage in emergency surgery for massive hemothorax along with limiting the amount of preoperative chest tube drainage is an efficient strategy to minimize perioperative allogeneic RBC transfusion.

Different-sized extracellular vesicles derived from stored red blood cells package diverse cargoes and cause distinct cellular effects

BACKGROUND

The formation of extracellular vesicles (EVs) occurs during cold storage of RBCs. Transfusion of EVs may contribute to adverse responses in recipients receiving RBCs. However, EVs are poorly characterized with limited data on whether distinct vesicles are formed, their composition, and potential biological effects.

STUDY DESIGN AND METHODS

Stored RBC-derived EVs were purified using protocols that separate larger microvesicle-like EVs (LEVs) from smaller exosome-like vesicles (SEVs). Vesicles were analyzed by electron microscopy, content of hemoglobin, heme, and proteins (by mass spectrometry), and the potential to mediate lipid peroxidation and endothelial cell permeability in vitro.

RESULTS

SEVs were characterized by having an electron-dense double membrane whereas LEVs had more uniform electron density across the particles. No differences in hemoglobin nor heme levels per particle were observed, however, due to smaller volumes, SEVs had higher concentrations of oxyHb and heme. Both particles contained antioxidant proteins peroxiredoxin-2 and copper/zinc superoxide dismutase, these were present in higher molecular weight fractions in SEVs suggesting either oxidized proteins are preferentially packaged into smaller vesicles and/or that the environment associated with SEVs is more pro-oxidative. Furthermore, total glutathione (GSH + GSSG) levels were lower in SEVs. Both EVs mediated oxidation of liposomes that were prevented by hemopexin, identifying heme as the pro-oxidant effector. Addition of SEVs, but not LEVs, induced endothelial permeability in a process also prevented by hemopexin.

CONCLUSION

These data show that distinct EVs are formed during cold storage of RBCs with smaller particles being more likely to mediate pro-oxidant and inflammatory effects associated with heme.

Large Animal Models for Simulating Physiology of Transfusion of Red Cell Concentrates-A Scoping Review of The Literature

Background and Objectives: Transfusion of red cell concentrates is a key component of medical therapy. To investigate the complex transfusion-associated biochemical and physiological processes as well as potential risks for human recipients, animal models are of particular importance. This scoping review summarizes existing large animal transfusion models for their ability to model the physiology associated with the storage of erythrocyte concentrates. Materials and Methods: The electronic databases PubMed, EMBASE, and Web of Science were systematically searched for original studies providing information on the intravenous application of erythrocyte concentrates in porcine, ovine, and canine animal models. Results: A total of 36 studies were included in the analysis. The majority of porcine studies evaluated hemorrhagic shock conditions. Pig models showed high physiological similarities with regard to red cell physiology during early storage. Ovine and canine studies were found to model typical aspects of human red cell storage at 42 days. Only four studies provided data on 24 h in vivo survival of red cells. Conclusions: While ovine and canine models can mimic typical human erythrocyte storage for up to 42 days, porcine models stand out for reliably simulating double-hit pathologies such as hemorrhagic shock. Large animal models remain an important area of translational research since they have an impact on testing new pharmacological or biophysical interventions to attenuate storage-related adverse effects and allow, in a controlled environment, to study background and interventions in dynamic and severe disease conditions.

Allogeneic Red Blood Cell Transfusion and Infectious Complications Following Pediatric Spinal Fusion: NSQIP-P Analysis

Substantial bleeding occurs during spinal fusion surgery in the pediatric population, and many patients receive allogeneic red blood cell transfusion (ARBT) for the treatment of resulting perioperative anemia. ARBT is thought to increase vulnerability to postoperative infections following major surgical procedures, but studies of this relationship in children undergoing spinal fusion have yielded conflicting results.

Evaluation of selected hematological, biochemical and oxidative stress parameters in stored canine CPDA-1 whole blood

Blood transfusions are mainly given to intensive care patients; therefore, additional complications that could arise from storage lesions in preserved blood should be avoided. It has been shown that human stored red blood cells are subject to changes that are considered to be a number of interdependent processes involving metabolic disarrangement and oxidative stress. The aim of our study was to determine alterations in selected hematological and biochemical parameters and to assess whether and when oxidative stress is a significant phenomenon in stored dog CPDA-1 whole blood. Ten ½ unit bags of whole blood donated from dogs and preserved with CPDA-1 (anticoagulant containing citrate, phosphate, dextrose and adenine) were stored for 5 weeks. Each week, a 9 ml sample was drawn aseptically to measure hematological parameters, selected metabolites, free hemoglobin content, osmotic fragility, antioxidant enzyme activity, total antioxidant capacity, malondialdehyde concentration and protein carbonyl content.

The results revealed an MCV decrease in the first week of storage and then a gradual increase; osmotic fragility decreased at that time and remained low throughout the study period. Leukodepletion became significant in the fourth week of storage. The free hemoglobin concentration continuously increased, with the greatest changes observed in the last two weeks of storage. The total antioxidant capacity changed in a reverse manner. Superoxide dismutase and glutathione peroxidase activities decreased from week 0 to week 3, and catalase activity tended to decrease over time. The highest malondialdehyde concentrations in blood supernatant were measured in the first week of storage, and the carbonyl concentration increased after 35 days.

Hematological changes and oxidative stress are already present in the first week of storage, resulting in depletion of the antioxidant system and subsequent accumulation of oxidation products as well as erythrocyte hemolysis, which are most pronounced at the end of the storage period.

Effect of microaggregate filter passage on feline whole blood stored for 35 days

OBJECTIVES

The aim of this study was to compare the characteristics of fresh and stored feline red blood cells (RBCs) after passage through an 18 μm microaggregate filter.

METHODS

Nine cats were recruited for a single blood donation using an open collection system. A simulated transfusion using a syringe driver and microaggregate filter was performed over 2 h with half the blood on the day of donation and the other half after 35 days of storage. Differences in haematological parameters, haemolysis percentage and osmotic fragility (OF) were compared on the day of donation pre-filter passage (D0-) vs day of donation post-filter (D0+) or day 35 storage pre-filter (D35-) and post-filter (D35+). Blood was cultured at D0+ and D35+.

RESULTS

There were no statistically significant differences in the D0- vs D0+ comparisons. There were statistically significant (P <0.05) increases in haemolysis percentage, red cell distribution width (RDW) percentage and mean OF, and decreases in packed cell volume (PCV), RBC count, haemoglobin and haematocrit for D0- vs D35-. The same was found for D0- vs D35+ with the addition of a significant increase in mean cell haemoglobin (MCH). For D35- vs D35+ only MCH significantly increased. At day 35, 6/9 units had haemolysis percentages that exceeded 1%. This increased to 8/9 of stored units post-filter passage. All blood units cultured negative.

CONCLUSIONS AND RELEVANCE

Fresh RBCs exhibited no in vitro evidence of injury following passage through an 18 μm microaggregate filter. Increased MCH was observed in the stored blood and may represent haemolysis induced by the filter. All other changes can be explained by storage lesion rather than filter passage. The findings highlight the importance of blood banking quality controls and the need for further research to assess the effects of transfusion technique, specifically filter passage, on storage lesion-affected feline blood.

Blood bank storage of red blood cells increases RBC cytoplasmic membrane order and bending rigidity

Blood banks around the world store blood components for several weeks ensuring its availability for transfusion medicine. Red blood cells (RBCs) are known to undergo compositional changes during storage, which may impact the cells' function and eventually the recipients' health. We extracted the RBC's cytoplasmic membrane (RBCcm) to study the effect of storage on the membranes' molecular structure and bending rigidity by a combination of X-ray diffraction (XRD), X-ray diffuse scattering (XDS) and coarse grained Molecular Dynamics (MD) simulations. Blood was stored in commercial blood bags for 2 and 5 weeks, respectively and compared to freshly drawn blood. Using mass spectrometry, we measured an increase of fatty acids together with a slight shift towards shorter tail lengths. We observe an increased fraction (6%) of liquid ordered (lo) domains in the RBCcms with storage time, and an increased lipid packing in these domains, leading to an increased membrane thickness and membrane order. The size of both, lo and liquid disordered (ld) lipid domains was found to decrease with increased storage time by up to 25%. XDS experiments reveal a storage dependent increase in the RBCcm's bending modulus κ by a factor of 2.8, from 1.9 kBT to 5.3 kBT. MD simulations were conducted in the absence of proteins. The results show that the membrane composition has a small contribution to the increased bending rigidity and suggests additional protein-driven mechanisms.

Hemolytic anemia blunts the cytokine response to transfusion of older red blood cells in mice and dogs

BACKGROUND

Transfusion of red blood cells (RBCs) stored for longer durations induces hemolysis and inflammatory cytokine production in murine and canine models. Despite immune system activation by stored RBCs, human randomized trials suggest that fresher RBC transfusions do not improve clinical outcomes. We hypothesized that underlying recipient hemolysis may affect cytokine responses to older RBC transfusions.

STUDY DESIGN AND METHODS

C57BL/6 mouse cohorts were infused with anti-TER119 antibody to induce hemolysis, rabbit anti-platelet antiserum to induce immune thrombocytopenia (ITP), or appropriate control antibodies. Two days later, mice were transfused with fresh or stored RBCs. Furthermore, in a prospective, randomized, blinded trial, 38 client-owned dogs with primary autoimmune hemolytic anemia (AIHA) and two dogs with ITP, requiring RBC transfusion, were enrolled and randomized to receive fresh (≤7 days) or old (≥21 days) stored RBC transfusions. Monocyte chemoattractant protein (MCP)-1 levels were assessed at defined times after transfusion.

RESULTS

Prior immune-mediated hemolysis blunted the MCP-1 response to stored RBC transfusion in mice (361 ± 111 pg/ml vs. 6836 ± 1528 pg/ml in mice with immune hemolysis vs. ITP, respectively; mean ± SD; p < .0001). Although hemolysis markers increased after transfusion of older RBCs, the cytokine response was also muted in dogs with AIHA. No differences in morbidity or mortality were evident comparing dogs randomized to fresh or old RBCs.

CONCLUSION

These data suggest that underlying hemolysis blunts inflammatory responses to old RBC transfusions. The canine data support randomized trial results suggesting a lack of clinical benefit with fresh RBC transfusions in subjects with underlying, baseline hemolysis.

Mechanistic insights into cell-free hemoglobin-induced injury during septic shock

Cell-free hemoglobin (CFH) levels are elevated in septic shock and are higher in nonsurvivors. Whether CFH is only a marker of sepsis severity or is involved in pathogenesis is unknown. This study aimed to investigate whether CFH worsens sepsis-associated injuries and to determine potential mechanisms of harm. Fifty-one, 10-12 kg purpose-bred beagles were randomized to receive Staphylococcus aureus intrapulmonary challenges or saline followed by CFH infusions (oxyhemoglobin >80%) or placebo. Animals received antibiotics and intensive care support for 96 h. CFH significantly increased mean pulmonary arterial pressures and right ventricular afterload in both septic and nonseptic animals, effects that were significantly greater in nonsurvivors. These findings are consistent with CFH-associated nitric oxide (NO) scavenging and were associated with significantly depressed cardiac function, and worsened shock, lactate levels, metabolic acidosis, and multiorgan failure. In septic animals only, CFH administration significantly increased mean alveolar-arterial oxygenation gradients, also to a significantly greater degree in nonsurvivors. CFH-associated iron levels were significantly suppressed in infected animals, suggesting that bacterial iron uptake worsened pneumonia. Notably, cytokine levels were similar in survivors and nonsurvivors and were not predictive of outcome. In the absence and presence of infection, CFH infusions resulted in pulmonary hypertension, cardiogenic shock, and multiorgan failure, likely through NO scavenging. In the presence of infection alone, CFH infusions worsened oxygen exchange and lung injury, presumably by supplying iron that promoted bacterial growth. CFH elevation, a known consequence of clinical septic shock, adversely impacts sepsis outcomes through more than one mechanism, and is a biologically plausible, nonantibiotic, noncytokine target for therapeutic intervention.NEW & NOTEWORTHY Cell-free hemoglobin (CFH) elevations are a known consequence of clinical sepsis. Using a two-by-two factorial design and extensive physiological and biochemical evidence, we found a direct mechanism of injury related to nitric oxide scavenging leading to pulmonary hypertension increasing right heart afterload, depressed cardiac function, worsening circulatory failure, and death, as well as an indirect mechanism related to iron toxicity. These discoveries alter conventional thinking about septic shock pathogenesis and provide novel therapeutic approaches.

Effect of Leukoreduction on Hematobiochemical Parameters and Storage Hemolysis in Canine Whole Blood Units

Simple Summary

During the storage of blood units, cells undergo many changes, defined as storage lesions; these are biochemical, morphological and immunological modifications and seem to be responsible for adverse post-transfusion effects in recipients. The pre-storage leukoreduction seems to reduce them. The aims of this study are both to evaluate the human filter effectiveness and the effect of pre-storage leukoreduction in stored canine whole blood units. We tested whole blood units, leukoreduced and not, obtained from seven enrolled subjects, until the 42nd day. The white blood cell (WBC) and platelet (PLT) counts are reported to express the leukoreduction effectiveness. As indicators of storage-induced hemolysis, the lactate dehydrogenase activity (LDH) and sodium, potassium, and chlorine electrolytes were measured in plasma, and the red blood cell (RBC) count, hemoglobin concentration (Hgb), and hematocrit (Hct) were obtained with the complete blood count (CBC). The mean corpuscular volume (MCV) values and morphological index obtained from blood smear evaluation were used as indices of morphological changes. We observed that the leukoreduction filter for human use is equally effective on canine whole blood and that leukoreduction has a partially protective role to prevent some storage lesions.

Abstract

Storage lesions (SLs) occur when the red blood cell quality is altered during the preservation of blood units. Pre-storage leukoreduction would limit the number of SLs. The aims of this study were to evaluate the effectiveness of a leukoreduction filter for human use and the effect of pre-storage leukoreduction on some ematobiochemical parameters in stored canine whole blood. Seven canine blood units were tested. Each one was divided into two units—one leukoreduced (LRWB) and one non-leukoreduced (nLRWB). On each unit, we determined the complete blood count (CBC), lactate-dehydrogenase (LDH), electrolytes (Na⁺, K⁺, Cl⁻), morphological index (MI) and hemolysis, on storage days 0, 7, 14, 21, 28, 35, and 42. Leukoreduction allowed a 98.30% recovery of the RBC count, retaining 99.69% and 94.91% of WBCs and PLTs, respectively. We detected a significant increase of LDH and MI with strongly higher values in nLRWB compared to LRWB. A progressive increase in electrolytes and LDH concentrations was observed as indices of stored hemolysis. LDH showed significantly lower values in LRWB units compared to nLRWB, suggesting its release from leukocytes. In the majority of units, hemolysis reached 1% on the 42nd day of storage. We assert the human leukoreduction filter effectiveness on canine whole blood, and we recommend using nLRWB before day 14, especially for critically ill patients. The difference of the basal hemolysis (day 0) percentages observed between subjects suggests that more studies should be performed to confirm a possible inter-individual donor biological variability of RBC membrane resistance, as happens in humans.

Association of Veterinary Hematology and Transfusion Medicine (AVHTM) Transfusion Reaction Small Animal Consensus Statement (TRACS) Part 2: Prevention and monitoring

OBJECTIVE

To systematically review available evidence to develop guidelines for the prevention of transfusion reactions and monitoring of transfusion administration in dogs and cats.

DESIGN

Evidence evaluation of the literature (identified through Medline searches through Pubmed and Google Scholar searches) was carried out for identified transfusion reaction types in dogs and cats. Evidence was evaluated using PICO (Population, Intervention, Comparison, Outcome) questions generated for each reaction type. Evidence was categorized by level of evidence (LOE) and quality (Good, Fair, or Poor). Guidelines for prevention and monitoring were generated based on the synthesis of the evidence. Consensus on the final recommendations and a proposed transfusion administration monitoring form was achieved through Delphi-style surveys. Draft recommendations and the monitoring form were made available through veterinary specialty listservs and comments were incorporated.

RESULTS

Twenty-nine guidelines and a transfusion administration monitoring form were formulated from the evidence review with a high degree of consensus CONCLUSIONS: This systematic evidence evaluation process yielded recommended prevention and monitoring guidelines and a proposed transfusion administration form. However, significant knowledge gaps were identified, demonstrating the need for additional research in veterinary transfusion medicine.

Preoperative autologous blood donation and transfusion in dogs undergoing elective surgical oncology procedures with high risk of hemorrhage

OBJECTIVE

To describe preoperative autologous blood donation (PABD) and transfusion in dogs undergoing elective surgical oncology procedures with a high risk of intraoperative hemorrhage.

STUDY DESIGN

Prospective study.

ANIMALS

Twelve dogs.

METHODS

Dogs undergoing surgical oncology procedures associated with a high risk of hemorrhage were enrolled. Blood was collected a minimum of 6 days before surgery and separated into fresh frozen plasma (FFP) and packed red blood cells (pRBC). Dogs received FFP at the start of surgery and pRBC intraoperatively when hemorrhage ensued. The mean packed cell volume/total solids (PCV/TS) were calculated on the day of PABD preoperatively, immediately postoperatively, and 24 hours after transfusion. The dogs were monitored for transfusion-related adverse reactions, including hyperthermia, hypotension, tachycardia, bradycardia, pale mucous membranes, prolonged capillary refill time, or tachypnea/dyspnea.

RESULTS

Dogs enrolled in the study underwent mandibulectomy, maxillectomy, chest wall resection, and liver lobectomy. Ten of the 12 dogs that underwent PABD received autologous transfusion at first signs of hemorrhage intraoperatively. Iatrogenic anemia was noted in two dogs (PCV 30% and 31%). The mean PCV/TS levels on the day of blood collection, preoperatively, immediately postoperatively (after transfusion), and 24 hours posttransfusion were 45.1%/7.1 g/dL, 42.2%/6.73 g/dL, 33.2%/5.42 g/dL, and 36.5%/5.65 g/dL, respectively. No dog developed transfusion-related complications.

CONCLUSION

Preoperative autologous blood donation was well tolerated and led to uneventful autologous transfusion in 10 of 12 dogs.

CLINICAL SIGNIFICANCE

Preoperative autologous blood donation and autologous transfusion are feasible for dogs undergoing elective surgical procedures with a high risk of hemorrhage.

Randomized controlled trial of 7, 28, vs 42 day stored red blood cell transfusion on oxygen delivery (VO2 max) and exercise duration

BACKGROUND

Few studies have rigorously assessed the impact of red blood cell (RBC) transfusion on oxygen delivery. Several large trials demonstrated no clinical outcome differences between transfusion of shorter-storage vs prolonged-storage RBCs. These trials did not directly assess functional measures of oxygen delivery. Therefore, it is not clear if 42-day stored RBCs deliver oxygen as effectively as 7-day stored RBCs.

STUDY DESIGN AND METHODS

Leukocyte-reduced RBCs were collected by apheresis in AS-3. Thirty subjects were randomized (1:1:1) to receive 2 units of autologous RBCs at either 7, 28, or 42 days following donation. VO₂ max testing, using a standardized protocol to exhaustion, was performed 2 days before (Monday) and 2 days after (Friday) the transfusion visit (Wednesday). The primary endpoint was the percent increase in VO₂ max between Monday and Friday. The secondary endpoint was the percent change in duration of exercise for the same time points.

RESULTS

Hemoglobin levels decreased by 2.8 ± 1.4 g/dL after donation and increased by 2.1 ± 0.6 g/dL after transfusion. This change in hemoglobin was associated with expected decreases (then increases after transfusion) in VO₂ max and exercise duration. No differences were observed between 7-day and 42-day RBC transfusion for percent increase in median [IQR] VO₂ max (10.5 [0.2-17.3] vs 10.9 [5.7-16.8], P = .41) or for percent increase in exercise duration (5.4 [4.1-6.9] vs 4.9 [2.0-7.2], P = .91), respectively. Results were similar for 28-day RBCs and were consistent across the ITT and per-protocol analysis populations.

CONCLUSION

These data indicate that 42-day, 28-day, and 7-day RBCs have similar ability to deliver oxygen.

Potential Consequences of the Red Blood Cell Storage Lesion on Cardiac Electrophysiology

Background The red blood cell (RBC) storage lesion is a series of morphological, functional, and metabolic changes that RBCs undergo following collection, processing, and refrigerated storage for clinical use. Since the biochemical attributes of the RBC unit shifts with time, transfusion of older blood products may contribute to cardiac complications, including hyperkalemia and cardiac arrest. We measured the direct effect of storage age on cardiac electrophysiology and compared it with hyperkalemia, a prominent biomarker of storage lesion severity. Methods and Results Donor RBCs were processed using standard blood-banking techniques. The supernatant was collected from RBC units, 7 to 50 days after donor collection, for evaluation using Langendorff-heart preparations (rat) or human induced pluripotent stem cell-derived cardiomyocytes. Cardiac parameters remained stable following exposure to "fresh" supernatant from red blood cell units (day 7: 5.8±0.2 mM K+), but older blood products (day 40: 9.3±0.3 mM K+) caused bradycardia (baseline: 279±5 versus day 40: 216±18 beats per minute), delayed sinus node recovery (baseline: 243±8 versus day 40: 354±23 ms), and increased the effective refractory period of the atrioventricular node (baseline: 77±2 versus day 40: 93±7 ms) and ventricle (baseline: 50±3 versus day 40: 98±10 ms) in perfused hearts. Beating rate was also slowed in human induced pluripotent stem cell-derived cardiomyocytes after exposure to older supernatant from red blood cell units (-75±9%, day 40 versus control). Similar effects on automaticity and electrical conduction were observed with hyperkalemia (10-12 mM K+). Conclusions This is the first study to demonstrate that "older" blood products directly impact cardiac electrophysiology, using experimental models. These effects are likely caused by biochemical alterations in the supernatant from red blood cell units that occur over time, including, but not limited to hyperkalemia. Patients receiving large volume and/or rapid transfusions may be sensitive to these effects.

Ovine red cell concentrates for transfusion research - is the storage lesion comparable to human red cell concentrates?

BACKGROUND AND OBJECTIVES

Sheep are increasingly being used as a large in vivo animal model of blood transfusion because they provide several advantages over small animals. Understanding the effects of storage duration on ovine (ov) red cell concentrates (RCCs) and how these changes compare with stored human (hu) RCCs is necessary to facilitate clinical translation of research findings.

MATERIALS AND METHODS

OvRCCs (n = 5) collected and processed in standard human blood collection packs, and equivalent huRCCs provided by Australian Red Cross Lifeblood (n = 5), were stored at 2-6°C for 42 days, with samples collected weekly. Haemolysis index was determined by measuring supernatant haemoglobin concentration. Biochemical parameters were evaluated using a blood gas analyser. Energy metabolites and biologically active lipids were measured using commercial assays. Osmotic fragility was determined by lysis in various saline concentrations. Extracellular vesicles were characterized by nanoparticle tracking analysis.

RESULTS

Ovine red blood cells (RBCs) are double in number, smaller in size and more fragile than human RBCs. Haematological values were unchanged throughout storage. In contrast, biochemical and metabolic values, and haemolysis index in three of the five ovRCCs exceeded huRCCs licensing criteria by day 42. Accumulation of extracellular vesicles and biologically active lipids was comparable between huRCCs and ovRCCs.

CONCLUSION

This study documents similarities and differences in the storage lesion of ovRCCs and huRCCs. This new information will guide the design of ovine transfusion models to enhance translation of findings to human transfusion settings.

Small Animal Transfusion Medicine

Transfusion medicine can be a lifesaving intervention. Component therapy has expanded the availability and blood products available. Patient safety and minimizing risk is important and can be accomplished through proper donor screening, collection, storage, compatibility testing, administration, and monitoring. The pros and cons of available products must be considered and tailored to each individual patient. Recent discoveries include new antigens and blood types, microbial effects on blood type, and the association between blood type and disease prevalence.

Red blood cell metabolism in Rhesus macaques and humans: comparative biology of blood storage

Macaques are emerging as a critical animal model in transfusion medicine, because of their evolutionary similarity to humans and perceived utility in discovery and translational science. However, little is known about the metabolism of Rhesus macaque red blood cells (RBC) and how this compares to human RBC metabolism under standard blood banking conditions. Metabolomic and lipidomic analyses, and tracing experiments with [1,2,3-¹³C₃]glucose, were performed using fresh and stored RBC (sampled weekly until storage day 42) obtained from Rhesus macaques (n=20) and healthy human volunteers (n=21). These results were further validated with targeted quantification against stable isotope-labeled internal standards. Metabolomic analyses demonstrated inter-species differences in RBC metabolism independent of refrigerated storage. Although similar trends were observed throughout storage for several metabolic pathways, species- and sex-specific differences were also observed. The most notable differences were in glutathione and sulfur metabolites, purine and lipid oxidation metabolites, acylcarnitines, fatty acyl composition of several classes of lipids (including phosphatidylserines), glyoxylate pathway intermediates, and arginine and carboxylic acid metabolites. Species-specific dietary and environmental compounds were also detected. Overall, the results suggest an increased basal and refrigerator-storage-induced propensity for oxidant stress and lipid remodeling in Rhesus macaque RBC cells, as compared to human red cells. The overlap between Rhesus macaque and human RBC metabolic phenotypes suggests the potential utility of a translational model for simple RBC transfusions, although inter-species storage-dependent differences need to be considered when modeling complex disease states, such as transfusion in trauma/hemorrhagic shock models.

Evaluation of hematologic, biochemical, and blood gas variables in stored canine packed red blood cells, and the impact of storage time on blood recipients

BACKGROUND

Canine packed red blood cells (pRBCs) can be stored under refrigeration for several days; however, cellular metabolism remains active inside the units, thus producing substances that affect their quality.

OBJECTIVES

We aimed to evaluate hematologic, biochemical, and blood gas variable alterations that occur in canine pRBCs during storage, and their effects on recipient clinicopathologic parameters.

METHODS

The study was conducted in two phases. In phase I, 15 pRBC units containing CPDA-1 were stored for 28 days; samples were collected weekly from the units of days 0 to 28 to measure the packed cell volume (PCV), pH, partial pressure carbon dioxide (PCO₂ ), partial pressure oxygen (PO₂ ), concentrations of lactate and potassium, and the percent hemolysis. In phase II, another 22 canine pRBC units stored for different time periods (maximum of 21 days) were transfused, and the recipients were evaluated before and after transfusion for changes in clinical parameters (heart rate, respiratory rate, systolic arterial pressure, and rectal temperature) and hematologic variables (PCV, lactate and potassium concentrations, pH, PCO₂ , the ratio of arterial oxygen partial pressure to fractional inspired oxygen [PO₂ /FiO₂ ] ratio, oxygen saturation [SaO₂ ], base excess, and bicarbonate [HCO₃ ]).

RESULTS

In the pRBC units, the PCV increased from 70% to 78.33%, the lactate concentration increased 627%, the potassium concentration increased 183%, the percent hemolysis reached 0.69%, and the pH decreased 9% after 28 days. However, the dogs who received transfusions were not negatively affected. There was a significant increase in PCVs, and a significant decrease in heart rates.

CONCLUSION

Canine pRBCs undergo hematologic, blood gas, and biochemical alterations during storage; however, the transfusion of pRBCs stored for up to 21 days increased PCVs without causing harm to the dogs.

In canine bacterial pneumonia circulating granulocyte counts determine outcome from donor cells

BACKGROUND

In experimental canine septic shock, depressed circulating granulocyte counts were associated with a poor outcome and increasing counts with prophylactic granulocyte colony-stimulating factor (G-CSF) improved outcome. Therapeutic G-CSF, in contrast, did not improve circulating counts or outcome, and therefore investigation was undertaken to determine whether transfusing granulocytes therapeutically would improve outcome.

STUDY DESIGN AND METHODS

Twenty-eight purpose-bred beagles underwent an intrabronchial Staphylococcus aureus challenge and 4 hours later were randomly assigned to granulocyte (40-100 × 109 cells) or plasma transfusion.

RESULTS

Granulocyte transfusion significantly expanded the low circulating counts for hours compared to septic controls but was not associated with significant mortality benefit (1/14, 7% vs. 2/14, 14%, respectively; p = 0.29). Septic animals with higher granulocyte count at 4 hours (median [interquartile range] of 3.81 3.39-5.05] vs. 1.77 [1.25-2.50]) had significantly increased survival independent of whether they were transfused with granulocytes. In a subgroup analysis, animals with higher circulating granulocyte counts receiving donor granulocytes had worsened lung injury compared to septic controls. Conversely, donor granulocytes decreased lung injury in septic animals with lower counts.

CONCLUSION

During bacterial pneumonia, circulating counts predict the outcome of transfusing granulocytes. With low but normal counts, transfusing granulocytes does not improve survival and injures the lung, whereas for animals with very low counts, but not absolute neutropenia, granulocyte transfusion improves lung function.

Effects of aged stored autologous red blood cells on human plasma metabolome

Cold storage of blood for 5 to 6 weeks has been shown to impair endothelial function after transfusion and has been associated with measures of end-organ dysfunction. Although the products of hemolysis, such as cell-free plasma hemoglobin, arginase, heme, and iron, in part mediate these effects, a complete analysis of transfused metabolites that may affect organ function has not been evaluated to date. Blood stored for either 5 or 42 days was collected from 18 healthy autologous volunteers, prior to and after autologous transfusion into the forearm circulation, followed by metabolomics analyses. Significant metabolic changes were observed in the plasma levels of hemolytic markers, oxidized purines, plasticizers, and oxidized lipids in recipients of blood stored for 42 days, compared with 5 days. Notably, transfusion of day 42 red blood cells (RBCs) increased circulating levels of plasticizers (diethylhexyl phthalate and derivatives) by up to 18-fold. Similarly, transfusion of day 42 blood significantly increased circulating levels of proinflammatory oxylipins, including prostaglandins, hydroxyeicosatrienoic acids (HETEs), and dihydroxyoctadecenoic acids. Oxylipins were the most significantly increasing metabolites (for 9-HETE: up to ∼41-fold, P = 3.7e-06) in day 42 supernatants. Measurements of arginine metabolism confirmed an increase in arginase activity at the expense of nitric oxide synthesis capacity in the bloodstream of recipients of day 42 blood, which correlated with measurements of hemodynamics. Metabolic changes in stored RBC supernatants impact the plasma metabolome of healthy transfusion recipients, with observed increases in plasticizers, as well as vasoactive, pro-oxidative, proinflammatory, and immunomodulatory metabolites after 42 days of storage.

Haptoglobin Therapeutics and Compartmentalization of Cell-Free Hemoglobin Toxicity

Hemolysis and accumulation of cell-free hemoglobin (Hb) in the circulation or in confined tissue compartments such as the subarachnoid space is an important driver of disease. Haptoglobin is the Hb binding and clearance protein in human plasma and an efficient antagonist of Hb toxicity resulting from physiological red blood cell turnover. However, endogenous concentrations of haptoglobin are insufficient to provide protection against Hb-driven disease processes in conditions such as sickle cell anemia, sepsis, transfusion reactions, medical-device associated hemolysis, or after a subarachnoid hemorrhage. As a result, there is increasing interest in developing haptoglobin therapeutics to target 'toxic' cell-free Hb exposures. Here, we discuss key concepts of Hb toxicity and provide a perspective on the use of haptoglobin as a therapeutic protein.

RBC Storage Lesion Studies in Humans and Experimental Models of Shock

The finding of toxicity in a meta-analysis of observational clinical studies of transfused longer stored red blood cells (RBC) and ethical issues surrounding aging blood for human studies prompted us to develop an experimental model of RBC transfusion. Transfusing older RBCs during canine pneumonia increased mortality rates. Toxicity was associated with in vivo hemolysis with release of cell-free hemoglobin (CFH) and iron. CFH can scavenge nitric oxide, causing vasoconstriction and endothelial injury. Iron, an essential bacterial nutrient, can worsen infections. This toxicity was seen at commonly transfused blood volumes (2 units) and was altered by the severity of pneumonia. Washing longer-stored RBCs mitigated these detrimental effects, but washing fresh RBCs actually increased them. In contrast to septic shock, transfused longer stored RBCs proved beneficial in hemorrhagic shock by decreasing reperfusion injury. Intravenous iron was equivalent in toxicity to transfusion of longer stored RBCs and both should be avoided during infection. Storage of longer-stored RBCs at 2 °C instead of higher standard temperatures (4-6 °C) minimized the release of CFH and iron. Haptoglobin, a plasma protein that binds CFH and increases its clearance, minimizes the toxic effects of longer-stored RBCs during infection and is a biologically plausible novel approach to treat septic shock.

Haptoglobin therapy has differential effects depending on severity of canine septic shock and cell-free hemoglobin level

BACKGROUND

During sepsis, higher plasma cell-free hemoglobin (CFH) levels portend worse outcomes. In sepsis models, plasma proteins that bind CFH improve survival. In our canine antibiotic-treated Staphylococcus aureus pneumonia model, with and without red blood cell (RBC) exchange transfusion, commercial human haptoglobin (Hp) concentrates bound and compartmentalized CFH intravascularly, increased CFH clearance, and lowered iron levels, improving shock, lung injury, and survival. We now investigate in our model how very high CFH levels and treatment time affect Hp's beneficial effects.

MATERIALS AND METHODS

Two separate canine pneumonia sepsis Hp studies were undertaken: one with exchange transfusion of RBCs after prolonged storage to raise CFH to very high levels and another with rapidly lethal sepsis alone to shorten time to treat. All animals received continuous standard intensive care unit supportive care for 96 hours.

RESULTS

Older RBCs markedly elevated plasma CFH levels and, when combined with Hp therapy, created supraphysiologic CFH-Hp complexes that did not increase CFH or iron clearance or improve lung injury and survival. In a rapidly lethal bacterial challenge model without RBC transfusion, Hp binding did not increase clearance of complexes or iron or show benefits seen previously in the less lethal model.

DISCUSSION

High-level CFH-Hp complexes may impair clearance mechanisms and eliminate Hp's beneficial effect during sepsis. Rapidly lethal sepsis narrows the therapeutic window for CFH and iron clearance, also decreasing Hp's beneficial effects. In designing clinical trials, dosing and kinetics may be critical factors if Hp infusion is used to treat sepsis.

The Effects of Storage Age of Blood in Massively Transfused Burn Patients: A Secondary Analysis of the Randomized Transfusion Requirement in Burn Care Evaluation Study

OBJECTIVES

Major trials examining storage age of blood transfused to critically ill patients administered relatively few blood transfusions. We sought to determine if the storage age of blood affects outcomes when very large amounts of blood are transfused.

DESIGN

A secondary analysis of the multicenter randomized Transfusion Requirement in Burn Care Evaluation study which compared restrictive and liberal transfusion strategies.

SETTING

Eighteen tertiary-care burn centers.

PATIENTS

Transfusion Requirement in Burn Care Evaluation evaluated 345 adults with burns greater than or equal to 20% of the body surface area. We included only the 303 patients that received blood transfusions.

INTERVENTIONS

The storage ages of all transfused red cell units were collected during Transfusion Requirement in Burn Care Evaluation. A priori measures of storage age were the the mean storage age of all transfused blood and the proportion of all transfused blood considered very old (stored ≥ 35 d).

MEASUREMENTS AND MAIN RESULTS

The primary outcome was the severity of multiple organ dysfunction. Secondary outcomes included time to wound healing, the duration of mechanical ventilation, and in-hospital mortality. There were 6,786 red cell transfusions with a mean (± SD) storage age of 25.6 ± 10.2 days. Participants received a mean of 23.4 ± 31.2 blood transfusions (range, 1-219) and a mean of 5.3 ± 10.7 units of very old blood. Neither mean storage age nor proportion of very old blood had any influence on multiple organ dysfunction severity, time to wound healing, or mortality. Duration of ventilation was significantly predicted by both mean blood storage age and the proportion of very old blood, but this was of questionable clinical relevance given extreme variability in duration of ventilation (adjusted r ≤ 0.01).

CONCLUSIONS

Despite massive blood transfusion, including very old blood, the duration of red cell storage did not influence outcome in burn patients. Provision of the oldest blood first by Blood Banks is rational, even for massive transfusion.

Random allogeneic blood transfusion in pigs: characterisation of a novel experimental model

Background

Organ cross-talk describes interactions between a primary affected organ and a secondarily injured remote organ, particularly in lung-brain interactions. A common theory is the systemic distribution of inflammatory mediators that are released by the affected organ and transferred through the bloodstream. The present study characterises the baseline immunogenic effects of a novel experimental model of random allogeneic blood transfusion in pigs designed to analyse the role of the bloodstream in organ cross-talk.

Methods

After approval of the State and Institutional Animal Care Committee, 20 anesthetized pig were randomized in a donor and an acceptor (each n = 8): the acceptor animals each received high-volume whole blood transfusion from the donor (35–40 ml kg⁻¹). Four animals received balanced electrolyte solution instead of blood transfusion (control group; n = 4). Afterwards the animals underwent extended cardiorespiratory monitoring for eight hours. Post mortem assessment included pulmonary, cerebral and systemic mediators of early inflammatory response (IL-6, TNF-alpha, iNOS), wet to dry ratio, and lung histology.

Results

No adverse events or incompatibilities occurred during the blood transfusion procedures. Systemic cytokine levels and pulmonary function were unaffected. Lung histopathology scoring did not display relevant intergroup differences. Neither within the lung nor within the brain an up-regulation of inflammatory mediators was detected. High volume random allogeneic blood transfusion in pigs neither impaired pulmonary integrity nor induced systemic, lung, or brain inflammatory response.

Conclusion

This approach can represent a novel experimental model to characterize the blood-bound transmission in remote organ injury.

Role of redox iron towards an increase in mortality among patients: a systemic review and meta-analysis

An increase in biochemical concentrations of non-transferrin bound iron (NTBI) within the patients with an increase in serum iron concentration was evaluated with the following objectives: (a) Iron overloading diseases/conditions with free radicle form of ‘iron containing’ reactive oxygen species (ROS) and its imbalance mediated mortality, and (b) Intervention with iron containing drugs in context to increased redox iron concentration and treatment induced mortality. Literature search was done within Pubmed and cochrane review articles. The Redox iron levels are increased during dys-erythropoiesis and among transfusion recipient population and are responsive to iron-chelation therapy. Near expiry ‘stored blood units’ show a significant rise in the ROS level. Iron mediated ROS damage may be estimated by the serum antioxidant level, and show reduction in toxicity with high antioxidant, low pro-oxidant levels. Iron drug therapy causes a significant increase in NTBI and labile iron levels. Hospitalized patients on iron therapy however show a lower mortality rate. Serum ferritin is a mortality indicator among the high-dose iron therapy and transfusion dependent population. The cumulative difference of pre-chelation to post chelation ROS iron level was 0.97 (0.62; 1.32; N=261) among the transfusion dependent subjects and 2.89 (1.81–3.98; N=130) in the post iron therapy ‘iron ROS’ group. In conclusion, iron mediated mortality may not be mediated by redox iron among multi-transfused and iron overloaded patients.

Transfusion of standard-issue packed red blood cells induces pulmonary vasoconstriction in critically ill patients after cardiac surgery-A randomized, double-blinded, clinical trial

BACKGROUND

Experimental and volunteer studies have reported pulmonary vasoconstriction during transfusion of packed red blood cells (PRBCs) stored for prolonged periods. The primary aim of this study was to evaluate whether transfusion of PRBCs stored over 21 days (standard-issue, siPRBCs) increases pulmonary artery pressure (PAP) to a greater extent than transfusion of PRBCs stored for less then 14 days (fresh, fPRBCs) in critically ill patients following cardiac surgery. The key secondary aim was to assess whether the pulmonary vascular resistance index (PVRI) increases after transfusion of siPRBCs to a greater extent than after transfusion of fPRBCs.

METHODS

The study was performed as a single-center, double-blinded, parallel-group, randomized clinical trial. Leukoreduced PRBCs were transfused while continuously measuring hemodynamic parameters. Systemic concentrations of syndecan-1 were measured to assess glycocalyx injury. After randomizing 19 patients between January 2014 and June 2016, the study was stopped due to protracted patient recruitment.

RESULTS

Of 19 randomized patients, 11 patients were transfused and included in statistical analyses. Eight patients were excluded prior to transfusion, 6 patients received fPRBCs (10±3 storage days), whereas 5 patients received siPRBCs (33±4 storage days). The increase in PAP (7±3 vs. 2±2 mmHg, P = 0.012) was greater during transfusion of siPRBCs than during transfusion of fPRBCs. In addition, the change in PVRI (150±89 vs. -4±37 dyn·s·cm-5·m2, P = 0.018) was greater after transfusion of siPRBCs than after transfusion of fPRBCs. The increase in PAP correlated with the change of systemic syndecan-1 concentrations at the end of transfusion (R = 0.64,P = 0.034).

CONCLUSION

Although this study is underpowered and results require verification in larger clinical trials, our findings suggest that transfusion of siPRBCs increases PAP and PVRI to a greater extent than transfusion of fPRBCs in critically ill patients following cardiac surgery. Glycocalyx injury might contribute to pulmonary vasoconstriction associated with transfusion of stored blood.

Blood transfusions, blood storage, and correlation with elevated pulmonary arterial pressures

BACKGROUND

The aim of this study was to determine if transfusion with RBCs is associated with a rise in mean pulmonary artery pressure (MPAP) and whether such a rise is influenced by the duration of RBC storage.

STUDY DESIGN AND METHODS

A retrospective chart review of intensive care unit patients with pulmonary artery catheters was conducted at two military medical centers.

RESULTS

RBC transfusion is associated with a sustained (≥4 hours) statistically significant 2- to 3-mm Hg rise in MPAP relative to both pretransfusion levels (p < 0.05) and compared to asanguinous fluid infusions (p < 0.05). The magnitude of the rise (all infusions, RBCs, and asanguinous) correlates positively with in-hospital mortality (p < 0.01) and hospital length of stay (p < 0.01). The duration of RBC storage was not statistically correlated with the magnitude of rise in the population studied. Mean infusion volume was greater for RBC (vs. asanguinous) infusions, but volume adjustment of MPAP values did not alter the pattern or statistical significance of the results.

CONCLUSIONS

Analysis of retrospectively collected data suggests that transfusion of RBC-containing fluids results in a sustained elevation of MPAP. In the patient population studied, the duration of RBC storage did not correlate with the magnitude of MPAP rise. Future prospective studies of transfusion effects should consider including assessment of MPAP and subpopulation analyses.

Impact of different standard red blood cell storage temperatures on human and canine RBC hemolysis and chromium survival

BACKGROUND

Storage temperature is a critical factor for maintaining red-blood cell (RBC) viability, especially during prolonged cold storage. The target range of 1 to 6°C was established decades ago and may no longer be optimal for current blood-banking practices.

STUDY DESIGN AND METHODS

Human and canine RBCs were collected under standard conditions and stored in precision-controlled refrigerators at 2°C, 4°C, or 6°C.

RESULTS

During 42-day storage, human and canine RBCs showed progressive increases in supernatant non-transferrin-bound iron, cell-free hemoglobin, base deficit, and lactate levels that were overall greater at 6°C and 4°C than at 2°C. Animals transfused with 7-day-old RBCs had similar plasma cell-free hemoglobin and non-transferrin-bound iron levels at 1 to 72 hours for all three temperature conditions by chromium-51 recovery analysis. However, animals transfused with 35-day-old RBCs stored at higher temperatures developed plasma elevations in non-transferrin-bound iron and cell-free hemoglobin at 24 and 72 hours. Despite apparent impaired 35-day storage at 4°C and 6°C compared to 2°C, posttransfusion chromium-51 recovery at 24 hours was superior at higher temperatures. This finding was confounded by a preparation artifact related to an interaction between temperature and storage duration that leads to removal of fragile cells with repeated washing of the radiolabeled RBC test sample and renders the test sample unrepresentative of the stored unit.

CONCLUSIONS

RBCs stored at the lower bounds of the temperature range are less metabolically active and produce less anaerobic acidosis and hemolysis, leading to a more suitable transfusion product. The higher refrigeration temperatures are not optimal during extended RBC storage and may confound chromium viability studies.

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.

Randomized trial of red cell washing for the prevention of transfusion-associated organ injury in cardiac surgery

Background. Experimental studies suggest that mechanical cell washing to remove pro-inflammatory components that accumulate in the supernatant of stored donor red blood cells (RBCs) might reduce inflammation and organ injury in transfused patients.

Methods. Cardiac surgery patients at increased risk of large-volume RBC transfusion were eligible. Participants were randomized to receive either mechanically washed allogenic RBCs or standard care RBCs. The primary outcome was serum interleukin-8 measured at baseline and at four postsurgery time points. A mechanism substudy evaluated the effects of washing on stored RBCs in vitro and on markers of platelet, leucocyte, and endothelial activation in trial subjects.

Results. Sixty adult cardiac surgery patients at three UK cardiac centres were enrolled between September 2013 and March 2015. Subjects received a median of 3.5 (interquartile range 2–5.5) RBC units, stored for a mean of 21 (sd 5.2) days, within 48 h of surgery. Mechanical washing reduced concentrations of RBC-derived microvesicles but increased cell-free haemoglobin concentrations in RBC supernatant relative to standard care RBC supernatant. There was no difference between groups with respect to perioperative serum interleukin-8 values [adjusted mean difference 0.239 (95% confidence intervals −0.231, 0.709), P=0.318] or concentrations of plasma RBC microvesicles, platelet and leucocyte activation, plasma cell-free haemoglobin, endothelial activation, or biomarkers of heart, lung, or kidney injury.

Conclusions. These results do not support a hypothesis that allogenic red blood cell washing has clinical benefits in cardiac surgery.

Clinical trial registration. ISRCTN 27076315.

Characterization of Storage-Induced Red Blood Cell Hemolysis Using Raman Spectroscopy

BACKGROUND

The therapeutic efficacy and safety of stored red blood cells (RBCs) relies on minimal in-bag hemolysis. The accuracy of current methods of measuring hemolysis can suffer as a result of specimen collection and processing artefacts.

OBJECTIVE

To test whether Raman spectroscopy could be used to assess hemolysis.

METHODS

RBCs were stored for as long as 42 days. Raman spectra of RBCs were measured before and after washing, and hemolysis was measured in supernatant by visible spectroscopy.

RESULTS

Raman spectra indicated increased concentrations of oxyhemoglobin (oxyHb) and methemoglobin (metHb), and decreased membrane fluidity with storage age. Changes in oxyHb and metHb were associated with the intraerythrocytic and extracellular fractions, respectively. Hemolysis increased in a storage age-dependent manner. Changes in Raman bands reflective of oxyHb, metHb, and RBC membranes correlated with hemolysis; the most statistically significant change was an increased intensity of metHb and decreased membrane fluidity.

CONCLUSIONS

These data suggest that Raman spectroscopy may offer a new label-free modality to assess RBC hemolysis during cold storage.

Haptoglobin improves shock, lung injury, and survival in canine pneumonia

During the last half-century, numerous antiinflammatory agents were tested in dozens of clinical trials and have proven ineffective for treating septic shock. The observation in multiple studies that cell-free hemoglobin (CFH) levels are elevated during clinical sepsis and that the degree of increase correlates with higher mortality suggests an alternative approach. Human haptoglobin binds CFH with high affinity and, therefore, can potentially reduce iron availability and oxidative activity. CFH levels are elevated over approximately 24-48 hours in our antibiotic-treated canine model of S. aureus pneumonia that simulates the cardiovascular abnormalities of human septic shock. In this 96-hour model, resuscitative treatments, mechanical ventilation, sedation, and continuous care are translatable to management in human intensive care units. We found, in this S. aureus pneumonia model inducing septic shock, that commercial human haptoglobin concentrate infusions over 48-hours bind canine CFH, increase CFH clearance, and lower circulating iron. Over the 96-hour study, this treatment was associated with an improved metabolic profile (pH, lactate), less lung injury, reversal of shock, and increased survival. Haptoglobin binding compartmentalized CFH to the intravascular space. This observation, in combination with increasing CFHs clearance, reduced available iron as a potential source of bacterial nutrition while decreasing the ability for CFH and iron to cause extravascular oxidative tissue injury. In contrast, haptoglobin therapy had no measurable antiinflammatory effect on elevations in proinflammatory C-reactive protein and cytokine levels. Haptoglobin therapy enhances normal host defense mechanisms in contrast to previously studied antiinflammatory sepsis therapies, making it a biologically plausible novel approach to treat septic shock.

Does red blood cell irradiation and/or anemia trigger intestinal injury in premature infants with birth weight ≤ 1250 g? An observational birth cohort study

BACKGROUND

Necrotizing enterocolitis (NEC) is a leading cause of neonatal morbidity and mortality in premature infants. To date, no effective biomarkers exist to predict which premature infants will develop NEC, limiting targeted prevention strategies. Multiple observational studies have reported an association between the exposure to red blood cell (RBC) transfusion and/or anemia and the subsequent development of NEC; however, the underlying physiologic mechanisms of how these factors are independently associated with NEC remain unknown.

METHODS

In this paper, we outline our prospective, multicenter observational cohort study of infants with a birth weight ≤ 1250 g to investigate the associations between RBC transfusion, anemia, intestinal oxygenation and injury that lead to NEC. Our overarching hypothesis is that irradiation of RBC units followed by longer storage perturbs donor RBC metabolism and function, and these derangements are associated with paradoxical microvascular vasoconstriction and intestinal tissue hypoxia increasing the risk for injury and/or NEC in transfused premature infants with already impaired intestinal oxygenation due to significant anemia. To evaluate these associations, we are examining the relationship between prolonged irradiation storage time (pIST), RBC metabolomic profiles, and anemia on intestinal oxygenation non-invasively measured by near-infrared spectroscopy (NIRS), and the development of NEC in transfused premature infants.

DISCUSSION

Our study will address a critical scientific gap as to whether transfused RBC characteristics, such as irradiation and metabolism, impair intestinal function and/or microvascular circulation. Given the multifactorial etiology of NEC, preventative efforts will be more successful if clinicians understand the underlying pathophysiologic mechanisms and modifiable risk factors influencing the disease.

TRIAL REGISTRATION

Our study is registered in ClinicalTrials.gov Identifier: NCT02741648 .

Decreased Hemolysis and Improved Platelet Function in Blood Components Washed With Plasma-Lyte A Compared to 0.9% Sodium Chloride

OBJECTIVES

Washing cellular blood products is accepted to ameliorate repeated severe allergic reactions but is associated with RBC hemolysis and suboptimal platelet function. We compared in vitro hemolysis and platelet function in blood components after washing with Plasma-Lyte A (PL-A) vs normal saline (NS).

METHODS

RBC (n = 14) were washed/resuspended in NS or PL-A. Free hemoglobin and heme were determined at 0, 24, 48, and 72 hours. Platelet concentrates (PCs; n = 21) were washed with NS or PL-A and resuspended in same washing solution (n = 13) or ABO-identical plasma (n = 8). Platelet aggregation and spreading were evaluated.

RESULTS

The 24-hour free hemoglobin and heme levels were higher in NS (P < .05). Improved platelet function was observed in PL-A-washed PCs (P < .001).

DISCUSSION

PL-A showed less RBC hemolysis and better platelet function than NS. Whether such differences would occur in vivo is unknown.

Critical developments of 2017: a review of the literature from selected topics in transfusion. A committee report from the AABB Clinical Transfusion Medicine Committee

BACKGROUND

The AABB compiles an annual synopsis of the published literature covering important developments in the field of Transfusion Medicine. For the first time, an abridged version of this work is being made available in TRANSFUSION, with the full-length report available as an Appendix S1 (available as supporting information in the online version of this paper).

STUDY DESIGN AND METHODS

Papers published in 2016 and early 2017 are included, as well as earlier papers cited for background. Although this synopsis is comprehensive, it is not exhaustive, and some papers may have been excluded or missed.

RESULTS

The following topics are covered: duration of red blood cell storage and clinical outcomes, blood donor characteristics and patient outcomes, reversal of bleeding in hemophilia and for patients on direct oral anticoagulants, transfusion approach to hemorrhagic shock, pathogen inactivation, pediatric transfusion medicine, therapeutic apheresis, and extracorporeal support.

CONCLUSION

This synopsis may be a useful educational tool.

Red blood cells ageing markers: a multi-parametric analysis

BACKGROUND

Red blood cells collected in citrate-phosphate-dextrose can be stored for up to 42 days at 4 °C in saline-adenine-glucose-mannitol additive solution. During this controlled, but nevertheless artificial, ex vivo ageing, red blood cells accumulate lesions that can be reversible or irreversible upon transfusion. The aim of the present study is to follow several parameters reflecting cell metabolism, antioxidant defences, morphology and membrane dynamics during storage.

MATERIALS AND METHODS

Five erythrocyte concentrates were followed weekly during 71 days. Extracellular glucose and lactate concentrations, total antioxidant power, as well as reduced and oxidised intracellular glutathione levels were quantified. Microvesiculation, percentage of haemolysis and haematologic parameters were also evaluated. Finally, morphological changes and membrane fluctuations were recorded using label-free digital holographic microscopy.

RESULTS

The antioxidant power as well as the intracellular glutathione concentration first increased, reaching maximal values after one and two weeks, respectively. Irreversible morphological lesions appeared during week 5, where discocytes began to transform into transient echinocytes and finally spherocytes. At the same time, the microvesiculation and haemolysis started to rise exponentially. After six weeks (expiration date), intracellular glutathione was reduced by 25%, reflecting increasing oxidative stress. The membrane fluctuations showed decreased amplitudes during shape transition from discocytes to spherocytes.

DISCUSSION

Various types of lesions accumulated at different chemical and cellular levels during storage, which could impact their in vivo recovery after transfusion. A marked effect was observed after four weeks of storage, which corroborates recent clinical data. The prolonged follow-up period allowed the capture of deep storage lesions. Interestingly, and as previously described, the severity of the changes differed among donors.

The potential adverse effects of haemolysis

Haemolysis occurs in many haematologic and non-haematologic diseases. Transfusion of packed red blood cells (pRBCs) can result in intravascular haemolysis, in which the RBCs are destroyed within the circulation, and extravascular haemolysis, in which RBCs are phagocytosed in the monocyte-macrophage system. This happens especially after RBCs have been stored under refrigerated conditions for long periods. The clinical implications and the relative contribution of intra- vs extra-vascular haemolysis are still a subject of debate. They have been associated with adverse effects in animal models, but it remains to be determined whether these may be involved in mediating adverse effects in humans.