Effects of storage on efficacy of red cell transfusion: When is it not safe?

Prevalence and screening of hemoglobinopathies and glucose-6-phosphate dehydrogenase deficiency in Yemeni blood donors

OBJECTIVES

This study aimed to determine the prevalence of total blood cell abnormalities, hemoglobinopathies and G6PD deficiency and evaluate the efficacy of red blood cell (RBC) indices, mentzer index (MI) and naked-eye single tube red cell osmotic fragility (NESTROF) test as screening tools for diagnosis of β thalassemia trait among Yemeni blood donors.

METHODS

A cross-sectional study was conducted with 106 volunteer blood donors who met the national standard criterion of blood donation. Various tests were performed, including complete blood count (CBC), serum ferritin, sickling test, G6PD assay, NESTROF test and high-performance liquid chromatography (HPLC).

RESULTS

The prevalence of hematological abnormalities among blood donors reached 68.9%, with functional RBC abnormalities at 51.9%, leukopenia at 10.4%, thrombocytosis at 1.9%, and thrombocytopenia at 4.7%. Additionally, hemoglobinopathies were found in 21.7% of donors, with β-thalassemia trait at 3.8%, sickle cell trait at 1.9%, and suspected α-thalassemia trait at 16%, while G6PD deficiency and iron deficiency were present in 12.3% and 17.9% of donors, respectively. The NESTROF test, MCV and MCH demonstrated a sensitivity rate of 100%. MI and MCH exhibited the highest specificity followed by NESTROF test in the screening of β-thalassemia trait.

CONCLUSIONS

The prevalence of hemoglobinopathies and G6PD deficiency appear to be common among Yemeni blood donors. These results emphasize the necessity of comprehensive blood donation screening programs to safeguard the blood supply and promote early detection and management of hemoglobinopathies and G6PD deficiency in Yemen.

Dynamic Aortic Pressure Augmentation as a Novel Method of Swine Terminal Blood Extraction

INTRODUCTION

Uncontrolled hemorrhage models require sufficient quantities of donor blood products to support resuscitation. To that end, we describe a novel method of whole blood extraction from donor swine using resuscitative endovascular balloon occlusion of the aorta (REBOA) to support hemodynamics during terminal blood extraction and its impact on the quality of banked blood.

METHODS

Ten adult Yorkshire-cross swine were anesthetized and instrumented with an REBOA catheter, femoral multistage venous cannula, and proximal/distal blood pressure monitoring. Hemodynamics during terminal blood extraction was supported with hand-titrated partial REBOA. Blood samples were taken at set time points for analysis.

RESULTS

The median collected blood volume was 3912 mL, with all animals surviving through the planned blood collection of 60% estimated total blood volume (ETBV). Median lactate and potassium levels remained within normal limits for swine through collection of 40% of the ETBV. Median hemoglobin through collection of 40% ETBV did not significantly change from values measured at the start of hemorrhage.

CONCLUSIONS

This method of whole blood extraction provided sufficient blood volume and blood quality appropriate for transfusion through 40% ETBV, with remaining collected blood likely still acceptable for allogeneic transfusion despite increased lactate levels. This method of whole blood extraction can efficiently provide a large volume of quality blood to support resuscitation for subsequent uncontrolled hemorrhage models.

Tired and stressed: direct holographic quasi-static stretching of aging echinocytes and discocytes in plasma using optical tweezers [Invited]

Red blood cells (RBCs) undergo a progressive morphological transformation from smooth biconcave discocytes into rounder echinocytes with spicules on their surface during cold storage. The echinocytic morphology impacts RBCs' ability to flow through narrow sections of the circulation and therefore transfusion of RBC units with a high echinocytic content are thought to have a reduced efficiency. We use an optical tweezers-based technique where we directly trap and measure linear stiffness of RBCs under stress without the use of attached spherical probe particles or microfluidic flow to induce shear. We study RBC deformability with over 50 days of storage performing multiple stretches in blood plasma (serum with cold agglutinins removed to eliminate clotting). In particular, we find that discocytes and echinocytes do not show significant changes in linear stiffness in the small strain limit (∼ 20 % change in length) up to day 30 of the storage period, but do find differences between repeated stretches. By day 50 the linear stiffness of discocytes had increased to approximately that measured for echinocytes throughout the entire period of measurements. These changes in stiffness corresponded to recorded morphological changes in the discocytes as they underwent storage lesion. We believe our holographic trapping and direct measurement technique has applications to directly control and quantify forces that stretch other types of cells without the use of attached probes.

Transfusion increased skin blood flow when initially low in volume-resuscitated patients without acute bleeding

Background

Alterations in skin blood flow is a marker of inadequate tissue perfusion in critically ill patients after initial resuscitation. The effects of red blood cell transfusions (RBCT) on skin perfusion are not described in this setting. We evaluated the effects of red blood cell transfusions on skin tissue perfusion in critically ill patients without acute bleeding after initial resuscitation.

Methods

A prospective observational study included 175 non-bleeding adult patients after fluid resuscitation requiring red blood cell transfusions. Using laser Doppler, we measured finger skin blood flow (SBF) at skin basal temperature (SBFBT), together with mean arterial pressure (MAP), heart rate (HR), hemoglobin (Hb), central venous pressure (CVP), lactate, and central or mixed venous oxygen saturation before and 1 h after RBCT. SBF responders were those with a 20% increase in SBFBT after RBCT.

Results

Overall, SBFBT did not significantly change after RBCT [from 79.8 (4.3-479.4) to 83.4 (4.9-561.6); p = 0.67]. A relative increase equal to or more than 20% in SBFBT after RBCT (SBF responders) was observed in 77/175 of RBCT (44%). SBF responders had significantly lower SBFBT [41.3 (4.3-279.3) vs. 136.3 (6.5-479.4) perfusion units; p < 0.01], mixed or central venous oxygen saturation (62.5 ± 9.2 vs. 67.3% ± 12.0%; p < 0.01) and CVP (8.3 ± 5.1 vs. 10.3 ± 5.6 mmHg; p = 0.03) at baseline than non-responders. SBFBT increased in responders [from 41.3 (4.3-279.3) to 93.1 (9.8-561.6) perfusion units; p < 0.01], and decreased in the non-responders [from 136.3 (6.5-479.4) to 80.0 (4.9-540.8) perfusion units; p < 0.01] after RBCT. Pre-transfusion SBFBT was independently associated with a 20% increase in SBFBT after RBCT. Baseline SBFBT had an area under receiver operator characteristic of 0.73 (95% CI, 0.68-0.83) to predict SBFBT increase; A SBFBT of 73.0 perfusion units (PU) had a sensitivity of 71.4% and a specificity of 70.4% to predict SBFBT increase after RBCT. No significant differences in SBFBT were observed after RBCT in different subgroup analyses.

Conclusion

The skin blood flow is globally unaltered by red blood cell transfusions in non-bleeding critically ill patients after initial resuscitation. However, a lower SBFBT at baseline was associated with a relative increase in skin tissue perfusion after RBCT.

Screening of subclinical functional hemoglobin and red blood cell abnormalities among blood donors of Fayoum University Hospital in Egypt: Are RET-He, and IRF useful screening tools?

BACKGROUND

The effectiveness of red cell transfusion in a given blood unit that relied on both quantity and quality of donated cells undoubtedly affects prognostic outcomes.

OBJECTIVE

We aimed to determine the frequency of subclinical functional hemoglobin and red cell abnormalities in donated blood of Fayoum University Hospital in Egypt. Additionally, to assess the usefulness of reticulocyte mean hemoglobin content (RET-He) and immature reticulocyte fraction (IRF) as screening measures for such abnormalities.

MATERIAL AND METHODS

This cross-sectional study enrolled 200 volunteer blood donors who met the national standard criterion of blood donation. Complete blood count with reticulocyte parameters, serum ferritin, sickling test, G6PD assay, Mentzer index, and naked-eye single tube red cell osmotic fragility test were carried out.

RESULTS

Functional red cell abnormalities represented 44 % of this cohort. Out of them, 4.5 % had iron deficiency, 11 % had a positive sickling test, 19 % had G6PD deficiency, and 9.5 % had suspicious thalassemia. The sensitivity and specificity test for RET-He in selective identification of functional hemoglobin abnormalities in donated blood were 83.3 % and 61.2 %, respectively at a cutoff value of 26.9. Though there was no statistically significant effect of RET-He on the selective detection of G6PD deficiency, IRF had a statistically significant high level with a p-value of 0.04.

CONCLUSION

Subclinical functional red cell abnormalities seem to be prevalent among blood donors. Reticulocyte/ erythrocyte indices could be useful screening tools for red cell abnormalities. Further studies are required for assessing the impact of transfusing such abnormalities to neonates and other critical recipients.

Intermittent scavenging of storage lesion from stored red blood cells by electrospun nanofibrous sheets enhances their quality and shelf-life

Transfusion of healthy red blood cells (RBCs) is a lifesaving process. However, upon storing RBCs, a wide range of damage-associate molecular patterns (DAMPs), such as cell-free DNA, nucleosomes, free-hemoglobin, and poly-unsaturated-fatty-acids are generated. DAMPs can further damage RBCs; thus, the quality of stored RBCs declines during the storage and limits their shelf-life. Since these DAMPs consist of either positive or negative charged species, we developed taurine and acridine containing electrospun-nanofibrous-sheets (Tau-AcrNFS), featuring anionic, cationic charges and an DNA intercalating group on their surfaces. We show that Tau-AcrNFS are efficient in scavenging DAMPs from stored human and mice RBCs ex vivo. We find that intermittent scavenging of DAMPs by Tau-AcrNFS during the storage reduces the loss of RBC membrane integrity and reduces discocytes-to-spheroechinocytes transformation in stored-old-RBCs. We perform RBC-transfusion studies in mice to reveal that intermittent removal of DAMPs enhances the quality of stored-old-RBCs equivalent to freshly collected RBCs, and increases their shelf-life by ~22%. Such prophylactic technology may lead to the development of novel blood bags or medical device, and may therefore impact healthcare by reducing transfusion-related adverse effects.

Erythrocyte-derived extracellular vesicles aggravate inflammation by promoting the proinflammatory macrophage phenotype through TLR4-MyD88-NF-κB-MAPK pathway

Transfusion of stored erythrocytes is associated with the increased risk of morbidity and mortality in critical infections, but the mechanism is incompletely understood. Previous studies have suggested that RBC-derived extracellular vesicles (EVs) may be potential risk factors for the occurrence of transfusion-related immunomodulation. The purpose of our study was to evaluate the effects of RBC-derived EVs under inflammatory conditions and explore the underlying mechanisms. In vivo, the activity of EVs was evaluated in cecal ligation and puncture (CLP)-induced sepsis. Our results showed that EVs significantly aggravated the inflammatory response to sepsis in serum and lung tissue by promoting the production of the proinflammatory factors tumor necrosis factor-α (TNF-α）-interleukin-6(IL-6), and interleukin-1β (IL-1β) and reduced the survival rate of septic mice in vivo. Importantly, adoptive transfer of EVs-pretreated bone marrow-derived macrophages (BMDMs) obviously aggravated systemic proinflammatory factors in mice after CLP surgery. In vitro, the proinflammatory properties of EVs were shown to elevate TNF-α, IL-6, and IL-1β levels in lipopolysaccharide (LPS)-stimulated BMDMs. Moreover, EVs promoted LPS-induced macrophage polarization into a proinflammatory phenotype. The underlying mechanism might involve EV-mediated up-regulation of TLR4-MyD88-NF-κB-MAPK activity to favor macrophage cytokine production.

Assessing red blood cell deformability from microscopy images using deep learning

Red blood cells (RBCs) must be highly deformable to transit through the microvasculature to deliver oxygen to tissues. The loss of RBC deformability resulting from pathology, natural aging, or storage in blood bags can impede the proper function of these cells. A variety of methods have been developed to measure RBC deformability, but these methods require specialized equipment, long measurement time, and highly skilled personnel. To address this challenge, we investigated whether a machine learning approach could be used to predict donor RBC deformability based on morphological features from single cell microscope images. We used the microfluidic ratchet device to sort RBCs based on deformability. Sorted cells are then imaged and used to train a deep learning model to classify RBC based image features related to cell deformability. This model correctly predicted deformability of individual RBCs with 81 ± 11% accuracy averaged across ten donors. Using this model to score the deformability of RBC samples was accurate to within 10.4 ± 6.8% of the value obtained using the microfluidic ratchet device. While machine learning methods are frequently developed to automate human image analysis, our study is remarkable in showing that deep learning of single cell microscopy images could be used to assess RBC deformability, a property not normally measurable by imaging. Measuring RBC deformability by imaging is also desirable because it can be performed rapidly using a standard microscopy system, potentially enabling RBC deformability studies to be performed as part of routine clinical assessments.

Incidence of and risk factors for thromboembolism during pregnancy and postpartum: A 10-year nationwide population-based study

OBJECTIVE

Knowledge of the incidence of pregnancy-related thromboembolism and its risk factors is clinically important because thromboembolism is the leading cause of maternal death. However, there are insufficient large population-based studies on this topic. The purpose of this study was to estimate the incidence of and identify the risk factors for thromboembolism during pregnancy and puerperium.

MATERIALS AND METHODS

We analyzed data from 2007 to 2016 using the Health Insurance Review and Assessment Service (HIRA) database. Women who gave birth in the Republic of Korea were identified. Thromboembolism was defined as the simultaneous presence of both the diagnostic and test codes. Risk factors for thromboembolism were identified using logistic regression.

RESULTS

A total of 1,188 delivery episodes with thromboembolism were extracted from 4,243,393 delivery episodes. The incidence of thromboembolism was 0.28 per 1,000 deliveries, and it increased over the 10-year period. The incidence of antepartum thromboembolism was 0.1 per 1,000 deliveries (418 cases), and the incidence of postpartum thromboembolism was 0.18 per 1,000 deliveries (770 cases). Thromboembolism was associated with ovarian hyperstimulation syndrome, low socioeconomic status, multiple birth, cesarean birth, preeclampsia, postpartum hemorrhage, placenta previa, advanced maternal age, hyperemesis and primiparity. The factors associated with mortality from thromboembolism were cesarean birth and preterm premature rupture of membranes.

CONCLUSION

The incidence of pregnancy-related thromboembolism increased over the 10-year study period. Low socioeconomic status, ovarian hyperstimulation syndrome, cesarean delivery and premature rupture of membranes were high-risk factors. This study provides an important reference for thromboprophylaxis for pregnancy-related thromboembolism.

The dielectric spectroscopy of human red blood cells during 37-day storage: β-dispersion parameterization

This study exploits dielectric spectroscopy to monitor the kinetics of red blood cells (RBC) storage lesions, focusing on those processes linked to cellular membrane interface known as β-dispersion. The dielectric response of RBC suspensions, exposed to blood-bank cold storage for 37 days, was studied using time-domain dielectric spectroscopy in the frequency range 500 kHz to 200 MHz. The measured dielectric processes are characterized by their dielectric strength (Δε) and their relaxation times (τ). Changes in the dielectric properties of the RBC suspensions, due to storage-related biophysical changes, were evaluated. For a quantitative characterization of RBC vitality, we characterized the shape of fresh and stored RBC and measured their deformability as expressed by their average elongation ratio, which was achieved under a shear stress of 3.0 Pa. During the second week of storage, an increment in the evolution of the relaxation times and in the dielectric permittivity strength of about 25% was observed. We propose that the characteristic increment of ATP, during the second and third weeks of storage, is responsible for the raise of the specific capacitance of cell membrane, which in turn explains the changes observed in the dielectric response when combined with the influence of the shape changes.

Impact of stored red cells on clinical outcome in critically ill

BACKGROUND

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

STUDY DESIGN AND METHODS

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

RESULTS

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

CONCLUSION

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

Fluid Management in Acute Respiratory Distress Syndrome

One of the defining features of acute respiratory distress syndrome (ARDS) is noncardiogenic pulmonary edema, resulting from increased permeability of the alveolar-capillary barrier and passage of protein-rich fluid into the interstitium and alveolar spaces. The loss of protein from the intravascular space disrupts the normal oncotic pressure differential and causes patients with ARDS to be particularly sensitive to the hydrostatic forces that correlate with intravascular volume. Conservative fluid management, in which diuretics are administered and intravenous fluid administration is minimized, may decrease hydrostatic pressure and increase serum oncotic pressure, potentially limiting the development of pulmonary edema. However, the cause of death in most patients with ARDS is multiorgan system failure, not hypoxemia, and the impact of conservative fluid management on the incidence of extrapulmonary organ failure during ARDS is unclear. These physiologic observations have led to a series of studies examining the impact of fluid management on the development of, resolution of, survival from, and long-term outcomes from ARDS. While questions remain, the current literature makes it clear that fluid management is an integral part of the care of patients with ARDS.

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.

Association between storage age of transfused red blood cells and clinical outcomes in critically ill adults: A meta-analysis of randomized controlled trials

OBJECTIVES

A meta-analysis was performed to assesses the effect of storage age of transfused red blood cells (RBCs) upon clinical outcomes in critically ill adults.

METHODS

A comprehensive search was conducted in the PubMed, OVID, Web of Science and Cochrane databases for randomized controlled trials (RCTs) comparing the transfusion of fresher versus older RBCs in critically ill adults from database inception to December 2017. The primary endpoint was short-term mortality, and the secondary endpoints were the duration of intensive care unit (ICU) and hospital stay. The pooled odds ratios (OR) and mean differences (MD) were calculated using Stata/SE 11.0.

RESULTS

A total of six RCTs were identified, of which four were multicenter studies, while two were single-center trials. The pooled results indicated that the transfusion of fresher RBCs was not associated to a decrease in short-term mortality compared with the transfusion of older RBCs (random-effects OR=1.04, 95% confidence interval (CI): 0.96-1.13, P=0.312; I²=0.0%; six trials; 18240 patients), regardless of whether the studies were of a multi-center (random-effects OR=1.04, 95% CI: 0.96-1.13, P=0.292; I²=0.0%) or single-center nature (random-effects OR=1.16, 95% CI: 0.28-4.71, P=0.839; I²=56.7%), or with low risk of bias (random-effects OR=1.04, 95% CI: 0.94-1.16, P=0.445; I²=0.0%). In addition, the transfusion of fresher RBCs did not reduce the geometric mean duration of ICU stay (1.0% increase in geometric mean, 95% CI: -3.0 to 5.1%, P=0.638; I²=81.5%; four trials; 7550 patients) or the geometric mean duration of hospital stay (0.0% increase in geometric mean, 95% CI: -3.9 to 4.1%, P=0.957; I²=7.4%; four trials; 7550 patients) compared with the transfusion of older RBCs.

CONCLUSIONS

The transfusion of fresher RBCs compared with older RBCs was not associated to better clinical outcomes in critically ill adults.

Hemodynamic Functionality of Transfused Red Blood Cells in the Microcirculation of Blood Recipients

The primary goal of red blood cell (RBC) transfusion is to supply oxygen to tissues and organs. However, due to a growing number of studies that have reported negative transfusion outcomes, including reduced blood perfusion, there is rising concern about the risks in blood transfusion. RBC are characterized by unique flow-affecting properties, specifically adherence to blood vessel wall endothelium, cell deformability, and self-aggregability, which define their hemodynamic functionality (HF), namely their potential to affect blood circulation. The role of the HF of RBC in blood circulation, particularly the microcirculation, has been documented in numerous studies with animal models. These studies indicate that the HF of transfused RBC (TRBC) plays an important role in the transfusion outcome. However, studies with animal models must be interpreted with reservations, as animal physiology may not reflect human physiology. To test this concept in humans, we have directly examined the effect of the HF of TRBC, as expressed by their deformability and adherence to vascular endothelium, on the transfusion-induced effect on the skin blood flow and hemoglobin increment in β-thalassemia major patients. The results demonstrated, for the first time in humans, that the TRBC HF is a potent effector of the transfusion outcome, expressed by the transfusion-induced increase in the recipients' hemoglobin level, and the change in the skin blood flow, indicating a link between the microcirculation and the survival of TRBC in the recipients' vascular system. The implication of these findings for blood transfusion practice and to vascular function in blood recipients is discussed.

Urinary Hepcidin-25 Is Elevated in Patients That Avoid Acute Kidney Injury Following Cardiac Surgery

Background:

Acute kidney injury (AKI) following cardiac surgery leads to increased morbidity and mortality. Characterization and validation of early biomarkers of AKI may ultimately facilitate early therapeutic intervention. We have previously identified that elevated urinary hepcidin-25 is inversely and independently associated with the development of AKI in adult cardiac surgery patients. Hepcidin-25 is an antimicrobial peptide that sequesters iron intracellularly, and its elevation following human ischemia reperfusion injury may represent a renoprotective response to minimize renal injury.

Objective:

Our goal was to validate urinary hepcidin-25 as a non-invasive biomarker in an independent cardiac surgery cohort, within the context of clinical AKI predictors.

Design:

Prospective observational cohort study.

Setting:

Adult cardiac surgery program at St. Boniface Hospital, Winnipeg, Manitoba, Canada.

Patients:

Adult cardiac surgery patients undergoing cardiopulmonary bypass (CPB), n = 306.

Measurements:

Urine hepcidin-25, measured on post-operative day (POD) 1.

Methods:

A prospective, observational cohort of adult CPB patients (n = 306) was collected with serial perioperative urine samples. Urine hepcidin-25 at POD 1 was measured by competitive ELISA. Its diagnostic performance was evaluated in conjunction with clinical parameters and the Thakar clinical prediction score, using multivariate logistic regression.

Results:

Urinary hepcidin-25 is elevated following cardiac surgery in AKI and non-AKI patients. Elevated urinary hepcidin-25 concentration was inversely associated with AKI on both univariate (odds ratio [OR]: 0.61, 95% confidence interval [CI]: 0.45-0.83, P = .002) and multivariate analysis (OR: 0.67, 95% CI: 0.50-0.95, P = .02). A combined model with clinical risk factors demonstrated that baseline estimated glomerular filtration rate (eGFR), diabetes mellitus, and urinary hepcidin-25 concentration had an overall area under the curve (AUC) of 0.82 (0.75-0.88) for predicting subsequent AKI development, which was superior to clinical prediction alone as determined by the Thakar score.

Limitations:

(1) A single-center observational study. (2) Polyclonal antibody–based competitive ELISA.

Conclusion:

Hepcidin-25 is inversely associated with AKI in a multivariate model when combined with eGFR and diabetes mellitus, with an overall AUC of 0.82. Notably, urinary hepcidin-25 improves on clinical AKI prediction compared to the Thakar score alone.

Transfusion Decision Making in Pediatric Critical Illness

Transfusion decision making (TDM) in the critically ill requires consideration of: (1) anemia tolerance, which is linked to active pathology and to physiologic reserve, (2) differences in donor RBC physiology from that of native RBCs, and (3) relative risk from anemia-attributable oxygen delivery failure vs hazards of transfusion, itself. Current approaches to TDM (e.g. hemoglobin thresholds) do not: (1) differentiate between patients with similar anemia, but dissimilar pathology/physiology, and (2) guide transfusion timing and amount to efficacy-based goals (other than resolution of hemoglobin thresholds). Here, we explore approaches to TDM that address the above gaps.

Red blood cell transfusion in surgical cancer patients: Targets, risks, mechanistic understanding and further therapeutic opportunities

Anemia is present in more than half of cancer patients and appears to be an independent prognostic factor of short- and long-term adverse outcomes. It increases in the advanced period of cancer and perioperatively, in patients with solid tumors who undergo surgery. As a result, allogeneic red blood cell (RBC) transfusion is an indispensable treatment in cancer. However, its safety remains controversial, based on several laboratory and clinical data reporting a linkage with increased risk for cancer recurrence, infection and cancer-related mortality. Immunological, inflammatory and thrombotic reactions mediated by the residual leukocytes and platelets, the stored RBCs per se, the biological response modifiers and the plasticizer of the unit may underlie infection and tumor-promoting effects. Although the causality between transfusion and infection has been established, the effects of transfusion on cancer recurrence remain confusing; this is mainly due to the extreme biological heterogeneity that characterizes RBC donations and cancer context. In fact, the functional interplay between donation-associated factors and recipient characteristics, including tumor biology per se, inflammation, infection, coagulation and immune activation state and competence may synergistically and individually define the clinical impact of each transfusion in any given cancer patient. Our understanding of how the potential risk is mediated is important to make RBC transfusion safer and to pave the way for novel, promising and highly personalized strategies for the treatment of anemia in surgical cancer patients.

Red blood cell storage time and transfusion: current practice, concerns and future perspectives

Red blood cells (RBCs) units are the most requested transfusion product worldwide. Indications for transfusion include symptomatic anaemia, acute sickle cell crisis, and acute blood loss of more than 30% of the blood volume, with the aim of restoring tissue oxygen delivery. However, stored RBCs from donors are not a qualitative equal product, and, in many ways, this is a matter of concern in the transfusion practice. Besides donor-to-donor variation, the storage time influences the RBC unit at the qualitative level, as RBCs age in the storage bag and are exposed to the so-called storage lesion. Several studies have shown that the storage lesion leads to post-transfusion enhanced clearance, plasma transferrin saturation, nitric oxide scavenging and/or immunomodulation with potential unwanted transfusion-related clinical outcomes, such as acute lung injury or higher mortality rate. While, to date, several studies have claimed the risk or deleterious effects of "old" vs "young" RBC transfusion regimes, it is still a matter of debate, and consideration should be taken of the clinical context. Transfusion-dependent patients may benefit from transfusion with "young" RBC units, as it assures longer inter-transfusion periods, while transfusion with "old" RBC units is not itself harmful. Unbiased Omics approaches are being applied to the characterisation of RBC through storage, to better understand the (patho)physiological role of microparticles (MPs) that are found naturally, and also on stored RBC units. Perhaps RBC storage time is not an accurate surrogate for RBC quality and there is a need to establish which parameters do indeed reflect optimal efficacy and safety. A better Omics characterisation of components of "young" and "old" RBC units, including MPs, donor and recipient, might lead to the development of new therapies, including the use of engineered RBCs or MPs as cell-based drug delivering tools, or cost-effective personalised transfusion strategies.

Transfusion and Acute Respiratory Distress Syndrome: Clinical Epidemiology, Diagnosis, Management, and Outcomes

Transfusion related acute lung injury (TRALI) is a life-threatening complication of blood product transfusion. It is the leading cause of blood product transfusion related death in the USA. The syndrome is defined by hypoxemic respiratory failure with bilateral infiltrates on chest X-ray in the setting of a blood transfusion and absence of cardiac failure. The exact incidence of TRALI is unknown, but the incidence is higher in the critically ill patient population. Multiple patient and donor related risk factors for TRALI exist, including critically illness, alcohol use, and receiving transfusions with high plasma volumes. Practitioners should have a low index of suspicion for the diagnosis of TRALI, and blood bank reporting is vital to aid in diagnosis and future prevention. Management is primarily supportive care, with supplemental oxygen as the mainstay for therapy. Despite the transient course of TRALI, its morbidity is severe with the majority of patients requiring mechanical ventilation and treatment in the intensive care unit. For patients that survive TRALI, outcomes are promising without residual pulmonary deficits. Prevention strategies over the past 10 years have helped to decrease the incidence of TRALI and have led to increased awareness of this condition in the medical field.

Red Blood Cell Transfusion in the Emergency Department

BACKGROUND

Transfusion of red blood cells (RBCs) is the primary management of anemia, which affects 90% of critically ill patients. Anemia has been associated with a poor prognosis in various settings, including critical illness. Recent literature has shown a hemoglobin transfusion threshold of 7 g/dL to be safe. This review examines several aspects of transfusion.

OBJECTIVE

We sought to provide emergency physicians with an updated review of indications for RBC transfusion in the emergency department.

DISCUSSION

The standard hemoglobin transfusion threshold was 10 g/dL. However, the body shows physiologic compensatory adaptations to chronic anemia. Transfusion reactions and infections are rare but can have significant morbidity and mortality. Products stored for <21 days have the lowest risk of reaction and infection. A restrictive threshold of 7 g/dL is recommended in the new American Association of Blood Banks guidelines and multiple meta-analyses and supported in gastrointestinal bleeding, sepsis, critical illness, and trauma. Patients with active ischemia in acute coronary syndrome and neurologic injury require additional study. The physician must consider the patient's hemodynamic status, comorbidities, risks and benefits of transfusion, and clinical setting in determining the need for transfusion.

CONCLUSIONS

RBC transfusion is not without risks, including transfusion reaction, infection, and potentially increased mortality. The age of transfusion products likely has no effect on products before 21 days of storage. A hemoglobin level of 7 g/dL is safe in the setting of critical illness, sepsis, gastrointestinal bleeding, and trauma. The clinician must evaluate and transfuse based on the clinical setting and patient hemodynamic status rather than using a specific threshold.

Donor-variation effect on red blood cell storage lesion: A close relationship emerges

Although the molecular pathways leading to the progressive deterioration of stored red blood cells (RBC storage lesion) and the clinical relevance of storage-induced changes remain uncertain, substantial donor-specific variability in RBC performance during storage, and posttransfusion has been established ("donor-variation effect"). In-bag hemolysis and numerous properties of the RBC units that may affect transfusion efficacy have proved to be strongly donor-specific. Donor-variation effect may lead to the production of highly unequal blood labile products even when similar storage strategy and duration are applied. Genetic, undiagnosed/subclinical medical conditions and lifestyle factors that affect RBC characteristics at baseline, including RBC lifespan, energy metabolism, and sensitivity to oxidative stress, are all likely to influence the storage capacity of individual donors' cells, although not evident by the donor's health or hematological status at blood donation. Consequently, baseline characteristics of the donors, such as membrane peroxiredoxin-2 and serum uric acid concentration, have been proposed as candidate biomarkers of storage quality. This review article focuses on specific factors that might contribute to the donor-variation effect and emphasizes the emerging need for using omics-based technologies in association with in vitro and in vivo transfusion models and clinical trials to discover biomarkers of storage quality and posttransfusion recovery in donor blood.

Blood haemogram in Ovis aries and Capra hyrcus: effect of storage time

The aim of the present study was to assess the effect of storage time at +4 °C on haematological profile in goat (n = 25) and sheep (n = 25). After collection, blood samples were immediately analyzed and then divided into four aliquots that were stored at 4 °C and tested at 24 h (T1), 48 h (T2), 72 h (T3), and 1 wk (T4), respectively. One-way repeated-measures analysis of variance (ANOVA) was used to determine statistically significant effect of storage conditions both in goats and in sheep. Our results showed that among the two species studied, goats showed highest blood stability after refrigeration at +4 °C. In goats, all hematological parameters, except PLT, showed no significant changes during all days of monitoring with respect to basal values (T0). In sheep, no significantly effect of storage time on RBC and WBC levels were found, whereas the other hematological parameters change significantly over the time. Our findings suggest that the blood storage time reported for goat may not be applied to sheep’s blood, which underscore the differences between these two species that are erroneously considered similar.

Use of n-of-1 (single patient) trials to assess the effect of age of transfused blood on health-related quality of life in transfusion-dependent patients

BACKGROUND

The impact of age of red blood cells on health-related quality of life (HRQL) in patients who require chronic transfusions is not known. We assessed this using n-of-1 trials in patient populations where large randomized trials have not been done to date.

STUDY DESIGN AND METHODS

Chronically transfusion-dependent adult patients were randomly assigned over time to four fresh (<7 days of storage) and four standard-issue (up to 42 days of storage) blood transfusions in prospective double-blinded multicrossover studies (n-of-1 trials). HRQL questionnaires were completed before and at 24 hours after each transfusion. Hemoglobin (Hb) levels were measured before each subsequent transfusion.

RESULTS

Twenty transfusion-dependent patients were enrolled, of whom nine (five myelodysplastic syndromes, two myelofibrosis, one β-thalassemia major, one Diamond-Blackfan anemia) completed at least six transfusions. Mean ages of fresh and standard-issue blood transfused were 4.0 and 23.2 days, respectively. There were no significant differences in the effect of standard and fresh blood on follow-up Hb levels or the eight HRQL dimensions assessed in all analyses.

CONCLUSIONS

In chronically transfused patients, there were no significant differences in HRQL or Hb levels between fresh versus standard blood. While larger trials are needed, these results support current practices in hospital blood transfusion laboratories using a first-in, first-out model of blood utilization for these transfusion-dependent patients. Use of n-of-1 trials to determine the benefits of transfusions in single patients appears to be feasible.

Blood banking-induced alteration of red blood cell oxygen release ability

BACKGROUND

Current blood banking procedures may not fully preserve red blood cell (RBC) function during storage, contributing to the decrease of RBC oxygen release ability. This study was undertaken to evaluate the impact of routine cold storage on RBC oxygen release ability.

MATERIALS AND METHODS

RBC units were collected from healthy donors and each unit was split into two parts (whole blood and suspended RBC) to exclude possible donor variability. Oxygen dissociation measurements were performed on blood units stored at 4 °C during a 5-week period. 2,3-diphosphoglycerate levels and fluorescent micrographs of erythrocyte band 3 were also analysed.

RESULTS

P50 and oxygen release capacity decreased rapidly during the first 3 weeks, and then did not change significantly. In contrast, the kinetic properties (PO2-t curve and T*50) of oxygen release changed slowly during the first 3 weeks of storage, but then decreased significantly in the last 2 weeks. 2,3-diphosphoglycerate decreased quickly during the first 3 weeks of storage to almost undetectable levels. Band 3 aggregated significantly during the last 2 weeks of storage.

DISCUSSION

RBC oxygen release ability appears to be sensitive to routine cold storage. The thermodynamic characteristics of RBC oxygen release ability changed mainly in the first 3 weeks of storage, due to the decrease of 2,3-diphosphoglycerate, whereas the kinetic characteristics of RBC oxygen release ability decreased significantly at the end of storage, probably affected by alterations of band 3.

Piezo1 regulates mechanotransductive release of ATP from human RBCs

Piezo proteins (Piezo1 and Piezo2) are recently identified mechanically activated cation channels in eukaryotic cells and associated with physiological responses to touch, pressure, and stretch. In particular, human RBCs express Piezo1 on their membranes, and mutations of Piezo1 have been linked to hereditary xerocytosis. To date, however, physiological functions of Piezo1 on normal RBCs remain poorly understood. Here, we show that Piezo1 regulates mechanotransductive release of ATP from human RBCs by controlling the shear-induced calcium (Ca(2+)) influx. We find that, in human RBCs treated with Piezo1 inhibitors or having mutant Piezo1 channels, the amounts of shear-induced ATP release and Ca(2+) influx decrease significantly. Remarkably, a critical extracellular Ca(2+) concentration is required to trigger significant ATP release, but membrane-associated ATP pools in RBCs also contribute to the release of ATP. Our results show how Piezo1 channels are likely to function in normal RBCs and suggest a previously unidentified mechanotransductive pathway in ATP release. Thus, we anticipate that the study will impact broadly on the research of red cells, cellular mechanosensing, and clinical studies related to red cell disorders and vascular disease.

The effects of hyperoxaemia on tissue oxygenation in patients with a nadir haematocrit lower than 20% during cardiopulmonary bypass

Excessive haemodilution and the resulting anaemia during CPB is accompanied by a decrease in the total arterial oxygen content, which may impair tissue oxygen delivery. Hyperoxic ventilation has been proven to improve tissue oxygenation in different pathophysiological states of anaemic tissue hypoxia. The aim of this study was to examine the influence of arterial hyperoxaemia on tissue oxygenation during CPB. Records of patients undergoing isolated CABG with CPB were retrospectively reviewed. Patients with nadir haematocrit levels below 20% during CPB were included in the study. Tissue hypoxia was defined as hyperlactataemia (lactate >2.2 mmol/L) coupled with low ScVO2 (ScVO2 <70%) during CPB. One hundred patients with normoxaemia and 100 patients with hyperoxaemia were included in the study. Patients with hyperoxaemia had lower tissue hypoxia incidence than patients with normoxaemia (p<0.001). Compared with patients without tissue hypoxia, patients with tissue hypoxia had significantly lower PaO2 values (p<0.001) and nadir haematocrit levels (p<0.001). Nadir haematocrit levels <18% (OR: 5.3; 95% CI: 2.67-10.6; p<0.001) and hyperoxaemia (OR: 0.28; 95% CI: 0.14-0.56; p<0.001) were independently associated with tissue hypoxia.

CONCLUSIONS

Hyperoxaemia during CPB may be protective against tissue hypoxia in patients with nadir haematocrit levels <20%.

Prolonged storage of packed red blood cells for blood transfusion

BACKGROUND

A blood transfusion is an acute intervention, used to address life- and health-threatening conditions on a short-term basis. Packed red blood cells are most often used for blood transfusion. Sometimes blood is transfused after prolonged storage but there is continuing debate as to whether transfusion of 'older' blood is as beneficial as transfusion of 'fresher' blood.

OBJECTIVES

To assess the clinical benefits and harms of prolonged storage of packed red blood cells, in comparison with fresh, on recipients of blood transfusion.

SEARCH METHODS

We ran the search on 1st May 2014. We searched the Cochrane Injuries Group Specialized Register, Cochrane Central Register of Controlled Trials (CENTRAL, The Cochrane Library), MEDLINE (OvidSP), Embase (OvidSP), CINAHL (EBSCO Host) and two other databases. We also searched clinical trials registers and screened reference lists of the retrieved publications and reviews. We updated this search in June 2015 but these results have not yet been incorporated.

SELECTION CRITERIA

Randomised clinical trials including participants assessed as requiring red blood cell transfusion were eligible for inclusion. Prolonged storage was defined as red blood cells stored for ≥ 21 days in a blood bank. We did not apply limits regarding the duration of follow-up, or country where the study took place. We excluded trials where patients received a combination of short- and long-stored blood products, and also trials without a clear definition of prolonged storage.

DATA COLLECTION AND ANALYSIS

We independently performed study selection, risk of bias assessment and data extraction by at least two review authors. The major outcomes were death from any cause, transfusion-related acute lung injury, and adverse events. We estimated relative risk for dichotomous outcomes. We measured statistical heterogeneity using I(2). We used a random-effects model to synthesise the findings.

MAIN RESULTS

We identified three randomised clinical trials, involving a total of 120 participants, comparing packed red blood cells with ≥ 21 days storage ('prolonged' or 'older') versus packed red blood cells with < 21 days storage ('fresh'). We pooled data to assess the effect of prolonged storage on death from any cause. The confidence in the results from these trials was very low, due to the bias in their design and their limited sample sizes.The estimated effect of packed red blood cells with ≥ 21 days storage versus packed red blood cells with < 21 days storage for the outcome death from any cause was imprecise (5/45 [11.11%] versus 2/46 [4.34%]; RR 2.36; 95% CI 0.65 to 8.52; I(2): 0%, P = 0.26, very low quality of evidence). Trial sequential analysis, with only two trials, shows that we do not yet have convincing evidence that older packed red blood cells induce a 20% relative risk reduction of death from any cause compared with fresher packed red blood cells. No trial included other outcomes of interest specified in this review, namely transfusion-related acute lung injury, postoperative infections, and adverse events. The safety profile is unknown.

AUTHORS' CONCLUSIONS

Recognising the limitations of the review, relating to the size and nature of the included trials, this Cochrane Review provides no evidence to support or reject the use of packed red blood cells for blood transfusion which have been stored for ≥ 21 days ('prolonged' or 'older') compared with those stored for < 21 days ('fresh'). These results are based on three small single centre trials with high risks of bias. There is insufficient evidence to determine the effects of fresh or older packed red blood cells for blood transfusion. Therefore, we urge readers to interpret the trial results with caution. The results from four large ongoing trials will help to inform future updates of this review.

Risk factors and outcomes of blood transfusions in adrenalectomy

BACKGROUND

Blood transfusion has been shown to be associated with adverse long-term and short-term outcomes. We sought to evaluate the preoperative risk factors associated with blood transfusion and its effects on postoperative outcomes after adrenalectomy.

METHODS

We performed a retrospective analysis of 4735 adrenalectomies (3664 laparoscopic and 1071 open) from 2005-2012 using the National Surgical Quality Improvement Program database. Data on preoperative risk factors and postoperative morbidity and mortality were evaluated.

RESULTS

Median age and body mass index were 54 y and 29.3 kg/m(2), respectively. Most patients were female (60.0%). Of the total, 60.6% patients had American Society of Anesthesiologists score ≥3. On multivariate analysis, increasing age (odds ratio [OR] = 1.02, P < 0.001), open adrenalectomy (OR = 14.0, P < 0.001), preoperative hematocrit <38% (OR = 2.96, P < 0.001), and operative time >150 min (OR: 3.69, P < 0.001) were associated with an increased need for intraoperative blood transfusions. The need for intraoperative blood transfusions was an independent predictor of postoperative complications including mortality (OR = 12.7, P < 0.001), overall morbidity (OR = 3.2, P < 0.001), serious morbidity (OR = 3.8, P < 0.001), wound complication (OR = 2.1, P = 0.006), cardiopulmonary complication (OR = 3.6, P < 0.001), septic complication (OR = 2.5, P = 0.007), reoperation (OR = 3.6, P < 0.001), and prolonged length of stay (OR = 4.3, P < 0.001). There was an independent and incremental increase (10%-20%) in the risk of morbidity and mortality with each unit of blood transfused (P < 0.01).

CONCLUSIONS

Age, open surgery, preoperative anemia, American Society of Anesthesiologists score, and prolonged operative time are associated with an increased need for blood transfusions in laparoscopic and open adrenalectomy. Intraoperative transfusion was independently and incrementally associated with significant morbidity and mortality after laparoscopic and open adrenalectomy.

In vitro assays and clinical trials in red blood cell aging: Lost in translation

The age of erythrocyte concentrates (EC) in transfusion medicine and the adverse outcomes when transfusing long-term-stored EC are highly controversial issues. Whereas the definition of a short-term-stored EC or a long-term-stored EC is unclear in clinical trials, data based on in vitro storage assays can help defining a limit in addition of the expiration date. The present review merges together these data in order to highlight an EC age cut-off and points out potential misleading consideration. The analysis of in vitro data highlights the presence of reversible and irreversible storage lesions and demonstrates that red blood cells (RBC) exhibit two limits during storage: one around 2 weeks and another one around 4 weeks of storage. Of particular importance, the first lesions to appear, i.e. the reversible ones, are per se reversible once transfused, whereas the irreversible lesions are not. In clinical trials, the EC age cut-off for short-term storage is in general fewer than 14 days (11 ± 4 days) and more disperse for long-term-stored EC (17 ± 13 days), regardless the clinical outcomes. Taking together, EC age cut-off in clinical trials does not totally fall into line of in vitro aging data, whereas it is the key criteria in clinical studies. Long-term-stored EC considered in clinical trials are not probably old enough to answer the question: "Does transfusion of long-term-stored EC (older than 4 weeks) result in worse clinical outcomes?" Depending on ethical concerns and clinical practices, older EC than currently assayed in clinical trials should have to be considered. These two worlds trying to understand the aging of erythrocytes and the impact on patients do not seem to speak the same language.

A multivariate analysis to assess the effect of packed red cell transfusion and the unit age of transfused red cells on postoperative complications in patients undergoing cardiac surgeries

BACKGROUND

Transfusion of blood components and age of transfused packed red cells (PRCs) are independent risk factors for morbidity and mortality in cardiac surgeries.

MATERIALS AND METHODS

We retrospectively examined data of patients undergoing cardiac surgery at our institute from January 1, 2012 to September 30, 2012. Details of transfusion (autologous and allogenic), postoperative length of stay (PLOS), postoperative complications were recorded along with other relevant details. The analysis was done in two stages, in the first both transfused and nontransfused individuals and in the second only transfused individuals were considered. Age of transfused red cells as a cause of morbidity was analyzed only in the second stage.

RESULTS

Of the 762 patients included in the study, 613 (80.4%) were males and 149 (19.6%) were females. Multivariate analysis revealed that factors like the number and age of transfused PRCs and age of the patient had significant bearing upon the morbidity. Morbidity was significantly higher in the patients transfused with allogenic PRCs when compared with the patients not receiving any transfusion irrespective of the age of transfused PRCs. Transfusion of PRC of over 21 days was associated with higher postoperative complications, but not with in-hospital mortality.

CONCLUSION

In patients undergoing cardiac surgery, allogenic blood transfusion increases morbidity. The age of PRCs transfused has a significant bearing on morbidity, but not on in-hospital mortality. Blood transfusion services will therefore have to weigh the risks and benefits of providing blood older than 21 days in cardiac surgeries.

Increased plasma catalytic iron in patients may mediate acute kidney injury and death following cardiac surgery

Catalytic iron, the chemical form of iron capable of participating in redox cycling, is a key mediator of acute kidney injury (AKI) in multiple animal models, but its role in human AKI has not been studied. Here we tested in a prospective cohort of 250 patients undergoing cardiac surgery whether plasma catalytic iron levels are elevated and associated with the composite outcome of AKI requiring renal replacement therapy or in-hospital mortality. Plasma catalytic iron, free hemoglobin, and other iron parameters were measured preoperatively, at the end of cardiopulmonary bypass, and on postoperative days 1 and 3. Plasma catalytic iron levels, but not other iron parameters, rose significantly at the end of cardiopulmonary bypass and were directly associated with bypass time and number of packed red blood cell transfusions. In multivariate analyses adjusting for age and preoperative eGFR, patients in the highest compared with the lowest quartile of catalytic iron on postoperative day 1 had a 6.71 greater odds of experiencing the primary outcome, and also had greater odds of AKI, hospital mortality, and postoperative myocardial injury. Thus, our data are consistent with and expand on findings from animal models demonstrating a pathologic role of catalytic iron in mediating adverse postoperative outcomes. Interventions aimed at reducing plasma catalytic iron levels as a strategy for preventing AKI in humans are warranted.

Ovarian thrombosis and uterine synechiae after arterial embolization for a late postpartum haemorrhage

Background

We report two unusual separate complications after uterine artery embolization for a late postpartum haemorrhage. This report appeared important to us in view of the apparent absence of any other publications on this topic.

Case presentation

We report the case of a 25-year-old woman, gravida 3, para 1, admitted for uterine bleeding 7 days after a spontaneous delivery at term, in our university hospital. A suction curettage and then, after persistent bleeding, uterine artery embolization were necessary. Immediately after the embolization, a bilateral ovarian thrombosis occurred, subsequently followed by amenorrhea, due to uterine synechiae, and depression. Hysteroscopic surgery was performed to remove the adhesions. A complete work-up for thrombophilia showed a heterozygous mutation of the factor V gene R506Q. The pathology examination found subinvolution of the placental bed. One month after treatment of the synechiae (and insertion of a copper IUD for contraception), the woman's menstrual cycle returned to normal. Her clinical examination 19 months later was normal.

Conclusions

This case teaches us that one rare complication can hide another! It is important to consider the diagnosis of subinvolution of the placental bed in cases of late PPH and to know the complications associated with vascular artery embolization in order to provide the most rapid and least invasive treatment.

•

Arterial embolization is associated with ovarian thrombosis.

•

Do not forget the subinvolution of the placental bed in late postpartum haemorrhage.

•

Suction curettage can lead to uterine synechiae.

Transfusion strategy: impact of haemodynamics and the challenge of haemodilution

Blood transfusion is associated with increased morbidity and mortality and numerous reports have emphasised the need for reduction. Following this there is increased attention to the concept of patient blood management. However, bleeding is relatively common following cardiac surgery and is further enhanced by the continued antiplatelet therapy policy. Another important issue is that cardiopulmonary bypass leads to haemodilution and a potential blood loss. The basic role of blood is oxygen transport to the organs. The determining factors of oxygen delivery are cardiac output, haemoglobin, and saturation. If oxygen delivery/consumption is out of balance, the compensation mechanisms are simple, as a decrease in one factor results in an increase in one or two other factors. Patients with coexisting cardiac diseases may be of particular risk, but studies indicate that patients with coexisting cardiac diseases tolerate moderate anaemia and may even benefit from a restrictive transfusion regimen. Further it has been shown that patients with reduced left ventricular function are able to compensate with increased cardiac output in response to bleeding and haemodilution if normovolaemia is maintained. In conclusion the evidence supports that each institution establishes its own patient blood management strategy to both conserve blood products and maximise outcome.