Association between length of storage of transfused red blood cells and multiple organ dysfunction syndrome in pediatric intensive care patients

Red blood cell transfusion management for people undergoing cardiac surgery for congenital heart disease

BACKGROUND

Congenital heart disease is the most common neonatal congenital condition. Surgery is often necessary. Patients with congenital heart disease are potentially exposed to red cell transfusion preoperatively, intraoperatively and postoperatively when admitted for cardiac surgery. There are a number of risks associated with red cell transfusion that may increase morbidity and mortality.

OBJECTIVES

To evaluate the association of red blood cell transfusion management with mortality and morbidity in people with congenital heart disease who are undergoing cardiac surgery.

SEARCH METHODS

We searched multiple bibliographic databases and trials registries, including the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE (Ovid), Embase (Ovid), CINAHL (EBSCOhost), Transfusion Evidence Library, ClinicalTrials.gov and the World Health Organization (WHO) ICTRP. The most recent search was on 2 January 2024, with no limitation by language of publication.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) comparing red blood cell transfusion interventions in patients undergoing cardiac surgery for congenital heart disease. Participants of any age (neonates, paediatrics and adults) and with any type of congenital heart disease (cyanotic or acyanotic) were eligible for inclusion. No comorbidities were excluded.

DATA COLLECTION AND ANALYSIS

Two of five (AA, CK, KW, SB, SF) review authors independently extracted data and assessed the risk of bias in the trials. We contacted study authors for additional information. Two review authors (CK, KW) used GRADE methodology to assess evidence certainty for critical outcomes and comparisons.

MAIN RESULTS

We identified 19 relevant trials. The trials had 1606 participants, all of whom were neonates or children. No trials were conducted in the preoperative period or with adults. The trials compared different types of red blood cell transfusions. No trial compared red blood cell transfusion versus no red blood cell transfusion. None of the trials was at low risk of bias overall. Eight trials had a high risk of bias in at least one domain, most commonly, blinding of participants and personnel. For our critical outcomes, we judged the certainty of the evidence based on GRADE criteria to be low or very low. Five trials (497 participants) compared a restrictive versus a liberal transfusion-trigger. It is very uncertain whether a restrictive transfusion-trigger has an effect on all-cause mortality in the short-term (0 to 30 days post-surgery) (risk ratio (RR) 1.12, 95% confidence interval (CI) 0.42 to 3.00; 3 RCTs, 347 participants; very low certainty evidence) or long term (31 days to two years post-surgery) (RR 0.33, 95% CI 0.01 to 7.87; 1 RCT, 60 participants; very low certainty evidence). The evidence is also very uncertain on the incidence of severe adverse cardiac events (RR 1.00, 95% CI 0.73 to 1.37; 2 RCTs, 232 participants) and infection (RR 0.81, 95% CI 0.47 to 1.39; 2 RCTs, 232 participants) (both very low certainty evidence). A restrictive transfusion-trigger may have little to no effect on the duration of mechanical ventilation (mean difference (MD) -1.65, 95% CI -3.51 to 0.2; 2 RCTs, 168 participants; low-certainty evidence) or of ICU stay (MD 0.15, 95% CI -0.72 to 1.01; 3 RCTs, 228 participants, low-certainty evidence). Five trials (231 participants) compared washed red blood cells in CPB prime versus unwashed red blood cells in CPB prime. Washing red blood cells in CPB prime may have little to no effect on all-cause mortality in the short term (0 to 30 days post-surgery) (RR 0.25, 95% CI 0.03 to 2.18; 2 RCTs, 144 participants) or long term (31 days to 2 years post-surgery) (RR 0.50, 95% CI 0.05 to 5.38; 1 RCT, 128 participants) (both low-certainty evidence). The evidence is very uncertain about the effect of washed CPB prime on severe cardiac adverse events (RR 0.88, 95% CI 0.47 to 1.64), infection (RR 1.00, 95% CI 0.50 to 1.99) and duration of ICU stay (MD -0.3, 95% CI -4.32 to 3.72) (1 RCT, 128 participants; very low certainty evidence). Two trials (76 participants) compared crystalloid (bloodless) CPB prime versus red-blood-cell-containing CPB prime. It is very uncertain whether bloodless prime has an effect on the duration of mechanical ventilation (median 8.0 hours, interquartile range (IQR) 6.8 to 9.0 hours versus median 7.0 hours, IQR 6.0 to 8.0 hours; 1 RCT, 40 participants) or duration of ICU stay (median 23.0 hours, IQR 21.8 to 41.5 hours versus median 23.5 hours, IQR 21.0 to 29.0 hours; 1 RCT, 40 participants) (both very low certainty evidence). Two trials (160 participants) compared ultrafiltration of CPB prime versus no ultrafiltration. It is very uncertain whether ultrafiltration of CPB prime has an effect on all-cause mortality in the short term (0 to 30 days post-surgery) (RR not estimable; 1 RCT, 50 participants; very low certainty evidence). Ultrafiltration may reduce the duration of mechanical ventilation (MD -16.00, 95% CI -25.00 to -7.00) and the duration of ICU stay (MD -0.6, 95% CI -0.84 to -0.36) (1 RCT, 50 participants; low-certainty evidence). One trial (59 participants) compared retrograde autologous CPB prime versus standard CPB prime. It is very uncertain whether retrograde autologous CPB prime has an effect on the duration of mechanical ventilation (MD 0.02, 95% CI -0.03 to 0.07) or duration of ICU stay (MD 0, 95% CI -0.01 to 0.01) (1 RCT, 59 participants; very low certainty evidence). One trial (178 participants) compared 'fresh' (not near expiry date) versus 'old' (near expiry date) red blood cell transfusion but did not report on our outcomes.

AUTHORS' CONCLUSIONS

No randomised controlled trial compared red blood cell transfusion against no red blood cell transfusion in people with congential heart disease undergoing cardiac surgery. There are only small, heterogeneous trials in children that compare different forms of red blood cell transfusion, and there are no trials at all in adults. There is therefore insufficient evidence to accurately assess the association of red blood cell transfusion with the morbidity and mortality of patients with congenital heart disease undergoing cardiac surgery. It is possible that trial outcomes are affected by the presence or absence of cyanosis, so this should be considered in future trial design. Further adequately powered, high-quality trials in both children and adults are required.

Stored RBC transfusions leads to the systemic inflammatory response syndrome in anemic murine neonates

OBJECTIVE

RBC transfusions (RBCT) are life-saving treatment for premature and critically ill infants. However, the procedure has been associated with the development of systemic inflammatory response syndrome (SIRS) and potentially multiple organ dysfunction syndrome (MODS) in neonates. The present study aimed to investigate the mechanisms of RBCT-related SIRS in severely anemic murine neonates.

METHODS

C57BL/6 (WT), TLR4-/- and myeloid-specific triggered myeloid receptor-1 (trem1)-/- mouse pups were studied in 4 groups (n = 6 each): (1) naïve controls, (2) transfused control, (3) anemic (hematocrit 20-24%) and (4) anemic with RBC transfused using our established murine model of phlebotomy-induced anemia (PIA) and RBC transfusion. Plasma was measured for quantifying inflammatory cytokines (IFN-γ, IL-1β, TNF-α, IL-6, MIP-1α, MIP-1β, MIP2 and LIX) using a Luminex assay. In vitro studies included (i) sensitization by exposing the cells to a low level of lipopolysaccharide (LPS; 500 ng/ml) and (ii) trem1-siRNA transfection with/without plasma supernatant from stored RBC to assess the acute inflammatory response through trem1 by qRT-PCR and immunoblotting.

RESULTS

Anemic murine pups developed cytokine storm within 2 h of receiving stored RBCs, which increased until 6 h post-transfusion, as compared to non-anemic mice receiving stored RBCTs ("transfusion controls"), in a TLR4-independent fashion. Nonetheless, severely anemic pups had elevated circulating endotoxin levels, thereby sensitizing circulating monocytes to presynthesize proinflammatory cytokines (IFN-γ, IL-1β, TNF-α, IL-6, MIP-1α, MIP-1β, MIP2, LIX) and express trem1. Silencing trem1 expression in Raw264.7 cells mitigated both endotoxin-associated presynthesis of proinflammatory cytokines and the RBCT-induced release of inflammatory cytokines. Indeed, myeloid-specific trem1-/- murine pups had significantly reduced evidence of SIRS following RBCTs.

CONCLUSION

Severe anemia-associated low-grade inflammation sensitizes monocytes to enhance the synthesis of proinflammatory cytokines and trem1. In this setting, RBCTs further activate these monocytes, thereby inducing SIRS. Inhibiting trem1 in myeloid cells, including monocytes, alleviates the inflammatory response associated with the combined effects of anemia and RBCTs in murine neonates.

Determination of free heme in stored red blood cells with an apo-horseradish peroxidase-based assay

Transfusion effectiveness of red blood cells (RBCs) has been associated with duration of the storage period. Storage-dependent RBC alterations lead to hemolysis and release of toxic free heme, but the increase of free heme levels over time is largely unknown. In the current study, an apo-horseradish peroxidase (apoHRP)-based assay was applied to measure levels of free heme at regular intervals or periodically in supernatants of RBCs until a maximum storage period of 42 days. Free heme levels increased with linear time-dependent kinetics up to day 21 and accelerated disproportionally after day 28 until day 42, as determined with the apoHRP assay. Individual time courses of free heme in different RBC units exhibited high variability. Notably, levels of free hemoglobin, an established indicator of RBC damage, and those of total heme increased with continuous time-dependent linear kinetics over the entire 42 day storage period, respectively. Supernatants from RBC units with high levels of free heme led to inflammatory activation of human neutrophils. In conclusion, determining free heme in stored RBCs with the applied apoHRP assay may become feasible for testing of RBC storage quality in clinical transfusion medicine.

Improving packed red blood cell storage with a high-viscosity buffered storage solution

BACKGROUND

Massive transfusion with older packed red blood cells is associated with increased morbidity and mortality. As packed red blood cells age, they undergo biochemical and structural changes known as the storage lesion. We developed a novel solution to increase viscosity in stored packed red blood cells. We hypothesized that packed red blood cell storage in this solution would blunt storage lesion formation and mitigate the inflammatory response after resuscitation.

METHODS

Blood was obtained from 8- to 10-week-old C57BL/6 male donor mice or human volunteers and stored as packed red blood cell units for 14 days for mice or 42 days for humans in either standard AS-3 storage solution or EAS-1587, the novel packed red blood cell storage solution. Packed red blood cells were analyzed for microvesicles, cell-free hemoglobin, phosphatidylserine, band-3 protein, glucose utilization, and osmotic fragility. Additional mice underwent hemorrhage and resuscitation with packed red blood cells stored in either AS-3 or EAS-1587. Serum was analyzed for inflammatory markers.

RESULTS

Murine packed red blood cells stored in EAS-1587 demonstrated reductions in microvesicle and cell-free hemoglobin accumulation as well as preserved band-3 expression, increase glucose utilization, reductions in phosphatidylserine expression, and susceptibility to osmotic stress. Serum from mice resuscitated with packed red blood cells stored in EAS-1587 demonstrated reduced proinflammatory cytokines. Human packed red blood cells demonstrated a reduction in microvesicle and cell-free hemoglobin as well as an increase in glucose utilization.

CONCLUSION

Storage of packed red blood cells in a novel storage solution mitigated many aspects of the red blood cell storage lesion as well as the inflammatory response to resuscitation after hemorrhage. This modified storage solution may lead to improvement of packed red blood cell storage and reduce harm after massive transfusion.

Neonatal and pediatric blood bank practice in the United States: Results from the AABB pediatric transfusion medicine subsection survey

BACKGROUND

There are limited standards guiding the selection and processing of blood components specific for neonatal and pediatric transfusions. Therefore, blood banks (BBs) and transfusion services must create their own policies and procedures.

STUDY DESIGN AND METHODS

The American Association of Blood Banks (AABB) Pediatric Transfusion Medicine Subsection Committee developed a 74-question survey to capture neonatal and pediatric BB practices in the United States.

RESULTS

Thirty-five centers completed the survey: a response rate 15.8%. Responses indicated that most carry a mixed inventory of red blood cells (RBCs); 94.2% allow more than one type of RBC product for small-volume (SV) and large-volume (LV) transfusions to neonatal and pediatric patients. Many had storage age thresholds for RBCs transfused to neonates (SV = 60%, LV = 67.7%) but not older pediatric patients. The use of Group O for nonurgent RBC transfusion in neonates was common (74.2%). Responses related to special processing of RBCs and platelets indicated that 100% RBC and platelets are leukocyte-reduced (LR) for neonates and 97% for non-neonates. Irradiation of RBCs and platelets was commonly performed for neonatal transfusion (88.6%). Providing cytomegalovirus (CMV) seronegative products, volume reduction, and washing were variable. All centers transfused single-donor apheresis platelets; 20% allowed pathogen reduction (PR). The majority of centers have strategies limiting the amount of incompatible plasma transfused; however, few titrate ABO isoagglutinins in plasma-containing products (20% for platelets and 9.1% for plasma).

CONCLUSIONS

Variability exists in BB practice for neonatal and pediatric transfusion. Future studies are needed to understand and define best BB practices in these patient populations.

Transfusion support: Considerations in pediatric populations

Over 400,000 units of blood and blood products are transfused to pediatric patients annually, yet only sparse high-quality data exist to guide the preparation and administration of blood products in this population. The direct application of data from studies in adult patients should be undertaken with caution, as there are dissimilarities in the pathology and physiology between adult and pediatric patients. We provide an overview of available evidence in the field of pediatric transfusion medicine, summarizing indications for blood product transfusion, thresholds for transfusion and indications for blood product modifications.

Exploration of risk factors for non-survival and for transfusion-associated complications in cats receiving red cell transfusions: 450 cases (2009 to 2017)

OBJECTIVES

To describe red blood cell transfusion practices and short-term outcomes in anaemic cats. To determine clinical variables associated with non-survival and transfusion-related complications.

MATERIAL AND METHODS

In this retrospective study, blood bank records from the Ontario Veterinary College Health Science Centre (OVC-HSC) were reviewed to identify cats that received packed red blood cells or whole blood from 2009 to 2017. We extracted cause of anaemia, history of previous transfusion, pre- and post-transfusion packed cell volume, pre-transfusion compatibility testing, volume and dose of blood product, age of red blood cell unit, transfusion-associated complications and patient survival.

RESULTS

A total of 450 transfusion events were recorded in 267 cats. Blood loss was the most common indication for blood transfusion (44.9%), followed by ineffective erythropoiesis (37.5%) and red blood cell destruction (22.5%). Transfusion-associated complications occurred in 10.2% events and there was a 20.2% mortality after transfusion. Mean increase in packed cell volume 24-hours after transfusion was greater in cats undergoing major cross-match testing before transfusion (7.2%) versus those that did not (4.0%). Non-survival was associated with higher packed cell volume before transfusion, low patient body temperature before transfusion, anaemia due to blood loss and number of transfusions administered. Older age of transfused blood units was associated with non-survival and transfusion-related complications.

CLINICAL IMPORTANCE

This study was observational and so our analyses were exploratory, but suggest that major cross-match before transfusion tended to have greater transfusion efficacy and transfusion of older blood products might have detrimental effects on survival.

Effect of Fresh vs Standard-issue Red Blood Cell Transfusions on Multiple Organ Dysfunction Syndrome in Critically Ill Pediatric Patients: A Randomized Clinical Trial

IMPORTANCE

The clinical consequences of red blood cell storage age for critically ill pediatric patients have not been examined in a large, randomized clinical trial.

OBJECTIVE

To determine if the transfusion of fresh red blood cells (stored ≤7 days) reduced new or progressive multiple organ dysfunction syndrome compared with the use of standard-issue red blood cells in critically ill children.

DESIGN, SETTING, AND PARTICIPANTS

The Age of Transfused Blood in Critically-Ill Children trial was an international, multicenter, blinded, randomized clinical trial, performed between February 2014 and November 2018 in 50 tertiary care centers. Pediatric patients between the ages of 3 days and 16 years were eligible if the first red blood cell transfusion was administered within 7 days of intensive care unit admission. A total of 15 568 patients were screened, and 13 308 were excluded.

INTERVENTIONS

Patients were randomized to receive either fresh or standard-issue red blood cells. A total of 1538 patients were randomized with 768 patients in the fresh red blood cell group and 770 in the standard-issue group.

MAIN OUTCOMES AND MEASURES

The primary outcome measure was new or progressive multiple organ dysfunction syndrome, measured for 28 days or to discharge or death.

RESULTS

Among 1538 patients who were randomized, 1461 patients (95%) were included in the primary analysis (median age, 1.8 years; 47.3% girls), in which there were 728 patients randomized to the fresh red blood cell group and 733 to the standard-issue group. The median storage duration was 5 days (interquartile range [IQR], 4-6 days) in the fresh group vs 18 days (IQR, 12-25 days) in the standard-issue group (P < .001). There were no significant differences in new or progressive multiple organ dysfunction syndrome between fresh (147 of 728 [20.2%]) and standard-issue red blood cell groups (133 of 732 [18.2%]), with an unadjusted absolute risk difference of 2.0% (95% CI, -2.0% to 6.1%; P = .33). The prevalence of sepsis was 25.8% (160 of 619) in the fresh group and 25.3% (154 of 608) in the standard-issue group. The prevalence of acute respiratory distress syndrome was 6.6% (41 of 619) in the fresh group and 4.8% (29 of 608) in the standard-issue group. Intensive care unit mortality was 4.5% (33 of 728) in the fresh group vs 3.5 % (26 of 732) in the standard-issue group (P = .34).

CONCLUSIONS AND RELEVANCE

Among critically ill pediatric patients, the use of fresh red blood cells did not reduce the incidence of new or progressive multiple organ dysfunction syndrome (including mortality) compared with standard-issue red blood cells.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT01977547.

Risk factors for outcomes of acute respiratory distress syndrome patients: a retrospective study

Background

The determination of risk factors for acute respiratory distress syndrome (ARDS) patients remains a challenge. Our study aims to explore the epidemiology and risk factors affecting outcomes of ARDS patients and provide a theoretical basis for patients' prognosis.

Methods

This retrospective study included 207 ARDS patients admitted to the general intensive care unit (ICU) in the Second Affiliated Hospital of Harbin Medical University from Jan 1st, 2016 to Jan 1st, 2017. The criteria were defined according to the Berlin Definition, and clinical data were collected from the medical record system. The mortality rate and duration of mechanical ventilation were compared in ARDS patients. Furthermore, logistic regression analysis was applied to screen clinically accessible risk factors for survival and duration of mechanical ventilation.

Results

The total mortality in ARDS patients was 39.13% (81/207) compared to 13.57% (151/1,113) in the whole ICU population. The period prevalence of mild, moderate and severe ARDS was 39.61% (82/207), 37.20% (77/207) and 23.19% (48/207), respectively. Logistic regression analysis showed that acute physiology and chronic health evaluation II (APACHE II) score (OR 3.4316; 95% CI: 1.3130-8.9686; P=0.0119), number of organ failure (OR 3.4928; 95% CI: 1.9775-6.1693; P<0.0001), mean arterial pressure (MAP) (OR 5.1049; 95% CI: 1.8317-14.2274; P=0.0018), driving pressure (OR 6.0017; 95% CI: 2.1746-16.5641; P=0.0005) and lactate level (OR 4.0754; 95% CI: 1.6114-10.3068; P=0.0030) were influence factors for survival; severity of ARDS (OR 1.6715; 95% CI: 1.0307-2.7108; P=0.0373), ventilator-associated pneumonia (VAP) (OR 7.3746; 95% CI: 2.9799-18.2505; P<0.0001) and transfusion history (OR 2.2822; 95% CI: 1.0462-4.9783; P=0.0381) were influence factors for duration of mechanical ventilation.

Conclusions

Higher APACHE II score, more organ failures, lower MAP, higher driving pressure and higher lactate level are risk factors for survival. Higher severity of ARDS, VAP and transfusion history are risk factors for prolonged duration of mechanical ventilation. Application of these parameters would enable intensivists to treat their patients more precisely and comprehensively.

The age of blood in pediatric intensive care units (ABC PICU): study protocol for a randomized controlled trial

Background

The “Age of Blood in Children in Pediatric Intensive Care Unit” (ABC PICU) study is a randomized controlled trial (RCT) that aims to determine if red blood cell (RBC) unit storage age affects outcomes in critically ill children. While RBCs can be stored for up to 42 days in additive solutions, their efficacy and safety after long-term storage have been challenged. Preclinical and clinical observational evidence suggests loss of efficacy and lack of safety of older RBC units, especially in more vulnerable populations such as critically ill children. Because there is a belief that shorter storage will improve outcomes, some physicians and institutions systematically transfuse fresh RBCs to children. Conversely, the standard practice of blood banks is to deliver the oldest available RBC unit (first-in, first-out policy) in order to decrease wastage.

Methods/design

The ABC PICU study, is a double-blind superiority trial comparing the development of “New or Progressive Multiple Organ Dysfunction Syndrome” (NPMODS) in 1538 critically ill children randomized to either transfusion with RBCs stored for ≤ 7 days or to standard-issue RBCs (oldest in inventory). Patients are being recruited from 52 centers in the US, Canada, France, Italy, and Israel.

Discussion

The ABC PICU study should have significant implications for blood procurement services. A relative risk reduction of 33% is postulated in the short-storage arm. If a difference is found, this will indicate that fresher RBCs do improve outcomes in the pediatric intensive care unit population and would justify that use in critically ill children.

If no difference is found, this will reassure clinicians and transfusion medicine specialists regarding the safety of the current system of allocating the oldest RBC unit in inventory and will discourage clinicians from preferentially requesting fresher blood for critically ill children.

Trial registration

ClinicalTrials.gov, ID: NCT01977547. Registered on 6 November 2013.

Electronic supplementary material

The online version of this article (10.1186/s13063-018-2809-y) contains supplementary material, which is available to authorized users.

Transfusion of Older Red Blood Cells Increases the Risk of Acute Kidney Injury After Orthotopic Liver Transplantation: A Propensity Score Analysis

BACKGROUND

Acute kidney injury (AKI) is a common and serious complication of orthotopic liver transplantation (OLT). Transfusion of older red blood cells (RBCs) has been implicated in poor outcomes in trauma, cardiac surgery, and critically ill patients. However, whether transfusion of older RBCs plays any role in post-OLT AKI remained unknown. The aim of this study was to investigate the effect of the age of transfused RBCs on post-OLT AKI.

METHODS

The clinical data of consecutive adult patients who received donation after cardiac death and underwent OLT from December 2011 to December 2015 were analyzed. These patients were divided into 2 groups: the newer blood group, who received exclusively RBCs that had been stored for <14 days; and the older blood group, who received RBCs that had been stored for 14 days or more. The incidence of post-OLT AKI, severe AKI, lengths of intensive care unit and hospital stay, and in-hospital mortality after OLT were analyzed.

RESULTS

Postoperative AKI occurred in 65.1% of patients in the older blood group and 40.5% of patients in the newer blood group (P < .01). The incidence of severe AKI after OLT was significantly higher, and the duration of intensive care unit stay was significantly longer, in the older blood group. After adjustment by the multivariable regression logistic analysis, transfusion of older blood was independently associated with post-OLT AKI (odds ratio [OR] = 2.47 [95% confidence interval {CI}, 1.13-5.41]; P = .024) and severe AKI (OR = 5.88 [95% CI, 2.06-16.80]; P = .001). After adjustment by the inverse probability of treatment weighting analysis, patients in the older blood group still had significantly higher incidences of postoperative AKI (OR = 2.13 [95% CI, 1.07-4.22]; P = .030) and severe AKI (OR = 3.34 [95% CI, 1.47-7.60]; P = .003) than those in the newer blood group.

CONCLUSIONS

Transfusion of older RBCs significantly increased the risk of postoperative AKI in liver transplant recipients.

Endotoxemia Results in Trapping of Transfused Red Blood Cells in Lungs with Associated Lung Injury

BACKGROUND

Red blood cell (RBC) transfusion is associated with organ failure, in particular in the critically ill. We hypothesized that endotoxemia contributes to increased trapping of RBCs in organs. Furthermore, we hypothesized that this effect is more pronounced following transfusion of stored RBCs compared with fresh RBCs.

METHODS

Adult male Sprague-Dawley rats were randomized to receive injection with lipopolysaccharide from E coli or vehicle and transfusion with fresh or stored biotinylated RBCs. After 24 h, the amount of biotinylated RBCs in organs was measured by flow cytometry, as well as the 24-h post-transfusion recovery. Markers of organ injury and histopathology of organs were assessed.

RESULTS

Endotoxemia resulted in systemic inflammation and organ injury. Following RBC transfusion, donor RBCs were recovered from the lung and kidney of endotoxemic recipients (1.2 [0.8-1.6]% and 2.2 [0.4-4.4]% of donor RBCs respectively), but not from organs of healthy recipients. Trapping of donor RBCs in the lung was associated with increased lung injury, but not with kidney injury. Stored RBCs induced organ injury in the spleen and yielded a lower 24-h post-transfusion recovery, but other effects of storage time were limited.

CONCLUSION

Endotoxemia results in an increased percentage of donor RBCs recovered from the lung and kidney, which is associated with lung injury following transfusion.

Pediatric red cell and platelet transfusions

The aim of pediatric transfusions should be based on the concept of avoiding unnecessary transfusions without jeopardizing the patient safety and providing correct blood components when there are well founded indications to transfuse. Despite considerable efforts from transfusion services to increase transfusion safety, transfusions are still associated with preventable and unpreventable adverse effects that may, in the worst case, have severe and fatal consequences. Transfusions to pediatric patients constitute a small proportion of all transfusions but have higher incidence of adverse events compared to adults. Pediatric transfusions consist of intrauterine transfusions, top-up transfusions to neonates and young children, exchange transfusions in the management of hemolytic disease of newborn (HDN), in addition to sickle cell crisis, chronic transfusion therapy in thalassemia patients, massive transfusion in trauma, HLA- and HPA-compatible platelets in immunized patients and neonates with fetal neonatal alloimmune thrombocytopenia (FNAIT). Packed red cells (PRCs) and platelet (PLT) concentrates are the most utilized blood components and will be reviewed here.

Comprehensive Analysis of Liberal and Restrictive Transfusion Strategies in Pediatric Intensive Care Unit

BACKGROUND

We prospectively compared restrictive and liberal transfusion strategies for critically ill children regarding hemodynamic and laboratory parameters.

METHODS

A total of 180 children requiring packed red blood cells (PRBCs) were randomized into two groups: the liberal transfusion strategy group (transfusion trigger < 10 g/dL, Group 1) and the restrictive transfusion strategy group (transfusion trigger ≤ 7 g/dL, Group 2). Basal variables including venous/arterial hemoglobin, hematocrit and lactate levels; stroke volume; and cardiac output were recorded at the beginning and end of the transfusion. Oxygen saturation, noninvasive total hemoglobin, noninvasive total oxygen content, perfusion index (PI), heart rate and systolic and diastolic blood pressures were assessed via the Radical-7 Pulse co-oximeter (Masimo, Irvine, CA, USA) with the Root monitor, initially and at 4 h.

RESULTS

In all, 160 children were eligible for final analysis. The baseline hemoglobin level for the PRBC transfusion was 7.38 ± 0.98 g/dL for all patients. At the end of the PRBC transfusion, cardiac output decreased by 9.9% in Group 1 and by 24% in Group 2 (p  < 0.001); PI increased by 10% in Group 1 and by 45% in Group 2 (p  < 0.001). Lactate decreased by 9.8% in Group 1 and by 31.68% in Group 2 (p < 0.001).

CONCLUSION

Restrictive blood transfusion strategy is better than liberal transfusion strategy with regard to the hemodynamic and laboratory values during the early period. PI also provides valuable information regarding the efficacy of PRBC transfusion in clinical practice.

Role of heme in lung bacterial infection after trauma hemorrhage and stored red blood cell transfusion: A preclinical experimental study

BACKGROUND

Trauma is the leading cause of death and disability in patients aged 1-46 y. Severely injured patients experience considerable blood loss and hemorrhagic shock requiring treatment with massive transfusion of red blood cells (RBCs). Preclinical and retrospective human studies in trauma patients have suggested that poorer therapeutic efficacy, increased severity of organ injury, and increased bacterial infection are associated with transfusion of large volumes of stored RBCs, although the mechanisms are not fully understood.

METHODS AND FINDINGS

We developed a murine model of trauma hemorrhage (TH) followed by resuscitation with plasma and leukoreduced RBCs (in a 1:1 ratio) that were banked for 0 (fresh) or 14 (stored) days. Two days later, lungs were infected with Pseudomonas aeruginosa K-strain (PAK). Resuscitation with stored RBCs significantly increased the severity of lung injury caused by P. aeruginosa, as demonstrated by higher mortality (median survival 35 h for fresh RBC group and 8 h for stored RBC group; p < 0.001), increased pulmonary edema (mean [95% CI] 106.4 μl [88.5-124.3] for fresh RBCs and 192.5 μl [140.9-244.0] for stored RBCs; p = 0.003), and higher bacterial numbers in the lung (mean [95% CI] 1.2 × 10(7) [-1.0 × 10(7) to 2.5 × 10(7)] for fresh RBCs and 3.6 × 10(7) [2.5 × 10(7) to 4.7 × 10(7)] for stored RBCs; p = 0.014). The mechanism underlying this increased infection susceptibility and severity was free-heme-dependent, as recombinant hemopexin or pharmacological inhibition or genetic deletion of toll-like receptor 4 (TLR4) during TH and resuscitation completely prevented P. aeruginosa-induced mortality after stored RBC transfusion (p < 0.001 for all groups relative to stored RBC group). Evidence from studies transfusing fresh and stored RBCs mixed with stored and fresh RBC supernatants, respectively, indicated that heme arising both during storage and from RBC hemolysis post-resuscitation plays a role in increased mortality after PAK (p < 0.001). Heme also increased endothelial permeability and inhibited macrophage-dependent phagocytosis in cultured cells. Stored RBCs also increased circulating high mobility group box 1 (HMGB1; mean [95% CI] 15.4 ng/ml [6.7-24.0] for fresh RBCs and 50.3 ng/ml [12.3-88.2] for stored RBCs), and anti-HMGB1 blocking antibody protected against PAK-induced mortality in vivo (p = 0.001) and restored macrophage-dependent phagocytosis of P. aeruginosa in vitro. Finally, we showed that TH patients, admitted to the University of Alabama at Birmingham ER between 1 January 2015 and 30 April 2016 (n = 50), received high micromolar-millimolar levels of heme proportional to the number of units transfused, sufficient to overwhelm endogenous hemopexin levels early after TH and resuscitation. Limitations of the study include lack of assessment of temporal changes in different products of hemolysis after resuscitation and the small sample size precluding testing of associations between heme levels and adverse outcomes in resuscitated TH patients.

CONCLUSIONS

We provide evidence that large volume resuscitation with stored blood, compared to fresh blood, in mice increases mortality from subsequent pneumonia, which occurs via mechanisms sensitive to hemopexin and TLR4 and HMGB1 inhibition.

Biochemical evaluation of storage lesion in canine packed erythrocytes

OBJECTIVES

To describe the biochemical changes - also known as the storage lesion - that occur in canine packed red blood cells during ex vivo storage.

MATERIALS AND METHODS

Ten 125-mL units of non-leuco-reduced packed red blood cells in citrate phosphate dextrose adenine were obtained from a commercial blood bank within 24 hours of donation. Samples were aseptically collected on days 1, 4, 7, 14, 28, 35 and 42 for measurement of sodium, potassium, chloride, lactate, glucose, pH and ammonia concentrations. All units were cultured on day 42. Friedman's repeated measures test with Dunn's multiple comparison test was used for non-parametric data. A repeated-measures analysis of variance with Tukey's multiple comparison test was used for parametric data. Alpha was set to 0·05.

RESULTS

All analytes changed significantly during storage. The mean ammonia on day 1 (58·14 g/dL) was significantly lower (P<0·05) than those on days 28 (1266 g/dL), 35 (1668 g/dL) and 42 (1860 g/dL). A significant increase in median lactate concentration over time was also observed, with day 1 (4·385 mmol/L) being significantly less (P<0·05) than days 14 (19·82 mmol/L), 21 (22·81 mmol/L), 35 (20·31 mmol/L) and 42 (20·81 mmol/L). Median pH was significantly decreased after day 7. All bacterial cultures were negative.

CLINICAL SIGNIFICANCE

Many biochemical alterations occur in stored canine packed red blood cells, although further studies are required to determine their clinical importance.

Critical Evaluation of the Lund Concept for Treatment of Severe Traumatic Head Injury, 25 Years after Its Introduction

When introduced in 1992, the Lund concept (LC) was the first complete guideline for treatment of severe traumatic brain injury (s-TBI). It was a theoretical approach, based mainly on general physiological principles-i.e., of brain volume control and optimization of brain perfusion and oxygenation of the penumbra zone. The concept gave relatively strict outlines for cerebral perfusion pressure, fluid therapy, ventilation, sedation, nutrition, the use of vasopressors, and osmotherapy. The LC strives for treatment of the pathophysiological mechanisms behind symptoms rather than just treating the symptoms. The treatment is standardized, with less need for individualization. Alternative guidelines published a few years later (e.g., the Brain Trauma Foundation guidelines and European guidelines) were mainly based on meta-analytic approaches from clinical outcome studies and to some extent from systematic reviews. When introduced, they differed extensively from the LC. We still lack any large randomized outcome study comparing the whole concept of BTF guidelines with other guidelines including the LC. From that point of view, there is limited clinical evidence favoring any of the s-TBI guidelines used today. In principle, the LC has not been changed since its introduction. Some components of the alternative guidelines have approached those in the LC. In this review, I discuss some important principles of brain hemodynamics that have been lodestars during formulation of the LC. Aspects of ventilation, nutrition, and temperature control are also discussed. I critically evaluate the most important components of the LC 25 years after its introduction, based on hemodynamic principles and on the results of own an others experimental and human studies that have been published since then.

Red blood cell storage duration and long-term mortality in patients undergoing cardiac intervention: a Danish register study

OBJECTIVES

To study the effect of red blood cell (RBC) storage duration on long-term mortality in patients undergoing cardiac intervention.

BACKGROUND

RBCs undergo numerous structural and functional changes during storage. Observational studies have assessed the association between RBC storage duration and patient outcomes with conflicting results.

METHODS

Between January 2006 and December 2014, 82 408 patients underwent coronary angiography. Of these, 1856 patients received one to four RBC units within 30 days after this procedure. Patients were allocated according to length of RBC storage duration: short-term (≤11 days), intermediate (IM)-term (12-23 days) and long-term (≥24 days). The study endpoints were 30-day and long-term all-cause mortality.

RESULTS

A total of 4168 RBC units were given to 1856 patients. The mean RBC storage duration was 8.5 ± 2.1, 17.7 ± 3.4 and 29.9 ± 3.4 days in the short-term, IM-term and long-term storage groups, respectively. There was no difference in baseline characteristics between the groups. The long-term storage group received significantly more units (2.4 ± 1.0 units) as compared to the short-term (2.0 ± 1.0 units; P < 0.001) and IM-term storage group (2.2 ± 1.0 units; P < 0.01). In the survival analysis, there was no significant difference in all-cause mortality between the groups (log-rank: 0.509 for 30-days mortality; 0.493 for 5-year mortality). Additional stratified analysis demonstrated no association between RBC storage duration and long-term mortality.

CONCLUSION

This study did not find an association between RBC storage duration and 30-days or long-term mortality in patients undergoing cardiac intervention.

Specific Etiologies Associated With the Multiple Organ Dysfunction Syndrome in Children: Part 2

OBJECTIVE

To describe a number of conditions and therapies associated with multiple organ dysfunction syndrome presented as part of the Eunice Kennedy Shriver National Institute of Child Health and Human Development Multiple Organ Dysfunction Workshop (March 26-27, 2015). In addition, the relationship between burn injuries and multiple organ dysfunction syndrome is also included although it was not discussed at the workshop.

DATA SOURCES

Literature review, research data, and expert opinion.

STUDY SELECTION

Not applicable.

DATA EXTRACTION

Moderated by an expert from the field, issues relevant to the association of multiple organ dysfunction syndrome with a variety of conditions and therapies were presented, discussed, and debated with a focus on identifying knowledge gaps and the research priorities.

DATA SYNTHESIS

Summary of presentations and discussion supported and supplemented by relevant literature.

CONCLUSIONS

Sepsis and trauma are the two conditions most commonly associated with multiple organ dysfunction syndrome both in children and adults. However, many other pathophysiologic processes may result in multiple organ dysfunction syndrome. In this article, we discuss conditions such as liver failure and pancreatitis, pathophysiologic processes such as ischemia and hypoxia, and injuries such as trauma and burns. Additionally, therapeutic interventions such as medications, blood transfusions, transplantation may also precipitate and contribute to multiple organ dysfunction syndrome. The purpose of this article is to describe the association of multiple organ dysfunction syndrome with a variety of conditions and therapies in an attempt to identify similarities, differences, and opportunities for therapeutic intervention.

Transfusion-related immunomodulation: review of the literature and implications for pediatric critical illness

Transfusion-related immunomodulation (TRIM) in the intensive care unit (ICU) is difficult to define and likely represents a complicated set of physiologic responses to transfusion, including both proinflammatory and immunosuppressive effects. Similarly, the immunologic response to critical illness in both adults and children is highly complex and is characterized by both acute inflammation and acquired immune suppression. How transfusion may contribute to or perpetuate these phenotypes in the ICU is poorly understood, despite the fact that transfusion is common in critically ill patients. Both hyperinflammation and severe immune suppression are associated with poor outcomes from critical illness, underscoring the need to understand potential immunologic consequences of blood product transfusion. In this review we outline the dynamic immunologic response to critical illness, provide clinical evidence in support of immunomodulatory effects of blood product transfusion, review preclinical and translational studies to date of TRIM, and provide insight into future research directions.

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

Background

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

Methods

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

Results

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

Conclusions

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

Iron metabolism following intravenous transfusion with stored versus fresh autologous erythrocyte concentrate in healthy dogs

OBJECTIVE To determine effects of IV transfusion with fresh (3-day-old) or stored (35-day-old) autologous erythrocyte concentrate on serum labile iron concentration, iron-binding capacity, and protein interaction with iron in dogs. ANIMALS 10 random-source healthy dogs. PROCEDURES Dogs were randomly assigned to receive autologous erythrocyte concentrate stored for 3 days (n = 5) or 35 days (5). One unit of whole blood was collected from each dog, and erythrocyte concentrates were prepared and stored as assigned. After erythrocyte storage, IV transfusion was performed, with dogs receiving their own erythrocyte concentrate. Blood samples were collected from each dog before and 5, 9, 24, 48, and 72 hours after transfusion. Serum was harvested for measurement of total iron, labile iron, transferrin, ferritin, hemoglobin, and haptoglobin concentrations. RESULTS For dogs that received fresh erythrocytes, serum concentrations of the various analytes largely remained unchanged after transfusion. For dogs that received stored erythrocytes, serum concentrations of total iron, labile iron, hemoglobin, and ferritin increased markedly and serum concentrations of transferrin and haptoglobin decreased after transfusion. CONCLUSIONS AND CLINICAL RELEVANCE Transfusion with autologous erythrocyte concentrate stored for 35 days resulted in evidence of intravascular hemolysis in healthy dogs. The associated marked increases in circulating concentrations of free iron and hemoglobin have the potential to adversely affect transfusion recipients.

The effect of red blood cell transfusion on the microcirculation of anemic children

Red blood cell transfusion can improve but also might temporarily reduce the microcirculation. The buccal microcirculation was visualized and total vessel density (TVD) determined with sidestream dark field imaging in 19 pediatric anemic (Hb 7.2 g/dL, 95 % CI 6.5-7.9) oncology or hematology patients receiving red blood cell transfusions (Tx) and in 18 age-matched healthy non-anemic controls. After transfusion, Hb (8.0 g/dL, 95 % CI 7.3-8.6) and TVD increased (14.7 ± 1.7 versus 16.6 ± 2.0 mm/mm(2)) significantly with a concomitant decrease in RBC velocity in medium-sized vessels (pre-Tx 711 ± 199 versus post-Tx 627 ± 163 μm/s). Compared to the controls, pre-Tx TVD (17.5 ± 1.3 mm/mm(2)) was lower and RBC velocity (476 ± 77 μm/s) was significantly higher. After transfusion, TVD and RBC velocity remained significantly lower and higher, respectively. In a subgroup, analysis of the transfused children with infection of TVD at baseline was lower with a larger increase after transfusion compared to anemic children without infection (ΔTVD 3.4 ± 2.6 versus ΔTVD 1.3 ± 1.5 mm/mm(2)).

CONCLUSION

With the rise of hemoglobin after transfusion, significant improvements of tissue perfusion were demonstrated but differences to non-anemic controls persisted. In particular, the microcirculation of anemic oncology patients with infection improved after transfusion.

WHAT IS KNOWN

• Transfusions can improve but also temporarily reduce the microcirculation. • In neonates, transfusion significantly increases total vessel density. What is New: • Pretransfusion, the microcirculation of the anemic children differed significantly from the controls. • After transfusion, the microcirculation improved but still differed from the controls. • These changes were most profound in anemic patients with concurrent infection, therefore transfusion threshholds might need to be higher.

Transfusion of recently donated (fresh) red blood cells (RBCs) does not improve survival in comparison with current practice, while safety of the oldest stored units is yet to be established: a meta-analysis

BACKGROUND AND OBJECTIVES

Preclinical studies generated the hypothesis that older stored red blood cells (RBCs) can increase transfusion risks. To examine the most updated and complete clinical evidence and compare results between two trial designs, we assessed both observational studies and randomized controlled trials (RCTs) studying the effect of RBC storage age on mortality.

MATERIALS AND METHODS

Five databases were searched through December 2014 for studies comparing mortality using transfused RBCs having longer and shorter storage times.

RESULTS

Analysis of six RCTs found no significant differences in survival comparing current practice (average storage age of 2 to 3 weeks) to transfusion of 1- to 10-day-old RBCs (OR 0·91, 95% CI 0·77-1·07). RBC storage age was lower in RCTs vs. observational studies (P = 0·01). The 31 observational studies found an increased risk of death (OR 1·13, 95% CI 1·03-1·24) (P = 0·01) with increasing age of RBCs, a different mortality effect than RCTs (P = 0·02).

CONCLUSION

RCTs established that transfusion of 1- to 10-day-old stored RBCs is not superior to current practice. The apparent discrepancy in mortality between analyses of RCTs and observational studies may in part relate to differences in hypotheses tested and ages of stored RBCs studied. Further trials investigating 1- to 10-day-old stored RBC benefits would seem of lower priority than studies to determine whether 4- to 6-week stored units have safety and efficacy equivalent to the 2- to 3-week-old stored RBCs commonly transfused today.

Red cell transfusions as an independent risk for mortality in critically ill children

Background

Severity of illness is an important consideration in making the decision to transfuse as it is the sicker patient that often needs a red cell transfusion. Red blood cell (RBC) transfusions could potentially have direct effects and interact with presenting illness by contributing to pathologies such as multi-organ dysfunction and acute lung injury thus exerting a considerable impact on overall morbidity and mortality. In this study, we examine if transfusion is an independent predictor of mortality, or if outcomes are merely a result of the initial severity as predicted by Pediatric Risk of Mortality (PRISM) III, Pediatric Index of Mortality (PIM2), and day 1 Pediatric Logistic Organ Dysfunction (PELOD) scores.

Methods

A single center retrospective study was conducted using data from a prospectively maintained transfusion database and center-specific data at our pediatric ICU between January 2009 and December 2012. Multivariate regression was used to control for the effects of clinical findings, therapy, and severity scores, with mortality as the dependent variable. Likelihood ratios and area under the curve were used to test the fidelity of severity scores by comparing transfused vs. non-transfused patients.

Results

There were 4975 admissions that met entry criteria. In multivariate analysis, PRISM III scores and serum hemoglobin were significant predictors of transfusion (p < 0.05). Transfused and non-transfused subjects were distinctly disparate, so multivariate regression was used to control for differences. Severity scores, age, volume transfused, and vasoactive agents were significantly associated with mortality whereas hemoglobin was not. A substantial number of transfusions (45 %) occurred in the first 24 h, and patients transfused later (24–48 h) were more likely to die compared to this earlier time point. Likelihood ratio testing revealed statistically significant differences in severity scoring systems to predict mortality in transfused vs. non-transfused patients.

Conclusions

This study suggests that RBC transfusion is an important risk factor that is statistically independent of severity. The timing of transfusions that related strongest to mortality remained outside the purview of severity scoring, as these happened beyond the timing of data collection for most scoring systems.

In a canine pneumonia model of exchange transfusion, altering the age but not the volume of older red blood cells markedly alters outcome

BACKGROUND

Massive exchange transfusion of 42-day-old red blood cells (RBCs) in a canine model of Staphylococcus aureus pneumonia resulted in in vivo hemolysis with increases in cell-free hemoglobin (CFH), transferrin-bound iron (TBI), non-transferrin-bound iron (NTBI), and mortality. We have previously shown that washing 42-day-old RBCs before transfusion significantly decreased NTBI levels and mortality, but washing 7-day-old RBCs increased mortality and CFH levels. We now report the results of altering volume, washing, and age of RBCs.

STUDY DESIGN AND METHODS

Two-year-old purpose-bred infected beagles were transfused with increasing volumes (5-10, 20-40, or 60-80 mL/kg) of either 42- or 7-day-old RBCs (n = 36) or 80 mL/kg of either unwashed or washed RBCs with increasing storage age (14, 21, 28, or 35 days; n = 40).

RESULTS

All volumes transfused (5-80 mL/kg) of 42-day-old RBCs resulted in alike (i.e., not significantly different) increases in TBI during transfusion as well as in CFH, lung injury, and mortality rates after transfusion. Transfusion of 80 mL/kg RBCs stored for 14, 21, 28, and 35 days resulted in increased CFH and NTBI in between levels found at 7 and 42 days of storage. However, washing RBCs of intermediate ages (14-35 days) does not alter NTBI and CFH levels or mortality rates.

CONCLUSIONS

Preclinical data suggest that any volume of 42-day-old blood potentially increases risks during established infection. In contrast, even massive volumes of 7-day-old blood result in minimal CFH and NTBI levels and risks. In contrast to the extremes of storage, washing blood stored for intermediate ages does not alter risks of transfusion or NTBI and CFH clearance.

Red blood cell transfusion is associated with increased hemolysis and an acute phase response in a subset of critically ill children

In healthy adults, transfusion of older stored red blood cells (RBCs) produces extravascular hemolysis and circulating non-transferrin-bound iron. In a prospective, observational study of critically ill children, we examined the effect of RBC storage duration on the extent of hemolysis by comparing laboratory measurements obtained before, and 4 hr after, RBC transfusion (N = 100) or saline/albumin infusion (N = 20). Transfusion of RBCs stored for longer than 4 weeks significantly increased plasma free hemoglobin (P < 0.05), indirect bilirubin (P < 0.05), serum iron (P < 0.001), and non-transferrin-bound iron (P < 0.01). However, days of storage duration poorly correlated (R(2) <0.10) with all measured indicators of hemolysis and inflammation. These results suggest that, in critically ill children, most effects of RBC storage duration on post-transfusion hemolysis are overwhelmed by recipient and/or donor factors. Nonetheless, we identified a subset of patients (N = 21) with evidence of considerable extravascular hemolysis (i.e., increased indirect bilirubin ≥0.4 mg/dL). In these patients, transfusion-associated hemolysis was accompanied by increases in circulating non-transferrin-bound iron and free hemoglobin and by an acute phase response, as assessed by an increase in median C-reactive protein levels of 21.2 mg/L (P < 0.05). In summary, RBC transfusions were associated with an acute phase response and both extravascular and intravascular hemolysis, which were independent of RBC storage duration. The 21% of transfusions that were associated with substantial hemolysis conferred an increased risk of inducing an acute phase response.

[Septic shock in intensive care units. Current focus on treatment]

Essential therapeutic principles in children with septic shock persist over time, although some new concepts have been recently incorporated, and fully awareness of pediatricians and intensivists is essential. Fluid resuscitation is a fundamental intervention, but the kind of ideal fluid has not been established yet, as each of these interventions has specific limitations and there is no evidence supportive of the superiority of one type of fluid. Should septic shock persists despite adequate fluid resuscitation, the use of inotropic medication and/or vasopressors is indicated. New vasoactive drugs can be used in refractory septic shock caused by vasopressors, and the use of hydrocortisone should be considered in children with suspected adrenal insufficiency, as it reduces the need for vasopressors. The indications for red blood cells transfusion or the optimal level of glycemia are still controversial, with no consensus on the threshold value for the use of these blood products or the initiation of insulin administration, respectively. Likewise, the use of high-volume hemofiltration is a controversial issue and further study is needed on the routine recommendation in the course of septic shock. Nutritional support is crucial, as malnutrition is a serious complication that should be properly prevented and treated. The aim of this paper is to provide update on the most recent advances as concerns the treatment of septic shock in the pediatric population.

Impact of supplemental vitamin K1 administration on postoperative blood component requirements after craniosynostosis repair: a prospective, placebo-controlled, randomized, blinded study

Total cranial vault craniosynostosis repairs often require additional blood transfusions in the intensive care unit. Vitamin K1 participates in hepatic production of procoagulant proteins, and body stores of vitamin K1 are limited and dietary dependent. Surgical stress and diet interference may place infants at risk for vitamin K deficiency. Through design of a surgically stratified, randomized, placebo-controlled, blinded pilot study, we evaluated impact of vitamin K1 supplementation on coagulation parameters in infants after craniosynostosis repair. Patients received intramuscular vitamin K1 or placebo coincident with surgical incision. Serum vitamin K1 levels, protein induced in vitamin K absence-prothrombin, and factor VII were obtained at predetermined intervals after surgery. Patients received blood products in the intensive care unit in accordance with transfusion thresholds. Fifteen patients (vitamin K1 = 6, placebo = 9) completed the study procedures. Despite group assignment, patients received an average of 3 postoperative transfusions. Variations were observed with respect to intraoperative resuscitation of patients between comparably trained pediatric anesthesiologists. Thirty-three percent of patients were vitamin K1 deficient on 1 or more laboratory specimens. All breast-fed patients became deficient. Compared with placebo, elevated serum vitamin K1 levels at 6, 12, and 24 hours in the active drug group (P < 0.0001) were not associated with increased factor VII levels or reduced need for postoperative blood products. However, lack of a standardized intraoperative resuscitation plan may contribute to postoperative coagulopathy and is a major study limitation.

Age of blood and adverse outcomes in a maternity population

BACKGROUND

In recent times there has been debate around whether longer storage time of blood is associated with increased rates of adverse outcomes after transfusion. It is unclear whether results focused on cardiac or critically ill patients apply to a maternity population. This study investigates whether older blood is associated with increased morbidity and readmission in women undergoing obstetric transfusion.

STUDY DESIGN AND METHODS

Women giving birth in hospitals in New South Wales, Australia, between July 2006 and December 2010 were included in the study population if they had received between 1 and 4 red blood cell units during the birth admission. Information on women's characteristics, transfusions, and outcomes were obtained from five routinely collected data sets including blood collection, birth, and hospitalization data. Generalized propensity score methods were used to determine the effect of age of blood on rates of severe morbidity and readmission, independent of confounding factors.

RESULTS

Transfusion data were available for 2990 women, with a median age of blood transfused of 20 days (interquartile range, 14-27 days). There were no differences in the maximum age of blood transfused between women with and without severe morbidity (21 [14-28] days vs. 22 [15-30] days) and in women readmitted or not (22 [14-28] days vs. 22 [16-30] days). After potential confounding factors were considered, no relationship was found between the age of blood transfused and rates of severe morbidity and readmission.

CONCLUSION

Among women receiving low-volume transfusions during a birth admission, there was no evidence of increased rates of adverse outcomes after transfusion with older blood.

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.

Innate immune function predicts the development of nosocomial infection in critically injured children

BACKGROUND

Critical injury has been associated with reduction in innate immune function in adults, with infection risk being related to degree of immune suppression. This relationship has not been reported in critically injured children.

HYPOTHESIS

Innate immune function will be reduced in critically injured children, and the degree of reduction will predict the subsequent development of nosocomial infection.

METHODS

Children (≤18 years old) were enrolled in this longitudinal, prospective, observational, single-center study after admission to the pediatric intensive care unit following critical injury, along with a cohort of outpatient controls. Serial blood sampling was performed to evaluate plasma cytokine levels and innate immune function as measured by ex vivo lipopolysaccharide-induced tumor necrosis factor α (TNF-α) production capacity.

RESULTS

Seventy-six critically injured children (and 21 outpatient controls) were enrolled. Sixteen critically injured subjects developed nosocomial infection. Those subjects had higher plasma interleukin 6 and interleukin 10 levels on posttrauma days 1-2 compared with those who recovered without infection and outpatient controls. Ex vivo lipopolysaccharide-induced TNF-α production capacity was lower on posttrauma days 1-2 (P = 0.006) and over the first week following injury (P = 0.04) in those who went on to develop infection. A TNF-α response of less than 520 pg/mL at any time in the first week after injury was highly associated with infection risk by univariate and multivariate analysis. Among transfused children, longer red blood cell storage age, not transfusion volume, was associated with lower innate immune function (P < 0.0001). Trauma-induced innate immune suppression was reversible ex vivo via coculture of whole blood with granulocyte-macrophage colony-stimulating factor.

CONCLUSIONS

Trauma-induced innate immune suppression is common in critically injured children and is associated with increased risks for the development of nosocomial infection. Potential exacerbating factors, including red blood cell transfusion, and potential therapies for pediatric trauma-induced innate immune suppression are deserving of further study.

The influence of the storage lesion(s) on pediatric red cell transfusion

PURPOSE OF REVIEW

This article will analyze and evaluate the current evidence regarding the use of older, longer-stored red blood cells (RBCs) for transfusion in pediatric patients and will examine some of the postulated mechanisms of injury related to prolonged refrigerated storage of RBCs and studies reporting clinical outcomes.

RECENT FINDINGS

Three randomized controlled trials and seven observational studies have been conducted entirely in pediatric patients. The outcomes, mortality and morbidity in critically ill patients and children undergoing cardiac surgery, and necrotizing enterocolitis in premature infants, have been inconsistent. However, many of these studies have been confounded by study design, mixed patient populations, red cell preparation, and other factors.

SUMMARY

Further exploration into the possible deleterious effects of older, longer-stored RBC transfusions on mortality and morbidity in different pediatric populations is merited. Understanding the potential mechanisms of injury should help explain the clinical findings.

Nonpulmonary treatments for pediatric acute respiratory distress syndrome: proceedings from the Pediatric Acute Lung Injury Consensus Conference

OBJECTIVE

To describe the recommendations from the Pediatric Acute Lung Injury Consensus Conference on nonpulmonary treatments in pediatric acute respiratory distress syndrome.

DESIGN

Consensus conference of experts in pediatric acute lung injury.

METHODS

A panel of 27 experts met over the course of 2 years to develop a taxonomy to define pediatric acute respiratory distress syndrome and to make recommendations regarding treatment and research priorities. The nonpulmonary subgroup comprised three experts. When published data were lacking, a modified Delphi approach emphasizing strong professional agreement was utilized.

RESULTS

The Pediatric Acute Lung Injury Consensus Conference experts developed and voted on a total of 151 recommendations addressing the topics related to pediatric acute respiratory distress syndrome, 30 of which related to nonpulmonary treatment. All 30 recommendations had strong agreement. Patients with pediatric acute respiratory distress syndrome should receive 1) minimal yet effective targeted sedation to facilitate mechanical ventilation; 2) neuromuscular blockade, if sedation alone is inadequate to achieve effective mechanical ventilation; 3) a nutrition plan to facilitate their recovery, maintain their growth, and meet their metabolic needs; 4) goal-directed fluid management to maintain adequate intravascular volume, end-organ perfusion, and optimal delivery of oxygen; and 5) goal-directed RBC transfusion to maintain adequate oxygen delivery. Future clinical trials in pediatric acute respiratory distress syndrome should report sedation, neuromuscular blockade, nutrition, fluid management, and transfusion exposures to allow comparison across studies.

CONCLUSIONS

The Consensus Conference developed pediatric-specific definitions for pediatric acute respiratory distress syndrome and recommendations regarding treatment and future research priorities. These recommendations for nonpulmonary treatment in pediatric acute respiratory distress syndrome are intended to promote optimization and consistency of care for patients with pediatric acute respiratory distress syndrome and identify areas of uncertainty requiring further investigation.

Red blood cell storage duration is not associated with clinical outcomes for acute chest syndrome in children with sickle cell disease

BACKGROUND

Providers commonly transfuse sickle cell disease (SCD) patients with fresh red blood cells (RBCs) as treatment for acute chest syndrome (ACS). The objective of this study was to determine if there is an association between the storage duration of RBCs and length of hospitalization and oxygen requirement after transfusion in pediatric SCD patients with ACS.

STUDY DESIGN AND METHODS

This is a retrospective cohort study of pediatric SCD patients with ACS treated with a simple RBC transfusion over 8.5 years at a single institution. Multivariate generalized estimation equation analysis was used to identify associations between storage duration of RBCs and outcome measures.

RESULTS

A total of 234 ACS episodes in 131 subjects were included. The median storage duration of the oldest unit of transfused RBCs was 17 days (interquartile range, 11-26). The majority of ACS episodes, 77.4%, were treated with 1 unit of transfused RBCs; 20.9% received 2 units; and 1.7% received 3 or more units of RBCs. There was no association between the storage duration of the oldest unit of transfused RBCs and either duration of hospitalization or supplemental oxygen requirement after transfusion in multivariate analyses.

CONCLUSION

This retrospective study is one of the first to investigate the role of the storage lesion in children with SCD and does not support the preferential transfusion of fresh RBCs for ACS. Ultimately, a randomized controlled trial is necessary to determine whether the storage age of RBCs affects outcomes for patients with SCD and ACS.

Longer RBC storage duration is associated with increased postoperative infections in pediatric cardiac surgery

OBJECTIVES

Infants and children undergoing open heart surgery routinely require multiple RBC transfusions. Children receiving greater numbers of RBC transfusions have increased postoperative complications and mortality. Longer RBC storage age is also associated with increased morbidity and mortality in critically ill children. Whether the association of increased transfusions and worse outcomes can be ameliorated by use of fresh RBCs in pediatric cardiac surgery for congenital heart disease is unknown.

INTERVENTIONS

One hundred and twenty-eight consecutively transfused children undergoing repair or palliation of congenital heart disease with cardiopulmonary bypass who were participating in a randomized trial of washed versus standard RBC transfusions were evaluated for an association of RBC storage age and clinical outcomes. To avoid confounding with dose of transfusions and timing of infection versus timing of transfusion, a subgroup analysis of patients only transfused 1-2 units on the day of surgery was performed.

MEASUREMENTS AND MAIN RESULTS

Mortality was low (4.9%) with no association between RBC storage duration and survival. The postoperative infection rate was significantly higher in children receiving the oldest blood (25-38 d) compared with those receiving the freshest RBCs (7-15 d) (34% vs 7%; p = 0.004). Subgroup analysis of subjects receiving only 1-2 RBC transfusions on the day of surgery (n = 74) also demonstrates a greater prevalence of infections in subjects receiving the oldest RBC units (0/33 [0%] with 7- to 15-day storage; 1/21 [5%] with 16- to 24-day storage; and 4/20 [20%] with 25- to 38-day storage; p = 0.01). In multivariate analysis, RBC storage age and corticosteroid administration were the only predictors of postoperative infection. Washing the oldest RBCs (> 27 d) was associated with a higher infection rate and increased morbidity compared with unwashed RBCs.

DISCUSSION

Longer RBC storage duration was associated with increased postoperative nosocomial infections. This association may be secondary in part, to the large doses of stored RBCs transfused, from single-donor units. Washing the oldest RBCs was associated with increased morbidity, possibly from increased destruction of older, more fragile erythrocytes incurred by washing procedures. Additional studies examining the effect of RBC storage age on postoperative infection rate in pediatric cardiac surgery are warranted.

Transfusion therapy in paediatric trauma patients: a review of the literature

Haemorrhage is a leading cause of death in paediatric trauma patients. Predefined massive transfusion protocols (MTP) have the potential to significantly reduce mortality by treating haemorrhagic shock and coagulopathy, in adhering to the principles of haemostatic resuscitation with rapid administration of balanced ratios of packed red blood cells (RBC), fresh frozen plasma (FFP) and platelets (PLT).

Because of their substantial physiological reserve, initial vital signs may not be good predictors of early haemorrhage in paediatric patients. Determining the triggers for MTP activation in paediatric trauma patients is challenging, and the optimal blood product ratio that will increase survival in massively bleeding paediatric trauma patients has yet to be determined. To date, only a few small descriptive studies and case reports have investigated the use of predefined MTP in paediatric trauma patients.

MTP with increased FFP or PLT to RBC ratios combined with viscoelastic haemostatic assay (VHA) guided haemostatic resuscitation have not yet been tested in paediatric populations but based on results from adult trauma patients, this therapeutic approach seems promising.

Considering the high prevalence of early coagulopathy in paediatric trauma patients, immediate identification and implementation of VHA-directed treatment of traumatic coagulopathy could ensure faster haemostasis and thereby, potentially, reduce bleeding as well as the total transfusion requirements and further improve outcome in paediatric trauma patients. Prospective randomized trials investigating this therapeutic approach in paediatric trauma patients are highly warranted.

The pathophysiology and consequences of red blood cell storage

Red cell transfusion therapy is a common treatment modality in contemporary medical practice. Although blood collection and administration is safer and more efficient than ever before, red cells undergo multiple metabolic and structural changes during storage that may compromise their functionality and viability following transfusion. The clinical relevance of these changes is a hotly debated topic that continues to be a matter of intense investigation. In the current review, we begin with an in-depth overview of the pathophysiological mechanisms underlying red cell storage, with a focus on altered metabolism, oxidative stress and red cell membrane damage. We proceed to review the current state of evidence on the clinical relevance and consequences of the red cell storage lesion, while discussing the strengths and limitations of clinical studies.

The use of an extracorporeal membrane oxygenation anticoagulation laboratory protocol is associated with decreased blood product use, decreased hemorrhagic complications, and increased circuit life

OBJECTIVES

To determine if a comprehensive extracorporeal membrane oxygenation anticoagulation monitoring protocol results in fewer hemorrhagic complications, reduced blood product usage, and increased circuit life.

DESIGN

In September 2011, we augmented our standard extracorporeal membrane oxygenation laboratory protocol to include anti-factor Xa assays, thromboelastography, and antithrombin measurements. We performed a retrospective chart review to determine outcomes for patients placed on extracorporeal membrane oxygenation prior to and after the initiation of our anticoagulation laboratory protocol.

SETTING

Tertiary care, academic children's hospital.

PATIENTS

All patients who were placed on extracorporeal membrane oxygenation at our institution from January 1, 2007, to September 30, 2013.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

There were 261 extracorporeal membrane oxygenation runs before the initiation of the protocol and 105 extracorporeal membrane oxygenation runs after the initiation of the protocol. There were no major changes to our extracorporeal membrane oxygenation circuit or changes to our transfusion threshold during the study period. The indication for extracorporeal membrane oxygenation, age, and severity of illness of the patients were similar before and after protocol initiation. Median blood product usage for packed RBCs, fresh frozen plasma, platelets, and cryoprecipitate decreased significantly after protocol initiation. The occurrence of cannula site bleeding decreased from 22% to 12% (p = 0.04), and surgical site bleeding decreased from 38% to 25% (p = 0.02). Median extracorporeal membrane oxygenation circuit life increased from 3.6 to 4.3 days (p = 0.02). A trend toward increased patient survival was noted, but it did not reach statistical significance.

CONCLUSIONS

We demonstrate an association between an extracorporeal membrane oxygenation anticoagulation laboratory protocol using anti-factor Xa assays, thromboelastography, and antithrombin measurements and a decrease in blood product transfusion, a decrease in hemorrhagic complications, and an increase in circuit life. To our knowledge, this is the first study to demonstrate clinical benefit associated with the use of these laboratory values for patients on extracorporeal membrane oxygenation.

Red blood cell storage lesion

OBJECTIVE

To summarize current understanding of the mechanisms responsible for changes occurring during red blood cell (RBC) storage, collectively known as the storage lesion, and to review the biological and clinical consequences of increasing storage time of RBCs.

DATA SOURCES

Human and veterinary clinical studies, experimental animal model studies, and reviews of the RBC storage lesion with no date restrictions.

HUMAN DATA SYNTHESIS

Experimental studies have characterized the evolution of human RBC and supernatant changes that occur during storage and form the basis for concern about the potential for harm from long-term storage of RBCs. Although 4 randomized controlled trials of varying sizes failed to find an association between RBC storage time and negative clinical outcomes, a recent meta-analysis and numerous observational clinical studies have demonstrated that transfusion of old versus fresh stored RBCs is associated with an increased risk of morbidity and mortality, particularly among trauma victims and cardiac surgery patients. Potential clinical consequences of RBC transfusion following development of the storage lesion include risk of organ dysfunction, organ failure, infections, and death.

VETERINARY DATA SYNTHESIS

Experimental animal models have contributed to the evidence supporting adverse consequences of the RBC storage lesion. Studies on relevant RBC storage issues such as the effect of different preservative solutions and leukoreduction have been completed. Transfusion with RBCs stored for 42 days increases mortality in dogs with experimental sepsis.

CONCLUSION

Storage of RBCs induces progressive biochemical, biomechanical, and immunologic changes that affect red cell viability, deformability, oxygen carrying capacity, microcirculatory flow, and recipient response. Most reports in the human and veterinary literature support the concept that there are deleterious effects of the RBC storage lesion, but additional studies with improved experimental design are needed to identify compelling reasons to modify current blood banking and transfusion practices.

Transfusion of stored red blood cells in trauma patients is not associated with increased procoagulant microparticles

BACKGROUND

We set out to determine the effects of transfusing stored red blood cells (RBCs) on the levels of procoagulant microparticles (MPs) in the blood of trauma patients.

METHODS

Blood was drawn and processed to platelet poor plasma for MP analysis for 409 injured patients seen in the trauma bay from February 2011 to January 2013. Blood from 27 noninjured volunteers was also analyzed. Quantification of total procoagulant MP (per microliter plasma) using a direct plasma analysis via flow cytometry was performed. Demographic data, Injury Severity Score (ISS), overall mortality, and units of transfused packed RBCs were collected. Data are presented as median (interquartile range [IQR]). Transfusion groups were assessed using t test or Wilcoxon rank-sum test as appropriate. The α level was set as 0.05 for statistical significance.

RESULTS

Median ISS was 12 (IQR, 5-19), 12% were transfused, median age was 48 years (IQR, 29-62 years), 68% were male, and overall mortality was 3%. Median units transfused were 3 (IQR, 2-5). The median number of all procoagulant MP was greater in trauma patients (median 758; IQR, 405-1,627) when compared with our control subjects (median, 232; IQR, 125-372; p < 0.0001). This difference remained significant after adjusting for age and sex (p < 0.0001). In 39 patients who had MP levels measured before transfusion with RBC, the procoagulant MP levels did not change after transfusion (p = 0.07). Patients transfused with RBCs that were 14 days or older did not have increased procoagulant MP levels when compared with those that received RBCs that were younger than 14 days (p = 0.5).This was also true for those who received RBCs that were 28 days or older when compared with those that received RBCs that were younger than 28 days (p = 0.84).

CONCLUSION

Procoagulant MP is significantly greater in trauma patients as compared with volunteers, even after adjusting for age and sex. We did not observe any change in the levels of procoagulant MPs after transfusion of stored RBCs.

LEVEL OF EVIDENCE

Epidemiologic/prognostic study, level III.

RBC transfusion in pediatric patients supported with extracorporeal membrane oxygenation: is there an impact on tissue oxygenation?

OBJECTIVE

To examine first the RBC transfusion practice in pediatric patients supported with extracorporeal membrane oxygenation and second the relationship between transfusion of RBCs and changes in mixed venous saturation (SvO2) and cerebral regional tissue oxygenation, as measured by near-infrared spectroscopy in patients supported with extracorporeal membrane oxygenation.

DESIGN

Retrospective observational study.

SETTING

Pediatric, cardiovascular, and neonatal ICUs of a tertiary care children's hospital.

PATIENTS

All pediatric patients supported with extracorporeal membrane oxygenation between January 1, 2010, and December 31, 2010.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

There were 45 patients supported with extracorporeal membrane oxygenation. The median (interquartile range) phlebotomy during extracorporeal membrane oxygenation was 75 mL/kg (33, 149 mL/kg). A total of 617 transfusions were administered (median, 9 per patient; range = 1-57). RBC volumes transfused during extracorporeal membrane oxygenation support were 254 mL/kg (136, 557) and 267 mL/kg (187, 393; p = 0.82) for cardiac and noncardiac patients, respectively. Subtracting the volume of RBCs used for extracorporeal membrane oxygenation circuit priming, median RBC transfusion volumes were 131 and 80 mL/kg for cardiac and noncardiac patients, respectively (p = 0.26). The cardiac surgical patients received the most RBCs (529 vs 74 mL/kg for nonsurgical cardiac patients). The median hematocrit maintained during extracorporeal membrane oxygenation support was 37%, with no difference between cardiac and noncardiac patients. Patients supported with extracorporeal membrane oxygenation were exposed to a median of 10.9 (range, 3-43) individual donor RBC units. Most transfusions resulted in no significant change in either SvO2 or cerebral near-infrared spectroscopy. Only 5% of transfusions administered (31/617) resulted in an increase in SvO2 of more than 5%, whereas an increase in cerebral near-infrared spectroscopy of more than 5 was only observed in 9% of transfusions (53/617). Most transfusions (73%) were administered at a time when the pretransfusion SvO2 was more than 70%.

CONCLUSIONS

Patients supported with extracorporeal membrane oxygenation were exposed to large RBC transfusion volumes for treatment of mild anemia resulting from blood loss, particularly phlebotomy. In the majority of events, RBC transfusion did not significantly alter global tissue oxygenation, as assessed by changes in SvO2 and cerebral near-infrared spectroscopy. Most transfusions were administered at a time at which the patient did not appear to be oxygen delivery dependent according to global measures of tissue oxygenation.