Use of low titer O whole blood in infants and young children undergoing cardiac surgery with cardiopulmonary bypass.

BACKGROUND: Low titer group O whole blood (LTOWB) is commonly used for severe bleeding in trauma patients. LTOWB may also benefit young children requiring cardiac surgery with cardiopulmonary bypass (CPB) at risk of severe bleeding. STUDY DESIGN AND METHODS: In this retrospective study, children <2 years old who underwent cardiac surgery with CPB were included. Comparisons were performed between those receiving component therapy (CT) versus those receiving LTOWB plus CT (LTOWB+CT). Outcomes included drainage tube (DT) output and total transfusion volumes. Optimization-based weighting was used for adjusted analyses between groups. RESULTS: There were 117 patients transfused with only CT and 127 patients transfused with LTOWB+CT. In the LTOWB+CT group, 66 were Group non-O and 61 were Group O. Total transfusion volumes given from the start of the operation until the first 24 h in the cardiac intensive care unit was a median (IQR) 41 (10, 93) mL/kg in the CT group and 48 (28, 77) mL/kg in the LTOWB+CT group, (p = .28). Median (IQR) DT output was 22 (15-32) in CT versus 22 (16-28) in LTOWB+CT groups, (p = .27). There were no differences in death, renal failure and a composite of death and renal failure between the two groups, but there were statistically fewer re-explorations for bleeding in the LTOWB+CT group (p < .001). CONCLUSIONS: The use of LTOWB appears to be safe in <2 years old undergoing cardiac surgery and may reduce re-explorations for severe bleeding. Large trials are needed to determine the efficacy and safety of LTOWB in this population with severe bleeding.

Red Blood Cell Transfusion: 2023 AABB International Guidelines.

Importance: Red blood cell transfusion is a common medical intervention with benefits and harms. Objective: To provide recommendations for use of red blood cell transfusion in adults and children. Evidence Review: Standards for trustworthy guidelines were followed, including using Grading of Recommendations Assessment, Development and Evaluation methods, managing conflicts of interest, and making values and preferences explicit. Evidence from systematic reviews of randomized controlled trials was reviewed. Findings: For adults, 45 randomized controlled trials with 20 599 participants compared restrictive hemoglobin-based transfusion thresholds, typically 7 to 8 g/dL, with liberal transfusion thresholds of 9 to 10 g/dL. For pediatric patients, 7 randomized controlled trials with 2730 participants compared a variety of restrictive and liberal transfusion thresholds. For most patient populations, results provided moderate quality evidence that restrictive transfusion thresholds did not adversely affect patient-important outcomes. Recommendation 1: for hospitalized adult patients who are hemodynamically stable, the international panel recommends a restrictive transfusion strategy considering transfusion when the hemoglobin concentration is less than 7 g/dL (strong recommendation, moderate certainty evidence). In accordance with the restrictive strategy threshold used in most trials, clinicians may choose a threshold of 7.5 g/dL for patients undergoing cardiac surgery and 8 g/dL for those undergoing orthopedic surgery or those with preexisting cardiovascular disease. Recommendation 2: for hospitalized adult patients with hematologic and oncologic disorders, the panel suggests a restrictive transfusion strategy considering transfusion when the hemoglobin concentration is less than 7 g/dL (conditional recommendations, low certainty evidence). Recommendation 3: for critically ill children and those at risk of critical illness who are hemodynamically stable and without a hemoglobinopathy, cyanotic cardiac condition, or severe hypoxemia, the international panel recommends a restrictive transfusion strategy considering transfusion when the hemoglobin concentration is less than 7 g/dL (strong recommendation, moderate certainty evidence). Recommendation 4: for hemodynamically stable children with congenital heart disease, the international panel suggests a transfusion threshold that is based on the cardiac abnormality and stage of surgical repair: 7 g/dL (biventricular repair), 9 g/dL (single-ventricle palliation), or 7 to 9 g/dL (uncorrected congenital heart disease) (conditional recommendation, low certainty evidence). Conclusions and Relevance: It is good practice to consider overall clinical context and alternative therapies to transfusion when making transfusion decisions about an individual patient.

Prolonged Elevations of Factor VIII and von Willebrand Factor Antigen After Multisystem Inflammatory Syndrome in Children.

Multisystem Inflammatory Syndrome in Children (MIS-C) is a late systemic inflammatory response to a recent mild or asymptomatic coronavirus disease of 2019 infection. The pathophysiology is incompletely understood but it often features significant coagulopathy along with cardiac and endothelial dysfunction. Endothelial inflammation has been primarily described in acute coronavirus disease of 2019 infection, with less characterization in MIS-C. Here we describe novel findings of nearly universal severe and prolonged factor VIII (FVIII) and von Willebrand factor antigen elevations in an institutional cohort of patients with MIS-C ages younger than or 21 years old (N=31). All patients had elevated acute phase reactants and D-dimer at presentation and met published criteria for MIS-C. FVIII was high at presentation in 97% of patients but continued to rise during the ensuing weeks of treatment to a mean 429%, peaking on median day 17 of illness as an outpatient. FVIII levels were >600% in multiple patients. von Willebrand factor antigen was measured less frequently but showed similar trends. These escalations occurred amidst resolving cardiac dysfunction and acute phase reactant normalization and despite patients receiving multimodal anti-inflammatory treatments and aspirin and enoxaparin thromboprophylaxis. No thrombotic events occurred. Endothelial dysfunction represented by very elevated FVIII levels may persist longer than other acute phase reactants may reflect.

Design and logistical considerations for the randomized adaptive non-inferiority storage-duration-ranging CHIlled Platelet Study.

BACKGROUND: Platelet transfusion is a potentially life-saving therapy for actively bleeding patients, ranging from those undergoing planned surgical procedures to those suffering unexpected traumatic injuries. Platelets are currently stored at room temperature (20°C-24°C) with a maximum storage duration of 7 days after donation. The CHIlled Platelet Study trial will compare the efficacy and safety of standard room temperature-stored platelets with platelets that are cold-stored (1°C-6°C), that is, chilled, with a maximum of storage up to 21 days in adult and pediatric patients undergoing complex cardiac surgical procedures. METHODS/RESULTS: CHIlled Platelet Study will use a Bayesian adaptive design to identify the range of cold storage durations for platelets that are non-inferior to standard room temperature-stored platelets. If cold-stored platelets are non-inferior at durations greater than 7 days, a gated superiority analysis will identify durations for which cold-stored platelets may be superior to standard platelets. We present example simulations of the CHIlled Platelet Study design and discuss unique challenges in trial implementation. The CHIlled Platelet Study trial has been funded and will be implemented in approximately 20 clinical centers. Early randomization to enable procurement of cold-stored platelets with different storage durations will be required, as well as a platelet tracking system to eliminate platelet wastage and maximize trial efficiency and economy. DISCUSSION: The CHIlled Platelet Study trial will determine whether cold-stored platelets are non-inferior to platelets stored at room temperature, and if so, will determine the maximum duration (up to 21 days) of storage that maintains non-inferiority. TRIAL REGISTRATION: ClinicalTrials.gov, NCT04834414.

Therapeutic plasma exchange and intravenous immune globulin in the treatment of heparin-induced thrombocytopenia: A systematic review.

BACKGROUND: Immunomodulatory strategies in heparin-induced thrombocytopenia (HIT) include the use of intravenous immune globulin (IVIG) and therapeutic plasma exchange (TPE). The optimal application of these therapies is unknown and outcomes data are limited. We investigated treatment categories and laboratory and clinical outcomes of IVIG and/or TPE in HIT with a systematic literature review. STUDY DESIGN AND METHODS: We searched MEDLINE, Embase, and Web of Science through December 2019 for studies combining controlled vocabulary and keywords related to thrombocytopenia, heparin, TPE, and IVIG. The primary outcome was treatment indication. Secondary outcomes were platelet recovery, HIT laboratory parameters, heparin re-exposure, and post-treatment course. Case-level data were analyzed by qualitative synthesis. RESULTS: After 4241 references were screened, we identified 60 studies with four main categories of IVIG and/or TPE use as follows: (a) treatment of refractory HIT (n = 35; 31%); (b) initial therapy (n = 45; 40%); (c) cardiopulmonary bypass surgery (CPB; n = 30; 27%); and (d) other (n = 2; 2%). IVIG was most commonly used for the treatment of refractory HIT while TPE was primarily used to facilitate heparin exposure during CPB. Both IVIG and TPE were equally used as initial therapy. Heparin re-exposure occurred without thrombotic event in 29 TPE-treated patients and three IVIG-treated patients. CONCLUSION: In patients with HIT, both TPE and IVIG are used for initial therapy or treatment of refractory HIT. However, TPE is more commonly used in patients undergoing CPB. Prospective studies may help clarify which treatment is indicated in HIT population subsets.

Vascular access practices for therapeutic apheresis: Results of a survey.

INTRODUCTION: Obtaining vascular access (VA) is a critical part of the therapeutic apheresis (TA) treatment plan. Currently, there are no guidelines for VA decision-making and maintenance related to TA procedures. MATERIALS AND METHODS: A 28-question survey to gather qualitative information regarding VA practices was distributed to the American Society for Apheresis (ASFA) 2018 Annual Meeting attendees and all ASFA members for voluntary participation. The descriptive analyses were reported as the number and frequency of responses for each question. RESULTS: Total participation was 206 with 147 (71.4%) answering some or all 16 VA focused questions. The majority of respondents were nurses or physicians (89.0%) at sites providing ≥100 procedures. The most common TA procedures were plasma exchange, red cell exchange, and leukocytapheresis. The VA evaluation was predominantly performed by the TA service (80.3%, 118/147). The majority of TA physicians and/or providers do not insert (91.7%, 132/144) or remove (81.2%, 117/143) VA catheters. When an emergent TA procedure is needed, the majority of respondents felt <2 hours was an acceptable turnaround time for VA placement (64.3%, 92/143). The most common anticoagulant for locking catheters and/or ports was heparin. The majority of TA services (54.3%, 76/140) collect data on aborted procedures due to catheter/line/port problems unrelated to infection, but only 41.4% (58/140) collect data on infections. CONCLUSION: VA contributes significantly to the overall risks associated with and the safety of TA. Our survey shows that there is substantial variation but common themes in TA VA practices. Several areas for future research may be identified.

Therapeutic plasma exchange for management of heparin-induced thrombocytopenia: Results of an international practice survey.

INTRODUCTION: Anti-heparin/platelet factor 4 antibody immune complexes resulting from heparin-induced thrombocytopenia (HIT) are removed by therapeutic plasma exchange (TPE). We sought to define TPE in HIT practice patterns using an international survey. METHODS: A 31-item online survey was disseminated through the American Society for Apheresis. After institutional duplicate responses were eliminated, a descriptive analysis was performed. RESULTS: The survey was completed by 94 respondents from 78 institutions in 18 countries. Twenty-nine institutions (37%) used TPE for HIT (YES cohort) and 49 (63%) did not (NO cohort). Most NO respondents (65%) cited "no requests received" as the most common reason for not using TPE. Of the 29 YES respondents, 10 (34%) gave incomplete information and were excluded from the final analysis, leaving 19 responses. Of these, 18 (95%) treated ≤10 HIT patients over a 2-year period. The most common indications were cardiovascular surgery (CS; 63%) and HIT-associated thrombosis (HT; 26%). The typical plasma volume processed was 1.0 (63% CS and 58% HT). For CS, the typical replacement fluid was plasma (42%) and for HT, it was determined on an individual basis (32%). For CS, patients were treated with a set number of TPE procedures (37%) or laboratory/clinical response (37%). For HT, the number of TPE procedures typically depended on laboratory/clinical response (42%). CONCLUSION: In a minority of responding institutions, TPE is most commonly used in HIT to prophylactically treat patients who will undergo heparin re-exposure during CS. Prospective studies are needed to more clearly define the role of TPE in HIT.

Reversal of acquired von Willebrand syndrome with allogeneic stem cell transplant for chronic lymphocytic leukemia.

Acquired von Willebrand syndrome (AVWS) is a rare, potentially fatal bleeding disorder caused by low activity of von Willebrand factor (VWF) in patients without congenital deficiency. The majority of adult cases are associated with hematological malignancy, including lymphoproliferative (48%) or myeloproliferative (15%) disorders (Federici et al., 2000). Both qualitative and quantitative defects occur, due to antibody-mediated clearance or functional interference, increased proteolysis, absorption to malignant cells or platelets, or increased shear stress due to valvular defects or mechanical vascular devices (Tiede et al., 2011). The predominant mechanism for decreased or absent VWF in malignancy is autoantibodies that are inhibitory to VWF function or shorten VWF survival (Kumar et al., 2002 [3]). Antibody-mediated clearance occurs through inactivating antibody directed towards VWF, antibody binding the non-active sites of VWF, and nonspecific antibodies that form circulating immune complexes with VWF, enhancing clearance by the reticuloendothelial system (Mannucci et al., 1984). Bleeding may be very difficult to treat due to reduced half-life of VWF-concentrates.

Hemostasis management and therapeutic plasma exchange: Results of a practice survey.

BACKGROUND: Patients undergoing therapeutic plasma exchange (TPE) may present with risks for hemorrhage or thrombosis. Use of replacement fluids devoid of coagulation factors will decrease factor levels and platelet levels. There are no established guidelines for hemostasis management in these situations. MATERIALS AND METHODS: A survey to evaluate current hemostasis management practice during TPE was conducted using online survey software. One response per institution was analyzed based on a hierarchical algorithm, excluding membrane filtration users, resulting in a maximum of 107 respondents. Descriptive analysis was performed with results reported as the number and frequency (%) of respondents to each question. RESULTS: Apheresis Medicine physicians, alone (59.4%) or jointly with the requesting provider (29.2%), choose the replacement fluid. Based on a theoretical patient case receiving five TPEs approximately every other day, the percent of respondents who would use albumin with or without normal saline was 94.7% with no history of a bleeding or clotting disorder, 1.1% with active bleeding, and 8.8% with hypofibrinogenemia (<100 mg/dL) due to recent TPE. More respondents would use albumin with or without normal saline for replacement fluid when a minor invasive procedure (49.5%) vs a major surgery (8.9%) was performed 1 day before TPE. Replacement fluid selection varied among respondents for several other clinical conditions. The most frequent use for cryoprecipitate by respondents (14.3%) was hypofibrinogenemia. CONCLUSIONS: These survey results demonstrate wide interinstitutional variation in replacement fluid selection to manage hemostasis in patients undergoing TPE. Further studies are needed to guide optimal hemostasis management with TPE.

Consensus Recommendations for RBC Transfusion Practice in Critically Ill Children From the Pediatric Critical Care Transfusion and Anemia Expertise Initiative.

OBJECTIVES: To date, there are no published guidelines to direct RBC transfusion decision-making specifically for critically ill children. We present the recommendations from the Pediatric Critical Care Transfusion and Anemia Expertise Initiative. DESIGN: Consensus conference series of multidisciplinary, international experts in RBC transfusion management of critically ill children. SETTING: Not applicable. INTERVENTION: None. SUBJECTS: Children with, or children at risk for, critical illness who receive or are at risk for receiving a RBC transfusion. METHODS: A panel of 38 content and four methodology experts met over the course of 2 years to develop evidence-based, and when evidence lacking, expert consensus-based recommendations regarding decision-making for RBC transfusion management and research priorities for transfusion in critically ill children. The experts focused on nine specific populations of critically ill children: general, respiratory failure, nonhemorrhagic shock, nonlife-threatening bleeding or hemorrhagic shock, acute brain injury, acquired/congenital heart disease, sickle cell/oncology/transplant, extracorporeal membrane oxygenation/ventricular assist/ renal replacement support, and alternative processing. Data to formulate evidence-based and expert consensus recommendations were selected based on searches of PubMed, EMBASE, and Cochrane Library from 1980 to May 2017. Agreement was obtained using the Research and Development/UCLA Appropriateness Method. Results were summarized using the Grading of Recommendations Assessment, Development, and Evaluation method. MEASUREMENTS AND RESULTS: The Transfusion and Anemia Expertise Initiative consensus conference developed and reached consensus on a total of 102 recommendations (57 clinical [20 evidence based, 37 expert consensus], 45 research recommendations). All final recommendations met agreement, defined a priori as greater than 80%. A decision tree to aid clinicians was created based on the clinical recommendations. CONCLUSIONS: The Transfusion and Anemia Expertise Initiative recommendations provide important clinical guidance and applicable tools to avoid unnecessary RBC transfusions. Research recommendations identify areas of focus for future investigation to improve outcomes and safety for RBC transfusion.

Recommendations on RBC Transfusion Support in Children With Hematologic and Oncologic Diagnoses From the Pediatric Critical Care Transfusion and Anemia Expertise Initiative.

OBJECTIVES: To present the recommendations and supporting evidence for RBC transfusions in critically ill children with hematologic and oncologic disease from the Pediatric Critical Care Transfusion and Anemia Expertise Initiative. DESIGN: Consensus conference series of international, multidisciplinary experts in RBC transfusion management of critically ill children. METHODS: The panel of 38 experts developed evidence-based and, when evidence was lacking, expert-based clinical recommendations and research priorities for RBC transfusions in critically ill children. The hematologic/oncologic subgroup included seven experts. Electronic searches were conducted using PubMed, EMBASE, and Cochrane Library databases from 1980 to May 2017. Agreement was obtained using the Research and Development/UCLA Appropriateness Method. Results were summarized using the Grading of Recommendations Assessment, Development, and Evaluation method. RESULTS: The hematologic/oncologic subgroup developed 14 recommendations (seven clinical, seven research); all achieved greater than 80% agreement. In patients with sickle cell disease, Transfusion and Anemia Expertise Initiative recommends: 1) RBC transfusion to achieve a target hemoglobin concentration of 10 g/dL rather than hemoglobin of less than 30% prior to surgical procedures requiring general anesthesia and 2) exchange transfusion over simple (nonexchange) transfusion if the child's condition is deteriorating (based on clinical judgment), otherwise a simple, nonexchange RBC transfusion is recommended. There is insufficient evidence to make recommendations on transfusion thresholds for patients with sickle cell disease prior to minor procedures, with acute stroke or with pulmonary hypertension. For patients with oncologic disease or undergoing hematopoietic stem cell transplant, a hemoglobin concentration of 7-8 g/dL is recommended. Due to lack of evidence, research is needed to clarify the appropriate transfusion thresholds in these patients. CONCLUSIONS: Transfusion and Anemia Expertise Initiative developed specific pediatric recommendations regarding RBC transfusion management in critically ill children with sickle cell disease, oncologic disease, and hematopoietic stem cell transplant and recommendations to help guide future research priorities.

The design of an adaptive clinical trial to evaluate the efficacy of platelets stored at low temperature in surgical patients.

BACKGROUND: Storage of platelets at 4°C compared with 22°C may increase both hemostatic activity and storage duration; however, the maximum duration of cold storage is unknown. We report the design of an innovative, prospective, randomized, Bayesian adaptive, "duration finding" clinical trial to evaluate the efficacy and maximum duration of storage of platelets at 4°C. METHODS: Patients undergoing cardiac surgery and requiring platelet transfusions will be enrolled. Patients will be randomized to receive platelets stored at 22°C up to 5 days or platelets stored at 4°C up to 5 days, 10 days, or 15 days. Longer durations of cold storage will only be used if shorter durations at 4°C appear noninferior to standard storage, based on a four-level clinical hemostatic efficacy score with a NIM of a half level. A Bayesian linear model is used to estimate the hemostatic efficacy of platelet transfusions based on the actual duration of storage at 4°C. RESULTS: The type I error rate, if platelets stored at 4°C are inferior, is 0.0247 with an 82% probability of early stopping for futility. With a maximum sample size of 1,500, the adaptive trial design has a power of over 90% to detect noninferiority and a high probability of correctly identifying the maximum duration of storage at 4°C that is noninferior to 22°C. CONCLUSION: An adaptive, duration-finding trial design will generate Level I evidence and allow the determination of the maximum duration platelet storage at 4°C that is noninferior to standard storage at 22°C, with respect to hemostatic efficacy. The adaptive trial design helps to ensure that longer cold storage durations are only explored once substantial supportive data are available for the shorter duration(s) and that the trial stops early if continuation is likely to be futile.

Pediatric Acquired von Willebrand Disease With Berlin Heart Excor Ventricular Assist Device Support.

BACKGROUND: The balance of hemostasis and anticoagulation is a concern for patients dependent upon ventricular assist devices (VADs). Bleeding is a common complication with both short- and long-term use of these devices. A better understanding of the risk factors and etiologies of bleeding associated with these devices is needed and could improve the overall results. We sought to determine the relationship of mechanical circulatory assist device use with acquired von Willebrand disease (avWD) in children. METHODS: Data were analyzed retrospectively via review of the medical record of 19 consecutive patients who were supported with the Berlin EXCOR VAD for greater than 24 hours. Laboratory testing for avWD was performed at the discretion of the clinical team, often in association with clinical bleeding. RESULTS: Of 19 pediatric patients, 10 (52.6%) had laboratory testing consistent with avWD. Median time to detection of avWD was 35 days postimplantation of device (range 0-310 days). Both minor mucosal bleeding and bleeding requiring intervention were highly prevalent in patients in whom avWD was identified (10/10 [100%] and 7/10 [70%]). The mean age of all patients was 3.3 years, but patients found to have avWD tended to be older (mean 5.3 years) and supported with larger volume VADs. CONCLUSIONS: This experience demonstrates a high prevalence of avWD following EXCOR implantation. Bleeding, older age, and larger VAD size may be associated with avWD. These results should stimulate critical evaluation of individualized anticoagulation regimens in pediatric VAD patients.

Impact of Graft-Recipient ABO Compatibility on Outcomes after Umbilical Cord Blood Transplant for Nonmalignant Disease.

Existing literature shows mixed conclusions regarding the impact of ABO incompatibility on outcomes after hematopoietic stem cell transplantation. Because the future for umbilical cord blood (UCB) expansion technologies is bright, we assessed whether this typically overlooked graft characteristic impacted various outcomes after UCB transplantation (UCBT) for nonmalignant disorders (NMDs). A prospectively maintained institutional blood and marrow transplant program database was queried for all patients undergoing first UCBT for NMDs. UCB and recipient ABO compatibility was considered as matched, major mismatched, minor mismatched, or bidirectional mismatched. The impact of ABO incompatibility was assessed on overall survival, graft failure, acute and chronic graft-versus-host disease (GVHD), time to neutrophil and platelet recovery, day 0 to day 100 RBC transfusion burden, and donor hematopoietic chimerism. Through December 2014, 270 patients have undergone first UCBT for various NMDs. In both univariable and multivariable analyses, ABO compatibility status did not appear to impact any outcomes assessed, although a trend toward increased grades III to IV acute GVHD was seen in recipients of major mismatched units. When considering UCBT for treatment of NMDs, ABO compatibility between the donor unit and intended recipient does not appear to be an important consideration in the UCB unit choice.

An in situ forming biodegradable hydrogel-based embolic agent for interventional therapies.

We present here the characteristics of an in situ forming hydrogel prepared from carboxymethyl chitosan and oxidized carboxymethyl cellulose for interventional therapies. Gelation, owing to the formation of Schiff bases, occurred both with and without the presence of a radiographic contrast agent. The hydrogel exhibited a highly porous internal structure (pore diameter 17±4 µm), no cytotoxicity to human umbilical vein endothelial cells, hemocompatibility with human blood, and degradability in lysozyme solutions. Drug release from hydrogels loaded with a sclerosant, tetracycline, was measured at pH 7.4, 6 and 2 at 37°C. The results showed that tetracycline was more stable under acidic conditions, with a lower release rate observed at pH 6. An anticancer drug, doxorubicin, was loaded into the hydrogel and a cumulative release of 30% was observed over 78 h in phosphate-buffered saline at 37°C. Injection of the hydrogel precursor through a 5-F catheter into a fusiform aneurysm model was feasible, leading to complete filling of the aneurysmal sac, which was visualized by fluoroscopy. The levels of occlusion by hydrogel precursors (1.8% and 2.1%) and calibrated microspheres (100-300 µm) in a rabbit renal model were compared. Embolization with hydrogel precursors was performed without clogging and the hydrogel achieved effective occlusion in more distal arteries than calibrated microspheres. In conclusion, this hydrogel possesses promising characteristics potentially beneficial for a wide range of vascular intervention procedures that involve embolization and drug delivery.