Prevalence and clinical implications of heightened plastic chemical exposure in pediatric patients undergoing cardiopulmonary bypass.

BACKGROUND: Phthalate chemicals are used to manufacture plastic medical products, including many components of cardiopulmonary bypass (CPB) circuits. We aimed to quantify iatrogenic phthalate exposure in pediatric patients undergoing cardiac surgery and examine the link between phthalate exposure and postoperative outcomes. STUDY DESIGN AND METHODS: The study included pediatric patients undergoing (n=122) unique cardiac surgeries at Children's National Hospital. For each patient, a single plasma sample was collected preoperatively and two additional samples were collected postoperatively upon return from the operating room and the morning after surgery. Concentrations of di(2-ethylhexyl) phthalate (DEHP) and its metabolites were quantified using ultra high-pressure liquid chromatography coupled to mass spectrometry. RESULTS: Patients were subdivided into three groups, according to surgical procedure: (1) cardiac surgery not requiring CPB support, (2) cardiac surgery requiring CPB with a crystalloid prime, and (3) cardiac surgery requiring CPB with red blood cells (RBCs) to prime the circuit. Phthalate metabolites were detected in all patients, and postoperative phthalate levels were highest in patients undergoing CPB with an RBC-based prime. Age-matched (<1 year) CPB patients with elevated phthalate exposure were more likely to experience postoperative complications. RBC washing was an effective strategy to reduce phthalate levels in CPB prime. DISCUSSION: Pediatric cardiac surgery patients are exposed to phthalate chemicals from plastic medical products, and the degree of exposure increases in the context of CPB with an RBC-based prime. Additional studies are warranted to measure the direct effect of phthalates on patient health outcomes and investigate mitigation strategies to reduce exposure.

Prevalence and Clinical Implications of Heightened Plastic Chemical Exposure in Pediatric Patients Undergoing Cardiopulmonary Bypass.

Importance: Phthalate chemicals are used to manufacture disposable plastic medical products, including blood storage bags and components of cardiopulmonary bypass (CPB) circuits. During cardiac surgery, patients can be inadvertently exposed to phthalate chemicals that are released from these plastic products. Objective: To quantify iatrogenic phthalate chemical exposure in pediatric patients undergoing cardiac surgery, and examine the link between phthalate exposure and post-operative outcomes. Design Setting and Participants: The study cohort included 122 pediatric patients undergoing cardiac surgery at Children's National Hospital. For each patient, a single plasma sample was collected pre-operatively and two additional samples were collected post-operatively upon return from the operating room (post-operative day 0) and the morning after surgery (post-operative day 1). Exposures: Concentrations of di(2-ethylhexyl)phthalate (DEHP) and its metabolites were quantified using ultra high-pressure liquid chromatography coupled to mass spectrometry. Main Outcomes and Measures: Plasma concentrations of phthalates, post-operative blood gas measurements, and post-operative complications. Results: Study subjects were subdivided into three groups, according to surgical procedure: 1) cardiac surgery not requiring CPB support, 2) cardiac surgery requiring CPB with crystalloid prime, and 3) cardiac surgery requiring CPB with red blood cells (RBCs) to prime the circuit. Phthalate metabolites were detected in all patients, and postoperative phthalate levels were highest in patients undergoing CPB with RBC-based prime. Age-matched (<1 year) CPB patients with elevated phthalate exposure were more likely to experience post-operative complications, including arrhythmias, low cardiac output syndrome, and additional post-operative interventions. RBC washing was an effective strategy to reduce DEHP levels in CPB prime. Conclusions and Relevance: Pediatric cardiac surgery patients are exposed to phthalate chemicals from plastic medical products, and the degree of exposure increases in the context of CPB with RBC-based prime. Additional studies are warranted to measure the direct effect of phthalates on patient health outcomes and investigate mitigation strategies to reduce exposure. Key Points: Question: Is cardiac surgery with cardiopulmonary bypass a significant source of phthalate chemical exposure in pediatric patients?Findings: In this study of 122 pediatric cardiac surgery patients, phthalate metabolites were quantified from blood samples before and after surgery. Phthalate concentrations were highest in patients undergoing cardiopulmonary bypass with red blood cell-based prime. Heightened phthalate exposure was associated with post-operative complications.Meaning: Cardiopulmonary bypass is a significant source of phthalate chemical exposure, and patients with heightened exposure may be at greater risk for postoperative cardiovascular complications.

The Recipient Epidemiology and Donor Evaluation Study-IV-Pediatric (REDS-IV-P): A research program striving to improve blood donor safety and optimize transfusion outcomes across the lifespan.

BACKGROUND: The Recipient Epidemiology and Donor Evaluation Study-IV-Pediatric (REDS-IV-P) is a new iteration of prior National Heart, Lung, and Blood Institute (NHLBI) REDS programs that focus on improving transfusion recipient outcomes across the lifespan as well as the safety and availability of the blood supply. STUDY DESIGN AND METHODS: The US program includes blood centers and hospitals (22 including 6 free-standing Children's hospitals) in four geographic regions. The Brazilian program has 5 participating hemocenters. A Center for Transfusion Laboratory Studies (CTLS) and a Data Coordinating Center (DCC) support synergistic studies and activities over the 7-year REDS-IV-P program. RESULTS: The US is building a centralized, vein-to-vein (V2V) database, linking information collected from blood donors, their donations, the resulting manufactured components, and data extracts from hospital electronic medical records of transfused and non-transfused patients. Simultaneously, the Brazilian program is building a donor, donation, and component database. The databases will serve as the backbone for retrospective and prospective observational studies in transfusion epidemiology, transfusion recipient outcomes, blood component quality, and emerging blood safety issues. Special focus will be on preterm infants, patients with sickle cell disease, thalassemia or cancer, and the effect of donor biologic variability and component manufacturing on recipient outcomes. A rapid response capability to emerging safety threats has resulted in timely studies related to Severe Acute Respiratory Syndrome Corona Virus-2 (SARS-CoV-2). CONCLUSIONS: The REDS-IV-P program endeavors to improve donor-recipient-linked research with a focus on children and special populations while also maintaining the flexibility to address emerging blood safety issues.

Glucose-6-phosphate dehydrogenase deficiency is more prevalent in Duffy-null red blood cell transfusion in sickle cell disease.

BACKGROUND: Resistance to malaria infection may be conferred by erythrocyte genetic variations including glucose-6-phosphate dehydrogenase (G6PD) deficiency and lack of Duffy antigens. In red blood cell (RBC) transfusion, G6PD deficiency may shorten transfusion survival. Because Duffy-null units are commonly transfused in sickle cell disease (SCD) due to antigen matching protocols, we examined whether Duffy-null donor RBC units have a higher prevalence of G6PD deficiency. MATERIALS AND METHODS: Pediatric patients with SCD on chronic transfusion therapy were followed prospectively for multiple transfusions. RBC unit segments were collected to measure G6PD activity and RBC genotyping. The decline in donor hemoglobin (ΔHbA) following transfusion was assessed from immediate posttransfusion estimates and HbA measurements approximately 1 month later. RESULTS: Of 564 evaluable RBC units, 59 (10.5%) were G6PD deficient (23 severe, 36 moderate deficiency); 202 (37.6%) units were Duffy-null. G6PD deficiency occurred in 40 (19.8%) Duffy-null units versus 15 (4.5%) Duffy-positive units (p < .0001). In univariate analysis, the fraction of Duffy-null RBC units per transfusion was associated with greater decline in HbA (p = .038); however, in multivariate analysis, severe G6PD deficiency (p = .0238) but not Duffy-null RBC (p = .0139) were associated with ΔHbA. CONCLUSION: Selection of Duffy-null RBC units may result in shorter in vivo survival of transfused RBCs due to a higher likelihood of transfusing units from G6PD deficient donors.

The mentored experience to enhance opportunities in research (METEOR) program.

PROBLEM: Medical students from groups that are underrepresented in medicine are less likely to pursue careers that incorporate research as compared to their white peers. Clinical and Translational Science Award (CTSA)-funded institutions encouraged centers to establish short-term, mentored summer research opportunities to motivate students underrepresented in medicine to enroll in medical school and ideally choose a career that incorporates research into their clinical practice. APPROACH: The Mentored Experience To Enhance Opportunities in Research (METEOR) Program was established in 2012 in partnership with the Clinical and Translational Science Institute at Children's National (CTSI-CN) and The George Washington University (GW) School of Medicine and Health Sciences. Rather than a single summer experience, the METEOR Program is innovative in that it is intended to support the success of participants throughout the duration of their medical school training and beyond. OUTCOMES: Scholarly output of participants of the first four cohorts included 23 empirical research articles in peer-reviewed journals, five review articles, eight case reports, one empirical research article in a student-led journal, one commentary in a professional journal, 20 university-based poster presentations, three national poster presentations, and one international poster presentation. Interviews revealed themes aligned with constructs of the Social Cognitive Career Theory. Overall mentorship was seen as a key component of the METEOR Program. In addition, the ability to come to campus prior to the start of medical school, as part of a cohesive cohort, along with the addition of lectures and field trips, further enhanced participants' experiences. NEXT STEPS: Our findings will be incorporated into improvements to the program for future cohorts and may inform the design of similar mentored research programs. With increased enrollment, quantitative studies of the effectiveness of the program are planned.

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

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

Transfusion practices for pediatric oncology and hematopoietic stem cell transplantation patients: Data from the National Heart Lung and Blood Institute Recipient Epidemiology and Donor Evaluation Study-III (REDS-III).

BACKGROUND: To evaluate transfusion practices in pediatric oncology and hematopoietic stem cell transplant (HSCT) patients. STUDY DESIGN AND METHODS: This is a multicenter retrospective study of children with oncologic diagnoses treated from 2013 to 2016 at hospitals participating in the National Heart Lung and Blood Institute Recipient Epidemiology and Donor Evaluation Study-III. Transfusion practices were evaluated by diagnosis codes and pre-transfusion laboratory values. RESULTS: A total of 4766 inpatient encounters of oncology and HSCT patients were evaluated, with 39.3% (95% confidence interval [CI]: 37.9%-40.7%) involving a transfusion. Red blood cells (RBCs) were the most commonly transfused component (32.4%; 95% CI: 31.1%-33.8%), followed by platelets (22.7%; 95% CI: 21.5%-23.9%). Patients in the 1 to <6 years of range were most likely to be transfused and HSCT, acute myeloid leukemia, and aplastic anemia were the diagnoses most often associated with transfusion. The median hemoglobin (Hb) prior to RBC transfusion was 7.5 g/dl (10-90th percentile: 6.4-8.8 g/dl), with 45.7% of transfusions being given at 7 to <8 g/dl. The median platelet count prior to platelet transfusion was 20 × 109 /L (10-90th percentile: 8-51 × 109 /L), and 37.9% of transfusions were given at platelet count of >20-50 × 109 /L. The median international normalized ratio (INR) prior to plasma transfusion was 1.7 (10-90th percentile: 1.3-2.7), and 36.3% of plasma transfusions were given at an INR between 1.4 and 1.7. DISCUSSION: Transfusion of blood components is common in hospitalized pediatric oncology/HSCT patients. Relatively high pre-transfusion Hb and platelet values and relatively low INR values prior to transfusion across the studied diagnoses highlight the need for additional studies in this population.

Flow-based analysis of cell division identifies highly active populations within plasma products during mixed lymphocyte cultures.

BACKGROUND: Leukoreduction to eliminate mononuclear cells within blood products is necessary to prevent graft-versus-host disease after transfusion. Published reports document low concentrations of mononuclear cells leftover in fresh-frozen plasma products, however the phenotype and the proliferative potential of these cells has not been tested. MATERIALS AND METHODS: We investigated residual cellular components contained within fresh and fresh-frozen plasma products and characterised their proliferative potential in co-cultures with unrelated allogeneic cells. We designed a flow-based assay to phenotype cells and quantify cell division by measuring the dilution of fluorescently labeled protein as cells divide. Leukocytes from consenting donors were purified from fresh liquid or fresh-frozen plasma units and cultured for three to seven days with unrelated irradiated allogeneic targets. RESULTS: We discovered a median of 1.6×107 viable lymphocytes were detectable in fresh plasma units after collection (n=8), comprised of a mixture of CD3+ CD8+ and CD3+ CD4+ cells. Furthermore, we identified a median of 8.4% of live CD3+ plasma lymphocytes divided as early as Day 4 when co-cultured with unrelated allogeneic cells, expanding to a median 88.8% by Day 7 (n=3). Although freezing the plasma product reduced the total number of viable leukocyte cells down to 2.3×105 (n=10), residual naive CD3+ cells were viable and demonstrated division through Day 7 of co-culture. DISCUSSION: The evidence of viable proliferative lymphocytes in fresh and fresh-frozen plasma products derived from centrifugation suggests that additional leukoreduction measures should be investigated to fully eradicate reactive lymphocytes from centrifuged plasma products.

Transfusion Practices in Pediatric Cardiac Surgery Requiring Cardiopulmonary Bypass: A Secondary Analysis of a Clinical Database.

OBJECTIVES: To describe blood component usage in transfused children with congenital heart disease undergoing cardiopulmonary bypass surgery across perioperative settings and diagnostic categories. DESIGN: Datasets from U.S. hospitals participating in the National Heart, Lung, and Blood Institute Recipient Epidemiology and Donor Evaluation Study-III were analyzed. SETTING: Inpatient admissions from three U.S. hospitals from 2013 to 2016. PATIENTS: Transfused children with congenital heart disease undergoing single ventricular, biventricular surgery, extracorporeal membrane oxygenation. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Eight hundred eighty-two transfused patients were included. Most of the 185 children with single ventricular surgery received multiple blood products: 81% RBCs, 79% platelets, 86% plasma, and 56% cryoprecipitate. In the 678 patients undergoing biventricular surgery, 85% were transfused plasma, 75% platelets, 74% RBCs, and 48% cryoprecipitate. All 19 patients on extracorporeal membrane oxygenation were transfused RBCs, plasma, and cryoprecipitate, and 18 were transfused platelets. Intraoperatively, patients commonly received all three components, while postoperative transfusions were predominantly single blood components. Pretransfusion hemoglobin values were normal/low-normal for age for all phases of care for single ventricular surgery (median hemoglobin 13.2-13.5 g/dL). Pretransfusion hemoglobin values for biventricular surgeries were higher intraoperatively compared with other timing (12.2 g/dL vs 11.2 preoperative and postoperative; p < 0.0001). Plasma transfusions for all patients were associated with a near normal international normalized ratio: single ventricular surgeries median international normalized ratio was 1.3 postoperative versus 1.8 intraoperative and biventricular surgeries median international normalized ratio was 1.1 intraoperative versus 1.7 postoperative. Intraoperative platelet transfusions with biventricular surgeries had higher median platelet count compared with postoperative pretransfusion platelet count (244 × 109/L intraoperative vs 69 × 109/L postoperative). CONCLUSIONS: Children with congenital heart disease undergoing cardiopulmonary bypass surgery are transfused many blood components both intraoperatively and postoperatively. Multiple blood components are transfused intraoperatively at seemingly normal/low-normal pretransfusion values. Pediatric evidence guiding blood component transfusion in this population at high risk of bleeding and with limited physiologic reserve is needed to advance safe and effective blood conservation practices.

Impact of universal irradiation on chronic transfusion for sickle cell disease.

BACKGROUND: Irradiation of blood products prevents transfusion-associated graft-versus-host disease, but most patients do not require this modification which could have an adverse impact on transfusion outcomes. We hypothesized that irradiation may increase transfusion requirements for patients with sickle cell disease (SCD) receiving chronic transfusion. STUDY DESIGN AND METHODS: Our pediatric hospital implemented a new policy of universal blood product irradiation in May 2018. We conducted a retrospective chart review of patients with SCD receiving chronic red blood cell (RBC) transfusion throughout the year before and after institution of this policy. The primary outcome was the change in RBC transfusion volume per patient weight transfused during the pre- vs. post- universal irradiation period. Secondary outcomes were the change in median pretransfusion laboratory values. RESULTS: Among 17 patients, 8 (47%) received more RBCs the year before irradiation and 9 (53%) received more the year after irradiation. Implementation of universal irradiation did not significantly increase transfusion volumes needed to clinically manage this population (median change +1.7 ml/kg/year, p = .54). Additionally, there were no significant changes in absolute reticulocyte count, hemoglobin, hemoglobin S%, white blood cell count, lactate dehydrogenase, total bilirubin, serum potassium, and ferritin during the two time periods. CONCLUSION: In a cohort of patients with SCD receiving simple chronic transfusion, irradiation did not impact transfusion requirements or pertinent pretransfusion laboratory values. Irradiation does not appear to have clinically significant consequences for SCD chronic transfusion management.

Screening for new red blood cell alloantibodies after transfusion in patients with sickle cell disease.

BACKGROUND: Patients with sickle cell disease (SCD) are frequent recipients of red blood cell (RBC) transfusions and are at risk for RBC alloimmunization. RBC alloimmunization is diagnosed by identifying RBC alloantibodies as part of pre-transfusion testing, but this testing fails to detect alloantibodies that have evanesced. It may be beneficial to screen for new RBC alloantibody development after transfusion before possible antibody evanescence. STUDY DESIGN AND METHODS: Our institution started a new initiative for episodically transfused patients with SCD to obtain at least one antibody screen 2-6 months after transfusion as part of their clinical care. A database was created to prospectively track all transfused patients for 1 year and their post-transfusion antibody screen results. Patients received prophylactically CEK-matched RBC units. RESULTS: During the study year, 138 patients with SCD received a total of 242 RBC transfusions. Patients with a history of an RBC alloantibody (n = 13, 9.4%) had previously received more RBC units than non alloimmunized patients (median 11 vs. 2 RBC units, p = .0002). A total of 337 post-transfusion antibody screens were obtained in 127 patients (92.0%) with 110 patients (79.7%) having at least one antibody screen 2-6 months post-transfusion. With this prospective testing, two new RBC alloantibodies (anti-C and -M) were identified in two patients. CONCLUSION: It is feasible to test for new RBC alloantibody development in most episodically transfused patients with SCD as part of their routine care. The yield of this screening appears low with CEK matching, but it could still provide important information for individual patients.

Transfusion practices in a large cohort of hospitalized children.

BACKGROUND: While previous studies have described the use of blood components in subsets of children, such as the critically ill, little is known about transfusion practices in hospitalized children across all departments and diagnostic categories. We sought to describe the utilization of red blood cell, platelet, plasma, and cryoprecipitate transfusions across hospital settings and diagnostic categories in a large cohort of hospitalized children. STUDY DESIGN AND METHODS: The public datasets from 11 US academic and community hospitals that participated in the National Heart Lung and Blood Institute Recipient Epidemiology and Donor Evaluation Study-III (REDS-III) were accessed. All nonbirth inpatient encounters of children 0-18 years of age from 2013 to 2016 were included. RESULTS: 61,770 inpatient encounters from 41,943 unique patients were analyzed. Nine percent of encounters involved the transfusion of at least one blood component. RBC transfusions were most common (7.5%), followed by platelets (3.9%), plasma (2.5%), and cryoprecipitate (0.9%). Children undergoing cardiopulmonary bypass were most likely to be transfused. For the entire cohort, the median (interquartile range) pretransfusion laboratory values were as follows: hemoglobin, 7.9 g/dl (7.1-10.4 g/dl); platelet count, 27 × 109 cells/L (14-54 × 109 cells/L); and international normalized ratio was 1.6 (1.4-2.0). Recipient age differences were observed in the frequency of RBC irradiation (95% in infants, 67% in children, p < .001) and storage duration of RBC transfusions (median storage duration of 12 [8-17] days in infants and 20 [12-29] days in children, p < .001). CONCLUSION: Based on a cohort of patients from 2013 to 2016, the transfusion of blood components is relatively common in the care of hospitalized children. The frequency of transfusion across all pediatric hospital settings, especially in children undergoing cardiopulmonary bypass, highlights the opportunities for the development of institutional transfusion guidelines and patient blood management initiatives.

Variation in Neonatal Transfusion Practice.

OBJECTIVE: To estimate the incidence of blood product transfusion, including red blood cells, platelets, and plasma, and characterize pretransfusion hematologic values for infants during their initial hospitalization after birth. STUDY DESIGN: Retrospective cohort study using data from 7 geographically diverse US academic and community hospitals that participated in the National Heart Lung and Blood Institute Recipient Epidemiology and Donor Evaluation Study-III (REDS-III) from 2013 to 2016. Pretransfusion hematologic values were evaluated closest to each transfusion and no more than 24 hours beforehand. RESULTS: Data from 60 243 infants were evaluated. The incidence of any transfusion differed by gestational age (P < .0001), with 80% (95% CI 76%-84%) transfused at <27 weeks of gestation (n = 329) and 0.5% (95% CI 0.5%-0.6%) transfused at ≥37 weeks of gestation (n = 53 919). The median pretransfusion hemoglobin was 11.2 g/dL (10th-90th percentile 8.8-14.1) for the entire cohort, ranging from 10.5 g/dL (8.8-12.3) for infants born extremely preterm at <27 weeks of gestation to 13.0 g/dL (10.5-15.5) for infants born at term. The median pretransfusion platelet count (×109/L) was 71 (10th-90th percentile 26-135) for the entire cohort, and was >45 for all gestational age groups examined. The median pretransfusion international normalized ratio for the entire cohort was 1.7 (10th-90th percentile 1.2-2.8). CONCLUSIONS: There is wide variability in pretransfusion hemoglobin, platelet count, and international normalized ratio values for neonatal transfusions. Our findings suggest that a large proportion of neonatal transfusions in the US are administered at thresholds greater than supported by the best-available evidence and highlight an opportunity for improved patient blood management.

Erythrocyte T-antigen activation in children: Patient characteristics and the hemolytic risk of transfusion.

BACKGROUND: T-antigen activation usually occurs upon red blood cell (RBC) membrane cryptantigen exposure due to bacterial enzymes. Although uncommon, the condition is probably underrecognized. There is concern about hemolysis after plasma and plasma-containing platelet transfusions due to naturally occurring anti-T antibody in healthy blood donors. However, experts have debated the extent and severity of clinical hemolysis due to anti-T. PROCEDURE: We retrospectively identified patients who tested positive for polyagglutination with Arachis hypogea and Glycine max lectins from 2008 to 2019. The records of the patients were reviewed to determine clinical symptoms, laboratory evidence of hemolysis, need for transfusion, and clinical outcomes. RESULTS: Ten patients were identified. At diagnosis, all were anemic and four had thrombocytopenia. Severe Streptococcus pneumoniae infection affected seven patients; one died. Seven of 10 patients (70%) had laboratory evidence of hemolysis. Peripheral blood smear findings in six patients included RBC agglutination and changes suggesting hemolysis (spherocytes and schistocytes), but three had unremarkable RBC morphology. Four patients required plasma or platelet transfusions; all survived to discharge. CONCLUSIONS: T-antigen activation is a rare entity. Most patients diagnosed at our hospital had hemolytic anemia and severe pneumococcal infection. Hemoglobin decreased after plasma and platelet transfusions in all patients assessed, but these transfusions were necessary to support treatment. RBCs were given to maintain appropriate hemoglobin levels.

Population pharmacokinetics and pharmacodynamics of Tranexamic acid in women undergoing caesarean delivery.

AIMS: The population pharmacokinetics (PK) and pharmacodynamics (PD) of tranexamic acid (TXA) have not been studied to prevent postpartum haemorrhage (PPH) in pregnant women. It is unclear which TXA dose assures sufficient PPH prevention. This study investigated population PK/PD of TXA in pregnant women who underwent caesarean delivery to determine the optimal prophylactic doses of TXA for future studies. METHODS: We analysed concentration (PK) and maximum lysis (PD) data from 30 pregnant women scheduled for caesarean delivery who received 5, 10 or 15 mg/kg of TXA intravenously using population approach. RESULTS: TXA PK was best described by a two-compartment model with first-order elimination and the following parameters: clearance (between-subject variability) of 9.4 L/h (27.7%), central volume of 10.1 L (47.4%), intercompartmental clearance of 22.4 L/h (66.7%), peripheral volume of 14.0 L (13.1%) and additive error of 1.4 mg/L. The relationship between TXA concentration and maximum lysis was characterized by a sigmoid Emax model with baseline lysis of 97%, maximum inhibition of 89%, IC50 of 6.0 mg/L (65.3%), hill factor of 8.5 (86.3%) and additive error of 7.3%. Simulations demonstrated that 500 and 650 mg of TXA maintained therapeutic targets for 30 minutes and 1 hour, respectively, in 90% of patients. CONCLUSION: This is the first population PK and PD study of TXA in pregnant women undergoing caesarean delivery. Our analysis suggests that a 650 mg dose provides adequate PPH prophylaxis up to 1 hour, which is less than the currently used 1000 mg of TXA in pregnant women.

Hemorrhage Risk Assessment on Admission: Utility for Prediction of Maternal Morbidity.

OBJECTIVE: Hemorrhage is a major cause of maternal morbidity and mortality prompting creation of innovative risk assessment tools to identify patients at highest risk. We aimed to investigate the association of hemorrhage risk assessment with maternal morbidity and to evaluate maternal outcomes after implementation of the risk assessment across hospital sites. STUDY DESIGN: We conducted a retrospective cohort analysis of a multicenter database including women admitted to labor and delivery from January 2015 to June 2018. The Association of Women's Health, Obstetric and Neonatal Nurses risk assessment tool was used to categorize patients as low, medium, or high risk for hemorrhage. Multivariate logistic regression was used to describe the association between hemorrhage risk score and markers of maternal morbidity and evaluate maternal outcomes before and after standardized implementations of the risk assessment tool. RESULTS: In this study, 14,861 women were categorized as low risk (26%), 26,080 (46%) moderate risk, and 15,730 (28%) high risk (N = 56,671 births). For women with high-risk scores, the relative risk (RR) ratio compared with low-risk women was 4.9 (RR: 95% confidence interval [CI]: 3.2-7.4) for blood transfusion and 5.2 (RR: 95% CI: 4.6-5.9) for estimated blood loss (EBL) ≥ 1,000 mL. For the second objective, 110,633 women were available for pre- and postimplementation analyses (39,027 and 71,606, respectively). A 20% reduction in rates of blood transfusion (0.5-0.4%, p = 0.02) and EBL ≥ 1,000 mL (6.3-5.9%, p = 0.014) was observed between pre- and postimplementations of the admission hemorrhage risk assessment tool. CONCLUSION: Women who were deemed high risk for hemorrhage using a hemorrhage risk assessment tool had five times higher risk for blood transfusion and EBL ≥ 1,000 mL compared with low-risk women. Given the low incidence of the outcomes explored, the hemorrhage risk assessment works moderately well to identify patients at risk for peripartum morbidity. KEY POINTS: · This study aimed to understand the utility of the AWOHNN hemorrhage risk assessment tool for predicting hemorrhage-related morbidity and to evaluate maternal outcomes before and after tool implementations.. · A high score using a hemorrhage risk assessment tool on admission is associated with five times higher risk for blood transfusion and/or estimated blood loss ≥ 1,000 mL, compared with a low score.. · Use of a hemorrhage risk assessment tool works moderately well to identify patients at highest risk for hemorrhage-related morbidity..

Optimal use of intravenous tranexamic acid for hemorrhage prevention in pregnant women.

BACKGROUND: Every 2 minutes, there is a pregnancy-related death worldwide, with one-third caused by severe postpartum hemorrhage. Although international trials demonstrated the efficacy of 1000 mg tranexamic acid in treating postpartum hemorrhage, to the best of our knowledge, there are no dose-finding studies of tranexamic acid on pregnant women for postpartum hemorrhage prevention. OBJECTIVE: This study aimed to determine the optimal tranexamic acid dose needed to prevent postpartum hemorrhage. STUDY DESIGN: We enrolled 30 pregnant women undergoing scheduled cesarean delivery in an open-label, dose ranging study. Subjects were divided into 3 cohorts receiving 5, 10, or 15 mg/kg (maximum, 1000 mg) of intravenous tranexamic acid at umbilical cord clamping. The inclusion criteria were ≥34 week's gestation and normal renal function. The primary endpoints were pharmacokinetic and pharmacodynamic profiles. Tranexamic acid plasma concentration of >10 µg/mL and maximum lysis of <17% were defined as therapeutic targets independent to the current study. Rotational thromboelastometry of tissue plasminogen activator-spiked samples was used to evaluate pharmacodynamic profiles at time points up to 24 hours after tranexamic acid administration. Safety was assessed by plasma thrombin generation, D-dimer, and tranexamic acid concentrations in breast milk. RESULTS: There were no serious adverse events including venous thromboembolism. Plasma concentrations of tranexamic acid increased in a dose-proportional manner. The lowest dose cohort received an average of 448±87 mg tranexamic acid. Plasma tranexamic acid exceeded 10 µg/mL and maximum lysis was <17% at >1 hour after administration for all tranexamic acid doses tested. Median estimated blood loss for cohorts receiving 5, 10, or 15 mg/kg tranexamic acid was 750, 750, and 700 mL, respectively. Plasma thrombin generation did not increase with higher tranexamic acid concentrations. D-dimer changes from baseline were not different among the cohorts. Breast milk tranexamic acid concentrations were 1% or less than maternal plasma concentrations. CONCLUSION: Although large randomized trials are necessary to support the clinical efficacy of tranexamic acid for prophylaxis, we propose an optimal dose of 600 mg in future tranexamic acid efficacy studies to prevent postpartum hemorrhage.

Application of a plasmin generation assay to define pharmacodynamic effects of tranexamic acid in women undergoing cesarean delivery.

Essentials Tranexamic acid (TXA) is an antifibrinolytic drug used to reduce bleeding. Assaying plasmin generation (PG) in plasma detects clinically relevant TXA levels in vitro and ex vivo. 3.1-16.2 µg/mL TXA half-maximally inhibits PG in plasma from women undergoing cesarean delivery. PG velocity shows the strongest dose-relationship at low TXA concentrations (≤10 µg/mL). ABSTRACT: Background Tranexamic acid (TXA) is used to reduce bleeding. TXA inhibits plasmin(ogen) binding to fibrin and reduces fibrinolysis. TXA antifibrinolytic activity is typically measured by clot lysis assays; however, effects on plasmin generation (PG) are unclear due to a lack of tools to measure PG in plasma. Aims Develop an assay to measure PG kinetics in human plasma. Determine effects of TXA on PG and compare with fibrinolysis measured by rotational thromboelastometry (ROTEM). Methods We characterized effects of plasminogen, tissue plasminogen activator, fibrinogen, and α2 -antiplasmin on PG in vitro. We also studied effects of TXA on PG in plasma from 30 pregnant women administered intravenous TXA (5, 10, or 15 mg/kg) during cesarean delivery. PG was measured by calibrated fluorescence. PG parameters were compared with TXA measured by mass spectrometry and ROTEM of whole blood. Results The PG assay is specific for plasmin and sensitive to tissue plasminogen activator, fibrin(ogen), and α2 -antiplasmin. Addition of TXA to plasma in vitro dose dependently prolonged the clot lysis time and delayed and reduced PG. For all doses of TXA administered intravenously, the PG assay detected delayed time-to-peak (≤3 hours) and reduced the velocity, peak, and endogenous plasmin potential (≤24 hours) in plasma samples obtained after infusion. The PG time-to-peak, velocity, and peak correlated significantly with TXA concentration and showed less variability than the ROTEM lysis index at 30 minutes or maximum lysis. Conclusions The PG assay detects pharmacologically relevant concentrations of TXA administered in vitro and in vivo, and demonstrates TXA-mediated inhibition of PG in women undergoing cesarean delivery.