Society of Cardiovascular Anesthesiologists Clinical Practice Improvement Advisory for Management of Perioperative Bleeding and Hemostasis in Cardiac Surgery Patients

Acute normovolemic hemodilution in cardiac surgery: Rationale and design of a multicenter randomized trial

BACKGROUND

Minimizing the use of blood component can reduce known and unknown blood transfusion risks, preserve blood bank resources, and decrease healthcare costs. Red Blood Cell (RBC) transfusion is common after cardiac surgery and associated with adverse perioperative outcomes, including mortality. Acute normovolemic hemodilution (ANH) may reduce bleeding and the need for blood product transfusion after cardiac surgery. However, its blood-saving effect and impact on major outcomes remain uncertain.

METHODS

This is a single-blinded, multinational, pragmatic, randomized controlled trial with a 1:1 allocation ratio conducted in Tertiary and University hospitals. The study is designed to enroll patients scheduled for elective cardiac surgery with planned cardiopulmonary bypass (CPB). Patients are randomized to receive ANH before CPB or the best available treatment without ANH. We identified an ANH volume of at least 650 ml as the critical threshold for clinically relevant benefits. Larger ANH volumes, however, are allowed and tailored to the patient's characteristics and clinical conditions.

RESULTS

The primary outcome is the percentage of patients receiving RBCs transfusion from randomization until hospital discharge, which we hypothesize will be reduced from 35% to 28% with ANH. Secondary outcomes are all-cause 30-day mortality, acute kidney injury, bleeding complications, and ischemic complications.

CONCLUSION

The trial is designed to determine whether ANH can safely reduce RBC transfusion after elective cardiac surgery with CPB.

STUDY REGISTRATION

This trial was registered on ClinicalTrials.gov in April 2019 with the trial identification number NCT03913481.

In vitro protamine addition for coagulation assessment using TEG 6s system during cardiopulmonary bypass: a pilot study

OBJECTIVE

Systemic heparinization during cardiopulmonary bypass (CPB) can significantly affect thromboelastography (TEG). This study investigated the feasibility of adding protamine in vitro to allow assessment of coagulation status using the TEG 6s system during CPB.

METHODS

In this prospective observational study, 21 patients undergoing elective cardiac valve surgery were evaluated. During CPB, protamine was added in vitro to the heparinized blood of these patients at a concentration of 0.05 mg/mL and analyzed with the TEG 6s (Pre). The TEG parameters were compared to those analyzed after CPB withdrawal and systemic protamine administration (Post).

RESULTS

The citrated kaolin maximal amplitude (CK-MA) and the citrated functional fibrinogen maximal amplitude (CFF-MA) exhibited strong correlations between Pre and Post measurements (r = 0.790 and 0.974, respectively, P < 0.001 for both), despite significant mean differences (-2.23 mm for CK-MA and -0.68 mm for CFF-MA). Bland-Altman analysis showed a clinically acceptable agreement between Pre and Post measurement of CK-MA and CFF-MA (the percentage error was 10.6% and 12.2%, respectively). In contrast, the citrated kaolin reaction time (CK-R) showed no significant correlation between Pre and Post measurements (r = 0.328, P = 0.146), with a mean difference of 1.42 min (95% CI: -0.45 to 3.29).

CONCLUSIONS

In vitro protamine addition allows assessment of coagulation status during CPB using the TEG 6s system. CK-MA and CFF-MA measured during CPB using this method revealed a strong correlation and agreement with post-CPB measurements, suggesting that our method potentially facilitates early prediction of post-CPB coagulation status and decision-making on transfusion strategies.

CLINICAL TRIAL REGISTRATION

The study was registered in the University Hospital Medical Information Network Clinical Trials Registry (UMIN-CTR, registration number: UMIN000041097, date of registration: July 13, 2020, https://center6.umin.ac.jp/cgi-open-bin/ctr_e/ctr_view.cgi?recptno=R000046925 ) before the recruitment of participants.

The association between heparin sensitivity index and postoperative blood loss in Chinese patients undergoing elective off-pump coronary artery bypass grafting: a single center retrospective study

BACKGROUND

The heparin sensitivity index (HSI) is closely associated with perioperative ischemic events and increased blood loss in cardiac surgery. Previous studies have produced conflicting results. Therefore, this study aimed to investigate the relationship between HSI and postoperative blood loss specifically in Chinese patients undergoing elective off-pump coronary artery bypass grafting (OPCAB).

METHODS

Patients underwent OPCAB between March 2021 and July 2022 were retrospectively included. Enrolled patients were classified into Low-HSI (HSILOW; HSI < 1.3) and Normal-HSI (HSINORM; HSI ≥ 1.3) groups. HSI = [(activated clotting time (ACT) after heparin) - (baseline ACT)] / [loading dose of heparin (IU/kg)]. Primary outcome included postoperative blood loss at 24 h. Secondary outcomes were total postoperative blood loss, transfusion requirement of red blood cell (RBC), fresh frozen plasma (FFP), platelet concentrates (PC), and other complications.

RESULTS

We retrospectively analyzed 303 Chinese OPCAB patients. HSILOW group had higher preoperative platelet (PLT) count (221 × 109/L vs. 202 × 109/L; P = 0.041) and platelet crit (PCT) value (0.23% vs. 0.22%; P = 0.040) compared to HSINORM group. Two groups showed no significant differences in postoperative blood loss at 24 h (460 mL vs. 470 mL; P = 0.252), total blood loss (920 mL vs. 980 mL; P = 0.063), RBC transfusion requirement (3.4% vs. 3.1%; P = 1.000), FFP transfusion requirement (3.4% vs. 6.2%; P = 0.380), and other complications. Preoperative high PLT count was associated with low intraoperative HSI value (odds ratio: 1.006; 95% confidence interval: 1.002, 1.011; P = 0.008).

CONCLUSIONS

Intraoperative HSI value was not associated with postoperative blood loss in Chinese patients undergoing OPCAB. Preoperative high PLT count was an independent predictor of low intraoperative HSI value.

Improvement of Transfusion Practice in Cardiothoracic Surgery Through Implementing a Patient Blood Management Program

Background

In this study, we examined the impact of a patient blood management (PBM) program on red blood cell (RBC) transfusion practices in cardiothoracic surgery.

Methods

The PBM program had 3 components: monitoring transfusions through an order communication system checklist, educating the medical team about PBM, and providing feedback to ordering physicians on the appropriateness of transfusion. The retrospective analysis examined changes in the hemoglobin levels triggering transfusion and the proportions of appropriate RBC transfusions before, during, and after PBM implementation. Further analysis was focused on patients undergoing cardiac surgery, with outcomes including 30-day mortality, durations of intensive care unit and hospital stays, and rates of pneumonia, sepsis, and wound complications.

Results

The study included 2,802 patients admitted for cardiothoracic surgery. After the implementation of PBM, a significant decrease was observed in the hemoglobin threshold for RBC transfusion. This threshold dropped from 8.7 g/dL before PBM to 8.3 g/dL during the PBM education phase and 8.0 g/dL during the PBM feedback period. Additionally, the proportion of appropriate RBC transfusions increased markedly, from 23.9% before PBM to 34.9% and 58.2% during the education and feedback phases, respectively. Among the 381 patients who underwent cardiac surgery, a significant reduction was noted in the length of hospitalization over time (p<0.001). However, other clinical outcomes displayed no significant differences.

Conclusion

PBM implementation effectively reduced the hemoglobin threshold for RBC transfusion and increased the rate of appropriate transfusion in cardiothoracic surgery. Although transfusion practices improved, clinical outcomes were comparable to those observed before PBM implementation.

A single-center, retrospective analysis to compare measurement of fibrinogen using the TEG6 analyzer to the Clauss measurement in children undergoing heart surgery

BACKGROUND

Newer generation viscoelastic tests, TEG6s, offer point-of-care hemostatic therapy in adult patients. However, their efficacy in estimating fibrinogen levels in pediatric patients undergoing cardiac surgery is not well established.

AIMS

This study evaluates TEG6s for estimating fibrinogen levels in pediatric cardiac surgery patients and its predictive capability for post-bypass hypofibrinogenemia.

METHODS

A single-center, retrospective study on pediatric patients (under 18 years) who underwent cardiac surgery with cardiopulmonary bypass from August 2020 and November 2022. Blood samples for estimated whole blood functional fibrinogen level via TEG6s (Haemonetics Inc.) and concurrent laboratory-measured plasma fibrinogen via von Clauss assay were collected at pre- and post-cardiopulmonary bypass.

RESULTS

Paired data for TEG6s estimated functional fibrinogen levels and plasma fibrinogen were analyzed for 432 pediatric patients pre-bypass. It was observed that functional fibrinogen consistently overestimated plasma fibrinogen across all age groups with a mean difference of 138 mg/dL (95% confidence interval [CI]: 128-149 mg/dL). This positive bias in the pre-bypass data was confirmed by Bland-Altman analysis. Post-bypass, functional fibrinogen estimates were comparable to plasma fibrinogen in all patient groups with a mean difference of -6 mg/dL (95% CI: -20-8 mg/dL) except for neonates, where functional fibrinogen levels underestimated plasma fibrinogen with a mean difference of -38 mg/dL (95% CI: -64 to -12 mg/dL). The predictive accuracy of functional fibrinogen for detecting post-bypass hypofibrinogenemia (plasma fibrinogen ≤250 mg/dL) demonstrated overall fair accuracy in all patients, indicated by an area under the curve of 0.73 (95% CI: 0.65-0.80) and good accuracy among infants, with an area under the curve of 0.80 (95% CI: 0.70-0.90). Similar performance was observed in predicting critical post-bypass hypofibrinogenemia (plasma fibrinogen ≤200 mg/dL). Based on these analyses, optimal cutoffs for predicting post-bypass hypofibrinogenemia were established as a functional fibrinogen level ≤270 mg/dL and MAFF ≤15 mm.

CONCLUSION

This study demonstrates that whole blood functional fibrinogen, as estimated by TEG6s, tends to overestimate baseline plasma fibrinogen levels in pediatric age groups but aligns more accurately post-cardiopulmonary bypass, particularly in neonates and infants, suggesting its potential as a point-of-care tool in pediatric cardiac surgery. However, the variability in TEG6s performance before and after bypass highlights the need for careful interpretation of its results in clinical decision-making. Despite its contributions to understanding TEG6s in pediatric cardiac surgery, the study's design and inherent biases warrant cautious application of these findings in clinical settings.

Recombinant Activated Factor VII (rFVIIa) for Bleeding After Thoracic Aortic Surgery: A Scoping Review of Current Literature

BACKGROUND

Bleeding after surgery on the thoracic aorta is a frequent complication, and can be associated with a significant increase in morbidity and mortality. Recombinant activated factor VII (rFVIIa) was developed initially for treating patients with hemophilia; however, it has been used increasingly "off-label" to achieve hemostasis after thoracic aortic procedures.

OBJECTIVE

This scoping review aimed to present the available literature on the role of rFVIIa in the management of refractory postoperative bleeding after thoracic aortic surgery.

METHODS/RESULTS

An electronic database search was conducted using Medline, Embase, Cochrane Library, and Google Scholar in June 2023. The authors included studies that reported the use of rFVIIa in patients undergoing surgical repair of ascending or descending aortic aneurysm or dissection. Single-case reports were excluded. Ten publications with a pooled number of 649 patients (319 patients received rFVIIa and 330 in the control groups) were identified: 3 case series, 6 retrospective studies, and 1 nonrandomized clinical trial. All studies reported the potential role of rFVIIa in correcting coagulopathy and reducing postoperative blood loss in this group of patients. Overall, there was not enough evidence to suggest that rFVIIa was associated with higher rates of thromboembolic complications or mortality.

CONCLUSION

Limited evidence suggests that rFVIIa may be useful in managing postoperative refractory bleeding in patients undergoing thoracic aortic surgery. However, the impact of rFVIIa on thromboembolic complications and mortality rates remains unclear.

Fresh frozen plasma transfusion after cardiac surgery

INTRODUCTION

Fresh frozen plasma (FFP) transfusion in the intensive care unit (ICU) is commonly used to treat coagulopathy and bleeding in cardiac surgery, despite suggestion that it may increase the risk of morbidity and mortality through mechanisms such as fluid overload and infection.

METHODS

We retrospectively studied consecutive adults undergoing cardiac surgery from the Medical Information Mart for Intensive Care III and IV databases. We applied propensity score matching to investigate the independent association of within-ICU FFP transfusion with mortality and other key clinical outcomes.

RESULTS

Of our 12,043 adults who met inclusion criteria, 1585 (13.2%) received perioperative FFP with a median of 2.48 units per recipient (interquartile range [IQR]: 2.04, 4.33) at a median time of 1.83 h (IQR: 0.75, 3.75) after ICU admission. After propensity matching of 952 FFP recipients to 952 controls, we found no significant association between FFP use and hospital mortality (odds ratio (OR): 1.58; 99% confidence interval (CI): 0.57, 3.71), suspected infection (OR: 0.72; 99% CI: 0.49, 1.08), or acute kidney injury (OR: 1.23; 99% CI: 0.91, 1.67). However, FFP was associated with increased days in hospital (adjusted mean difference (AMD): 1.28; 99% CI: 0.27, 2.41; p = .0050), days in intensive care (AMD: 1.28; 99% CI: 0.27, 2.28; p = .0011), and chest tube output in millilitres up to 8 h after transfusion (AMD: 92.98; 99% CI: 52.22, 133.74; p < .0001).

CONCLUSIONS

After propensity matching, FFP transfusion was not associated with increased hospital mortality, but was associated with increased length of stay and no decrease in bleeding in the early post-transfusion period.

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.

An analysis of quality of life and functional outcomes as reported in randomized trials for red cell transfusions

BACKGROUND

Meta-analyses of randomized controlled trials (RCTs) evaluating thresholds for red blood cell (RBC) transfusion typically focus on mortality; however, other outcomes are highly relevant. The aim of this study is to summarize the effects of different transfusion thresholds on the outcomes of quality of life (QoL) and function.

STUDY DESIGN

We extracted data from RCTs identified in a recently published Cochrane systematic review. Primary analysis was descriptive.

RESULTS

A total of 23 RCTs with 13,743 adult participants were included. Fifteen RCTs included patients in the postoperative period, of which 9 RCTs were conducted in hip (n = 3024) and 6 (n = 8672) in cardiac surgeries; 5 RCTs (n = 489) were in patients with hematological malignancies; 2 in the setting of bleeding (gastrointestinal bleed [n = 936] and postpartum [n = 521]); and one RCT (n = 936) included critically ill patients. QoL and function were reported using a variety of questionnaires and tools. The timing of assessments varied between trials. No clear clinical differences in QoL outcomes were identified in comparisons between restrictive and liberal transfusion thresholds.

DISCUSSION

There is no evidence that a liberal transfusion strategy improves QoL and functional outcomes. However, the substantial limitations of many included studies indicate the need for further well-designed and adequately powered trials.

2021 MiECTiS focused update on the 2016 position paper for the use of minimal invasive extracorporeal circulation in cardiac surgery

The landmark 2016 Minimal Invasive Extracorporeal Technologies International Society (MiECTiS) position paper promoted the creation of a common language between cardiac surgeons, anesthesiologists and perfusionists which led to the development of a stable framework that paved the way for the advancement of minimal invasive perfusion and related technologies. The current expert consensus document offers an update in areas for which new evidence has emerged. In the light of published literature, modular minimal invasive extracorporeal circulation (MiECC) has been established as a safe and effective perfusion technique that increases biocompatibility and ultimately ensures perfusion safety in all adult cardiac surgical procedures, including re-operations, aortic arch and emergency surgery. Moreover, it was recognized that incorporation of MiECC strategies advances minimal invasive cardiac surgery (MICS) by combining reduced surgical trauma with minimal physiologic derangements. Minimal Invasive Extracorporeal Technologies International Society considers MiECC as a physiologically-based multidisciplinary strategy for performing cardiac surgery that is associated with significant evidence-based clinical benefit that has accrued over the years. Widespread adoption of this technology is thus strongly advocated to obtain additional healthcare benefit while advancing patient care.

Viscoelastic testing: Critical appraisal of new methodologies and current literature

United States Food and Drug Administration (FDA)-approved viscoelastic testing (VET) methodologies have significantly changed in the last 10 years, with the availability of cartridge-based VET. Some of these cartridge-based methodologies use harmonic resonance-based clot detection. While VET has always allowed for the evaluation of real-time clot formation, cartridge-based VET provides increased ease of use as well as greater portability and robustness of results in out-of-laboratory environments. Here we review the use of VET in a variety of clinical contexts, including cardiac surgery, trauma, liver transplant, obstetrics, and hypercoagulable states such as COVID-19. As of now, high quality randomized trial evidence for new generation VET (TEG 6s, HemoSonics Quantra, ROTEM sigma) is limited. Nevertheless, the use of VET-guided transfusion algorithms appears to result in reduced blood usage without worsening of patient outcomes. Future work comparing the new generation VET instruments and continuing to validate clinically important cut-offs will help move the field of point-of-care coagulation monitoring forward and increase the quality of transfusion management in bleeding patients.

Individualized heparin monitoring and management reduces protamine requirements in cardiac surgery on minimal invasive extracorporeal circulation; A prospective randomized study

INTRODUCTION

Individualized heparin and protamine management is increasingly used as a strategy to reduce coagulation activation and bleeding complications. While it is associated with increased heparin requirements during Cardiopulmonary Bypass (CPB), the impact on protamine administration remains controversial. We aim to investigate the effect of heparin level-guided monitoring on protamine dosing during cardiac surgery where low-anticoagulation protocols are implemented.

METHODS

This is a prospective, randomized, controlled trial. A total of 132 patients undergoing elective full-spectrum cardiac surgery with Minimal Invasive Extracorporeal Circulation (MiECC) were recruited. All patients were managed by the same anaesthetic, surgical and perfusion team. Patients were randomly allocated in two groups; the individualized heparin-protamine titration (IHPT) group and the conventional heparinization and reversal group by using ACT (cACT) with a 0.75:1, protamine: heparin ratio. Titration was accomplished with the Hepcon HMS Plus (Medtronic, Minneapolis, MN) system. The primary outcome of the study was the total protamine dose used. Secondary outcomes comprised of the total heparin dose, the percentage of patients achieving target ACT, 24-h transfusion requirements, postoperative bleeding, duration of mechanical ventilation, major morbidity and length of hospital stay. Patients in each group were divided in two subgroups according to the target ACT; those operated for coronary artery bypass grafting (CABG) using a target ACT >300 s and the rest (non-CABG) patients operated with a target ACT >400 s, respectively.

RESULTS

Protamine requirements were significantly reduced when IHPT was implemented; CABG (118 ± 24 mg vs 163 ± 61 mg; p < 0.001) and non-CABG cases (151 ± 46 mg vs 197 ± 45 mg; p < 0.001). Moreover, heparin requirements were significantly higher in the non-CABG subgroup managed with IHPT (34,539 ± 7658 IU vs 29,893 ± 9037 IU; p = 0.02). In overall, no significant differences were detected with respect to postoperative bleeding, transfusion of RBC or other blood products.

CONCLUSIONS

Individualized heparin monitoring and management reduces protamine requirements in cardiac surgery with MiECC implementing reduced anticoagulation strategy.

TRIAL REGISTRATION

clinicaltrials.gov; NCT04215588.

Patient blood management programmes: keeping the ball rolling

Patient blood management programmes have been endorsed by the World Health Organization and multiple medical societies. It seems important to review the progress and results of patient blood management programmes so necessary modifications or new initiatives can be added to achieve their major goals. In this issue of the British Journal of Anaesthesia, Meybohm and colleagues show that a nationwide patient blood management programme had an impact and was potentially cost-effective in centres that previously utilised large amounts of allogeneic blood transfusions. Before implementing a programme, each institution might need to identify the area(s) of deficiency with respect to established patient blood management methods, which will warrant specific focus in subsequent clinical practice reviews.

Retrospective study assessing outcomes in cardiac surgery after implementation of Quantra

BACKGROUND

The Quantra QPlus System is a cartridge-based device with a unique ultrasound technology that can measure the viscoelastic properties of whole blood during coagulation. These viscoelastic properties correlate directly with hemostatic function. The primary objective of this study was to assess blood product utilization in cardiac surgery patients before and after the implementation of the Quantra QPlus System.

METHODS

Yavapai Regional Medical Center implemented the Quantra QPlus System to aid in their efforts to reduce the transfusion of allogenic blood products and improve outcomes in patients undergoing cardiac surgery. A total of 64 patients were enrolled prior to the utilization of the Quantra (pre-Quantra cohort), and 64 patients were enrolled after (post-Quantra cohort). The pre-Quantra cohort had been managed via standard laboratory assays along with physician discretion for transfusion decisions. The utilization of blood products and frequency of transfusions were compared and analyzed between the two cohorts. (using the Student's t-test) RESULTS: The implementation of the Quantra resulted in a change in the pattern of blood product utilization leading to a demonstrated decrease in the amount of blood products transfused and the associated costs. The amount of FFP transfused was significantly decreased by 97% (P = 0.0004), whereas cryoprecipitate decreased by 67% (P = 0.3134), platelets decreased by 26% (P = 0.4879), and packed red blood cells decreased by 10% (P = 0.8027) however these trends did not reach statistical significance. The acquisition cost of blood products decreased by 41% for total savings of roughly $40,682.

CONCLUSIONS

Use of the Quantra QPlus System has the potential to improve patient blood management and decrease costs. STUDY REGISTERED AT CLINICALTRIALS.GOV: NCT05501730.

The qLabs® FIB system, a novel point-of-care technology for a rapid and accurate quantification of functional fibrinogen concentration from a single drop of citrated whole blood

Hypofibrinogenemia is often associated with excessive bleeding and requires immediate treatment. The qLabs FIB® is a handheld and easy-to-use point-of-care (POC) device designed for the rapid measurement of functional fibrinogen concentration from a single drop of citrated whole blood. The aim of this study was to evaluate the analytical performances of the qLabs FIB system. Fibrinogen concentrations from 110 citrated whole blood specimen were measured by both the qLabs FIB and the Clauss laboratory reference methods (STA®-Liquid Fib assay on STA-R® Max from Stago). A three-laboratories comparison study was conducted to assess reproducibility and repeatability of the qLabs FIB using plasma quality control material. In addition, single-site assays were conducted to assess the repeatability from citrated whole blood specimen covering the qLabs FIB reportable range. A very strong correlation between the qLabs FIB and the Clauss laboratory reference method was observed (r = 0.95). Using a clinical cut-off value of 2.0 g/L, the area under the receiver operating characteristic curve (ROC) of citrated whole blood was 0.99 and sensibility and specificity were 100 % and 93.5 %, respectively. Percent CVs for reproducibility and repeatability assessed from quality control material, were both <5 %. Repeatability assessed from citrated whole blood specimen showed a CV of 2.6 to 6.5 %. In conclusion, the qLabs FIB system enables a rapid and reliable measurement of functional fibrinogen levels from citrated whole blood and exhibits a strong prediction power at the 2 g/L clinical cut-off when compared to the Clauss laboratory reference. Further clinical studies should demonstrate its ability to quickly confirm the diagnosis of acquired hypofibrinogenemia and help identify patients who may benefit from targeted hemostatic treatment.

Treatment Strategies in Anemic Patients Before Cardiac Surgery

Both preoperative anemia and the transfusion of red blood cells have been associated with increased morbidity and mortality after cardiac surgery. To reduce the need for blood transfusion during surgery and improve patient outcomes, patient blood management programs have been developed. A primary focus of patient blood management in the preoperative period is the identification, diagnosis, and treatment of preoperative anemia, as anemia is associated with an increased risk of preoperative blood transfusion. In this narrative review, the authors focus on the laboratory screening of anemia before surgery and the evidence and limitations of different treatment strategies in anemic patients scheduled for cardiac surgery. To accurately correct preoperative anemia, the timely detection and definition of the etiology of anemia before elective cardiac surgery are crucial. Multiple randomized studies have been performed using preoperative iron supplementation and/or administration of erythropoiesis-stimulating agents in patients undergoing cardiac surgery. Although preoperative iron substitution in patients with iron deficiency is recommended, the evidence of its effectiveness is limited. In patients with nonpure iron deficiency anemia, combined therapy with erythropoiesis-stimulating agents and intravenous iron is recommended. Combined therapy might effectively reduce the need for red blood cell transfusion, even if applied shortly before cardiac surgery. The therapeutic effect on morbidity and mortality remains unclear. Nonetheless, the timely preoperative assessment of anemia and determination of iron status, eventually leading to targeted therapy, should become a standard of care and might potentially improve patient outcomes.

Impact of Preoperative Hematocrit, Body Mass Index, and Red Cell Mass on Allogeneic Blood Product Usage in Adult Cardiac Surgical Patients: Report From a Statewide Quality Initiative

OBJECTIVE

The study aims were to evaluate current blood transfusion practice in cardiac surgical patients and to explore associations between preoperative anemia, body mass index (BMI), red blood cell (RBC) mass, and allogeneic transfusion.

DESIGN

Multicenter retrospective study.

SETTING

Academic and non-academic centers.

PARTICIPANTS AND INTERVENTIONS

After Institutional Review Board approval, 26,499 patients who underwent coronary artery bypass grafting ± valve replacement/repair between 2011 and 2019 were included from the Maryland Cardiac Surgery Quality Initiative database. Patients were stratified into BMI categories (<25, 25 to <30, and ≥30 kg/m²), and a multivariable logistic regression model was fit to determine if preoperative hematocrit, BMI, and RBC mass were associated independently with allogeneic transfusion.

RESULTS

Preoperative anemia was found in 55.4%, and any transfusion was administered to 49.3% of the entire cohort. Females and older patients had lower BMI and RBC mass. Increased RBC and cryoprecipitate transfusions occurred more frequently after surgery in the lower BMI group. After adjustments, increased transfusion was associated with a BMI <25 relative to a BMI ≥30 at an odds ratio (OR) of 1.26 (95% confidence interval [CI]: 1.08-1.39). For each 1% increase in preoperative hematocrit, transfusion was decreased by 9% (OR: 0.91; 95% CI: 0.90-0.92). For every 500 mL increase in RBC mass, there was a 43% reduction of transfusion (OR: 0.57; 95% CI: 0.55-0.58).

CONCLUSIONS

Transfusion probability modeling based on calculated RBC mass eliminated sex differences in transfusion risk based on preoperative hematocrit, and may better delineate which patients may benefit from more rigorous perioperative blood conservation strategy.

Minimum protamine dose required to neutralize heparin in cardiac surgery: a single-centre, prospective, observational cohort study

PURPOSE

Excess protamine contributes to coagulopathy following cardiopulmonary bypass (CPB) and may increase blood loss and transfusion requirements. The primary aim of this study was to find the least amount of protamine necessary to neutralize residual heparin following CPB using the gold standard assays of anti-IIa and anti-Xa activity. Secondary objectives were to evaluate whether the post-CPB activated clotting time could be used as a surrogate marker for quantifying heparin neutralization.

METHODS

Twenty-eight consecutive patients undergoing elective cardiac surgery were enrolled. Protamine administration was standardized through an infusion pump at 25 mg·min-1. Blood samples were withdrawn prior to and following administration of 150, 200, 250, and 300 mg protamine and analyzed for activated clotting time and anti-IIa and -Xa activity.

RESULTS

Following a mean (standard deviation) cumulative heparin dose of 67,700 (19,400) units and a CPB duration of 113 (71) min, protamine requirements varied widely. Eight out of 25 (32%) patients showed complete neutralization of anti-IIa and -Xa activity at the first sampling point (150 mg protamine; protamine:heparin ratio, 0.3 [0.1]). A protamine:heparin ratio of 0.5 (0.2) was sufficient for heparin neutralization in > 90% of patients. After CPB, a low to mid-range activated clotting time correlated well with anti-IIa and -Xa activity.

CONCLUSIONS

The protamine:heparin ratio required to neutralize residual unfractionated heparin (UFH) following CPB is variable. A protamine:heparin ratio of 0.3 was sufficient to neutralize UFH in some patients, while a ratio of 0.5 is sufficient to neutralize both residual anti-IIa and -Xa activity in most patients. Larger studies are necessary to confirm these findings and evaluate their clinical implications.

STUDY REGISTRATION

ClinicalTrials.gov (NCT03787641); registered 26 December 2018.

The Quantra System: System Description and Protocols for Measurements

Over the past two decades, the TEG 5000 (Haemonetics Corp, Braintree, MA) and ROTEM delta (Werfen, Bedford, MA) have been the principal viscoelastic (VET) technologies. These legacy technologies are based on the "cup and pin" principle. The Quantra System (HemoSonics, LLC, Durham, NC) is a new device that assesses blood viscoelastic properties by ultrasound (SEER Sonorheometry). It is cartridge based, automated device that provides simplified specimen management and increased results reproducibility. In the present chapter, we provide a description of the Quantra and its principle of operation, currently available cartridges/assays with their respective clinical indications, device operation, and results interpretation.

Prothrombin complex concentrate in cardiac surgery for the treatment of coagulopathic bleeding

BACKGROUND

Coagulopathy following cardiac surgery is associated with considerable blood product transfusion and high morbidity and mortality. The treatment of coagulopathy following cardiac surgery is challenging, with the replacement of clotting factors being based on transfusion of fresh frozen plasma (FFP). Prothrombin complex concentrate (PCCs) is an alternative method to replace clotting factors and warrants evaluation. PCCs are also an alternative method to treat refractory ongoing bleeding post-cardiac surgery compared to recombinant factor VIIa (rFVIIa) and also warrants evaluation.   OBJECTIVES: Assess the benefits and harms of PCCs in people undergoing cardiac surgery who have coagulopathic non-surgical bleeding.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL) in the Cochrane Library, MEDLINE, Embase and Conference Proceedings Citation Index-Science (CPCI-S) on the Web of Science on 20 April 2021. We searched Clinicaltrials.gov (www.

CLINICALTRIALS

gov), and the World Health Organisation (WHO) International Clinical Trials Registry Platform (ICTRP; apps.who.int/trialsearch/), for ongoing or unpublished trials. We checked the reference lists for additional references. We did not limit the searches by language or publication status.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) and non-randomised trials (NRSs).  DATA COLLECTION AND ANALYSIS: We used standard methodological procedures expected by Cochrane.   MAIN RESULTS: Eighteen studies were included  (4993 participants). Two were RCTs (151 participants) and 16 were NRSs. Both RCTs had low risk of bias (RoB) in almost all domains. Of the 16 NRSs, 14 were retrospective cohort analyses with one prospective study and one case report. The nine studies used in quantitative analysis were judged to have critical RoB, three serious and three moderate.   1. PCC versus standard treatment Evidence from RCTs showed PCCs are likely to reduce the number of units transfused compared to standard care (MD -0.89, 95% CI -1.78 to 0.00; participants = 151; studies = 2; moderate-quality evidence). Evidence from NRSs agreed with this, showing that PCCs may reduce the mean number of units transfused compared to standard care but the evidence is uncertain (MD -1.87 units, 95% CI -2.53 to -1.20; participants = 551; studies = 2; very low-quality evidence). There was no evidence from RCTs showing a difference in the incidence of red blood cell (RBC) transfusion compared to standard care (OR 0.53, 95% CI 0.20 to 1.40; participants = 101; studies = 1; low-quality evidence). Evidence from NRSs disagreed with this, showing that PCCs may reduce the mean number of units transfused compared to standard care but the evidence is uncertain (OR 0.54, 95% CI 0.30 to 0.98; participants = 1046; studies = 4; low-quality evidence). There was no evidence from RCTs showing a difference in the number of thrombotic events with PCC compared to standard care (OR 0.68 95% CI 0.20 to 2.31; participants = 152; studies = 2; moderate-quality evidence). This is supported by NRSs, showing that PCCs may have no effect on the number of thrombotic events compared to standard care but the evidence is very uncertain (OR 1.32, 95% CI 0.87 to 1.99; participants = 1359; studies = 7; very low-quality evidence). There was no evidence from RCTs showing a difference in mortality with PCC compared to standard care  (OR 0.53, 95% CI 0.12 to 2.35; participants = 149; studies = 2; moderate-quality evidence). This is supported by evidence from NRSs, showing that PCCs may have little to no effect on mortality compared to standard care but the evidence is very uncertain (OR 1.02, 95% CI 0.69 to 1.51; participants = 1334; studies = 6; very low-quality evidence). Evidence from RCTs indicated that there was little to no difference in postoperative bleeding (MD -107.05 mLs, 95% CI -278.92 to 64.83; participants = 151, studies = 2; low-quality evidence).  PCCs may have little to no effect on intensive care length of stay (RCT evidence: MD -0.35 hours, 95% CI -19.26 to 18.57; participants = 151; studies = 2; moderate-quality evidence) (NRS evidence: MD -18.00, 95% CI -43.14 to 7.14; participants = 225; studies = 1; very low-quality evidence) or incidence of renal replacement therapy (RCT evidence: OR 0.72, 95% CI 0.14 to 3.59; participants = 50; studies = 1; low-quality evidence) (NRS evidence: OR 1.46, 95% CI 0.71 to 2.98; participants = 684; studies = 2; very low-quality evidence). No studies reported on additional adverse outcomes.   2. PCC versus rFVIIa For this comparison, all evidence was provided from NRSs.  PCC likely results in a large reduction of RBCs transfused intra-operatively in comparison to rFVIIa (MD-4.98 units, 95% CI -6.37 to -3.59; participants = 256; studies = 2; moderate-quality evidence).  PCC may have little to no effect on the incidence of RBC units transfused comparative to rFVIIa; evidence is very uncertain (OR 0.16, 95% CI 0.02 to 1.56; participants = 150; studies = 1; very low-quality evidence). PCC may have little to no effect on the number of thrombotic events comparative to rFVIIa; evidence is very uncertain (OR 0.51, 95% CI 0.23 to 1.16; participants = 407; studies = 4; very low-quality evidence). PCC may have little to no effect on the incidence of mortality (OR 1.07, 95% CI 0.38 to 3.03; participants = 278; studies = 3; very low-quality evidence) or intensive care length of stay comparative to rFVIIa (MD -40 hours, 95% CI -110.41 to 30.41; participants = 106; studies = 1; very low-quality evidence); evidence is very uncertain . PCC may reduce bleeding (MD -674.34 mLs, 95% CI -906.04 to -442.64; participants = 150; studies = 1; very low-quality evidence) and incidence of renal replacement therapy (OR 0.29, 95% CI 0.12 to 0.71; participants = 106; studies = 1; very low-quality evidence) comparative to rFVIIa; evidence is very uncertain. No studies reported on other adverse events.  AUTHORS' CONCLUSIONS: PCCs could potentially be used as an alternative to standard therapy for coagulopathic bleeding post-cardiac surgery compared to FFP as shown by moderate-quality evidence and it may be an alternative to rFVIIa in refractory non-surgical bleeding but this is based on moderate to very low quality of evidence.

Platelet Transfusion and In-Hospital Mortality in Veno-Arterial Extracorporeal Membrane Oxygenation Patients

Thrombocytopenia is common during extracorporeal membrane oxygenation (ECMO), and platelets are sometimes transfused to meet arbitrary goals. We performed a retrospective cohort study of veno-arterial (VA) ECMO patients from a single academic medical center and explored the relationship between platelet transfusion and in-hospital mortality using multivariable logistic regression. One hundred eighty-eight VA ECMO patients were included in the study. Ninety-one patients (48.4%) were transfused platelets during ECMO. Patients who received platelet transfusion had more coronary artery disease, lower platelet counts at cannulation, higher predicted mortality, lower nadir platelet counts, more ECMO days, and more red blood cell (RBC) and plasma transfusion. Mortality was 19.6% for patients who received no platelets, 40.8% for patients who received 1-3 platelets, and 78.6% for patients who received 4 or more platelets ( P &lt; 0.001). After controlling for confounding variables including baseline severity of illness, central cannulation, postcardiotomy status, RBC and plasma transfusion, major bleeding, and total ECMO days, transfusion of 4 or more platelets remained associated with in-hospital mortality; OR = 4.68 (95% CI = 1.18-27.28), P = 0.03. Our findings highlight the need for randomized controlled trials that compare different platelet transfusion triggers, so that providers can better understand when platelet transfusion is indicated in VA ECMO patients.

The Choice between Plasma-Based Common Coagulation Tests and Cell-Based Viscoelastic Tests in Monitoring Hemostatic Competence: Not an either-or Proposition

There has been a significant interest in the last decade in the use of viscoelastic tests (VETs) to determine the hemostatic competence of bleeding patients. Previously, common coagulation tests (CCTs) such as the prothrombin time (PT) and partial thromboplastin time (PTT) were used to assist in the guidance of blood component and hemostatic adjunctive therapy for these patients. However, the experience of decades of VET use in liver failure with transplantation, cardiac surgery, and trauma has now spread to obstetrical hemorrhage and congenital and acquired coagulopathies. Since CCTs measure only 5 to 10% of the lifespan of a clot, these assays have been found to be of limited use for acute surgical and medical conditions, whereby rapid results are required. However, there are medical indications for the PT/PTT that cannot be supplanted by VETs. Therefore, the choice of whether to use a CCT or a VET to guide blood component therapy or hemostatic adjunctive therapy may often require consideration of both methodologies. In this review, we provide examples of the relative indications for CCTs and VETs in monitoring hemostatic competence of bleeding patients.

Titrated versus conventional anticoagulation management for thrombin generation in cardiac surgery: a randomized controlled trial

PURPOSE

Optimal heparin titration during cardiopulmonary bypass (CPB) may reduce coagulation system activation and preserve hemostatic function post-CPB. Our objective was to assess if the Heparin Management System (HMS) Plus improves heparin titration, thereby leading to higher thrombin generation post-CPB compared with activated clotting time (ACT)-guided management.

METHODS

We conducted a randomized controlled trial of 100 patients undergoing cardiac surgery with CPB at a single center. A total of 50 patients were randomized to conventional ACT-guided management, and 50 to the HMS Plus system. The primary outcome was change in thrombin generation post-CPB compared with baseline, as assessed by calibrated automated thrombography. Secondary outcomes included intraoperative blood loss, chest drain output up to 72 hr, and transfusions. In an exploratory analysis, we compared the quintile of patients with the highest average heparin concentration on CPB (≥ 4.0 mg⋅kg-1) with the rest of the cohort.

RESULTS

A total of 100 patients were included in an intent-to-treat analysis. We observed no difference in post-CPB thrombin generation or secondary outcomes. However, patients in the HMS Plus group had higher average heparin concentrations while on CPB than patients in the conventional management group did (mean difference, -0.21; 95% confidence interval, -0.42 to -0.01). The quintile of patients with the highest average heparin concentration (4.0 mg⋅kg-1) had higher thrombin generation post-CPB than the rest of the cohort did.

CONCLUSIONS

The HMS Plus system did not show significant benefits in thrombin generation, bleeding outcomes, or transfusion in patients undergoing cardiac surgery with CPB. Higher average heparin concentrations on CPB were associated with higher post-CPB thrombin generation.

STUDY REGISTRATION

www.

CLINICALTRIALS

gov (NCT03347201); first submitted 12 October 2017.

Use of intraoperative haemostatic checklists on blood management in patients undergoing cardiac surgery: a scoping review protocol

INTRODUCTION

A major complication of cardiac surgery is bleeding which can require surgical re-exploration and the transfusion of allogeneic blood products. Re-operative procedures for bleeding have been associated with higher rates of mortality and morbidity, therefore an intervention to reduce this complication would be important. Previous investigation has demonstrated that low-cost solutions, such as the use of an intraoperative haemostatic checklist may result in the reduction of bleeding and subsequent transfusion. The goals of this scoping review aim to assess the efficacy of the use of intraoperative haemostatic checklists on blood management in patients undergoing cardiac surgery. Specifically, the objective is to understand if the use of intraoperative haemostatic checklists has been associated with a reduction in bleeding and blood product utilisation in patients undergoing non-emergent cardiac surgery.

METHODS AND ANALYSIS

A scoping review of literature identifying randomised control and observational trials, reporting on haemostatic checklists in cardiac surgery, will be undertaken. The proposed review will be guided by the methodological framework proposed by Arksey and O'Malley. A search will be conducted for published and unpublished (grey) literature. Published literature will be searched in the following electronic databases: Scopus, MEDLINE, EMBASE and the Cochrane Library. Relevant grey literature will be identified through conference abstracts. Outcomes chosen are patient centred to ensure reduced bleeding and overall positive experience that reduces complications intraoperatively.

ETHICS AND DISSEMINATION

This study does not require ethical approval as the data used are from available publications. Our dissemination strategy includes peer-review publication, presentation at conferences and relevant stakeholders.

Improving the recognition and management of hemorrhage: A scoping review of nursing and midwifery education

BACKGROUND

Hemorrhage is a frequent complication that nurses and midwives must recognize and manage to avoid life-threatening consequences for patients. There is currently no synthesis of evidence on educational interventions in nursing and midwifery regarding hemorrhage, thus limiting the definition of best practices.

OBJECTIVE

To map the literature on nursing and midwifery education regarding the recognition and management of hemorrhage.

DESIGN

Scoping review based on the Joanna Briggs Institute guidelines.

DATA SOURCES

Quantitative studies evaluating the effect of educational interventions with students, nurses, or midwives published in English or French, with no time limit.

REVIEW METHODS

Study selection, data extraction, and quality assessment were conducted by two independent reviewers. We characterized educational interventions based on the Guideline for Reporting Evidence-Based Practice Educational Interventions and Teaching. We categorized learning outcomes using the New World Kirkpatrick Model. Methodological quality appraisal was performed with tools from the Joanna Briggs Institute. Findings were synthesized using descriptive statistics and graphical methods RESULT: Most of the 38 studies used a single-group design (n = 26, 68%) and were conducted with professionals (n = 28, 74%) in hospital settings (n = 20, 53%). Most were of low (n = 14; 37%) or moderate (n = 18, 47%) methodological quality. Most interventions focused on postpartum hemorrhage (n = 34, 89%) and combined two or more teaching strategies (n = 25, 66%), often pairing an informational segment (e.g., lecture, readings) with a practical session (e.g., workshop, simulation). Learning outcomes related to the management (n = 27; 71%) and recognition of hemorrhage (n = 19, 50%), as well as results for patients and organizations (n = 9, 24%).

CONCLUSION

Considerable heterogeneity in interventions and learning outcomes precluded conducting a systematic review of effectiveness. High-quality, controlled studies are needed, particularly in surgery and trauma. Reflection on the contribution of nurses and midwives to the detection, monitoring, and management of hemorrhage could enrich the content and expected outcomes of hemorrhage education.

Viscoelastic Monitoring in Liver Transplantation

Cirrhosis and liver transplantation (LT) surgery are associated with substantial alterations to the patient's coagulation status. Accurate monitoring of these changes during LT can help manage bleeding proactively and potentially reduce transfusion requirements. Unlike conventional coagulation tests (CCTs), viscoelastic monitoring (VEM) can provide an accurate, real-time, point-of-care assessment of coagulation status during LT and hence has become an invaluable tool for anesthetists and intensive care physicians. However, it remains an enigmatic subject for transplantation surgeons who are more conversant with CCTs. This review discusses the principles of VEM, provides a primer to understanding and interpreting its output, and explains how it can be used to make real-world clinical decisions during LT.

The use of FEIBA for refractory bleeding in cardiac surgery - a systematic review

INTRODUCTION

Significant blood loss during cardiac surgery is associated with a significant increase in morbidity and mortality. Factor Eight Inhibitor Bypassing Activity (FEIBA), a hemostatic bypassing agent mainly used in hemophiliac patients, has also been used for intractable surgical bleeding during cardiac surgical procedures in non-hemophiliac patients. However, concerns exist that its use may be linked to increased incidence of perioperative adverse effects including thrombotic complications.

AREAS COVERED

A systematic literature search was performed on MEDLINE, EMBASE, and the Cochrane Central Register of Controlled Trials databases for all studies that reported the administration of FEIBA for treatment of bleeding during adult cardiac surgery in non-hemophiliac patients. After selecting of title and abstracts, two authors assessed the methodological quality of the full-text articles prior to final inclusion in the manuscript.

EXPERT OPINION

The safety profile of FEIBA was determined through an aggregate count of adverse events. Major complications included renal failure, re-operation for unresolved bleeding, postoperative mortality, and thromboembolic events. Overall, there is insufficient robust evidence to make a definitive conclusion about the safety or efficacy of using of FEIBA as a hemostatic agent in the setting of cardiac surgery.

Comparison of coagulation monitoring using ROTEM and Sonoclot devices in cardiac surgery. A single-centre prospective observational study

BACKGROUND

Viscoelastic tests (VETs) are recommended during cardiac surgery to monitor coagulation status and guide transfusion. We compared the results of two VETs, the Sonoclot Analyzer and the ROTEM Sigma. Agreement between viscoelastic tests' subdiagnoses and overall diagnosis severity was assessed. Correlations with conventional coagulation tests (CCT) and the discriminatory potential of numerical VET outputs for transfusion thresholds was determined.

METHODS

Single-centre, prospective observational study in a tertiary academic centre. In fifty adult patients undergoing elective cardiac surgery, parallel Sonoclot, ROTEM and CCT analysis was performed before heparin, or after protamine or coagulation product administration. All patients completed the study, resulting in 139 data points.

RESULTS

Agreement on the severity of coagulation disorders was acceptable (83%), but poor (27%) on the differentiation of the underlying causes. Correlations between ROTEM parameters and CCT were good (post-protamine: FIBTEM A5 (r2 = 0.90 vs fibrinogen) and EXTEM-FIBTEM A5 difference (r2 = 0.81 vs platelet count) ). Sonoclot correlated less (Clot Rate (r2 = 0.25 vs fibrinogen) and Platelet Function (r2 = 0.43 vs platelet count)). This was reflected in the discriminatory potential of these parameters as found by linear mixed modelling. We suggest clinically useful grey zones for VET cutoff interpretation.

CONCLUSIONS

ROTEM and Sonoclot accord well on the detection of severity of coagulation dysfunction, but not on the diagnosis of the underlying cause. ROTEM correlated more closely with CCT then Sonoclot. We propose a testing strategy that could lead to a cost-effective approach to the bleeding cardiac surgery patient.

Nanomechanics of Blood Clot and Thrombus Formation

Mechanical properties have been extensively studied in pure elastic or viscous materials; however, most biomaterials possess both physical properties in a viscoelastic component. How the biomechanics of a fibrin clot is related to its composition and the microenvironment where it is formed is not yet fully understood. This review gives an outline of the building mechanisms for blood clot mechanical properties and how they relate to clot function. The formation of a blood clot in health conditions or the formation of a dangerous thrombus go beyond the mere polymerization of fibrinogen into a fibrin network. The complex composition and localization of in vivo fibrin clots demonstrate the interplay between fibrin and/or fibrinogen and blood cells. Studying these protein–cell interactions and clot mechanical properties may represent new methods for the evaluation of cardiovascular diseases (the leading cause of death worldwide), creating new possibilities for clinical diagnosis, prognosis, and therapy.

Expected final online publication date for the Annual Review of Biophysics, Volume 51 is May 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

Clinical application of viscoelastic point-of-care tests of coagulation-shifting paradigms

Bleeding during cardiac surgery, liver transplant, trauma and post partum hemorrhage are often multifactorial and these factors are dynamic as new factors crop up during the course of management. Conventional tests of coagulation offer information of a part of the coagulation system and also is time consuming. Viscoelastic point of care tests (VE POCTs) like rotational thromboelastometry, thromboelastogram and Sonoclot, are based on analysis of the viscoelastic properties of clotting blood and provide information for the entire coagulation pathway. In this comprehensive review being presented here, we have examined the pros and cons of VE POCTs including clinical, cost and survival benefits. The recommendations of the various guidelines regarding use of VE POCTs in various scenarios have been discussed. The review also tried to offer suggestions as to their optimal role in management of bleeding during cardiac surgeries, extracorporeal membrane oxygenation, left ventricular assist devices, liver transplant and briefly in trauma and postpartum hemorrhage.

Tranexamic acid in cardiac surgery: Are low doses enough?

OBJECTIVES

Tranexamic acid is used to prevent hyperfibrinolysis and reduce postoperative bleeding and blood transfusions in on-pump cardiac surgery. We evaluate the efficacy of low or high dose tranexamic acid in a prospective cohort study conducted in Valencia.

MATERIALS AND METHODS

A total of 427 patients were recruited between January 2019 and January 2020, 207 in the Hospital General Universitario (low dose [LD]) and 220 in the Hospital Universitario y Politécnico La Fe (high dose [HD] and intermediate dose [ID]). We recorded the presence of hyperfibrinolysis on rotational thromboelastometry, intra- and postoperative administration of blood products, chest tube output within the first 12 h, and incidence of convulsions. Univariate and multivariate comparisons were performed. Univariate analysis of all categories was performed after propensity score matching between LD and HD and between LD and ID.

RESULTS

There were no statistically significant differences in: appearance of hyperfibrinolysis, administration of blood products, postoperative chest tube output within the first 12 h, or occurrence of convulsions. Group LD received less fibrinogen than group HD (P = .014) and ID (P = .040) but more fresh frozen plasma than group ID (P = .0002).

CONCLUSIONS

Administration of low-dose tranexamic acid is as effective as higher doses in hyperfibrinolysis prophylaxis and the prevention of postoperative bleeding in cardiac surgery.

Fibrinogen and Bleeding in Adult Cardiac Surgery: A Review of the Literature

Background: Fibrinogen is a substrate for blood clots formation. In cardiac surgery, a number of different mechanisms lead to a decrease in fibrinogen levels and consequent impaired haemostasis. Patients undergoing cardiac surgery are therefore frequently exposed to blood loss and allogeneic blood transfusion, which are risk factors associated with morbidity and mortality. Thus, particular efforts in fibrinogen management should be made to decrease bleeding and the need for blood transfusion. Therefore, fibrinogen remains an active focus of investigations from basic science to clinical practice. This review aims to summarise the latest evidence regarding the role of fibrinogen and current practices in fibrinogen management in adult cardiac surgery. Methods: The PubMed database was systematically searched for literature investigating the role and disorders of fibrinogen in cardiac surgery and diagnostic and therapeutic procedures related to fibrinogen deficiency aimed at reducing blood loss and transfusion requirements. Clinical trials and reviews from the last 10 years were included. Results: In total, 146 articles were analysed. Conclusion: The early diagnosis and treatment of fibrinogen deficiency is crucial in maintaining haemostasis in bleeding patients. Further studies are needed to better understand the association between fibrinogen levels, bleeding, and fibrinogen supplementation and their impacts on patient outcomes in different clinical settings.

Red Blood Cell Transfusion

Red blood cell (RBC) transfusions are necessary to increase a patient's oxygen carrying capacity. The optimal transfusion trigger remains elusive, but a restrictive transfusion trigger of 7 g/dL has been shown in studies to reduce RBC transfusions without adversely affecting patient outcomes. Patient blood management programs have been shown effective at reducing RBC transfusions. Hemoglobin-based oxygen carriers and induced pluripotent stem cell derived RBCs are being developed to help mitigate RBC shortages and RBC transfusion limitations. Numerous challenges still exist that need to be overcome before they can have widespread clinical use.

Low-Level Laser Therapy Effects on Rat Blood Hemostasis Via Significant Alteration in Fibrinogen and Plasminogen Expression Level

Introduction: There are many documents about the significant role of low-level laser therapy (LLLT) in different processes such as regenerator medicine and bone formation. The aim of this study is to assess the role of LLLT in blood hemostasis in rats via bioinformatic investigation. Methods: The differentially expressed plasma proteins of treated rats via LLLT from the literature and the added 50 first neighbors were investigated via network analysis to find the critical dysregulated proteins and biological processes by using Cytoscape software, the STRING database, and ClueGO. Results: A scale-free network including 55 nodes was constructed from queried and added first neighbor proteins. Fibrinogen gamma, fibrinogen alpha, and plasminogen were highlighted as the central genes of the analyzed network. Fibrinolysis was determined as the main group of biological processes that were affected by LLLT. Conclusion: Findings indicate that LLLT affects blood hemostasis which is an important point in approving the therapeutic application of LLLT and also in preventing its possible complication.

Tranexamic acid in cardiac surgery: Are low doses enough?

OBJECTIVES

Tranexamic acid is used to prevent hyperfibrinolysis and reduce postoperative bleeding and blood transfusions in on-pump cardiac surgery. We evaluate the efficacy of low or high dose tranexamic acid in a prospective cohort study conducted in Valencia.

MATERIALS AND METHODS

A total of 427 patients were recruited between January 2019 and January 2020, 207 in the Hospital General Universitario (low dose [LD]) and 220 in the Hospital Universitario y Politécnico La Fe (high dose [HD] and intermediate dose [ID]). We recorded the presence of hyperfibrinolysis on rotational thromboelastometry, intra- and postoperative administration of blood products, chest tube output within the first 12h, and incidence of convulsions. Univariate and multivariate comparisons were performed. Univariate analysis of all categories was performed after propensity score matching between LD and HD and between LD and ID.

RESULTS

There were no statistically significant differences in: appearance of hyperfibrinolysis, administration of blood products, postoperative chest tube output within the first 12h, or occurrence of convulsions. Group LD received less fibrinogen than group HD (P=.014) and ID (P=.040) but more fresh frozen plasma than group ID (P=.0002).

CONCLUSIONS

Administration of low-dose tranexamic acid is as effective as higher doses in hyperfibrinolysis prophylaxis and the prevention of postoperative bleeding in cardiac surgery.

The strengths and weaknesses of viscoelastic testing compared to traditional coagulation testing

Optimized acute bleeding management requires timely and reliable laboratory testing to detect and diagnose coagulopathies and guide transfusion therapy. Conventional coagulation tests (CCT) are inexpensive with minimal labor requirements, but CCTs may have delayed turnaround times. In addition, abnormal CCT values may not reflect in vivo coagulopathies that require treatment and may lead to overtransfusion. The use of viscoelastic testing (VET) has been rapidly expanding and is recommended by several recent bleeding guidelines. This review is intended to compare CCT to VET, review the strengths and weaknesses of both approaches, and evaluate and summarize the clinical studies that compared CCT-based and VET-based transfusion algorithms. Most studies of CCT vs VET transfusion algorithms favor the use of VET in the management of massively bleeding patients due to reductions in blood product utilization, bleeding, costs, and lengths of stay.

The role of viscoelastic testing in assessing peri-interventional platelet function and coagulation

We carried out a literature search in MEDLINE (PubMed) and EMBASE literature databases to provide a concise review of the role of viscoelastic testing in assessing peri-interventional platelet function and coagulation. The search identified 130 articles that were relevant for the review, covering the basic science of VHA and VHA in clinical settings including cardiac surgery, cardiology, neurology, trauma, non-cardiac surgery, obstetrics, liver disease, and COVID-19. Evidence from these articles is used to describe the important role of VHAs and platelet function testing in various peri-interventional setups. VHAs can help us to comprehensively assess the contribution of platelets and coagulation dynamics to clotting at the site-of-care much faster than standard laboratory measures. In addition to standard coagulation tests, VHAs are beneficial in reducing allogeneic transfusion requirements and bleeding, in predicting ischemic events, and improving outcomes in several peri-interventional care settings. Further focused studies are needed to confirm their utility in the peri-interventional case.

A prognostic model for the preoperative identification of patients at risk for receiving transfusion of packed red blood cells in cardiac surgery

BACKGROUND

Patients undergoing cardiothoracic surgery are at substantial risk for blood transfusion. Increased awareness and patient blood management have resulted in a significant reduction over the past years. The next step is preoperative treatment of patients at high risk for packed red blood cells (RBC) transfusion, with the ultimate goal to eventually prevent RBC transfusion. A prediction model was developed to select patients at high risk for RBC transfusion.

MATERIALS AND METHODS

Data of all patients that underwent cardiac surgery in our center between 2008 and 2013 (n = 2951) were used for model development, and between 2014 and 2016 for validation (n = 1136). Only preoperative characteristics were included in a multinomial regression model with three outcome categories (no, RBC, other transfusion). The accuracy of the estimated risks and discriminative ability of the model were assessed. Clinical usefulness was explored.

RESULTS

Risk factors included are sex, type of surgery, redo surgery, age, height, body mass index, preoperative hemoglobin level, and preoperative platelet count. The model has excellent discriminative ability for predicting RBC transfusion versus no transfusion (area under the curve [AUC] = 94%) and good discriminative ability for RBC transfusion versus other transfusion (AUC = 84%). With a cut-off value of RBC risk of 16.8% and higher, the model is well able to identify a high proportion of patients at risk for RBC transfusion (sensitivity = 87.1%, specificity = 82.3%).

CONCLUSION

In the current study, a prediction tool was developed to be used for risk stratification of patients undergoing elective cardiac surgery at risk for blood transfusions.

Year in Review 2020: Noteworthy Literature in Cardiothoracic Anesthesiology

The year 2020 was marred by the emergence of a deadly pandemic that disrupted every aspect of life. Despite the disruption, notable research accomplishments in the practice of cardiothoracic anesthesiology occurred in 2020 with an emphasis on optimizing care, improving outcomes, and expanding what is possible for patients undergoing cardiac surgery. This year's edition of Noteworthy Literature Review will focus on specific themes in cardiac anesthesiology that include preoperative anemia, predictors of acute kidney injury following cardiac surgery, pain management modalities, anticoagulation strategies after transcatheter aortic valve replacement, mechanical circulatory support, and future directions in research.

How Do We Use Dashboards to Enhance Quality in Cardiac Anesthesia?

The use of clinical dashboards has expanded significantly in healthcare in recent years in a variety of settings. The ability to analyze data related to quality metrics in one screen is highly desirable for cardiac anesthesiologists, as they have considerable influence on important clinical outcomes. Building a robust quality program within cardiac anesthesia relies on consistent access and review of quality outcome measures, process measures, and operational measures through a clinical dashboard. Signals and trends in these measures may be compared to other cardiac surgical programs to analyze gaps and areas for quality improvement efforts. In this article, the authors describe how they designed a clinical cardiac anesthesia dashboard for quality efforts at their institution.

Clinical impact of rotational thromboelastometry in cardiac surgery

Patients undergoing cardiac surgery are at high risk of postoperative bleeding, which is related to worse prognosis and survival. The use of ROTEM®, together with the implementation of a specific treatment algorithm, to reduce the risk of postoperative bleeding. An observational, comparative, cross-case study with historical controls. A total of 1772 consecutive patients admitted to intensive care unit after having undergone cardiac surgery, was divided into 3 groups: Group 1: Coagulation was only monitored by the classical coagulation test (control group). Group 2: Monitorization was done by ROTEM®, according to a protocol designed in our center. Group 3: VerifyNow® was added to ROTEM®, implementing a specific treatment algorithm. We observed a decreased of red blood cell transfusion (Group 1 55.5%, Group 2 52.7%, Group 3 46.6%, P<0.01). Postoperative results include a significant reduction in complications with a marked improvement in overall survival in the ROTEM® - guided groups. Conclusions: Monitoring of hemostasis by POCT'S (ROTEM® and VerifyNow®) in patients undergoing cardiac surgery and cardiac transplantation was associated with a decreased incidence of blood transfusion, postoperative clinical complications, and mortality.

Efficacy, Safety, and Strategies for Recombinant-Activated Factor VII in Cardiac Surgical Bleeding: A Narrative Review

As perioperative bleeding continues to be a major source of morbidity and mortality in cardiac surgery, the search continues for an ideal hemostatic agent for use in this patient population. Transfusion of blood products has been associated both with increased costs and risks, such as infection, prolonged mechanical ventilation, increased length of stay, and decreased survival. Recombinant-activated factor VII (rFVIIa) first was approved for the US market in 1999 and since that time has been used in a variety of clinical settings. This review summarizes the existing literature pertaining to perioperative rFVIIa, in addition to society recommendations and current guidelines regarding its use in cardiac surgery.

Minimal invasive extracorporeal circulation preserves coagulation integrity

INTRODUCTION

Coagulopathy after cardiac surgery is a serious multifactorial complication that results in postoperative bleeding requiring transfusion of red blood cells and procoagulant products. Use of cardiopulmonary bypass represents the major contributing factor affecting coagulation. We sought to prospectively investigate the effect of contemporary minimal invasive extracorporeal circulation (MiECC) on coagulation parameters using point-of-care (POC) rotational thromboelastometry and the relation to postoperative bleeding.

METHODS

Patients undergoing elective cardiac surgery on MiECC were prospectively recruited. Anticoagulation strategy was based on individualized heparin management and heparin level-guided protamine titration. Rotational thromboelastometry testing was performed before induction of anesthesia and after aortic cross-clamp release. A strict POC-guided transfusion protocol was implemented. The primary endpoint was the assessment of viscoelastic properties of the coagulating blood at the end of surgery compared to preoperative values and the relation to postoperative bleeding and 24-hour transfusion requirements.

RESULTS

Fifty patients were included in the study with a significant proportion having complex surgery. Thirteen patients (26%) required blood transfusion (mean rate: 0.5 ± 1 units per patient), 5/50 (10%) received coagulation factors while no patient received fresh frozen plasma, platelets or fibrinogen. Thromboelastometry analysis showed that the major derangement was CT EXTEM > 100 seconds in 28/50 (56%) and A10 EXTEM < 40 mm in one (2%) patient without clinical significance. Platelet function was preserved throughout surgery. A10-FIBTEM was found predictive of postoperative bleeding at 12 hours.

CONCLUSIONS

MiECC preserves clot quality throughout surgery acting in both key determinants of clot strength; fibrinogen and platelets. This is clinically translated into minimal postoperative bleeding and restricted use of blood products and coagulation factors.

Thrombocytopenia: Perioperative Considerations for Patients Undergoing Cardiac Surgery

The etiologies of thrombocytopenia in patients presenting for cardiac surgery are extensive, but clinically relevant conditions generally can be categorized by those related to decreased platelet production or increased platelet destruction. Many causes require mere acknowledgment and availability of allogeneic platelet transfusion; others have unique considerations for which providers should be familiar. The purpose of this review is to provide an overview of the common causes of thrombocytopenia, summarize the literature, and discuss perioperative considerations for patients undergoing cardiac surgery.