Heparin Resistance During Cardiopulmonary Bypass in Adult Cardiac Surgery

Heparin resistance in a patient with severe acute pancreatitis: a case report

INTRODUCTION

Severe acute pancreatitis is a life-threatening condition characterized by systemic inflammatory response syndrome and an increased risk of complications such as venous thrombosis, all of which contributes to a high mortality rate. Heparin resistance, although rare, can lead to ineffective anticoagulation and thrombus formation during unfractionated heparin therapy, complicating management.

METHODS

We report a case of heparin resistance in which, despite increasing the unfractionated heparin dosage, the patient's activated partial thromboplastin time remained subtherapeutic.

RESULTS

Laboratory findings indicated normal antithrombin levels but undetectable anti-Xa activity, confirming non-antithrombin-mediated heparin resistance. A multidisciplinary approach led to the successful management of thrombosis with rivaroxaban, resulting in substantial clinical improvement.

DISCUSSION

This case highlights the importance of early recognition and management of heparin resistance in patients with severe acute pancreatitis. Combined monitoring of activated partial thromboplastin time and anti-Xa activity is crucial for optimizing anticoagulation therapy and preventing complications such as deep vein thrombosis.

ICU 'Magic Numbers': The Role of Biomarkers in Supporting Clinical Decision-Making

Critical care medicine is a highly complex field where diagnosing diseases and selecting effective therapies pose daily challenges for clinicians. In critically ill patients, biomarkers can play a crucial role in identifying and addressing clinical problems. Selecting the right biomarkers and utilizing them effectively can lead to more informed decisions, ultimately impacting patient outcomes. However, each biomarker has its strengths and limitations, making a thorough understanding essential for accurate diagnosis and treatment management. For instance, neuron-specific enolase (NSE) is commonly used to predict outcomes in out-of-hospital cardiac arrest (OHCA), procalcitonin (PCT) levels strongly correlate with bacterial infections, and NT-proBNP serves as a reliable indicator of cardiac stress. Additionally, serum creatinine (SCr) remains fundamental in renal diagnostics, while prealbumin helps differentiate catabolic and anabolic phases in critically ill patients. This narrative review highlights a carefully selected set of biomarkers known for their clinical utility and reliability in guiding critical care decisions. Further refining the application of biomarkers-especially by integrating them into a multimodal approach-will enhance clinicians' ability to navigate the challenges of critical care, always striving to improve patient outcomes.

2024 EACTS/EACTAIC/EBCP Guidelines on cardiopulmonary bypass in adult cardiac surgery

Clinical practice guidelines consolidate and evaluate all pertinent evidence on a specific topic available at the time of their formulation. The goal is to assist physicians in determining the most effective management strategies for patients with a particular condition. These guidelines assess the impact on patient outcomes and weigh the risk-benefit ratio of various diagnostic or therapeutic approaches. While not a replacement for textbooks, they provide supplementary information on topics relevant to current clinical practice and become an essential tool to support the decisions made by specialists in daily practice. Nonetheless, it is crucial to understand that these recommendations are intended to guide, not dictate, clinical practice, and should be adapted to each patient's unique needs. Clinical situations vary, presenting a diverse array of variables and circumstances. Thus, the guidelines are meant to inform, not replace, the clinical judgement of healthcare professionals, grounded in their professional knowledge, experience and comprehension of each patient's specific context. Moreover, these guidelines are not considered legally binding; the legal duties of healthcare professionals are defined by prevailing laws and regulations, and adherence to these guidelines does not modify such responsibilities. The European Association for Cardio-Thoracic Surgery (EACTS), the European Association of Cardiothoracic Anaesthesiology and Intensive Care (EACTAIC) and the European Board of Cardiovascular Perfusion (EBCP) constituted a task force of professionals specializing in cardiopulmonary bypass (CPB) management. To ensure transparency and integrity, all task force members involved in the development and review of these guidelines submitted conflict of interest declarations, which were compiled into a single document available on the EACTS website (https://www.eacts.org/resources/clinical-guidelines). Any alterations to these declarations during the development process were promptly reported to the EACTS, EACTAIC and EBCP. Funding for this task force was provided exclusively by the EACTS, EACTAIC and EBCP, without involvement from the healthcare industry or other entities. Following this collaborative endeavour, the governing bodies of EACTS, EACTAIC and EBCP oversaw the formulation, refinement, and endorsement of these extensively revised guidelines. An external panel of experts thoroughly reviewed the initial draft, and their input guided subsequent amendments. After this detailed revision process, the final document was ratified by all task force experts and the leadership of the EACTS, EACTAIC and EBCP, enabling its publication in the European Journal of Cardio-Thoracic Surgery, the British Journal of Anaesthesia and Interdisciplinary CardioVascular and Thoracic Surgery. Endorsed by the EACTS, EACTAIC and EBCP, these guidelines represent the official standpoint on this subject. They demonstrate a dedication to continual enhancement, with routine updates planned to ensure that the guidelines remain current and valuable in the ever-progressing arena of clinical practice.

Performance of Hemochron ACT-LR and ACT+ Test Cuvettes in Monitoring Low to Moderate Heparin Concentrations: An In Vitro Study

OBJECTIVES

According to the manufacturer, the Hemochron ACT-LR cuvette is designated for heparin concentrations of 0 to 2.5 IU/mL, while the optimal concentration range for the ACT+ cartridge is 1 to 6 IU/mL. We hypothesized that at low to moderate heparin concentrations, the ACT-LR is more reliable than the ACT+.

DESIGN

An in vitro study.

SETTING

A tertiary care university hospital.

PARTICIPANTS

Twenty healthy adult volunteers.

INTERVENTIONS

Donor blood samples were spiked with unfractionated heparin to concentrations of 0, 0.5, 1.0, 1.5, 2.0, and 2.5 IU/mL. From each concentration, 3 measurements were made with each test cassette using 3 different Hemochron Signature Elite devices, for a total of 720 ACT tests. The Bland-Altman method and intraclass correlation coefficients were used to analyze the data.

MEASUREMENTS AND MAIN RESULTS

All 360 ACT+ tests yielded a result. Of 360, 38 (11%) ACT-LR tests ran above the upper measurement range; of these, 36 were from the 120 measurements at heparin concentrations ≥2.0 IU/mL. The bias between all ACT-LR and ACT+ measurements ​​was 52 (95% CI, 48-56) celite seconds, and the limits of agreement were wide. Based on the intraclass correlation coefficients, the reliability of ACT+ was better than or equal to that of ACT-LR.

CONCLUSIONS

The performance of ACT+ is equal to that of ACT-LR up to a concentration of 0.5 IU/mL, above which ACT+ is superior to ACT-LR, questioning the rationale for a specific low-range test. However, there is a significant bias between ACT-LR and ACT+ measurements that needs to be considered if switching from one test to the other.

Bivalirudin anticoagulation for cardiopulmonary bypass during cardiac surgery

INTRODUCTION

Heparin is the primary anticoagulant for cardiopulmonary bypass (CPB) support during cardiac surgery. While widely used, ∼2% of cardiac surgery patients develop heparin-induced thrombocytopenia (HIT) and 4-26% develop heparin resistance. Bivalirudin is an alternative anticoagulant mainly used for percutaneous coronary interventions. Given the challenges associated with heparin anticoagulation, we conducted a review to explore the use of bivalirudin for CPB surgery.

METHODS

PubMed and Embase scoping review included 2 randomized controlled trials, a retrospective comparison study, 3 pilot studies, and 30 case reports. To provide a contemporary series, we searched for articles published from 2010 to 2023. Our review included studies from both adult and pediatric populations.

RESULTS

While data is limited, bivalirudin seems to supply similar effectiveness and safety as heparin for CPB anticoagulation. Across the three comparative studies, the heparin cohorts had a 0-9% mortality rate and 0-27% rate of major bleeding/reoperation compared to a 0-3% mortality and 0-6% major bleeding/reoperation rate for the bivalirudin cohorts. Bivalirudin was successfully used as an anticoagulant in a wide range of CPB surgeries (e.g., heart transplants, ventricular assisted device placements, and valve repairs). Successful patient outcomes were reported with bivalirudin infusion of ∼2 mg/kg/hour, activated clotting time monitoring (target >400 s or 2.5× baseline), use of cardiotomy suctions, minimization of stagnant blood, and post-bypass modified ultrafiltration.

CONCLUSION

Bivalirudin is a safe and effective anticoagulant for CPB, especially for patients with HIT or heparin resistance. Further comparative research is called for to optimize bivalirudin utilization for CPB during cardiac surgery.

Approaches to management of HIT in complex scenarios, including cardiac surgery

Although heparin-induced thrombocytopenia (HIT) presents management challenges for any population, it adds complexity to the management of certain patient populations, including those undergoing cardiac surgery and those with refractory HIT and/or acute bleeding. For each of these scenarios, we review alternative management strategies when standard therapies-heparin cessation and the initiation of a nonheparin anticoagulant-are either insufficient or not practicable. In patients with HIT undergoing cardiac surgery, we review the clinical experience for heparin reexposure using therapeutic plasma exchange (TPE) or antiplatelet therapy. In patients with refractory HIT despite adequate nonheparin anticoagulation, we address the use of intravenous immune globulin, TPE, and rituximab. Finally, in patients with active bleeding, we discuss bleeding management and the risks associated with platelet transfusion. Although they may facilitate a patient-centered approach, most of these strategies are supported by limited evidence.

Red blood cells as potential materials for microRNA biomarker study: overcoming heparin-related challenges

microRNAs (miRNAs) have been intensively studied as valuable biomarkers in cardiometabolic disease. Typically, miRNAs are detected in plasma or serum, but the use of samples collected in heparinized tubes is problematic for miRNA studies using quantitative PCR (qPCR). Heparin and its derivatives interfere with qPCR-based analysis, leading to a substantial reduction or even complete loss of detectable miRNA levels. Given that red blood cells (RBCs) express abundant miRNAs, whose expression is altered in cardiometabolic disease, RBCs could serve as an attractive alternative in biomarker studies. Here, we aim to explore the stability of miRNAs in RBCs collected from whole blood with different anticoagulants and thereby the potential of RBCs as alternative materials for miRNA biomarker studies. miRNA profiling was performed in human RBCs via RNA sequencing, followed by qPCR validation of selected miRNAs in RBCs and plasma in both heparinized and EDTA tubes. RNA sequencing revealed abundant miRNA presence in RBCs isolated from blood collected in EDTA tubes. miR-210-3p, miR-21-5p, miR-16-5p, and miR-451a were detected at comparable levels in RBCs isolated from both heparinized and EDTA tubes but not in plasma from heparinized tubes. Of note, miR-210-3p levels were consistently lower in RBCs from individuals with type 2 diabetes compared with healthy controls, regardless of anticoagulant type, supporting their potential as biomarker materials. In conclusion, RBCs offer a promising alternative for miRNA biomarker studies, overcoming heparin-related challenges.NEW & NOTEWORTHY microRNAs are valuable biomarkers in cardiometabolic disease, but heparinized tubes hinder their detection because of qPCR interference. RBCs, which express abundant microRNAs like miR-210-3p, may serve as an alternative. microRNAs, including miR-210-3p, are consistently detectable in RBCs at comparable levels between heparinized and EDTA tubes. miR-210-3p levels in RBCs are similarly reduced in heparinized tubes of patients with type 2 diabetes. Thus, RBCs offer a promising solution for miRNA biomarker studies, overcoming heparin-related challenges.

Bivalirudin anticoagulation for an infant with heparin resistance on ECMO: A case report

RATIONALE

Extracorporeal membrane oxygenation (ECMO) technology in the field of intense care for children in China has developed rapidly, and it has become a key strategy for the rescue treatment of critically ill children and an advanced extracorporeal life support system. Compared with adults and children, neonatal respiratory disease with ECMO support has the best prognosis, with an average survival rate of 74%. Bleeding and thrombotic events during ECMO are common, morbid, and potentially lethal. Therefore, how to balance the coagulation state is the key to ECMO management.

PATIENT CONCERNS

A full-term male infant (2h 5min) was hospitalized for respiratory distress and cyanosis. With a history of premature rupture of membranes (>7 hours) and a birth weight of 3000 g, the patient had Apgar scores of 7, 8, and 9 at 1, 5, and 10 minutes, respectively.

DIAGNOSES

This infant has the indication of extracorporeal membrane lung support. After full communication, venoarterial-ECMO was performed, and intravenous infusion of heparin was used for anticoagulation management.

INTERVENTIONS

We encountered an unreliable heparin monitoring in an infant on ECMO, which considered as heparin resistance. Subsequently, we switched the anticoagulant from heparin to bivalirudin and managed by using multiple laboratory tests including activated clotting time (ACT) and activated partial thromboplastin time. The phenomenon of inconsistent monitoring results occurred later. To help the clinic to adjust the anticoagulation dose accurately, we adopted additional tests such as thrombin-antithrombin complex (TAT) and fibrin/fibrinogen degradation products and applied comparison of thrombela stogram (TEG)-ACT with anticoagulated specimens and bedside non-anticoagulated ACT, then recommended clinicians to use activated partial thromboplastin time combined with TAT.

OUTCOMES

In collaboration with other symptomatic supportive treatments, the ECMO flow was gradually reduced, the respiratory and circulatory functions were stable after reducing the flow rate, there was no bleeding tendency, and the ECMO was finally evacuated.

LESSONS

Due to the unique physiological characteristics of newborns, the hemostatic changes differ significantly from those in adults. Precise monitoring of anticoagulation becomes a critical and challenging task. Bivalirudin can be effectively used for anticoagulation management in neonatal ECMO; however, due to its unique characteristics, precise dose adjustment poses a challenge. Selecting the optimal laboratory monitoring indicators is crucial in this regard. In some cases, bedside ACT may not be the optimal anticoagulation monitoring parameter, and when necessary, comparative analysis can be conducted using anticoagulant-sample ACTs such as thrombela stogram-ACT. Traditional markers such as D-dimer/fibrinogen degradation products and newer indicators like TAT can reflect the activation of coagulation and assist in monitoring the anticoagulation effect, especially when there is conflicting information among the monitoring parameters.

Heparin-Bead Extraction Enhanced Fluorogenic Aptamer-Thrombin Composite Reporter Enables Sensitive and Rapid Detection of Functional Antithrombin

Antithrombin (AT) deficiency in the extracorporeal circulation during cardiac surgery leads to uncontrolled inflammation and vascular damage in patients. AT levels decrease in sepsis, major trauma, extracorporeal membrane oxygenation, and eclampsia. Monitoring plasma AT levels facilitates the accurate restoration of AT to baseline values through precise supplementation. Traditional methods of chromogenic assay and enzyme-linked immunosorbent assay (ELISA) kits encounter challenges, such as interference, inconsistency, and delayed response times, making real-time, reliable antithrombin monitoring a clinical gap. To address this critical need, we develop a heparin-bead extraction enhanced fluoroGenic aptamer-thrombin composite reporter (HExGATOR) for the rapid, sensitive, and precise detection of functional AT in plasma. Our design employs thrombin-binding aptamers and a fluorescence "turn on" technology such that a signal is produced upon the interaction of AT with the otherwise "turned off" aptamer-thrombin complex. The prominent signal-background interference originating from plasma is remarkably diminished by using a heparin-bead solid-phase extraction of AT. We achieved highly sensitive and rapid detection of AT in 5 to 20 min with a limit of detection of 15.11 nM. This approach offers a promising alternative to traditional AT tests in clinical settings, potentially facilitating personalized anticoagulant therapy.

Effect of endothelium on the anticoagulant activity of a covalent antithrombin-heparin complex

We developed a covalent antithrombin-heparin complex (ATH) with superior In vivo anticoagulant efficacy compared to non-covalent antithrombin (AT) + unfractionated heparin (H). Previous in vitro studies of ATH, investigating the mechanisms behind its efficacy, were done in the absence of endothelium. Since the endothelial surface modulates hemostasis, we investigated its impact on the in vitro anticoagulant properties of ATH and AT+H. Discontinuous second order rate constant enzyme inhibition assays, fibrin formation, and plasma clot generation were performed in the presence of ATH or AT+H, with and without endothelium present. ATH had an increased rate of direct inhibition of IIa and Xa, and increased inhibition of IIa-induced fibrin formation, compared to AT+H. When compared at equal anti-Xa levels, ATH was less effective than AT+H at catalyzing inhibition of plasma clot generation. These results were found in both the presence and absence of endothelium. Endothelium decreased the rate of IIa inhibition, and reduced clot time in IIa-induced fibrin formation and plasma clot generation assays, for both ATH and AT+H. Endothelium did not impact the activity of ATH differently to AT+H. This supports the growing body of evidence suggesting ATH may be a beneficial anticoagulant for potential clinical use.

Heparin resistance management during cardiac surgery: a literature review and future directions

INTRODUCTION

Heparin, a commonly used anticoagulant in cardiac surgery, binds to antithrombin III (ATIII) to prevent clot formation. However, heparin resistance (HR) can complicate surgical procedures, leading to increased thromboembolic risks and bleeding complications. Proper diagnosis and management of HR are essential for optimizing surgical outcomes.

METHODOLOGY

Diagnosis of HR involves assessing activated clotting time (ACT) and HR assays. Management strategies were identified through a comprehensive review of the literature, including studies exploring heparin dosage adjustments, antithrombin supplementation, and alternative anticoagulants in cardiac surgery patients with HR. A thorough search of relevant studies on HR was conducted using multiple scholarly databases and relevant keywords, resulting in 59 studies that met the inclusion criteria.

DISCUSSION

HR occurs when patients do not respond adequately to heparin therapy, requiring higher doses or alternative anticoagulants. Mechanisms of HR include AT III deficiency, PF4 interference, and accelerated heparin clearance. Diagnosis involves assessing ACT and HR assays. HR in cardiac surgery can lead to thromboembolic events, increased bleeding, prolonged hospital stays, and elevated healthcare costs. Management strategies include adjusting heparin dosage, supplementing antithrombin levels, and considering alternative anticoagulants. Multidisciplinary management of HR involves collaboration among various specialities. Strategies include additional heparin doses, fresh frozen plasma (FFP) administration, and antithrombin concentrate supplementation. Emerging alternatives to heparin, such as direct thrombin inhibitors and nafamostat mesilate, are also being explored.

CONCLUSION

Optimizing the management of HR is crucial for improving surgical outcomes and reducing complications in cardiac surgery patients. Multidisciplinary approaches and emerging anticoagulation strategies hold promise for addressing this challenge effectively.

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.

Management of Therapeutic-intensity Unfractionated Heparin: A Narrative Review on Critical Points

Nowadays, unfractionated heparin (UFH) use is limited to selected patient groups at high risk of both bleeding and thrombosis (patients in cardiac surgery, in intensive care unit, and patients with severe renal impairment), rendering its management extremely challenging, with many unresolved questions despite decades of use. In this narrative review, we revisit the fundamental concepts of therapeutic anticoagulation with UFH and address five key points, summarizing controversies underlying the use of UFH and discussing the few recent advances in the field: (1) laboratory tests for UFH monitoring have significant limitations; (2) therapeutic ranges are not well grounded; (3) the actual influence of antithrombin levels on UFH's anticoagulant activity is not well established; (4) the concept of UFH resistance lacks supporting data; (5) scarce data are available on UFH use beyond acute venous thromboembolism. We therefore identified key issues to be appropriately addressed in future clinical research: (1) while anti-Xa assays are often considered as the preferred option, we call for a vigorous action to improve understanding of the differences between types of anti-Xa assays and to solve the issue of the usefulness of added dextran; (2) therapeutic ranges for UFH, which were defined decades ago using reagents no longer available, have not been properly validated and need to be confirmed or reestablished; (3) UFH dose adjustment nomograms require full validation.

Antithrombin Levels and Heparin Responsiveness during Venoarterial Extracorporeal Membrane Oxygenation: A Prospective Single-center Cohort Study

BACKGROUND

Unfractionated heparin, administered during venoarterial extracorporeal membrane oxygenation to prevent thromboembolic events, largely depends on plasma antithrombin for its antithrombotic effects. Decreased heparin responsiveness seems frequent on extracorporeal membrane oxygenation; however, its association with acquired antithrombin deficiency is poorly understood. The objective of this study was to describe longitudinal changes in plasma antithrombin levels during extracorporeal membrane oxygenation support and evaluate the association between antithrombin levels and heparin responsiveness. The hypothesis was that extracorporeal membrane oxygenation support would be associated with acquired antithrombin deficiency and related decreased heparin responsiveness.

METHODS

Adults receiving venoarterial extracorporeal membrane oxygenation were prospectively included. All patients received continuous intravenous unfractionated heparin using a standardized protocol (target anti-Xa 0.3 to 0.5 IU/ml). For each patient, arterial blood was withdrawn into citrate-containing tubes at 11 time points (from hour 0 up to day 7). Anti-Xa (without dextran or antithrombin added) and antithrombin levels were measured. The primary outcome was the antithrombin plasma level. In the absence of consensus, antithrombin deficiency was defined as a time-weighted average of antithrombin less than or equal to 70%. Data regarding clinical management and heparin dosage were collected.

RESULTS

Fifty patients, including 42% postcardiotomy, were included between April 2020 and May 2021, with a total of 447 samples. Median extracorporeal membrane oxygenation duration was 7 (interquartile range, 4 to 12) days. Median antithrombin level was 48% (37 to 60%) at baseline. Antithrombin levels significantly increased throughout the follow-up. Time-weighted average of antithrombin levels was 63% (57 to 73%) and was less than or equal to 70% in 32 (64%) of patients. Overall, 45 (90%) patients had at least one antithrombin value less than 70%, and 35 (70%) had at least one antithrombin value less than 50%. Antithrombin levels were not significantly associated with heparin responsiveness evaluated by anti-Xa assay or heparin dosage.

CONCLUSIONS

Venoarterial extracorporeal membrane oxygenation support was associated with a moderate acquired antithrombin deficiency, mainly during the first 72 h, that did not correlate with heparin responsiveness.

EDITOR’S PERSPECTIVE

Development and Validation of a Nomogram for Predicting Heparin Resistance in Neonates and Young Infants Undergoing Cardiac Surgery: A Retrospective Study

BACKGROUND

Heparin resistance (HR) is a common finding in pediatric cardiac surgery and generally refers to decreased sensitivity to heparin. Antithrombin (AT) deficiency is considered the primary mechanism of HR; however, the etiology of HR may be multifactorial. Early identification of HR might help optimize heparin anticoagulation management. This study aimed to develop a predictive nomogram for HR in neonates and young infants undergoing cardiac surgery.

METHODS

From January 2020 to August 2022, a total of 296 pediatric patients 1 to 180 days of age were included in this retrospective study. The patients were randomly divided into development and validation cohorts in a 7:3 ratio. Univariable logistic regression and the Least Absolute Shrinkage and Selection Operator (LASSO) regularization were used for variable selection. A multivariable logistic regression was performed to identify predictors and establish a nomogram to predict HR risk. Discrimination, calibration, and clinical usefulness were assessed in the development and validation cohorts.

RESULTS

After the multistep variable selection, AT activity, platelet count, and fibrinogen were predictors for HR in neonates and young infants. The prediction model constructed using these 3 factors achieved an area under the receiver operating characteristic curve (ROC-AUC) of 0.874 and 0.873 in the development and validation cohorts. The Hosmer-Lemeshow test did not find evidence of a lack of fit ( P = .768). The calibration curve of the nomogram was close to the ideal diagonal line. Furthermore, the model performed well in neonate and infant subgroups.

CONCLUSIONS

A nomogram based on preoperative variables was developed to predict the HR risk in neonates and young infants undergoing cardiac surgery. This provides clinicians with a simple tool for the early prediction of HR, which may help optimize heparin anticoagulation strategies in this vulnerable patient population.

Clinical guidance for unfractionated heparin dosing and monitoring in critically ill patients

INTRODUCTION

Unfractionated heparin is a widely used anticoagulant in critically ill patients. It has a well-established safety profile and remains an attractive option for clinicians due to its short half-life and reversibility. Heparin has a unique pharmacokinetic profile, which contributes to significant inter-patient and intra-patient variability in effect. The variability in anticoagulant effect combined with heparin's short half-life mean close monitoring is required for clinical efficacy and preventing adverse effects. To optimize heparin use in critically ill patients, effective monitoring assays and dose adjustment strategies are needed.

AREAS COVERED

This paper explores the use of heparin as an anticoagulant and optimal approaches to monitoring in critically ill patients.

EXPERT OPINION

Conventional monitoring assays for heparin dosing have significant limitations. Emerging data appear to favor using anti-Xa assay monitoring for heparin anticoagulation, which many centers have successfully adopted as the standard. The anti-Xa assay appears have important benefits relative to the aPTT for heparin monitoring in critically ill patients, and should be considered for broader use.

Epidemiology of anticoagulation for children supported by extracorporeal membrane oxygenation in the United States: A Pediatric Hospital Information System database study

INTRODUCTION

Due to the risk of thrombosis, nearly all children supported by extracorporeal membrane oxygenation (ECMO) receive systemic anticoagulation. While heparin has traditionally been used, there are reports of increased use of direct thrombin inhibitors. We sought to describe the use of anticoagulation in children supported by ECMO in the United States using a large administrative database.

METHODS

We performed a retrospective cohort study of children supported by ECMO within the Pediatric Health Information System (PHIS) database. Pediatric encounters involving ECMO from 2012 to 2020 were identified. Data regarding demographics, diagnoses, anticoagulation, complications, and outcomes were extracted for eligible encounters.

RESULTS

Eleven thousand five hundred ninety-five encounters that involved ECMO were identified. Fifty-four percent were male with an age range of 0-17 years and a median (IQR) age of 0 (0-2) years. Unfractionated heparin (UFH) only was used in 94% (95% CI: 93.6-94.5%) of encounters and UFH followed by bivalirudin in 5% (95% CI: 4.3-5.1%) of cases. There was a significant difference in the use of bivalirudin from 2012 to 2020 (p < 0.001). Differences in anticoagulation regimens were observed between infants and children (p = 0.004) and between those with and without cardiac indications for ECMO (p < 0.001). Four percent (95% CI: 4.1-4.8%) of encounters were associated with diagnostic coding for thrombosis and differences in occurrence of thrombosis were observed between different anticoagulant regimens (p < 0.001).

CONCLUSIONS

Though the majority of children on ECMO in the United States receive heparin anticoagulation, there is an increase in use of direct thrombin inhibitors. Prospective studies must evaluate the efficacy of different anticoagulants in this patient population.

Protamine dosing and its impact in cardiac surgery transfusion practice-A retrospective bi-institutional analysis

BACKGROUND

Bleeding after cardiac surgery is common and continues to require 10-20% of the national blood supply. Transfusion of allogeneic blood is associated with increased morbidity and mortality. Excessive protamine in the absence of circulating heparin after weaning off CPB can cause anticoagulation and precipitate bleeding. Hence, adequate dose calculation of protamine is crucial yet under evaluated.

STUDY DESIGN

Retrospective cohort study.

METHODS

We conducted a retrospective bi-institutional analysis of cardiac surgical patients who underwent cardiopulmonary bypass (CPB)-assisted cardiac surgery to assess the impact of protamine dosing in transfusion practice. Total 762 patients were identified from two institutions using electronic medical records and the Society of Thoracic Surgery (STS) database who underwent cardiac surgery using CPB. Patients were similar in demographics and other baseline characteristics. We divided patients into two groups based on mg of protamine administered to neutralize each 100 U of unfractionated heparin (UFH)-low-ratio group (Protamine: UFH ≤ 0.8) and high-ratio group (Protamine: UFH > 0.8).

RESULTS

We observed a higher rate of blood transfusion required in high-ratio group (ratio >0.8) compared with low-ratio group (ratio ≤0.8) (p < .001). The increased requirement was consistently demonstrated for intraoperative transfusions of red blood cells, plasma, platelets, and cryoprecipitate.

CONCLUSION

High protamine to heparin ratio may cause increased bleeding and transfusion in cardiac surgical patients. Protamine to heparin ratio of 0.8 or lower is sufficient to neutralize circulating heparin after weaning off cardiopulmonary bypass.

Coatings for Cardiovascular Stents-An Up-to-Date Review

Cardiovascular diseases (CVDs) increasingly burden health systems and patients worldwide, necessitating the improved awareness of current treatment possibilities and the development of more efficient therapeutic strategies. When plaque deposits narrow the arteries, the standard of care implies the insertion of a stent at the lesion site. The most promising development in cardiovascular stents has been the release of medications from these stents. However, the use of drug-eluting stents (DESs) is still challenged by in-stent restenosis occurrence. DESs' long-term clinical success depends on several parameters, including the degradability of the polymers, drug release profiles, stent platforms, coating polymers, and the metals and their alloys that are employed as metal frames in the stents. Thus, it is critical to investigate new approaches to optimize the most suitable DESs to solve problems with the inflammatory response, delayed endothelialization, and sub-acute stent thrombosis. As certain advancements have been reported in the literature, this review aims to present the latest updates in the coatings field for cardiovascular stents. Specifically, there are described various organic (e.g., synthetic and natural polymer-based coatings, stents coated directly with drugs, and coatings containing endothelial cells) and inorganic (e.g., metallic and nonmetallic materials) stent coating options, aiming to create an updated framework that would serve as an inception point for future research.

Delirium after Cardiac Surgery-A Narrative Review

Postoperative delirium (POD) after cardiac surgery is a well-known phenomenon which carries a higher risk of morbidity and mortality. Multiple patient-specific risk factors and pathophysiologic mechanisms have been identified and therapies have been proposed to mitigate risk of delirium development postoperatively. Notably, cardiac surgery frequently involves the use of an intraoperative cardiopulmonary bypass (CPB), which may contribute to the mechanisms responsible for POD. Despite our greater understanding of these causative factors, a substantial reduction in the incidence of POD remains high among cardiac surgical patients. Multiple therapeutic interventions have been implemented intraoperatively and postoperatively, many with conflicting results. This review article will highlight the incidence and impact of POD in cardiac surgical patients. It will describe some of the primary risk factors associated with POD, as well as anesthetic management and therapies postoperatively that may help to reduce delirium.

Beyond the self: a novel framework to enhance non-technical team skills for anesthesiologists

Human factors and non-technical skills (NTS) have been identified as essential contributors to both the propagation and prevention of medical errors in the operating room. Despite extensive study and interventions to nurture and enhance NTS in anesthesiologists, gaps to effective team practice and patient safety remain. Furthermore, the link between added NTS training and clinically significant improved outcomes has not yet been demonstrated. We performed a narrative review to summarize the literature on existing systems and initiatives used to measure and nurture NTS in the clinical operating room setting. Controlled interventions performed to nurture NTS (N.=13) were identified and compared. We comment on the body of current evidence and highlight the achievements and limitations of interventions published thus far. We then propose a novel education and training framework to further develop and enhance non-technical skills in both individual anesthesiologists and operating room teams. We use the cardiac anesthesiology environment as a starting point to illustrate its use, with clinical examples. NTS is a key component of enhancing patient safety. Effective framing of its concepts is central to apply individual characteristics and skills in team environments in the OR and achieve tangible, beneficial patient outcomes.

International Survey on Perioperative Management of Patients With Infective Endocarditis

OBJECTIVES

To estimate the current practice in the perioperative management of patients undergoing cardiac surgery due to infective endocarditis.

DESIGN

A prospective, open, 24-item, web-based cross-sectional survey.

SETTING

Online survey endorsed by the European Association of Cardiothoracic Anesthesiology and Intensive Care (EACTAIC).

PARTICIPANTS

Members of the EACTAIC.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

A total of 156 responses from 44 countries were received, with a completion rate of 99%. The response rate was 16.6%. Most respondents (76%) practiced cardiac anesthesia in European hospitals, and most respondents stated that a multidisciplinary endocarditis team was not established at their center, that cardiac anesthesiologists appeared to be involved infrequently in those teams (36%), and that they were not involved in decision-making on indication and timing of surgery (88%). In contrast, the cardiac anesthesiologist performed intraoperative antibiotic therapy (62%) and intraoperative transesophageal echocardiography (90%). Furthermore, there was a relative heterogeneity concerning perioperative monitoring, as well as for coagulation and transfusion management.

CONCLUSIONS

This international survey evaluated current practice among cardiac anesthesiologists in the perioperative management of patients with infective endocarditis and the anesthesiologist's role in multidisciplinary decision-making. Heterogeneity in treatment approaches was identified, indicating relevant knowledge gaps that should encourage further clinical research to optimize treatment and postoperative outcomes in this specific population.

Multidrug-resistant bacterial infection in adult patients following cardiac surgery: clinical characteristics and risk factors

BACKGROUND

The prevalence of infections with multidrug-resistant organism (MDRO) pose great challenges for anti-infective therapy. Previous research on MDRO infections after cardiac surgery was limited. Therefore, understanding and mastering the clinical characteristics and risk predictors of MDRO infection after cardiac surgery is of great significance for standardized management of perioperative patients.

METHODS

The medical records of adult patients with MDRO infection after cardiac surgery from January 2018 to October 2021 were collected, and patients were divided into MDR infection group (n = 176) and non-MDR infection group (n = 233). Univariate and multivariate regression analysis of variables was performed to determine the risk predictors of MDRO infection.

RESULTS

The incidence of MDRO infection was 8.6%. Acinetobacter baumannii, Klebsiella pneumoniae and Pseudomonas aeruginosa were the most common, accounting for 37.3%, 23.5% and 18.0%, respectively. The main infection type were lower respiratory tract infection (LTRI = 29.0%). Univariate analysis showed that underwent coronary artery bypass graft (CABG) (P = 0.001) and secondary operation (P = 0.008), pre-infection exposure to vancomycin (P < 0.001) and linezolid (P = 0.002), combination antibiotics (P < 0.001), four antibiotics in combination (P = 0.005), glucocorticoid use (P = 0.029), preoperative hypoalbuminemia (P = 0.003) were risk factors for post-operative MDRO infection. Multivariate regression analysis showed that underwent CABG (OR = 1.228, 95%CI = 1.056∽1.427, P = 0.008), secondary operation (OR = 1.910, 95%CI = 1.131∽3.425, P = 0.015) and pre-infection exposure to linezolid (OR = 3.704, 95%CI = 1.291∽10.629, P = 0.005) were independent risk predictors for MDRO infection. The risk of MDRO infection increased with the length of stay in the ICU (P < 0.001) and the length of stay before diagnosis of infection (P = 0.003), and the difference was statistically significant. Meanwhile, the length of stay after infection (P = 0.005) and the total length of hospital stay (P < 0.001) were significantly longer in the MDRO infection group, and the all-cause mortality was numerically higher in the MDRO infection group (31.3% versus 23.2%).

CONCLUSIONS

The morbidity and mortality of MDRO infection was high in adult cardiac surgery, and many risk factors influence the occurrence of MDRO infection. In the future, clinicians should focus on high-risk patients, strengthen multidisciplinary collaboration on infection prevention and control measures, reduce the morbidity and mortality of MDRO infection, and improve the prognosis of in-hospital patients.

Update on Anticoagulation Strategies in Patients with ECMO-A Narrative Review

The use of extracorporeal membrane oxygenation (ECMO) has recently increased exponentially. ECMO has become the preferred mode of organ support in refractory respiratory or circulatory failure. The fragile balance of haemostasis physiology is massively altered by the patient's critical condition and specifically the aetiology of the underlying disease. Furthermore, an application of ECMO conveys another disturbance of haemostasis due to blood-circuit interaction and the presence of an oxygenator. The purpose of this review is to summarise current knowledge on the anticoagulation management in patients undergoing ECMO therapy. The unfractionated heparin modality with monitoring of activated partial thromboplastin tests is considered to be a gold standard for anticoagulation in this specific subgroup of intensive care patients. However, alternative modalities with other agents are comprehensively discussed. Furthermore, other ways of monitoring can represent the actual state of coagulation in a more complex fashion, such as thromboelastometric/graphic methods, and might become more frequent. In conclusion, the coagulation system of patients with ECMO is altered by multiple variables, and there is a significant lack of evidence in this area. Therefore, a highly individualised approach is the best solution today.

Relationship between estimated and observed heparin sensitivity indices in cardiac and thoracic aortic surgery

BACKGROUND

Little evidence exists on the relationship between the estimated heparin sensitivity index (HSI) based on commonly available clinical and laboratory data and observed HSI in the adult population. This retrospective study assessed the relationship between the observed and estimated HSIs.

METHODS

This study was conducted in an academic, single-institution setting. Patients aged ≥ 20 years who underwent cardiac and thoracic aortic surgery and requiring cardiopulmonary bypass were included. Clinical and laboratory data, including age, sex, and platelet count, were collected. The fibrinogen-albumin ratio index was calculated by dividing the fibrinogen value by the albumin value, multiplied by 10.The HSI was calculated using the formula: (activated clotting time after initial heparin administration-baseline activated clotting time)/initial heparin dose (IU/kg). The estimated HSI was based on the results of multiple regression analysis that included clinically relevant factors. The intraclass correlation coefficient between the observed and estimated HSIs was used to assess.

RESULTS

In total, 560 patients with valid activated clotting time (ACT) values after initial heparin administration were included in the final analysis to explore associated factors using the estimated HSI. Multiple regression analysis revealed that hemodialysis, platelet count, fibrinogen-to-albumin ratio index, baseline activated clotting time, and initial heparin dose were significantly associated with the HSI. The mean (standard deviation) observed and estimated HSIs were 1.38 (0.43) and 1.55 (0.13), respectively, with an intra-class correlation coefficient of 0.10.

CONCLUSIONS

The correlation between the observed and estimated HSIs was low, and a formula with high accuracy for estimating the HSI is needed.

Extracorporeal Membrane Oxygenation

The utilization of extracorporeal membrane oxygenation (ECMO) for cardiopulmonary support continues to increase globally, with > 190,000 ECMO cases reported to the international Extracorporeal Life Support Organization Registry. The present review aims to synthesize important contributions to the literature surrounding the management of mechanical ventilation, prone positioning, anticoagulation, bleeding complications, and neurologic outcomes for infants, children, and adults undergoing ECMO in 2022. Additionally, issues related to cardiac ECMO, Harlequin syndrome, and anticoagulation during ECMO will be discussed.