The weight-based heparin dosing nomogram compared with a "standard care" nomogram. A randomized controlled trial

A cardiac extracellular matrix-based bilayer vascular graft with controlled microstructures for the reconstruction of small-diameter blood vessels

Despite recent progress, challenges with small-diameter vascular grafts, including mechanical strength, intimal hyperplasia, thrombosis, and poor endothelialization, remain unresolved. The present study reports a novel bilayer vascular graft designed to mimic the anatomical features of small-diameter blood vessels. The electrospun graft consists of a dense micro/nanofibrous inner layer of cardiac extracellular matrix (cECM), polycaprolactone (PCL) loaded with heparin (P-cECM-H), and a super porous and micro-fibrous PCL outer layer. Liquid chromatography-mass spectrometry (LC-MS/MS) proteome analysis of the cECM revealed that it is enriched with several bioactive proteins related to angiogenesis, wound regeneration, cell migration, etc. The porosities of the two layers are tailored according to endothelial and smooth muscle cell biology. The graft exhibited excellent mechanical properties, and the heparinized P-cECM inner layer improved hemocompatibility and anticoagulation efficacy. A significant increase in endothelial cell proliferation was noted in the P-cECM-H group after 7 days compared with the control group (p < 0.05). The bilayer graft maintained 100 % patency after 10 weeks of rat abdominal aorta implantation. Histological evaluation revealed smooth muscle cell infiltration inside the highly porous outer layer and neointima regeneration in the inner layer with a complete endothelial lining. RNA sequencing (RNA-Seq) analysis further confirmed smooth muscle formation and endothelial layer formation. The gene expression data also suggested that the hypoxia-inducible factor-1 (HIF-) and vascular endothelial growth factor (VEGF) signaling pathways are involved in endothelial layer remodeling. These promising results indicate that cECM could be a key material for vascular tissue regeneration.

Optimizing the Dosing of Heparin for Therapeutic Anticoagulation in Neurocritical Care Patients at High Risk of Bleeding: Report on a Quality Improvement Initiative

Background: Heparin infusions are used to treat and prevent thromboembolic complications in neurocritical care, but optimal dosing in patients with acute intracranial pathology or recent neurosurgery is uncertain, due to elevated risk of hemorrhage. Many institutions customize heparin nomograms for such patients but fail to methodically evaluate their effectiveness. Context: Neurocritical care unit in an academic medical center in the United States. Problem: Several incidents of heparin infusions failing to reach their partial thromboplastin time (PTT) goal within 24 hours of initiation occurred. This created a concern that existing heparin dosing protocol should be adjusted to attain goal PTT more rapidly to better treat thrombotic events. Objective: To reduce time to therapeutic effectiveness of weight-based heparin in neurocritical care patients at high risk of bleeding. Study Design: Quality improvement initiative, comparing data from a retrospective chart review (historical comparison cohort) and a prospective observational quality improvement initiative (QI cohort). Patients: Adult patients with acute intracranial pathology and acute indications for therapeutic anticoagulation but considered at high risk of intracranial hemorrhage. Interventions: Increase heparin dosing nomogram from 12 units/kg/h (historical cohort) to 18 units/kg/h (quality improvement cohort), without an initial bolus in either. Measurements: Primary endpoint was time to therapeutic activated partial thromboplastin time (aPTT) in hours, assessed with a Kaplan-Meier curve. Any known bleeding or thrombotic complications were recorded. Results: Time to reach therapeutic target aPTT was shorter in quality improvement cohort than in historical cohort (see Figure 1 in full text for details). Bleeding complications occurred in 3 of 21 patients in each cohort. Conclusions: Quality improvement initiatives such as this can make documented improvements in health care provided to neurocritical care patients.

Results of an international survey on the management of therapeutic intensity unfractionated heparin: communication from the SSCs of the ISTH

BACKGROUND

Unfractionated heparin (UFH) remains the anticoagulant of choice in critically ill patients. However, its laboratory monitoring and clinical management are particularly challenging.

OBJECTIVES

Our objective was to describe current practices and variations among centers of the ISTH.

METHODS

Between November 2023 and February 2024, we surveyed 142 clinicians and laboratory medicine specialists from 15 countries involved in the care of patients receiving therapeutic-intensity UFH.

RESULTS

UFH monitoring was based on an anti-Xa assay or on activated partial thromboplastin time in 54% and 46% of respondents, respectively. Different therapeutic ranges were used depending on local protocols and indications; the 0.3 to 0.7 IU/mL anti-Xa range was commonly used, except for patients on mechanical circulatory support with a lower range, mostly 0.3 to 0.5 IU/mL. Most respondents managed therapeutic UFH administration with weight-based dosing (88%), while fewer used a nomogram (57%) for dose adjustment. When a nomogram was used, it was primarily based on anti-Xa monitoring (86%). The situations when respondents administered antithrombin varied widely; 22% reported using it when antithrombin levels were below 60 IU/dL(%) and 20% reported never using it.

CONCLUSION

Our survey results revealed considerable heterogeneity in UFH management approaches, reflecting a knowledge gap and a paucity of evidence to guide decision-making. Key issues requiring well-designed up-to-date studies were identified that include optimal approaches to heparin monitoring, assays and reagents to be used, therapeutic range based on indications, the use of weight-adjusted nomograms for initial dosing and titrating of UFH infusion, and indications for antithrombin supplementation. Survey results provide a strong rationale for the development of international guidance addressing these issues.

Time to Target Anti-Xa Level in Obese Vs Nonobese Patients Using an Adjusted Body Weight Heparin Infusion Protocol for the Treatment of Venous Thromboembolism

BACKGROUND

Unfractionated heparin (UFH) is a first-line option for the acute treatment of venous thromboembolism (VTE). Weight-based dosing protocols have demonstrated a decreased time to therapeutic anticoagulation, however, there are limited data on their utilization in obese patients, including the type of weight used.

OBJECTIVE

The purpose of this study was to determine equivalency in time to reach target antifactor-Xa (anti-Xa) for obese and nonobese patients using the same adjusted body weight (AdjBW)-based UFH infusion protocol.

METHODS

This was a single-center retrospective study of patients aged 18 years or older receiving an infusion of UFH for the treatment of VTE. The primary outcome was the median time to first target anti-Xa. Secondary outcomes included the percentage of first anti-Xa levels at 6 hours that were within, below, or above the target range and the median time to the second consecutive anti-Xa level within the target range. The safety outcome of evidence of major bleed was also evaluated.

RESULTS

Of the 166 patients assessed (75 obese and 91 nonobese), there was no observed difference in median time to first target anti-Xa in obese vs nonobese patients when using an AdjBW UFH protocol (12.45 vs 13.03 hours, P = 0.49). The percentage of patients achieving a target anti-Xa at first evaluation did not differ between obese and nonobese groups (32.0% vs 34.07%, P = 0.78). A total of 14 patients across groups experienced evidence of major bleed, with no observed difference between obese and nonobese groups (8.00% vs 8.89%, P = 0.84).

CONCLUSIONS AND RELEVANCE

There was no observed difference in median time to first target anti-Xa in obese vs nonobese patients when using an AdjBW heparin infusion protocol, with no observed difference in evidence of major bleed. Our findings support the use of AdjBW in weight-based UFH dosing.

Evaluation of unfractionated heparin therapy for venous thromboembolism using adjusted body weight in elderly or higher weight patients

The use of weight-based unfractionated heparin (UFH) infusions is the standard of care in hospital management of venous thromboembolism (VTE). Initial dosing strategies for UFH in older adults and higher body weight patients remain uncertain given differences in pharmacokinetics and concerns for over-anticoagulation. Methods: This was a single-center, retrospective, pre-post study involving older adults aged ≥ 65 years and patients weighing ≥ 100 kg with suspected or confirmed VTE to determine if the use of adjusted body weight (AdjBW)-based UFH regimens improves time to therapeutic anti-Xa levels compared to total body weight (TBW)-based regimens Patients received weight-based UFH infusions, dosed according to either TBW or AdjBW, to target a therapeutic anti-Xa level. Each cohort consisted of 40 patients, stratified by whether they met age or weight criteria to ensure equal representation of elderly and higher body weight patients between cohorts. The median time to therapeutic anti-Xa levels was shorter in the AdjBW group compared to the TBW group (13.6 h versus 20.9 h; point estimate 5.3 h (95% CI 0.2 to 9.9)). This finding was driven by those aged ≥ 65 years and those who received a bolus dose at the start of the infusion. Among older adults and higher weight adults with suspected or confirmed VTE, the use of AdjBW to guide heparin infusion initiation was associated with shorter time to therapeutic anti-Xa levels. This finding driven by the older adult sample and the subgroup analyses did not find a statistically significant difference in time to therapeutic anti-Xa levels in higher body weight patients aged less than 65 years.

Pulmonary embolism prophylaxis and treatment: What's right, what's wrong, and the future

Recognition of the importance of effective pulmonary embolism treatment and prophylaxis has improved inpatient care in many settings. Recommended drug treatment and prophylaxis of acute pulmonary embolism have changed little over the past 10 years. However, new information has emerged, which when combined with early pharmacology studies of unfractionated heparin and low molecular weight heparin, clearly shows important deficits in current practice that, if remedied, could reduce risk and likely save lives. These involve ensuring improved bioavailability of low molecular weight heparin prophylaxis dosing by abandoning once-daily dosing, adopting weight- or weight-category based dosing, and dosing twice daily or by continuous infusion in critically ill patients. For pulmonary embolism treatment, failure to recognize that presenting patients often have subnormal perfusion resulting in unpredictable bioavailability of subcutaneous anticoagulant has meant undertreatment, and delay in reaching a therapeutic anticoagulant level, assuredly resulting in failure of timely improvement as well as recurrent thromboembolism. Intravenous anticoagulant should be rapidly adopted as first treatment for acute pulmonary embolism until normal hemodynamic values are restored and cutaneous perfusion returns. Treatments under development include clinical investigation of intensive care unit (ICU) patients receiving intravenous low molecular weight heparin prophylaxis, weight-based, targeting an anticoagulant level in anti-Xa units that is both effective and safe. The same would be useful for pulmonary embolism treatment, although return to initial anticoagulation with unfractionated heparin is more easily monitored by activated partial thromboplastin time (aPTT) and is an easy standard of care to adopt. Pulmonary embolism clot removal is being accomplished by suction thrombectomy and catheter-directed lysis, each with its own different procedural characteristics. Whether either confers benefit compared to conscientiously administered intravenous anticoagulation cannot be shown in ongoing studies using subcutaneous treatment in control patients with subnormal perfusion. Factor XI/XIa inhibition is another treatment approach being studied. Another approach to lytic therapy under study, administering an inhibitor of alpha-2-antiplasmin, may cause less bleeding than tissue plasminogen activators.

Guidance-Based Appropriateness of Hemostasis Testing in the Acute Setting

In this review, we aim to highlight the extent of inappropriate hemostasis testing and provide practical guidance on how to prevent it. We will focus on the acute setting, including but not limited to the emergency department and intensive care unit. To this end, we will first discuss the significance of inappropriateness, in the general context of laboratory medicine. This includes acknowledging the importance of the phenomenon and attempting to define it. Next, we describe the harmful consequences of inappropriate testing. Finally, we focus on the inappropriate use of hemostasis testing in the acute setting. The second section describes how interventions-in particular, the implementation of guidance for testing-can efficiently reduce inappropriateness. In the third section, we summarize the available recommendations for rational use of hemostasis testing (platelet count, activated partial thromboplastin time, prothrombin time/international normalized ratio, fibrinogen, thrombin time, D-dimer, anti-Xa assay, antithrombin, ADAMTS13 activity, antiheparin-PF4 antibodies, viscoelastometric tests, coagulation factors, and platelet function testing), as supported by guidelines, recommendations, and/or expert opinions. Overall, this review is intended to be a toolkit in the effort to promote the appropriate use of hemostasis testing. Hopefully, the new In Vitro Diagnostic Medical Device Regulation (EU) 2017/746 (IVDR) should help in improving the availability of evidence regarding clinical performance of hemostasis assays.

Anti-factor Xa during unfractionated heparin therapy in critically ill patients: Development of prediction models using machine learning

Objective

Unfractionated heparin (UFH) is a widely used therapy in intensive care units (ICUs) and is associated with an increased risk of serious adverse events or death if the therapeutic target is not reached quickly. Adjusting UFH dosage is challenging, and no reliable algorithms exist for predicting anti-Xa levels in ICUs. This study aimed to develop and evaluate machine learning algorithms to predict anti-Xa levels during UFH therapy, helping clinicians optimize dosing.

Methods

This single-center retrospective cohort study was conducted using Rennes University Hospital's clinical data warehouse from December 21, 2019 to November 22, 2021. Critically ill patients ≥ 18 years on UFH, without other anticoagulants and complete data, were included. Anti-Xa levels were classified as infra-therapeutic (<0.3), therapeutic (0.3-0.7), or supra-therapeutic (>0.7). Models incorporated UFH rate, bolus, prior anti-Xa, kidney function, inflammation, volemic state, extracorporeal membrane oxygenation, and bilirubinemia. Performance was assessed using the area under the receiver operating characteristic curve (AUROC), area under the precision-recall curve (AUPRC), sensitivity, and specificity.

Results

A total of 3790 anti-Xa intervals, corresponding to 211 patients, were included in the study. Out of several machine learning algorithms, random forest achieved the best results with an AUROC score of 0.80 [0.77;0.83], an AUPRC score of 0.61 [0.58;0.65], sensitivity of 0.56 [0.53;0.59] and specificity of 0.82 [0.82;0.82].

Conclusion

In this cohort study, machine learning-based prediction models achieved good performance for predicting anti-Xa results during UFH therapy in an ICU setting. Further validation with prospective multicenter data is needed in order to confirm the model's generalizability and support its integration into clinical practice to assist clinicians in selecting the optimal heparin dose.

Anticoagulation approach in morbid obesity: a comprehensive review on venous thromboembolism management

Obesity is a recognized risk factor for venous thromboembolism (VTE), associated with distinct challenges in managing anticoagulation therapy. There is still limited evidence regarding the impact of extreme body weight on the pharmacokinetics, pharmacodynamics, efficacy, and safety of various anticoagulant medications. To our knowledge, this is the first comprehensive review to address both prophylactic and therapeutic anticoagulant dosages specifically for managing VTE in patients with a body mass index (BMI) ≥40 kg/m2 or weight ≥120 kg. Our aim was to synthesize the findings of relevant studies alongside the latest recommendations on anticoagulation in this unique population. We gathered and analyzed data on all classes of anticoagulants available for VTE management, including vitamin K antagonists (VKAs), unfractionated heparin (UFH), low-molecular-weight heparin (LMWH), fondaparinux, and direct oral anticoagulants (DOACs), offering insights into their efficacy and safety profiles. Additionally, we explored special subpopulations of morbidly obese patients, such as those with cancer, renal dysfunction, or those undergoing bariatric surgery, recognizing the nuanced therapeutic challenges they present. The current evidence for anticoagulant therapy in morbidly obese patients with VTE is evidently insufficient, underscoring the need for a tailored approach and meticulous monitoring to achieve an optimal therapeutic balance.

Pulmonary Embolism in Critically Ill Patients-Prevention, Diagnosis, and Management

Critically ill patients in the intensive care unit (ICU) are often immobilized and on mechanical ventilation, placing them at increased risk for thromboembolic diseases, particularly deep vein thrombosis (DVT) and, to a lesser extent, pulmonary embolism (PE). While these conditions are frequently encountered in the emergency department, managing them in the ICU presents unique challenges. Although existing guidelines are comprehensive and effective, they are primarily designed for patients presenting with PE in the emergency department and do not fully address the complexities of managing critically ill patients in the ICU. This review aims to summarize the available data on these challenging cases, offering a practical approach to the prevention, diagnosis, and treatment of PE, particularly when it is acquired in the ICU.

Right lobe living donor liver transplantation – experience from the Department of Hepatobiliary Surgery

Background. Living-donor liver transplant (LDLT) is a life-saving procedure for patients with end-stage liver diseases.

Objective: to evaluate the outcomes of the first independent LDLT performed at the Department of Hepatobiliary Surgery, Vakhidov Republican Specialized Surgical Research and Practical Medical Center of Surgery, and to demonstrate that liver transplantation (LT) is a feasible procedure at our institution.

Materials and methods. From October 2021 to December 2023, 40 right lobe LDLTs were performed in our department. Short-term and long-term outcomes in recipients were assessed. The outcomes of transplant hepatectomy were also evaluated.

Results. Hepatic artery thrombosis developed in 1 case (2.5%); arterial anastomotic stenosis was detected in 3 cases (7.5%), which were repaired by endovascular balloon dilation; splenic artery steal syndrome was diagnosed in 3 cases (7.5%), which was resolved by endovascular splenic artery embolization. One patient (2.5%) developed portal vein thrombosis. Two patients (5%) had portal vein stenosis 10 months after transplantation; endovascular balloon angioplasty was performed with good clinical effect. Biliary complications accounted for 45%, of which 89% were biliary leaks and 11% were anastomotic biliary stricture. In-hospital mortality was 12.5%.

Conclusion. The results of our experience and analysis of post-transplant complications are comparable with those of the world literature and are acceptable at the stage of implementation of the LT program. Transplantation is feasible at our center, but it is necessary to improve surgical and conservative treatment techniques in order to minimize early and late postoperative complications.

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.

Implementation of a living donor liver transplantation program in the Republic of Uzbekistan: a report of the first 40 cases

BACKGROUND

Living donor liver transplantation (LDLT) is an effective treatment for patients with end-stage liver disease. This study was performed to evaluate the outcomes of the initial series of LDLT procedures performed in the Republic of Uzbekistan and to demonstrate that liver transplantation is viable under the conditions in this country.

METHODS

Between October 2021 and December 2023, we performed 40 LDLTs. We evaluated both immediate and long-term outcomes.

RESULTS

Thrombosis of the hepatic artery developed in one case (2.5%). Arterial anastomotic stenoses were diagnosed in three cases (7.5%) and were successfully treated with endovascular balloon vasodilation. Splenic artery steal syndrome arose in three patients (7.5%) and was managed with endovascular embolization of the splenic artery. One patient (2.5%) developed portal vein thrombosis. Portal vein stenosis occurred in two patients (5%) at 10 months posttransplantation and was addressed with endovascular balloon angioplasty, yielding good clinical outcomes. Biliary complications were observed in 45% of the cases, with bile leakages accounting for 89% of these issues and strictures of the biliary anastomoses for 11%. The in-hospital mortality rate was 12.5%.

CONCLUSIONS

Our research findings and analysis of complications align with the international literature, and the results are deemed acceptable during this implementation phase of the liver transplantation program. Accordingly, liver transplantation is feasible in the Republic of Uzbekistan; however, improvements in surgical and therapeutic methods are necessary to minimize the development of both early and late postoperative complications.

Single-center experience of intraoperative ligation of the splenic artery for prevention of splenic artery steal syndrome in patients after living donor liver transplant

Background. Living donor liver transplant is an effective method of treatment in patients with different types of endstage liver diseases. Unfortunately, patients undergoing such a complex treatment sometimes develop various vascular complications. Splenic artery steal syndrome has emerged as a cause of graft ischemia in living donor liver transplant recipients and may lead to high liver enzyme levels, cholestasis, hepatic artery thrombosis, and even a graft loss in some severe cases.

Objective. Evaluation of the first results in the experience of our center with a routine intraoperative ligation of the splenic artery during the procedure of right lobe living donor liver transplantation in adult recipients for the prevention of the steal syndrome development in the postoperative period.

Material and methods. Living donor liver transplant recipients with known hepatic arterial flow impairment were retrospectively studied. Patients were allocated into groups with regard whether the splenic artery had been ligated or not during the transplant procedure. Arterial complications were reviewed in both groups.

Results. None of 30 patients with ligated splenic artery developed splenic artery steal syndrome after living donor liver transplant. splenic artery steal syndrome occurred in 60% patients with non-ligated splenic artery. Surgical technique of performing arterial anastomosis was not related to the splenic artery steal syndrome development (p<0.01 There was no local ischemic necrosis noted in the spleen in patients with the ligated splenic artery.

Conclusion. Based on the analysis of our own experience and literature data, the splenic artery ligation appears to be an effective and safe method for preventing a splenic artery steal syndrome in patients following right lobe liver transplantation, with a minimal risk of ischemic complications for the spleen. However, further studies with larger sample sizes are needed to obtain more reliable results. Ultrasound examination and endovascular intervention are the primary tools for an early detection of abnormalities and rapid restoration of arterial blood flow in the hepatic artery of the graft.

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

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.

Improving Compliance with a Nurse-Driven Protocol for Unfractionated Heparin Infusions in Patients with Venous Thromboembolism

BACKGROUND

Unfractionated heparin (UFH) is a high-risk medication that can cause bleeding and/or thrombotic complications if not managed appropriately. Between January and July 2019, our institution experienced a high number of patient safety events related to UFH infusion for the treatment of venous thromboembolism (VTE).

PURPOSE

The aim of this quality improvement (QI) initiative was to prevent these safety events by improving compliance with our institution's nurse-driven VTE UFH infusion protocol.

METHODS

Baseline data for patients on the VTE UFH protocol were collected to identify improvement opportunities. Compliance with eight standards of care related to the VTE UFH infusion protocol was measured. Time to first therapeutic activated partial thromboplastin time (aPTT) was recorded to assess the benefit of improved compliance.

INTERVENTIONS

Institutional policy updates were made to clarify the management of UFH infusions and documentation in the electronic health record. A multidisciplinary workgroup implemented order set changes, nursing communication orders, UFH infusion reports, and a nursing education module to promote compliance with the protocol.

RESULTS

The overall rate of compliance with the VTE UFH infusion protocol increased from 79.4% at baseline to 85.2% following implementation of the QI initiative, and the median time to first therapeutic aPTT decreased from 831.5 minutes to 808 minutes over the same period.

CONCLUSIONS

A multidisciplinary initiative to address improvement opportunities in a nurse-driven UFH protocol for VTE treatment increased compliance with the protocol and decreased the time to first therapeutic aPTT.

From Trendelenburg to PERTs: Evolution in the Management of Massive Pulmonary Embolism

Massive pulmonary embolism (MPE) is a serious condition affecting the pulmonary arteries and is difficult to diagnose, triage, and treat. The American College of Chest Physicians (AHA) and the European Society of Cardiology (ESC) have different classification approaches for PE, with the AHA defining three subtypes and the ESC four. Misdiagnosis is common, leading to delayed or inadequate treatment. The incidence of PE-related death rates has been increasing over the years, and mortality rates vary depending on the subtype of PE, with MPE having the highest mortality rate. The current definition of MPE originated from early surgical embolectomy cases and discussions among experts. However, this definition fails to capture patients at the point of maximal benefit because it is based on late findings of MPE. Pulmonary Embolism Response Teams (PERTs) have emerged as a fundamental shift in the management of MPE, with a focus on high-risk and MPE cases and a goal of rapidly connecting patients with appropriate therapies based on up-to-date evidence. This review highlights the challenges in diagnosing and managing MPE and emphasizes the importance of PERTs and risk stratification scores in improving outcomes for patients with PE.

Successful microvascular surgery in patients with thrombophilia in head and neck surgery: a case series

BACKGROUND

In this case series, a perioperative anticoagulation protocol for microvascular head and neck surgery in patients with thrombophilia is presented. Microvascular free-flap surgery is a standard procedure in head and neck surgery with high success rates. Nevertheless, flap loss-which is most often caused by thrombosis-can occur and has far-reaching consequences, such as functional impairment, prolonged hospitalization, and increased costs. The risk of flap loss owing to thrombosis is significantly increased in patients with thrombophilia. Therefore, perioperative anticoagulation is mandatory. To date, no perioperative anticoagulation protocol exists for these high-risk patients.

CASE PRESENTATION

We present three exemplary male Caucasian patients aged 53-57 years with free flap loss owing to an underlying, hidden thrombophilia.

CONCLUSION

We present a modified anticoagulation protocol for microvascular surgery in these high-risk patients, enabling successful microsurgical reconstruction.

Implementation of a Heparin Infusion Calculator in the Electronic Health Record System as a Risk-Mitigation Strategy in a Community Teaching Hospital Emergency Department

INTRODUCTION

According to the Institute for Safe Medication Practices, unfractionated heparin is a high-risk medication due to the potential for medication errors and adverse events. Unfractionated heparin is often started in the emergency department for patients with acute coronary syndromes or coagulopathies. Risk-mitigation strategies should be implemented to ensure appropriate initiation and monitoring of this high-risk medication. In 2019, an unfractionated heparin calculator was built into the electronic health record at a community medical center. The purpose of this study was to evaluate the impact of the calculator as a risk-mitigation strategy.

METHODS

Patients ≥18 years old admitted between January 1, 2020, and December 31, 2020, were included if they were administered an unfractionated heparin infusion in the emergency department. Patient encounters were excluded if unfractionated heparin order was discontinued before administration. Patient encounters were classified into the unfractionated heparin calculator arm if the unfractionated heparin calculator was used to determine initial dosing, and the remaining patient encounters were classified into the unfractionated heparin no calculator arm. Unfractionated heparin orders were reviewed if a baseline activated partial thromboplastin time was collected and if the correct initial bolus dose and infusion rate were administered. The primary objective is to determine whether the use of unfractionated heparin initiation calculator reduced the rate of medication administration errors. Medication administration errors are defined as baseline activated partial thromboplastin time not collected or incorrectly collected or the administration of incorrect initial bolus dose and infusion rate.

RESULTS

A total of 356 patient encounters with unfractionated heparin orders were included in the primary analysis. There were 13.9% errors (39 of 279) present when the calculator was used and 23.3% (18 of 77) when the calculator was not used (P = .046). There was 86% correct administration of heparin (240 of 279) when the calculator was used and 76% correct administrations (59 of 77) when the calculator was not used.

DISCUSSION

The use of the unfractionated heparin infusion calculator in the emergency department led to decrease in medication administration errors. This is the first study to evaluate the integration of an unfractionated heparin calculator into the electronic health record.

Value function assessment to different RL algorithms for heparin treatment policy of patients with sepsis in ICU

Heparin is a critical aspect of managing sepsis after abdominal surgery, which can improve microcirculation, protect organ function, and reduce mortality. However, there is no clinical evidence to support decision-making for heparin dosage. This paper proposes a model called SOFA-MDP, which utilizes SOFA scores as states of MDP, to investigate clinic policies. Different algorithms provide different value functions, making it challenging to determine which value function is more reliable. Due to ethical restrictions, we cannot test all policies on patients. To address this issue, we proposed two value function assessment methods: action similarity rate and relative gain. We experimented with heparin treatment policies for sepsis patients after abdominal surgery using MIMIC-IV. In the experiments, TD(0) shows the most reliable performance. Using the action similarity rate and relative gain to assess AI policy from TD(0), the agreement rates between AI policy and "good" physician's actual treatment are 64.6% and 73.2%, while the agreement rates between AI policy and "bad" physician's actual treatment are 44.1% and 35.8%, the gaps are 20.5% and 37.4%, respectively. External validation using action similarity rate and relative gain based on eICU resulted in agreement rates of 61.5% and 69.1% with the "good" physician's treatment, and 45.2% and 38.3% with the "bad" physician's treatment, with gaps of 16.3% and 30.8%, respectively. In conclusion, the model provides instructive support for clinical decisions, and the evaluation methods accurately distinguish reliable and unreasonable outcomes.

Pharmacokinetic Modeling Using Real-World Data to Optimize Unfractionated Heparin Dosing in Pediatric Patients on Extracorporeal Membrane Oxygenation and Evaluate Target Achievement-Clinical Outcomes Relationship

Unfractionated heparin (UFH) is a commonly used anticoagulant for pediatric patients undergoing extracorporeal membrane oxygenation (ECMO), but evidence is lacking on the ideal dosing. We aimed to (1) develop a population pharmacokinetic (PK) model for UFH, measured through anti-factor Xa assay; (2) optimize UFH starting infusions and dose titrations through simulations; and (3) explore UFH exposure-clinical outcomes relationship. Data from 218 patients admitted to Utah's Primary Children's Hospital were retrospectively collected. A 1-compartment PK model with time-varying clearance (CL) adequately described UFH PK. Weight on CL and volume of distribution and ECMO circuit change on CL were significant covariates. The typical estimates for initial CL and first-order rate constant to reach steady-state CL were 0.57 L/(h·10 kg) and 0.02/h. Comparable to non-ECMO patients, the typical steady-state CL was 0.81 L/(h·10 kg). Simulations showed that a 75 IU/kg UFH bolus dose followed by starting infusions of 25 and 20 IU/h/kg for patients aged younger than 6 years and 6 years or older, respectively, achieved the therapeutic target in 56.6% of all patients, whereas only 3.1% exceeded the target. The proposed UFH titration schemes achieved the target in more than 90% of patients while less than 0.63% were above the target after 24 and 48 hours of treatment. The median intensive care unit survival time in patients within and below the target at 24 hours was 136 and 66 hours, respectively. In conclusion, PK model of UFH was developed for pediatric patients on ECMO. The proposed UFH dosing scheme attained the anti-factor Xa target rapidly and safely.

Laboratory Monitoring of Heparin Anticoagulation in Hemodialysis: Rationale and Strategies

Unfractionated heparin (UFH) and low-molecular-weight heparins (LMWHs) are commonly used to prevent clotting of the hemodialysis extracorporeal circuit and optimize hemodialysis adequacy. There is no consensus on the optimal dosing for UFH and LMWHs during hemodialysis. In clinical practice, semiquantitative clotting scoring of the dialyzer and venous chamber may help to guide UFH and LMWH dose adjustment. Laboratory monitoring has not been shown to improve clinical outcomes and is therefore not routinely indicated in most hemodialysis patients. It might, however, be considered in select patients, such as those with extremes of body weight or history of repeated clotting or bleeding. Methods for laboratory monitoring include the activated partial thromboplastin time, activated clotting time, and antifactor Xa assays for UFH and antifactor Xa assay for LMWHs. Target ranges for anticoagulation in hemodialysis have been suggested but not clearly defined. When utilizing these tests, issues such as availability, standardization, interfering factors, and interpretation must be considered. In this narrative review, we discuss the rationale and methods of monitoring anticoagulation in hemodialysis.

Vascular complications after liver transplantation: contemporary approaches to detection and treatment. A literature review

Vascular complications (VCs) after liver transplantation (LT) are rare but are one of the most dreaded conditions that can potentially lead to graft loss and recipient death. This paper has analyzed the international experience in the early diagnosis of various VCs that can develop following LT, as well as the optimal timing and methods of treatment of these complications.

Investigating predictors of progression from mild cognitive impairment to Alzheimer's disease based on different time intervals

BACKGROUND

Mild cognitive impairment (MCI) is the early stage of AD, and about 10-12% of MCI patients will progress to AD every year. At present, there are no effective markers for the early diagnosis of whether MCI patients will progress to AD. This study aimed to develop machine learning-based models for predicting the progression from MCI to AD within 3 years, to assist in screening and prevention of high-risk populations.

METHODS

Data were collected from the Alzheimer's Disease Neuroimaging Initiative, a representative sample of cognitive impairment population. Machine learning models were applied to predict the progression from MCI to AD, using demographic, neuropsychological test and MRI-related biomarkers. Data were divided into training (56%), validation (14%) and test sets (30%). AUC (area under ROC curve) was used as the main evaluation metric. Key predictors were ranked utilising their importance.

RESULTS

The AdaBoost model based on logistic regression achieved the best performance (AUC: 0.98) in 0-6 month prediction. Scores from the Functional Activities Questionnaire, Modified Preclinical Alzheimer Cognitive Composite with Trails test and ADAS11 (Unweighted sum of 11 items from The Alzheimer's Disease Assessment Scale-Cognitive Subscale) were key predictors.

CONCLUSION

Through machine learning, neuropsychological tests and MRI-related markers could accurately predict the progression from MCI to AD, especially in a short period time. This is of great significance for clinical staff to screen and diagnose AD, and to intervene and treat high-risk MCI patients early.

Evaluation of anti-Xa levels in patients with venous thromboembolism within the first 48 h of anticoagulation with unfractionated heparin

Background: A 2019 study by Prucnal and colleagues found that the majority of patients treated with unfractionated heparin for pulmonary embolism did not maintain therapeutic activated partial thromboplastin time levels during the first 48 h of therapy. Objective: The purpose of this study was to evaluate the ability of an institution's unfractionated heparin dosing protocol to achieve and maintain therapeutic anti-Xa levels within the first 48 h of therapy in patients with venous thromboembolism. Methods: This retrospective study included 205 patients from May 2016 through September 2020. Patients were divided into two cohorts: bolus plus infusion (N = 89) and infusion only (N = 116). The primary objective was to determine the number of patients who achieved at least one therapeutic level. Results: Overall, 200 patients (97.6%) had at least one therapeutic level with no statistically significant difference between cohorts (p = 0.65). No more than 60% of patients achieved a therapeutic level at any of the 6-h intervals throughout the timeframe. The median time to the first therapeutic level in the overall group was 12.8 h with no statistically significant difference between the bolus plus infusion and infusion-only cohorts (13.3 h versus 12.7 h, respectively, p = 0.48). Conclusions: Most patients were able to achieve at least one therapeutic level within the first 48 h, but fewer were able to maintain therapeutic levels. Further studies are warranted to determine whether alternative dosing strategies would yield consistent achievement of therapeutic levels and affect patient-oriented outcomes.

A Review of the Usefulness of Catheter-Directed Thrombolysis for Pulmonary Embolism

Venous thromboembolic disease (VTE) is a health problem; around 10 million cases occur yearly with substantial morbidity and mortality. Those who survive may be left with long-term sequelae. Those sequelae might include chronic thromboembolic pulmonary hypertension, persistent right ventricular dysfunction, exercise intolerance, and reduced quality of life. Current PE management consists of anticoagulation alone, systemic thrombolysis, catheter-directed thrombolysis, and surgical embolectomy. The severity of patients with pulmonary embolism (PE) depends on the clinic and not exclusively on the extent of radiological or anatomical involvement. In this review, we present the main clinical and functional characteristics of patients in whom thrombotic fragmentation plus catheter-guided thrombolysis is used to manage acute PE of intermediate-high risk and torpid evolution within the first hours of admission.

[Sustainable anticoagulation in COVID-19: Review of severity prediction and clinical reasoning]

OBJECTIVE

To identify the procoagulant phenomenon in SARS-CoV-2 patients and propose sustainable therapeutic guidance for low-income countries.

METHODS

A systematic review was conducted. It identified 5 observational studies from a scrutiny from 78 results. 712 patients were examined and the results were grouped according to mortality and severity. The comparison of the groups was interpreted using descriptive statistics.

RESULTS

D-dimer values were significantly associated with greater severity and mortality. Prothrombin was associated in some observations with higher mortality, but in terms of severity it was inconclusive.

CONCLUSION

COVID-19 disease has significant procoagulant activity and its timely treatment can alter the prognosis. The explored evidence supports sustainable methods. More evidence is needed to improve management. An early systematic approach to patients with sustainable therapeutic measures tailored to the health system is recommended.

Application of anti-Xa assay in monitoring unfractionated heparin therapy in contemporary antithrombotic management

INTRODUCTION

Unfractionated heparin remains the most widely used agent in the prevention and acute treatment of thrombosis. Pharmacological complexities of this intriguing agent mandate frequent monitoring of its anticoagulant properties to maintain safe and effective hematological outcomes. Although activated partial thromboplastin time has been the standard test to monitor unfractionated heparin therapy for many decades, the anti-Xa assay has emerged as a substitute or adjunct in many institutions.

AREAS COVERED

This brief report outlines the key features of anti-Xa assay in monitoring unfractionated heparin in acute management of thrombosis in various contemporary settings, with emphasis on evidence for clinical outcomes. PubMed.gov database was utilized to obtain the pertinent literature.

EXPERT OPINION

The anti-Xa activity is primarily a reflection of UFH concentration and does not account for other hematological variables frequently present in contemporary anticoagulation management. The advantage of the anti-Xa assay in monitoring UFH therapy is predicated upon its limitations to account for global physiological hemostasis. There are significant disease and drug interactions that may potentially result in false in-vitro analysis of anti-Xa activity. Routine application of the anti-Xa assay is not evidence-based at this time.

Combinations of rapid immunoassays for a speedy diagnosis of heparin-induced thrombocytopenia

BACKGROUND

Early recognition and treatment of heparin-induced thrombocytopenia (HIT) are key to prevent severe complications.

OBJECTIVE

To assess the diagnostic performance of rapid immunoassays (IA) in detecting anti-PF4/heparin-antibodies.

METHODS

Diagnostic performances of lateral-flow IA (LFIA; STic Expert HIT) and latex IA (LIA; HemosIL HIT-Ab) were analyzed in pilot (n = 74) and derivation cohorts (n = 267). Two novel algorithms based on the combination of HIT clinical probability with sequentially performed LIA and chemiluminescent IA (CLIA; HemosIL AcuStar-HIT-IgG) were compared with published rapid diagnostic algorithms: the "Lausanne algorithm" sequentially combining CLIA and particle-gel IA (PaGIA) and the "Hamilton algorithm" based on simultaneously performed LIA and CLIA.

RESULTS

LFIA missed 6/30 HIT. The sensitivity and specificity of LIA were 90.9% and 93.5%. The Lausanne algorithm correctly predicted HIT in 19/267 (7.1%), excluded it in 240/267 (89.9%), leaving 8/267 (3%) cases unsolved. The algorithm sequentially combining CLIA and LIA predicted HIT in 19/267 (7.1%) with 1/19 wrong prediction, excluded it in 236/267 (88.4%), leaving 11/267 (4.1%) cases unsolved. The algorithm employing LIA as a first assay predicted HIT in 22/267 (8.2%), excluded it in 235/267 (88%), leaving 9/267 (3.4%) cases unsolved. Finally, the Hamilton algorithm correctly predicted HIT in 10/267 (3.7%), excluded it in 229/267 (85.7%), leaving 28/267 (10.5%) cases unsolved.

CONCLUSION

LFIA cannot be used to exclude or predict HIT when using frozen plasma. A Bayesian approach sequentially employing two rapid immunoassays for anti-PF4/heparin antibodies is most effective for the accurate diagnosis of HIT. Based on retrospective data, the combination LIA/CLIA is a candidate for a prospective validation.

Predicting Therapeutic Response to Unfractionated Heparin Therapy: Machine Learning Approach

Background

Unfractionated heparin (UFH) is an anticoagulant drug that is considered a high-risk medication because an excessive dose can cause bleeding, whereas an insufficient dose can lead to a recurrent embolic event. Therapeutic response to the initiation of intravenous UFH is monitored using activated partial thromboplastin time (aPTT) as a measure of blood clotting time. Clinicians iteratively adjust the dose of UFH toward a target, indication-defined therapeutic aPTT range using nomograms, but this process can be imprecise and can take ≥36 hours to achieve the target range. Thus, a more efficient approach is required.

Objective

In this study, we aimed to develop and validate a machine learning (ML) algorithm to predict aPTT within 12 hours after a specified bolus and maintenance dose of UFH.

Methods

This was a retrospective cohort study of 3019 patient episodes of care from January 2017 to August 2020 using data collected from electronic health records of 5 hospitals in Queensland, Australia. Data from 4 hospitals were used to build and test ensemble models using cross-validation, whereas data from the fifth hospital were used for external validation. We built 2 ML models: a regression model to predict the aPTT value after a UFH bolus dose and a multiclass model to predict the aPTT, classified as subtherapeutic (aPTT <70 seconds), therapeutic (aPTT 70-100 seconds), or supratherapeutic (aPTT >100 seconds). Modeling was performed using Driverless AI (H2O), an automated ML tool, and 17 different experiments were iteratively conducted to optimize model accuracy.

Results

In predicting aPTT, the best performing model was an ensemble with 4x LightGBM models with a root mean square error of 31.35 (SD 1.37). In predicting the aPTT class using a repurposed data set, the best performing ensemble model achieved an accuracy of 0.599 (SD 0.0289) and an area under the receiver operating characteristic curve of 0.735. External validation yielded similar results: root mean square error of 30.52 (SD 1.29) for the aPTT prediction model, and accuracy of 0.568 (SD 0.0315) and area under the receiver operating characteristic curve of 0.724 for the aPTT multiclassification model.

Conclusions

To the best of our knowledge, this is the first ML model applied to intravenous UFH dosing that has been developed and externally validated in a multisite adult general medical and surgical inpatient setting. We present the processes of data collection, preparation, and feature engineering for replication.

Gerinnungsdiagnostik im klinischen Alltag – Teil 2

Während bei einer Vitamin-K-Antagonisten-Therapie die Therapieüberwachung (International Normalized Ratio [INR]) obligat ist, gilt dies für direkte orale Antikoagulanzien (DOAK) oder niedermolekulares Heparin (NMH) nur in ausgewählten klinischen Szenarien. Bei DOAK steht die Bestimmung von Tal- und Spitzenspiegeln des Medikaments im Plasma im Vordergrund, bei NMH die Anti-Xa-Aktivität. Der Zeitpunkt der Probenabnahme in Relation zur Einnahme ist für die Bewertung essenziell. Eine neu aufgetretene Thrombozytopenie im Rahmen stationärer Behandlungen ist häufig. Einordnung der Grunderkrankung, Tag des Auftretens sowie Erfassung medikamentöser Einflüsse und ihrer Dynamik ermöglichen oft die Eingrenzung der Ursache. Die Thrombophilietestung nach venöser Thromboembolie wird aufgrund fehlender therapeutischer Konsequenz zunehmend seltener durchgeführt. Ein Antiphospholipidsyndrom darf aber nicht übersehen werden, da sowohl die Therapiedauer als auch die Wahl des Antikoagulans davon abhängen.

Comparison of Managing Factor Xa Inhibitor to Unfractionated Heparin Transitions by aPTT Versus a Treatment Guideline Utilizing Heparin Anti-Xa Levels

BACKGROUND

There are inadequate data on the optimal strategy for transitioning factor Xa inhibitors (FXai; apixaban, rivaroxaban) to unfractionated heparin (UFH) infusions.

OBJECTIVE

In patients transitioning from an FXai to an UFH infusion, this study compared the safety and efficacy of monitoring UFH infusions using an activated partial thromboplastin time (aPTT) titration scale versus utilizing an UFH-calibrated anti-Xa titration scale aided by a novel institutional guideline.

METHODS

A retrospective cohort analysis was conducted on adult patients transitioning from an FXai to an UFH infusion at 2 medical centers from June 1, 2018, to November 1, 2020. One institution utilized aPTT while the other institution primarily used UFH-calibrated anti-Xa. The primary endpoint was a composite of death, major bleeding, or new thrombosis during the hospitalization with a planned noninferiority analysis. Secondary outcomes were also collected including the amount and duration of UFH administered between cohorts.

RESULTS

The incidence rate of the primary composite endpoint was 6.3% in the anti-Xa group and 11% in the aPTT group (P < 0.001 for noninferiority, P = 0.138 for superiority) meeting noninferiority criteria. No statistical differences were seen in new thrombosis, major bleeding, or any bleeding.

CONCLUSION AND RELEVANCE

This represents the first report of a comparison between aPTT versus anti-Xa monitoring in relation to clinical outcomes for patients transitioning from an FXai to an UFH infusion. A transition guideline primarily utilizing an UFH-calibrated anti-Xa assay appears to be a safe alternative to aPTT monitoring and can aid facilities in the management of patients during these complex transitions.

Monitoring of Unfractionated Heparin Therapy in the Intensive Care Unit Using a Point-of-Care aPTT: A Comparative, Longitudinal Observational Study with Laboratory-Based aPTT and Anti-Xa Activity Measurement

Continuous intravenous unfractionated heparin (UFH) is administered routinely in the intensive care unit (ICU) for the anticoagulation of patients, and monitoring is performed by the activated partial thromboplastin time (APTT) or anti-Xa activity. However, these strategies are associated with potentially large time intervals before dose adjustments, which could be detrimental to the patient. The aim of the study was to compare a point-of-care (POCT) version of the APTT to (i) laboratory-based APTT and (ii) measurements of anti-Xa activity in terms of correlation, agreement and turnaround time (TAT). Thirty-five ICU patients requiring UFH therapy were prospectively included and followed longitudinally for a maximum duration of 15 days. UFH was administered according to a local adaptation of Raschke and Amanzadeh’s aPTT nomograms. Simultaneous measurements of POCT-APTT (CoaguCheck® aPTT Test, Roche Diagnostics) on a drop of fresh whole blood, laboratory-based APTT (C.K. Prest®, Stago) and anti-Xa activity (STA®Liquid anti-Xa, Stago) were systematically performed two to six times a day. Antithrombin, C-reactive protein, fibrinogen, factor VIII and lupus anticoagulant were measured. The time tracking of sampling and analysis was recorded. The overall correlation between POCT-APTT and laboratory APTT (n = 795 pairs) was strongly positive (rs = 0.77, p < 0.0001), and between POCT-APTT and anti-Xa activity (n = 729 pairs) was weakly positive (rs = 0.46, p < 0.0001). Inter-method agreement (Cohen’s kappa (k)) between POCT and laboratory APTT was 0.27, and between POCT and anti-Xa activity was 0.30. The median TATs from sample collection to the lab delivery of results for lab-APTT and anti-Xa were 50.9 min (interquartile range (IQR), 38.4−69.1) and 66.3 min (IQR, 49.0−91.8), respectively, while the POCT delivered results in less than 5 min (p < 0.0001). Although the use of the POCT-APTT device significantly reduced the time to results, the results obtained were poorly consistent with those obtained by lab-APTT or anti-Xa activity, and therefore it should not be used with the nomograms developed for lab-APTT.

Reassessing the Pediatric Dosing Recommendations for Unfractionated Heparin Using Real-World Data: a Pharmacokinetic-Pharmacodynamic Modeling Approach

Optimal pediatric dosing of unfractionated heparin (UFH) is challenging due to paucity of clinical outcome and pharmacokinetic-pharmacodynamic (PK/PD) studies in pediatrics. This study aimed to: (i) develop a PK/PD model for UFH, quantified by anti-factor Xa assay and the UFH effect measured by activated partial thromboplastin time (aPTT) (ii) evaluate pediatric UFH infusions in achieving anti-factor Xa (0.3 - 0.7 IU/mL) therapeutic target by simulations. Electronic health record data were retrospectively collected from 633 patients < 19 years old admitted to Texas Children's Hospital. The PK/PD model was developed using a 70% (training)-30% (test) data split approach. A one-compartment PK model with linear elimination adequately described the UFH PK. An allometrically scaled body weight on clearance (CL) and volume of distribution (Vd) with an age-dependent maturation function of extracellular water on Vd were the covariates identified. Comparable with literature, the typical values for CL and Vd were 3.28 L/(hr·50 kg) and 8.83 L/50 kg, respectively. A linear model adequately described the UFH-aPTT relationship with an estimated slope of 150. Simulations of the currently recommended starting infusions (28 IU/hr/kg for pediatrics < 1 year old or 20 IU/hr/kg for pediatrics > 1 year old) showed that anti-factor Xa therapeutic target was achieved only in 15.3%, 14.6%, 36.9% and 45.11% of subjects in the age groups of < 1 year, 1-6 years, 6-12 years, and 12-19 years, respectively. In conclusion, the UFH anti-factor Xa target is not achieved initially especially in young pediatrics, suggesting the need to optimize UFH dosing to achieve higher therapeutic success. This article is protected by copyright. All rights reserved.

SMART on FHIR in spine: integrating clinical prediction models into electronic health records for precision medicine at the point of care

Recent applications of artificial intelligence have shown great promise for improving the quality and efficiency of clinical care. Numerous clinical decision support tools exist in today's electronic health records (EHRs) such as medication dosing support, order facilitators (eg, procedure specific order sets), and point of care alerts. However, less has been done to integrate artificial intelligence (AI)-enabled risk predictors into EHRs despite wide availability of validated risk prediction tools. An interoperability standard known as SMART on FHIR (substitutable medical applications and reusable technologies on fast health interoperability resources) offers a promising path forward, enabling digital innovations to be seamlessly integrated with the EHR with regard to the user interface and patient data. For the next step in progress towards the goal of learning healthcare and informatics-enabled spine surgery, we propose the application of SMART on FHIR to integrate existing and new risk predictions tools in spine surgery through an EHR add-on-application.

Evaluation of the activated partial thromboplastin time and its influential factors in ischemic heart disease patients under heparin treatment

This study aimed to detect the defects of the current methods used to monitor unfractionated heparin (UFH) anticoagulant effect and find possible assistive parameters for activated partial thromboplastin time (aPTT) test to improve treatment performance. The required information was gathered from patients' case records, treatment charts and laboratory reports. Kendall's tau correlation coefficient was calculated for analysing the relationship between variables. The partial least squares (PLS) and the stepwise multiple regression were operated, and the area under the receiver operating characteristic curve (AUC) and the r-squared (r2) were used to show the analytical ability of the models, respectively. Overall, 102 UFH-receiving ischemic heart disease patients participated in this study. The aPTT value varied from 30 to 95 s (mean ± SD = 44 ± 14). Therapeutic aPTT values were observed in 15% of hospitalization days. The aPTT value showed statistically significant correlations with mean UFH infusion (U/kg/h), age, prothrombin time (PT), smoking, international normalized ratio, haemoglobin (Hgb) and blood triglyceride level. Triglyceride level and PT were efficacious predictors of aPTT value (P < 0.001, r2 = 0.336). Moreover, blood urea nitrogen (BUN) and blood creatinine (Cr) levels were the best predictors for mortality. The mean BUN/Cr ratio was 18 ± 5 and 25 ± 12 in nonexpired and expired subjects, respectively. If calibrated institution-specific therapeutic aPTT ranges and updated weight-based UFH nomograms get employed, aPTT test, along with the BUN/Cr ratio and Hgb level, as assistive parameters for predicting haemorrhagic incidents, would be near ideal monitoring method in UFH-receiving patients.

Time is of the essence: A single-center experience of hepatic arterial supply impairment management in pediatric liver transplant recipients

BACKGROUND

Impairment of hepatic arterial flow including hepatic arterial thrombosis (HAT), hepatic arterial stenosis (HAS), and splenic artery steal syndrome (SASS) is potentially life-threatening complications. The proposed early diagnosis and urgent treatment strategy of graft arterial flow reduction aim to decrease morbidity and mortality.

METHODS

Pediatric patients with known hepatic arterial flow impairment were retrospectively reviewed. Patients were grouped by occlusive (HAT) and non-occlusive (HAS/SASS) arterial flow reduction. Patients with HAT were further divided in two groups based on the estimated maximal hepatic artery occlusion time ≤8 and >8 hours.

RESULTS

Impairment of hepatic arterial flow developed in 32 of 416 pediatric liver transplant recipients. HAT, HAS, and SASS incidences were 4.1% (n = 17), 2.2% (n = 9), and 1.4% (n = 6), respectively. Neither graft loss nor death occurred in the non-occlusive group. The probabilities of sepsis (OR, 1.7; 95% CI, 1.14-2.53; P=.008) and graft loss or death (OR, 1.42; 95% CI, 1.04-1.92; P=.046) were higher in the occlusive group. Patients with estimated maximal duration of hepatic artery occlusion ≤ 8 hours (n = 7; 41.2%) did not have ischemic-type biliary lesions and sepsis (P=.044 and 0.010, respectively) but had excellent 3-year graft survival compared with > 8 hours group (100% vs 40%; P=.037). Multivariate analysis revealed HAT manifestation by fever was associated with increased chances of graft loss or death.

CONCLUSION

Occlusive arterial complications impose higher risks of graft loss and death. Thorough arterial supply monitoring by Doppler ultrasonography and urgent endovascular arterial flow restoration may salvage both graft and the recipient.

Ensuring successful implementation of communication-and-resolution programmes

BACKGROUND

Communication-and-resolution programmes (CRP) aim to increase transparency surrounding adverse events, improve patient safety and promote reconciliation by proactively meeting injured patients' needs. Although early adopters of CRP models reported relatively smooth implementation, other organisations have struggled to achieve the same. However, two Massachusetts hospital systems implementing a CRP demonstrated high fidelity to protocol without raising liability costs.

STUDY QUESTION

What factors may account for the Massachusetts hospitals' ability to implement their CRP successfully?

SETTING

The CRP was collaboratively designed by two academic medical centres, four of their community hospitals and a multistakeholder coalition.

DATA AND METHODS

Data were synthesised from (1) key informant interviews around the time of implementation and 2 years later with individuals important to the CRP's success and (2) notes from 89 teleconferences between hospitals' CRP implementation teams and study staff to discuss implementation progress. Interview transcripts and teleconference notes were analysed using standard methods of thematic content analysis. A total of 45 individuals participated in interviews (n=24 persons in 38 interviews), teleconferences (n=32) or both (n=11).

RESULTS

Participants identified facilitators of the hospitals' success as: (1) the support of top institutional leaders, (2) heavy investments in educating physicians about the programme, (3) active cultivation of the relationship between hospital risk managers and representatives from the liability insurer, (4) the use of formal decision protocols, (5) effective oversight by full-time project managers, (6) collaborative group implementation, and (7) small institutional size.

CONCLUSION

Although not necessarily causal, several distinctive factors appear to be associated with successful CRP implementation.

Incidence and risk factors for PTT prolongation in patients receiving low-dose unfractionated heparin thromboprophylaxis

Low-dose unfractionated heparin (LDUH) prophylaxis decreases the incidence of venous thromboembolism (VTE) in hospitalized patients, but increases the risk of bleeding events. Patients who develop a prolonged activated partial thromboplastin time (aPTT) while on LDUH may be at higher risk for bleeding complications. To determine the incidence and risk factors for aPTT prolongation in hospitalized patients receiving LDUH thromboprophylaxis, we performed a retrospective pharmacoepidemiologic cohort study of adult patients admitted to an academic medical center from September 2013 through September 2015. Among 3857 patients with at least one aPTT checked within 24 h of LDUH administration, aPTT prolongation > 1.5 times the upper limit of normal occurred in 131 (3.4%). Age 68-78 years (OR 1.6, 95% CI 1.01-2.4), age > 78 years (OR 1.9, 95% CI 1.3-2.9), female gender (OR 1.9, 95% CI 1.4-2.5), black race (OR 1.6, 95% CI 1.1-2.3), low BMI (OR 1.8, 95% CI 1.3-2.5), being admitted to a surgical service (OR 0.5, 95% CI 0.3-0.8), and receipt of high-dose (> 10,000 units in a day) unfractionated heparin prophylaxis (OR 1.4, 95% CI 1.003-2.0), were independently associated with aPTT prolongation after LDUH exposure. LDUH VTE prophylaxis is associated with aPTT prolongation in 3.4% of general hospitalized patients. We demonstrated several factors independently associated with aPTT prolongation. Monitoring aPTT levels may be indicated for select patients on LDUH thromboprophylaxis who are at high risk or consequence of bleeding and for aPTT prolongation.

Effectiveness of a Calculation-Free Weight-Based Unfractionated Heparin Nomogram With Anti-Xa Level Monitoring Compared With Activated Partial Thromboplastin Time

BACKGROUND

Accurate monitoring of intravenous unfractionated heparin (UFH) is essential to mitigate the risk of adverse drug events associated with dosing errors. Although recent data support anti-factor Xa (anti-Xa) monitoring preferentially over activated partial thromboplastin time (aPTT) to improve time to therapeutic anticoagulation, the utility of incorporating anti-Xa monitoring with a calculation-free weight-based UFH nomogram has not been formally evaluated.

OBJECTIVE

The primary objective of this study was to evaluate the time to therapeutic anticoagulation of a calculation-free weight-based UFH nomogram integrated with anti-Xa monitoring versus a historical control of aPTT monitoring utilizing manual dose calculations.

METHODS

This was a retrospective analysis of patients with anti-Xa monitoring and a novel calculation-free weight-based UFH nomogram compared with a historical control with aPTT monitoring and manual calculations.

RESULTS

A total of 103 patients in the aPTT cohort and 100 patients in the anti-Xa cohort were analyzed. The anti-Xa cohort achieved goal therapeutic target 3.8 hours sooner than the aPTT cohort (P = 0.03). Patients with anti-Xa monitoring required 1 fewer adjustment per 2.5 patient-days of UFH with the venous thromboembolism nomogram (P = 0.02). Patients in the aPTT cohort required more infusion interruptions because of supratherapeutic values (P = 0.007) and boluses because of subtherapeutic values (P = 0.044). There were no differences in rates of thromboembolism, major bleeding, or clinically relevant nonmajor bleeding between the cohorts.

CONCLUSION AND RELEVANCE

This study demonstrated that anti-Xa UFH monitoring integrated with a calculation-free nomogram results in faster time to therapeutic anticoagulation and fewer dose adjustments compared with aPTT monitoring with manual calculations.

Challenges and Opportunities in the Pharmacological Treatment of Acute Venous Thromboembolism in Children

Venous thromboembolism (VTE) is an important but historically under-recognized problem in pediatrics, with an incidence concentrated in hospitalized children. A number of specific VTE diseases with discrete triggers have been described, but the most common pediatric trigger is the presence of central venous access devices. VTE diseases, though heterogenous in etiology, are linked by the common therapeutic strategies shared by their management. Historically, the most commonly used drug therapies have been unfractionated heparin, low-molecular-weight heparins, and vitamin K antagonists, based on extrapolation from adult data rather than any specific pediatric trials. Although these widely used drugs appear safe and effective in expert hands, the historical lack of pediatric data is problematic in view of the recognized significant differences between children and adults with regards to hemostatic physiology, VTE etiology, and drug pharmacokinetics. The increasing adult usage of novel VTE pharmacotherapies such as direct oral anticoagulants (DOACs) has led to considerable interest in exploring the pediatric applications of these newer drugs. This review summarizes the advantages and disadvantages of existing VTE pharmacotherapies and outlines emerging novel pediatric VTE therapies, particularly DOACs, within the context of the current pediatric trial landscape.

Treatment of Acute Venous Thromboembolism

"Acute venous thromboembolism is a common disease seen by nearly all hospitalists. The advent of low molecular weight heparin (LMWH) several decades ago ushered in the era of early hospital discharge and home treatment. More recently, the direct oral anticoagulants (DOACs) have further simplified outpatient treatment and some offer treatment without parenteral therapy. Use of DOACs for cancer-associated venous thromboembolism is emerging and is a welcome evolution of care to spare oncologic patients the burden of daily LMWH injections."