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

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 For each patient, arterial blood was withdrawn into citrate-containing tubes at 11 time points (from hour 0 up to day 7).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

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.

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.

[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.

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.

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.

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."

Clinical Impact of a Radiologic Quality Initiative Promoting More Timely Communication of Critical Pulmonary Embolus Results

BACKGROUND

A section quality initiative was implemented beginning 2013 requiring positive pulmonary embolism (PE) results to be documented and communicated within 90 minutes of exam completion. The objective of this study is to evaluate the effect of this quality initiative on different intervals comprising the total patient processing time, namely the time from when the imaging exam was ordered to study completion interval, the time from study completion to positive PE result communication (TAT interval) or treatment initiation (TTT interval), the time from result communication to treatment initiation (TRCTI interval), and the total patient processing time (TPT interval).

METHODS

This was a retrospective, single-institution, IRB-approved cohort study that included 830 patients with the diagnosis of acute PE confirmed by CT pulmonary angiography. A maximum of 10 positive exams per month were identified and analyzed over an 84-month period from January 2010 to December 2016. The following data were obtained: time when exam ordered, time of imaging study completion, time of report completion, time of result communication, time of treatment, type of treatment, and reasons for any treatment delay. Analysis was done by determining the mean time spent in various intervals, the cumulative relative frequency of interval completion, and the fraction of the entire patient processing time spent in each interval.

RESULTS

Mean analysis demonstrated a decrease in all time intervals in the postpolicy period (ordered to study completion: Δ24.50%, p = 0.004; TAT: Δ23.91%, p < 0.001; TRCTI: Δ16.86%, p = 0.031; TTT: Δ17.40%, p = 0.005; TPT: Δ15.94%, p = 0.002). Cumulative relative frequency analysis demonstrated a higher rate of interval completion in the postpolicy period (TAT: p < 0.001; TRCTI: p = 0.007; TPT: p = 0.025). Interval fraction analysis demonstrated changes in the fraction of processing time spent in varying intervals (TAT: -Δ14.42%, p = 0.002; TRCTI: +Δ17.65%, p = 0.001).

CONCLUSION

Total patient processing time decreased after the policy implementation with a more significant decrease in TAT compared to other intervals. Radiologic processing time does not appear to be the rate-limiting step in total patient processing time.

Toward Optimal Heparin Dosing by Comparing Multiple Machine Learning Methods: Retrospective Study

Background

Heparin is one of the most commonly used medications in intensive care units. In clinical practice, the use of a weight-based heparin dosing nomogram is standard practice for the treatment of thrombosis. Recently, machine learning techniques have dramatically improved the ability of computers to provide clinical decision support and have allowed for the possibility of computer generated, algorithm-based heparin dosing recommendations.

Objective

The objective of this study was to predict the effects of heparin treatment using machine learning methods to optimize heparin dosing in intensive care units based on the predictions. Patient state predictions were based upon activated partial thromboplastin time in 3 different ranges: subtherapeutic, normal therapeutic, and supratherapeutic, respectively.

Methods

Retrospective data from 2 intensive care unit research databases (Multiparameter Intelligent Monitoring in Intensive Care III, MIMIC-III; e–Intensive Care Unit Collaborative Research Database, eICU) were used for the analysis. Candidate machine learning models (random forest, support vector machine, adaptive boosting, extreme gradient boosting, and shallow neural network) were compared in 3 patient groups to evaluate the classification performance for predicting the subtherapeutic, normal therapeutic, and supratherapeutic patient states. The model results were evaluated using precision, recall, F1 score, and accuracy.

Results

Data from the MIMIC-III database (n=2789 patients) and from the eICU database (n=575 patients) were used. In 3-class classification, the shallow neural network algorithm performed the best (F1 scores of 87.26%, 85.98%, and 87.55% for data set 1, 2, and 3, respectively). The shallow neural network algorithm achieved the highest F1 scores within the patient therapeutic state groups: subtherapeutic (data set 1: 79.35%; data set 2: 83.67%; data set 3: 83.33%), normal therapeutic (data set 1: 93.15%; data set 2: 87.76%; data set 3: 84.62%), and supratherapeutic (data set 1: 88.00%; data set 2: 86.54%; data set 3: 95.45%) therapeutic ranges, respectively.

Conclusions

The most appropriate model for predicting the effects of heparin treatment was found by comparing multiple machine learning models and can be used to further guide optimal heparin dosing. Using multicenter intensive care unit data, our study demonstrates the feasibility of predicting the outcomes of heparin treatment using data-driven methods, and thus, how machine learning–based models can be used to optimize and personalize heparin dosing to improve patient safety. Manual analysis and validation suggested that the model outperformed standard practice heparin treatment dosing.

Bleeding and Thrombotic Risk in Low Dose Heparin Infusion as Compared to Standard Dose Heparin Infusion

Intravenous unfractionated heparin (UFH) remains one of the most commonly used anticoagulants in the hospital setting. The optimal protocol for initiation and maintenance of UFH has been difficult to determine. Over the past two decades, weight-based nomogram protocols have gained favor. Herein, we present a retrospective study of 377 patients at a single tertiary academic center treated with low intensity (LI) and standard intensity (SI) UFH protocols for therapeutic anticoagulation. UFH levels are measured by anti-Xa assay activity with therapeutic levels of 0.30 to 0.70 IU/mL for SI and 0.25 to 0.35 IU/mL for LI.  Patients treated on the LI protocol were more likely to have had a previous history of bleeding and lower baseline hemoglobin. Incidence of new or worsening thrombus while on UFH was comparable between both protocols (odds ratio (OR) 0.93, 95% confidence interval (CI) 0.29-2.98, p=0.899). Patients on LI protocol had higher incidence of bleeding while on UFH (OR 1.21, 95% CI 0.51-2.89, p=0.667). Our study thus suggests that the LI protocol may have comparable efficacy to the SI protocol in treating venous thromboembolism (VTE) and that target anti-Xa levels of 0.25 to 0.35 IU/mL may be more optimal in high-risk patients.

Rivaroxaban Precision Dosing Strategy for Real-World Atrial Fibrillation Patients

Rivaroxaban is a direct-acting oral anticoagulant approved to prevent strokes in patients with atrial fibrillation. Dosage recommendations are approved for all adult patients to receive either 15 mg or 20 mg once daily depending upon renal function. There are a number of reasons to believe rivaroxaban dosing could be more effective and/or safer for more patients if increased dosing precision is available. Because real-world patients are more diverse than those studied in phase III clinical trials, we evaluated the extremes of creatinine clearance (CrCl) on rivaroxaban clearance using a published population pharmacokinetic model and applying exposure variation limits (±20%) based on published literature. The proposed dosing recommendations are 10 mg once daily (CrCl 15-29 ml/min), 15 mg once daily (CrCl 30-69 ml/min), 10 mg twice daily (CrCl 70-159 ml/min), and 15 mg twice daily (CrCl 160-250 ml/min). These new dosing recommendations should be prospectively tested for predictive accuracy and to assess the impact on AF patient efficacy and safety.

Unfractionated heparin dosing in obese patients

Background The effect of obesity on the pharmacokinetics and pharmacodynamics of unfractionated heparin is not clearly understood, therefore to reduce the risk of bleeding, maximal dose (capped) nomograms are often used. This can lead to inadequate anticoagulation and increased mortality and morbidity. In Queensland, Australia, statewide nomograms recommend total-body-weight-based dosing, with capped initial bolus and maintenance doses. Objective To determine if current practices for unfractionated heparin dosing leads to inadequate anticoagulation in obese patients. Setting Princess Alexandra Hospital, Queensland, Australia. Method A retrospective audit of unfractionated heparin dosing in 200 patients divided into cohorts of; < 100 kg (defined as non-obese), 100-124.9 kg, 125-150 kg and > 150 kg, Main outcomes measured Mean maintenance doses in U/h and U/kg/h required to achieve two consecutive therapeutic activated partial thromboplastin times' and the corresponding time to achieve this endpoint. Results The mean ± standard deviation maintenance doses required to achieve two consecutive therapeutic activated partial thromboplastin times' in U/h were 1229 ± 316, 1673 ± 523, 2031 ± 596 and 2146 ± 846, and in U/kg/h were 16 ± 4.1, 15.1 ± 4.8, 14.9 ± 4.2 and 11.6 ± 4.2 for the weight cohorts respectively. The median time (inter-quartile range) to therapeutic activated partial thromboplastin times' for obese patients was 39 (21.5-56) h. Conclusions Our results suggest inadequate dosing in obese patients. We recommend the use of larger absolute doses (U/h) of nfractionated heparin but reduced uncapped total body weight-based doses-(U/kg/h) as patient weight increases.

Anticoagulant treatment for subsegmental pulmonary embolism

BACKGROUND

Acute pulmonary embolism (PE) is a common cause of death, accounting for 50,000 to 200,000 deaths annually. It is the third most common cause of mortality among the cardiovascular diseases, after coronary artery disease and stroke. The advent of multi-detector computed tomographic pulmonary angiography (CTPA) has allowed better assessment of PE regarding visualisation of the peripheral pulmonary arteries, increasing its rate of diagnosis. More cases of peripheral PEs, such as isolated subsegmental PE (SSPE) and incidental PE, have thereby been identified. These two conditions are usually found in patients with few or none of the classic PE symptoms such as haemoptysis or pleuritic pain, acute dyspnoea or circulatory collapse. However, in patients with reduced cardiopulmonary reserve, classic PE symptoms can be found with isolated SSPEs. Incidental SSPE is found casually in asymptomatic patients, usually by diagnostic imaging performed for other reasons (for example routine CT for cancer staging in oncology patients). Traditionally, all PEs are anticoagulated in a similar manner independent of their location, or number and size of the thrombi. It has been suggested that many patients with SSPE may be treated without benefit, increasing adverse events by a possible unnecessary use of anticoagulants. Patients with isolated SSPE, or incidental PE, may have a more benign clinical presentation compared to those with proximal PEs. However, the clinical significance in patients, and their prognosis, needs to be studied to evaluate whether anticoagulation therapy is required. This is the second update of the Cochrane systematic review published in 2014.

OBJECTIVES

To assess the effectiveness and safety of anticoagulation therapy versus control in patients with isolated subsegmental pulmonary embolism (SSPE) or incidental SSPE.

SEARCH METHODS

The Cochrane Vascular Information Specialist searched the Cochrane Vascular Specialised Register, CENTRAL, MEDLINE, Embase, CINAHL and AMED databases and World Health Organization International Clinical Trials Registry Platform and ClinicalTrials.gov trials registers to 26 November 2019. We also undertook reference checking to identify additional studies.

SELECTION CRITERIA

We included randomised controlled trials of anticoagulation therapy versus control in patients with SSPE or incidental SSPE.

DATA COLLECTION AND ANALYSIS

Two review authors inspected all citations identified to ensure reliable assessment. If relevant studies were identified, we planned for two review authors to independently extract data and to assess the methodological quality of identified trials using the criteria recommended in the Cochrane Handbook for Systematic Reviews of Interventions.

MAIN RESULTS

We did not identify any studies that met the inclusion criteria.

AUTHORS' CONCLUSIONS

There is no evidence from randomised controlled trials to assess the effectiveness and safety of anticoagulation therapy versus control in patients with isolated subsegmental pulmonary embolism (SSPE) or incidental SSPE. Well-conducted research is required before informed practice decisions can be made.

Analysis of Partial Thromboplastin Times in Patients With Pulmonary Embolism During the First 48 Hours of Anticoagulation With Unfractionated Heparin

OBJECTIVE

The objective was to determine the proportion of patients with pulmonary embolism (PE) treated with unfractionated heparin (UFH) who achieved therapeutic activated partial thromboplastin time (aPTT) values within 48 hours of treatment.

METHODS

Retrospective analysis of a PE response team (PERT) database was performed at a large, urban, academic teaching hospital. Inclusion criteria were adult patients with acute PE for whom the PERT was consulted and who received anticoagulation (AC) with UFH according to guideline standard dosing. aPTT values during 6-hour time periods during the first 48 hours of AC were collected and analyzed.

RESULTS

A total of 505 patients met inclusion criteria. For patients receiving a bolus and infusion of UFH, the proportions (95% confidence interval [CI]) of patients in the therapeutic range were 19.0% (14.2% to 25.0%) at 12 hours, 26.3% (26.3% to 33.1%) at 24 hours, 28.3% (22.0% to 35.4%) at 36 hours, and 28.4% (20.8% to 37.5%) at 48 hours. For titrated infusion only, the proportions (95% CIs) of patients were 23.3% (16.2% to 32.3%) at 12 hours, 41.4% (31.6% to 51.9%) at 24 hours, 37.0% (26.8% to 48.5%) at 36 hours, and 42.1% (30.2% to 55.0%) at 48 hours. No patient had all therapeutic aPTT values.

CONCLUSIONS

The majority of patients with acute PE spend most of their first 48 hours outside of the therapeutic range of AC when treated with guideline standard dosing of UFH. Over half of the patients fail to achieve any therapeutic PTT level within 24 hours of UFH initiation, and no patient had all therapeutic aPTTs. Future research should focus on identifying factors associated with achieving therapeutic AC with UFH.

Evaluating anticoagulation sensitivity among elderly patients managed with an institution’s heparin protocol using initial anti-factor Xa levels

Purpose

The purpose of this study was to assess an institution’s heparin protocols in elderly and nonelderly adult populations to see if a response difference was observed.

Methods

This was a retrospective cohort study of hospitalized adults who were prescribed unfractionated heparin due to surgery, acute coronary syndrome (ACS), or deep vein thrombosis/pulmonary embolism (DVT/PE) from February 11, 2016, through August 1, 2017. Patients were divided into nonelderly adults 18 to 69 years of age and elderly patients 70 years of age or older. The anti-factor Xa (anti-Xa) level after protocol initiation was compared to the institution’s goal range of 0.3 to 0.7 IU/mL. Outcomes of each protocol in the elderly population were compared to outcomes in their nonelderly counterparts to determine if there was a difference in heparin response.

Results

A total of 325 patients were included in the analysis, comprising 150 elderly and 175 nonelderly adults. Elderly patients had a higher initial anti-Xa levels than did their nonelderly adult counterparts in the ACS, DVT/PE, and surgery protocols, with P values of 0.02, &lt;0.001, and 0.01, respectively. Only the ACS protocol demonstrated increased frequency of above-target-level anti-Xa levels in the elderly (P = 0.03).

Conclusion

Elderly patients had significantly higher initial anti-Xa levels than did nonelderly adult patients across all protocols. This study identifies the need to further study elderly patients’ increased heparin sensitivity to determine if a separate dosing protocol is needed.

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.

A multipredictor model to predict the conversion of mild cognitive impairment to Alzheimer's disease by using a predictive nomogram

Predicting the probability of converting from mild cognitive impairment (MCI) to Alzheimer's disease (AD) is still a challenging task. This study aims at providing a personalized MCI-to-AD conversion estimation by using a multipredictor nomogram that integrates neuroimaging features, cerebrospinal fluid (CSF) biomarker, and clinical assessments. To do so, 290 MCI patients were collected from the Alzheimer's Disease Neuroimaging Initiative (ADNI), of whom 76 has converted to AD and 214 remained with MCI. All subjects were randomly divided into a primary and validation cohort. Radiomics signature (Rad-sig) was obtained based on 17 cerebral cortex features selected by using Least Absolute Shrinkage and Selection Operator (LASSO) algorithm. Clinical factors and amyloid-beta peptide (Aβ) concentration were selected by using Spearman correlation between the converted and not-converted patients. Then, a nomogram that combines image features, clinical factor, and Aβ concentration was constructed and validated. Furthermore, we explored the associations between various predictors from the macro- to the microperspective by assessing gene expression patterns. Our results showed that the multipredictor nomogram (C-index 0.978 and 0.956 in both cohorts, respectively) outperformed the nomogram using either Rad-sig or Aβ concentration as individual predictors. Significant associations were found between neuropsychological scores, cerebral cortex features, Aβ levels, and underlying gene pathways. Our study may have a clinical impact as a powerful predictive tool for predicting the conversion probability of MCI and providing associations between cognitive impairment, structural changes, Aβ levels, and underlying biological patterns from the macro- to the microperspective.

Unfractionated heparin infusion for treatment of venous thromboembolism based on actual body weight without dose capping

Controversy exists regarding the use of dose capping of weight-based unfractionated heparin (UFH) infusions in obese and morbidly obese patients. The primary objective of this study was to compare time to first therapeutic activated partial thromboplastin time (aPTT) in hospitalized patients receiving UFH for acute venous thromboembolism (VTE) among three body mass index (BMI) cohorts: non-obese (< 30 kg/m2), obese (30–39.9 kg/m2), and morbidly obese (⩾ 40 kg/m2). In this single-center, retrospective cohort study, patients were included if they ⩾ 18 years of age, had a documented VTE, and were on an infusion of UFH for at least 24 hours. Weight-based UFH doses were calculated using actual body weight. A total of 423 patients met the inclusion criteria, with 230 (54.4%), 146 (34.5%), and 47 (11.1%) patients in the non-obese, obese, and morbidly obese cohorts, respectively. Median times to therapeutic aPTT were 16.4, 16.6, and 17.1 hours in each cohort. Within 24 hours, the cumulative incidence rates for therapeutic aPTT were 70.7% for the non-obese group, 69.9% for the obese group, and 61.7% for the morbidly obese group (obese vs non-obese: HR = 1.02, 95% CI: 0.82–1.26, p = 0.88; morbidly obese vs non-obese: HR = 0.87, 95% CI: 0.62–1.21, p = 0.41). There was no significant difference in major bleeding events between BMI groups (obese vs non-obese, p = 0.91; morbidly obese vs non-obese, p = 0.98). Based on our study, heparin dosing based on actual body weight without a dose cap is safe and effective.

Evaluation of Time to Therapeutic Anticoagulation and Associated Outcomes in Critically Ill, Obese Patients With Pulmonary Embolism Receiving Unfractionated Heparin

BACKGROUND

Delays in time to therapeutic activated partial thromboplastin time (aPTT) have been associated with poor outcomes in patients with acute pulmonary embolism (PE).

OBJECTIVE

To investigate the relationship between time to therapeutic anticoagulation and in-hospital mortality in critically ill, obese patients with acute PE.

METHODS

This study examined 204 critically ill patients with a body mass index (BMI) ≥30 kg/m² receiving unfractionated heparin (UFH) for PE treatment. Patients achieving therapeutic anticoagulation within 24 hours of UFH initiation (early) were compared to those in >24 hours (delayed). Additional end points included 30-day mortality, median time to therapeutic aPTT, proportion of therapeutic and supratherapeutic aPTT values, hemodynamic deterioration, thrombolytic therapy after UFH initiation, length of stay, and bleeding.

RESULTS

No difference in in-hospital or 30-day all-cause mortality was seen (odds ratio [OR]: 1.33, confidence interval [CI]: 0.647-2.72; OR: 1.003, CI: 0.514-1.96). Patients in the early group had a greater proportion of therapeutic aPTT values (66.7% vs 50%, P < .001) and higher percentage of supratherapeutic aPTT values (20.9% vs 11.3%, P < .001); however, no increase in clinically significant bleeding was evident (15.2% vs 10.9%, P = .366).

CONCLUSION

In this population, a shorter time to therapeutic aPTT was not associated with improved survival.

Systematic review of interventions to improve safety and quality of anticoagulant prescribing for therapeutic indications for hospital inpatients

PURPOSE

Anticoagulation-associated adverse drug events are common in hospitalised patients and result in morbidity, mortality, increased length of hospital stay and higher costs of care. Many are preventable. We reviewed the literature to identify and assess interventions intended to improve safety or quality anticoagulant prescribing.

METHODS

A systematic search of EMBASE, MEDLINE, the Cochrane Library, Pretty Darn Quick-Evidence and Health Systems Evidence was undertaken to identify controlled studies assessing system-level interventions to improve prescribing of oral or parenteral therapeutic anticoagulation for any indication in hospitalised adults. Data were extracted for safety and quality outcomes, with studies grouped by intervention type for meta-analysis and narrative review.

RESULTS

Of 10,640 records screened, 19 trials evaluating 12,742 participants were included for analysis. No study specifically evaluated prescribing of low molecular weight heparins (LMWHs) or direct acting oral anticoagulants (DOACs). Our findings suggest that physician-led anticoagulation consultation services may reduce bleeding rates in high-risk patients. On meta-analysis, decision supported warfarin dosing resulted in higher proportion of time with international normalised ratio in therapeutic range (p = 0.0007). Studies of other clinical decision support systems and heparin monitoring systems did not demonstrate improved safety, and quality findings were inconsistent. Systematic education and feedback programs were not efficacious.

CONCLUSIONS

There is currently insufficient high-quality evidence to recommend any reviewed intervention, though several warrant closer evaluation. Adequately powered controlled trials assessing safety outcomes and evidence-based quality markers in high-risk patient groups and studies of interventions to improve safety of LMWH and DOAC prescribing are needed.

Derivation and Validation of Age- and Body Mass Index-Adjusted Weight-Based Unfractionated Heparin Dosing

Unfractionated heparin dosing is unpredictable and subject to numerous pharmacokinetic changes including distribution and metabolic changes associated with obesity and age. Weight-based dosing is commonly used to better predict the dose for a patient when targeting a therapeutic range. A dosing equation that adjusts weight-based doses for age and body mass index may improve therapeutic dose prediction. We conducted a 2-phase observational study with a derivation and validation period to develop an equation to adjust weight-based unfractionated heparin for age and body mass index to target a therapeutic activated partial thromboplastin time of 60 to 80 seconds. The first phase retrospectively identified patients who acheived therapeutic anticoagulation and utilized linear regression to determine a predictive equation for weight-based dosing that adjusts for age and body mass index. The second phase prospectively identified patients in an observational manner and compared the dose of unfractionated heparin on which they became therapeutic against both the weight-based dose and the predicted dose adjusted for age and body mass index. The correlation between predictive age and body mass index adjusted dose and actual therapeutic dose was 0.703 compared to the correlation between the empiric weight-based dose and actual therapeutic dose which was 0.532 (P = .05). Age and body mass index adjusted weight-based dosing significantly improved therapeutic dose prediction for unfractionated heparin. Further study in a prospective, randomized trial is warranted for validation of this approach in a real world setting.

Comparison of Treatment Result Between Anticoagulation Alone and Catheter-Directed Thrombolysis Plus Anticoagulation in Acute Lower Extremity Deep Vein Thrombosis

Purpose

Deep vein thrombosis (DVT) is the third most common cause of cardiovascular morbidity and mortality. Anticoagulation has been the primary treatment modality for acute DVT. However, catheter-directed thrombolysis (CDT) has recently become widely accepted as an additional therapy to anticoagulation. We assessed comparative outcomes in patients with acute DVT who underwent anticoagulation therapy alone (ACA) group and those treated with CDT group.

Materials and Methods

We retrospectively reviewed medical records of 149 patients with DVT from January 2011 to December 2015. We compared patients who received ACA group (n=120) and those who received CDT plus anticoagulation (CDT group, n=29). We analyzed the prevalence of lesions, thrombus removal rate in each lesion, and recurrence-free rate between the two groups.

Results

We found thrombus involvement in a total of 281 lesions in the ACA group and 85 lesions in the CDT group. For the distribution of lesions in each group, those in the femoral vein accounted for 34.2% of all lesions and those in the popliteal vein accounted for 31.7%. During follow-up, the overall thrombus removal rate was 91.1% in the ACA group and 87.0% in the CDT group (P=0.273). The recurrence-free rate was higher in the CDT group in a log-rank test; however, there was no statistically significant difference between the two groups (P=0.594).

Conclusion

According to our results, there was no significant difference in thrombus removal and recurrence-free rates between the CDT and ACA groups. ACA still has an important role in the treatment of DVT.