Acutely injured patients on dabigatran

Spontaneous rectal sheath bleed while on DOAC anticoagulation

A man in his 80s was transferred from his nursing home residence with sudden onset right-sided abdominal pain. The nursing home staff reported that he was walking to the bathroom when he became diaphoretic, reported he was feeling unwell, then sat on the ground and was reluctant to move. Past medical history was significant for longstanding atrial fibrillation for which he was taking apixaban 2.5 mg twice daily. A CT scan of the abdomen and pelvis was performed which showed a 21×11 cm rectus sheath haematoma on the right extending into the lumbar region. Surgical review advised no invasive intervention. Two units of red cell concentrate were transfused and he was monitored for 5 days before being transferred back to the nursing home.

Treatment and outcomes of anticoagulated geriatric trauma patients with traumatic intracranial hemorrhage after falls

Introduction

Emergency physicians and trauma surgeons are increasingly confronted with pre-injury direct oral anticoagulants (DOACs). The objective of this study was to assess if pre-injury DOACs, compared to vitamin K antagonists (VKA), or no oral anticoagulants is independently associated with differences in treatment, mortality and inpatient rehabilitation requirement.

Methods

We performed a review of the prospectively maintained institutional trauma registry at an urban academic level 1 trauma center. We included all geriatric patients (aged ≥ 65 years) with tICH after a fall, admitted between January 2011 and December 2018. Multivariable logistic regression analysis controlling for demographics, comorbidities, vital signs, and tICH types were performed to identify the association between pre-injury anticoagulants and reversal agent use, neurosurgical interventions, inhospital mortality, 3-day mortality, and discharge to inpatient rehabilitation.

Results

A total of 1453 tICH patients were included (52 DOAC, 376 VKA, 1025 control). DOAC use was independently associated with lower odds of receiving specific reversal agents [odds ratio (OR) 0.28, 95% confidence interval (CI) 0.15–0.54] than VKA patients. DOAC use was independently associated with requiring neurosurgical intervention (OR 3.14, 95% CI 1.36–7.28). VKA use, but not DOAC use, was independently associated with inhospital mortality, or discharge to hospice care (OR 1.62, 95% CI 1.15–2.27) compared to controls. VKA use was independently associated with higher odds of discharge to inpatient rehabilitation (OR 1.41, 95% CI 1.06–1.87) compared to controls.

Conclusion

Despite the higher neurosurgical intervention rates, patients with pre-injury DOAC use were associated with comparable rates of mortality and discharge to inpatient rehabilitation as patients without anticoagulation exposure. Future research should focus on risk assessment and stratification of DOAC-exposed trauma patients.

In-Hospital Clinical Outcomes in Patients with Fragility Fractures of the Lumbar Spine, Thoracic Spine, and Pelvic Ring: A Comparison of Data before and after Certification as a DGU® Geriatric Trauma Centre

Background and Objectives: The implementation of orthogeriatric co-management (OGCM) reflects the demand for interdisciplinary collaborations due to the increasing comorbidities of geriatric trauma patients. This study aimed to assess clinical in-hospital outcomes in lumbar spine, thoracic spine, and pelvic ring fragility fracture patients before and after the implementation of a Geriatric Trauma Centre (GTC) certified by the German Trauma Society (DGU^®). Materials and Methods: In this observational, retrospective cohort study, geriatric trauma patients (>70 years of age) were stratified into either a pre-GTC group (hospital admission between 1 January 2012 and 31 December 2013) or a post-GTC group (hospital admission between 1 January 2017 and 31 December 2018). Patients’ pre-injury medical complexity was measured by ASA class (American Society of Anaesthesiologists classification), the use of anticoagulant medication, and the ACCI (Age-adjusted Charlson Comorbidity Index). Outcome parameters were patients’ in-hospital length of stay (LOS) and mortality rates, as well as new in-hospital findings and diagnoses. Further, the necessity of deviation from initial management plans due to complications was assessed using the Adapted Clavien–Dindo Scoring System in Trauma (ACDiT score of ≥1). Results: Patients in the post-GTC group (n = 111) were older (median age 82.0 years) compared to the pre-GTC group (n = 108, median age 80.0 years, p = 0.016). No differences were found in sex, body mass index, ASA class, or ACCI (all p > 0.05). Patients in the post-GTC group used vitamin K antagonists or direct oral anticoagulants more frequently (21.3% versus 10.8%). The incidence of non-surgical treatment and mortality was comparable between groups, while LOS tended to be shorter in the post-GTC group (7.0 days versus 9.0 days, p = 0.076). In the post-GTC group, the detection of urinary tract infections (UTI) increased (35.2% versus 16.2%, p = 0.001), and the delirium diagnoses tended to increase (13.0% versus 6.3%, p = 0.094), while an ACDiT score of ≥1 was comparable between groups (p = 0.169). Conclusions: In this study including lumbar spine, thoracic spine, and pelvic ring geriatric fragility fractures, patients in the post-GTC group were more medically complex. More UTIs and the tendency for increased delirium detection was observed in the post-GTC group, likely due to improved diagnostic testing. Nonetheless, the necessity of deviation from initial management plans (ACDiT score of ≥1) was comparable between groups, potentially a positive result of OGCM.

ROTEM Testing for Direct Oral Anticoagulants

Direct oral anticoagulants (DOACs) are increasingly used worldwide for the prevention of stroke in patients with atrial fibrillation and to prevent or treat venous thromboembolism. In situations such as serious bleeding, the need for urgent surgery/intervention or the management of a thromboembolic event, the laboratory measurement of DOACs levels or anticoagulant activity may be required. Rotational thromboelastometry (ROTEM) is a viscoelastic hemostatic assay (VHA) which has been used in emergencies (trauma and obstetrics), and surgical procedures (cardiac surgery and liver transplants), but experience with this assay in DOACs-treated patients is still limited. This article reviews the use of ROTEM in the setting of DOACs therapy, focusing on DOACs-associated bleeding and the use of this VHA for the management of reversal strategies for DOACs-associated anticoagulation.

Platelet-like particles improve fibrin network properties in a hemophilic model of provisional matrix structural defects

Following injury, a fibrin-rich provisional matrix is formed to stem blood loss and provide a scaffold for infiltrating cells, which rebuild the damaged tissue. Defects in fibrin network formation contribute to impaired healing outcomes, as evidenced in hemophilia. Platelet-fibrin interactions greatly influence fibrin network structure via clot contraction, which increases fibrin density over time. Previously developed hemostatic platelet-like particles (PLPs) are capable of mimicking platelet functions including binding to fibrin fibers, augmenting clotting, and inducing clot retraction. In this study, we aimed to apply PLPs within a plasma-based in vitro hemophilia B model of deficient fibrin network structure to determine the ability of PLPs to improve fibrin structure and wound healing responses within hemophilia-like abnormal fibrin network formation. PLP impact on structurally deficient clot networks was assessed via confocal microscopy, a micropost deflection model, atomic force microscopy and an in vitro wound healing model of early cell migration within a provisional fibrin matrix. PLPs improved clot network density, force generation, and stiffness, and promoted fibroblast migration within an in vitro model of early wound healing under hemophilic conditions, indicating that PLPs could provide a biomimetic platform for improving wound healing events in disease conditions that cause deficient fibrin network formation.

The novel oral anticoagulants (NOACs) have worse outcomes compared with warfarin in patients with intracranial hemorrhage after TBI

INTRODUCTION

Novel oral anticoagulant (NOAC) use is increasing in trauma patients. The reversal of these agents after hemorrhage is still evolving. The aim of our study was to evaluate outcomes after traumatic brain injury in patients on NOACs.

METHODS

3-year (2014-2016) analysis of our prospectively maintained traumatic brain injury (TBI) database. We included all TBI patients with intracranial hemorrhage (ICH) on anticoagulants. Patients were stratified into two groups, those on NOACs and on warfarin, and were matched in a 1:2 ratio using propensity score matching for demographics, injury and vital parameters, type, and size of ICH. Outcome measures were progression of ICH, mortality, skilled nursing facility (SNF) disposition, and hospital and intensive care unit (ICU) length of stay (LOS).

RESULTS

We analyzed 1,459 TBI patients, of which 210 patients were matched (NAOCs, 70; warfarin, 140). Matched groups were similar in age (p = 0.21), mechanism of injury (p = 0.61), Glasgow Coma Scale (GCS) score (p = 0.54), Injury Severity Score (p = 0.62), and type and size of ICH (p = 0.09). Patients on preinjury NOACs had higher rate of progression (p = 0.03), neurosurgical intervention (p = 0.04), mortality (p = 0.04), and longer ICU LOS (p = 0.04) compared with patients on warfarin. However, there was no difference in hospital LOS (p = 0.22) and SNF disposition (p = 0.14). On sub-analysis of severe TBI patients (GCS ≤ 8), rate of progression (p = 0.59), neurosurgical intervention (p = 0.62), or mortality (p = 0.81) was similar in both groups.

CONCLUSIONS

The use of NOACs generally carries a high risk of bleeding and can be detrimental in head injuries with ICH. NOAC use is associated with increased risk of progression of ICH, neurosurgical intervention, and mortality after a mild and moderate TBI. Primary care physicians and cardiologists need to reconsider the data on the need for anticoagulation and the type of agent used and weigh it against the risk of bleeding. In addition, development of reversal agents for the NOACs and implementation of a strict protocol for the reversal of these agents may lead to improved outcomes.

LEVEL OF EVIDENCE

Therapeutic studies, level III.

Fibrin Nanoparticles Coupled with Keratinocyte Growth Factor Enhance the Dermal Wound-Healing Rate

Expediting the wound-healing process is critical for patients chronically ill from nonhealing wounds and diseases such as hemophilia or diabetes or who have suffered trauma including easily infected open wounds. FDA-approved external tissue sealants include the topical application of fibrin gels, which can be 500 times denser than natural fibrin clots. With lower clot porosity and higher polymerization rates than physiologically formed fibrin clots, the commercial gels quickly stop blood loss but impede the later clot degradation kinetics and thus retard tissue-healing rates. The fibrin nanoparticles (FBNs) described here are constructed from physiologically relevant fibrin concentrations that support new tissue and dermal wound scaffold formation when coupled with growth factors. The FBNs, synthesized in a microfluidic droplet generator, support cell adhesion and traction generation, and when coupled to keratinocyte growth factor (KGF), support cell migration and in vivo wound healing. The FBN-KGF particles enhance cell migration in vitro greater than FBN alone or free KGF and also improve healing outcomes in a murine full thickness injury model compared to saline, bulk fibrin sealant, free KGF, or bulk fibrin mixed with KGF treatments. Furthermore, FBN can be potentially administered with other tissue-healing factors and inflammatory mediators to improve wound-healing outcomes.

Reversing anti–factor Xa agents and the unmet needs in trauma patients

Andexanet alfa, a reversing agent for anticoagulants that inhibit factor Xa, has recently been licensed in the United States. We discuss the impact of this licensure on current practice and review in detail the problems of a neglected and growing clinical area: reversing the anticoagulation effect of factor Xa inhibitors in bleeding trauma patients. We identify areas of practice that need research so that care of bleeding trauma patients receiving direct factor Xa inhibitors can be improved.

Signal detection for bleeding associated with the use of direct oral anticoagulants

PURPOSE

The potential link between serious or life-threatening bleeding and the use of direct oral anticoagulants (DOACs) was evaluated.

METHODS

Qualitative and quantitative reviews of case reports of bleeding events involving dabigatran, rivaroxaban, apixaban, edoxaban, and warfarin through March 31, 2017, were performed. A disproportionality analysis was conducted for each DOAC using an empirical Bayesian approach based on the relative reporting rate. Subanalyses were performed to assess (1) bleeding events (including mortality and life-threatening events) associated with DOACs among all adverse-event reports and (2) warfarin-related bleeding events. These analyses were conducted based on clinical definitions from the Medical Dictionary for Regulatory Activities.

RESULTS

During the Food and Drug Administration Adverse Event Reporting System (FAERS) review period, 35 adverse-event terms (in any system organ class) with a disproportionality score (EB₀₅) of >7.5 for DOACs were identified; this accounted for 40,109 adverse-event reports. Adverse events with the highest disproportionality scores included atrial thrombosis, increased factor X level, dysfunctional uterine bleeding, high-frequency ablation, pericardial hemorrhage, and internal hemorrhage. Adverse events with the highest EB₀₅ (>5) included internal hemorrhage, hemorrhage, and exsanguination; events with the greatest number of patient experiences included hemorrhage (6,881 events), internal hemorrhage (2,569 events), and hematoma (1,995 events). Warfarin-related events (including death or life-threatening events) were also assessed. A total of 8,729 adverse events were associated with warfarin use. The most common of these included hemorrhage (6,225 events), hematoma (2,199 events), and internal hemorrhage (270 events).

CONCLUSION

The disproportionality analysis of the FAERS database suggests a quantitative signal between DOAC use and life-threatening or serious bleeding.

Effects of dabigatran on the cellular and protein phase of coagulation in patients with coronary artery disease on dual antiplatelet therapy with aspirin and clopidogrel

There is growing interest in understanding the effects of adding an oral anticoagulant in patients on dual antiplatelet therapy (DAPT). Vitamin K antagonists (VKAs) and clopidogrel represent the most broadly utilised oral anticoagulant and P2Y12 receptor inhibitor, respectively. However, VKAs can interfere with clopidogrel metabolism via the cytochrome P450 (CYP) system which in turn may result in an increase in platelet reactivity. Dabigatran is a direct acting (anti-II) oral anticoagulant which does not interfere with CYP and has favourable safety and efficacy profiles compared with VKAs. The pharmacodynamic (PD) effects on platelet reactivity and clot kinetic of adjunctive dabigatran therapy in patients on DAPT are poorly explored. In this prospective, randomised, double-blind, placebo-controlled PD study, patients (n=30) on maintenance DAPT with aspirin and clopidogrel were randomised to either dabigatran 150 mg bid or placebo for seven days. PD testing was performed before and after treatment using four different assays exploring multiple pathways of platelet aggregation and fibrin clot kinetics: light transmittance aggregometry (LTA), multiple electrode aggregometry (MEA), kaolin-activated thromboelastography (TEG) and turbidimetric assays. There were no differences in multiple measures of platelet reactivity investigating purinergic and non-purinergic signaling pathways assessed by LTA, MEA and TEG platelet mapping. Dabigatran significantly increased parameters related to thrombin activity and thrombus generation, and delayed fibrin clot formation, without affecting clot structure or fibrinolysis. In conclusion, in patients on DAPT with aspirin and clopidogrel, adjunctive dabigatran therapy is not associated with modulation of profiles of platelet reactivity as determined by several assays assessing multiple platelet signalling pathways. However, dabigatran significantly interferes with parameters related to thrombin activity and delays fibrin clot formation.

Direct Oral Anticoagulants in Emergency Trauma Admissions

BACKGROUND

Direct (non-vitamin-K-dependent) oral anticoagulants (DOAC) are given as an alternative to vitamin K antagonists (VKA) to prevent stroke and embolic disease in patients with atrial fibrillation that is not due to pathology of the heart valves. Fatal hemorrhage is rarer when DOACs are given (nonvalvular atrial fibrillation: odds ratio [OR] 0.68; 95% confidence interval [95% CI: 0.48; 0.96], and venous thromboembolism: OR 0.54; [0.22; 1.32]). 48% of emergency trauma patients need an emergency operation or early surgery. Clotting disturbances elevate the mortality of such patients to 43%, compared to 17% in patients without a clotting disturbance. This underscores the impor tance of the proper, targeted treatment of trauma patients who are aking DOAC.

METHODS

This review is based on articles retrieved by a selective search in PubMed and on a summary of expert opinion and the recommendations of the relevant medical specialty societies.

RESULTS

Peak DOAC levels are reached 2-4 hours after the drug is taken. In patients with normal renal and hepatic function, no drug accumulation, and no drug interactions, the plasma level of DOAC 24 hours after administration is generally too low to cause any clinically relevant risk of bleeding. The risk of drug accumulation is higher in patients with renal dysfunction (creatinine clearance [CrCl] of 30 mL/min or less). Dabigatran levels can be estimated from the thrombin time, ecarin clotting time, and diluted thrombin time, while levels of factor Xa inhibitors can be estimated by means of calibrated chromogenic anti-factor Xa activity tests. Routine clotting studies do not reliably reflect the anticoagulant activity of DOAC. Surgery should be postponed, if possible, until at least 24-48 hours after the last dose of DOAC. For patients with mild, non-life threatening hemorrhage, it suffices to discontinue DOAC; for patients with severe hemorrhage, there are special treatment algorithms that should be followed.

CONCLUSION

DOACs in the setting of hemorrhage are a clinical challenge in the traumatological emergency room because of the inadequate validity of the relevant laboratory tests. An emergency antidote is now available only for dabigatran.

Reversal of dabigatran anticoagulation ex vivo: Porcine study comparing prothrombin complex concentrates and idarucizumab

Urgent surgery or life-threatening bleeding requires prompt reversal of the anticoagulant effects of dabigatran. This study assessed the ability of three- and four-factor prothrombin complex concentrate (PCC) and idarucizumab (specific antidote for dabigatran) to reverse the anticoagulant effects of dabigatran in a porcine model of trauma. Twelve animals were given dabigatran etexilate (DE) orally and dabigatran intravenously, before infliction of trauma. Six animals received tranexamic acid plus fibrinogen concentrate 12 minutes post-injury. Six PCCs (each 30 and 60 U/kg) and idarucizumab (30 and 60 mg/kg) were added to blood samples ex vivo. Coagulation was assessed by several coagulation assays. All coagulation parameters were altered after dabigatran infusion (plasma level: 442 ± 138 ng/ml). Both threeand four-factor PCCs mostly or completely reversed the effects of dabigatran on thromboelastometry variables and PT but not on aPTT. Idarucizumab neutralised plasma concentrations of dabigatran, and reversed the effects of the drug on coagulation variables. Thrombin generation showed dose-dependent over-correction following the addition of PCC, implying that elevated levels of thrombin are required to overcome dabigatran-induced coagulopathy. In contrast, treatment with idarucizumab returned thrombin generation to baseline levels. Following trauma, therapy with tranexamic acid plus fibrinogen improved correction of coagulation parameters by PCC, and thromboelastometry parameters by idarucizumab. All investigated PCCs improved dabigatran- and trauma-induced coagulopathy to a similar degree. In conclusion, this study shows that three- and four-factor PCCs are similarly effective for dabigatran reversal. Idarucizumab also reversed the effects of dabigatran and, unlike PCCs, was not associated with over-correction of thrombin generation.

Note: This study was performed at the RWTH Aachen University Hospital, Pauwelsstrasse 30, D-52074 Aachen, Germany.

Antithrombotic Reversal Agents

The actively bleeding anticoagulated patient presenting to the emergency department requires rapid evaluation and treatment, which is made increasingly complicated by the ever-evolving antithrombotic treatment options used in medicine. Even with excellent supportive care, the timeliness with which reversal decisions need to be made continues to demand of the emergency practitioner a familiarity with the properties and general characteristics of a variety of antithrombotic agents. Reversal options vary and may include vitamin K, FFP, PCC, rFVIIa, platelets, and desmopressin, among others.

Targeted Thromboelastographic (TEG) Blood Component and Pharmacologic Hemostatic Therapy in Traumatic and Acquired Coagulopathy

Trauma-induced coagulopathy (TIC) is a recently described condition which traditionally has been diagnosed by the common coagulation tests (CCTs) such as prothrombin time/international normalized ratio (PT/INR), activated partial thromboplastin time (aPTT), platelet count, and fibrinogen levels. The varying sensitivity and specificity of these CCTs have led trauma coagulation researchers and clinicians to use Viscoelastic Tests (VET) such as Thromboelastography (TEG) to provide Targeted Thromboelastographic Hemostatic and Adjunctive Therapy (TTHAT) in a goal directed fashion to those trauma patients in need of hemostatic resuscitation. This review describes the utility of VETs, in particular, TEG, to provide TTHAT in trauma and acquired non-trauma-induced coagulopathy.

The Anticoagulated trauma patient in the age of the direct oral anticoagulants: a Canadian perspective

Background

The anticoagulated trauma patient presents a particular challenge to the critical care physician. Our understanding of these patients is defined and extrapolated by experience with patients on warfarin pre-injury. Today, many patients who would have been on warfarin are now prescribed the Direct Oral Anticoagulants (DOACs) a class of anticoagulants with entirely different mechanisms of action, effects on routine coagulation assays and approach to reversal.

Methods

Trauma registry data from Toronto’s (Ontario, Canada) two Level 1 trauma centres were used to identify patients on oral anticoagulation pre-injury from June 1, 2014 to June 1, 2015. The trauma registry and medical records were reviewed and used to extract demographic and clinical data.

Results

We found 81 patients were on oral anticoagulants pre-injury representing 3.2% of the total trauma population and 33% of the orally anticoagulated patients were prescribed a DOAC prior to presentation. Comparison between the DOAC and warfarin groups showed similar age, mechanisms of injury, indications for anticoagulation, injury severity score and rate of intracranial hemorrhage. Patients on DOACs had higher initial mean hemoglobin vs warfarin (131 vs 120) and lower serum creatinine (94.8 vs 129.5). The percentage of patients receiving a blood transfusion in the trauma bay and total in-hospital transfusion was similar between the two groups however patients on DOACs were more likely to receive tranexamic acid vs patients on warfarin (32.1% vs 9.1%) and less likely to receive prothrombin concentrates (18.5% vs 60%). Patients on DOACs were found to have higher survival to discharge (92%) vs patients on warfarin (72%).

Conclusion

Patients on DOACs pre-injury now represent a significant proportion of the anticoagulated trauma population. Although they share demographic and clinical similarities with patients on warfarin, patients on DOACs may have improved outcomes despite lack of established drug reversal protocols and challenging interpretation of coagulation assays.

Level of Evidence: III; Study Type: Retrospective Review.

Management of Patients on Non-Vitamin K Antagonist Oral Anticoagulants in the Acute Care and Periprocedural Setting: A Scientific Statement From the American Heart Association

Non-vitamin K oral anticoagulants (NOACs) are now widely used as alternatives to warfarin for stroke prevention in atrial fibrillation and management of venous thromboembolism. In clinical practice, there is still widespread uncertainty on how to manage patients on NOACs who bleed or who are at risk for bleeding. Clinical trial data related to NOAC reversal for bleeding and perioperative management are sparse, and recommendations are largely derived from expert opinion. Knowledge of time of last ingestion of the NOAC and renal function is critical to managing these patients given that laboratory measurement is challenging because of the lack of commercially available assays in the United States. Idarucizumab is available as an antidote to rapidly reverse the effects of dabigatran. At present, there is no specific antidote available in the United States for the oral factor Xa inhibitors. Prothrombin concentrate may be considered in life-threatening bleeding. Healthcare institutions should adopt a NOAC reversal and perioperative management protocol developed with multidisciplinary input.

Direct oral anticoagulants compared with warfarin in patients with severe blunt trauma

METHODS

We queried our Trauma Quality Improvement Program registry for patients who presented between 6/1/2011 and 9/1/2015 with severe (injury severity score (ISS)>15) blunt traumatic injury during anticoagulant use. Patients were then grouped into those prescribed warfarin and patients prescribed any of the available novel Direct Oral Anticoagulants (DOAC) medications. We excluded severe (AIS≧4) head injuries.

RESULTS

There were no differences between DOAC and warfarin groups in terms of age, gender mean ISS, median hospital or intensive care unit lengths of stay, complication proportions, numbers of complications per patient, or the proportion of patients requiring transfusion. Finally, excluding patients who died, the observed proportion of discharge to skilled nursing facility was similar. In our sample of trauma patients, DOAC use was associated with significantly lower mortality (DOAC group 8.3% vs. warfarin group 29.5%, p<0.015). The ratio of units transfused per patient was also lower in the DOAC group (2.8±1.8 units/patient in the DOAC group vs. 6.7±6.4 units per patient in the warfarin group; p=0.001).

CONCLUSION

In conclusion, we report an association with decrease in mortality and a decrease in transfused blood products in severely injured trauma patients with likely minimal or no head injury taking novel DOACs over those anticoagulated with warfarin for outpatient anticoagulation.

The Severity of Bleeding and Mortality in Trauma Patients Taking Dabigatran

BACKGROUND

Dabigatran, a direct thrombin inhibitor, has been shown to be more effective than warfarin in the prevention of stroke in patients with atrial fibrillation. Until recently, it lacked a reversal agent, and its contribution to the risk of transfusion in injured patients is unknown.

OBJECTIVE

We sought to determine whether patients who sustain traumatic injuries while taking dabigatran receive more blood transfusions than matched patients taking warfarin, aspirin, clopidogrel, or controls.

METHODS

This retrospective, single-center cohort consisted of injured patients who were taking dabigatran before admission to a major trauma center (January 2010-December 2013) who were compared with cohorts of patients taking warfarin, clopidogrel, or aspirin and a control group. The outcome was bleeding risk as measured by the use of blood products, with mortality as a secondary outcome. Outcomes were controlled for by age, sex, injury severity, and blunt mechanism.

RESULTS

Thirty-eight patients were taking dabigatran. Compared with the general trauma population, patients taking dabigatran were more likely to be male, older, and to have higher injury severity. Patients taking dabigatran received transfusions (odds ratio [OR] 1.31 [95% confidence interval {CI} 0.56-3.04]), packed red blood cells (OR 1.43 [95% CI 0.54-3.77]), frozen plasma (OR 1.20 [95% CI 0.42-3.49]), and platelets (OR 2.01 [95% CI 0.63-6.37]) as often as matched controls. The mortality rate among patients on dabigatran was 12.5% (OR 1.51 [95% CI 0.39-5.89]) compared with 9.1% in matched controls. None of these results was statistically significant.

CONCLUSIONS

In this small study, injured patients taking dabigatran were transfused as often and had similar in-hospital mortality as matched controls who were not taking anticoagulants.

Evaluation of the chromogenic anti-factor IIa assay to assess dabigatran exposure in geriatric patients with atrial fibrillation in an outpatient setting

Background

Dabigatran etexilate may be underutilized in geriatric patients because of inadequate clinical experience in individuals with severe renal impairment and post-marketing reports of bleeding events. Assessing the degree of anticoagulation may improve the risk:benefit ratio for dabigatran. The aim of this prospective study was to identify whether therapeutic drug monitoring of dabigatran anticoagulant activity using a chromogenic anti-factor IIa assay is a viable option for therapy individualization.

Methods

Plasma dabigatran concentration was assessed in nine patients with nonvalvular atrial fibrillation aged 75 years or older currently receiving dabigatran etexilate for prevention of stroke, using an anti-factor IIa chromogenic assay and HPLC-MS/MS. Trough concentrations were evaluated on two separate occasions to determine intrapatient variation.

Results

Blood was collected at 13.1 ± 2.3 h (mean ± SD) post dose from patients prescribed dabigatran etexilate 150 mg twice daily (5/9 patients) or dabigatran etexilate 75 mg twice daily (4/9 patients). Results from the anti-factor IIa chromogenic assay correlated with dabigatran concentrations as assessed by HPLC-MS/MS (r² = 0.81, n = 16). There was no correlation between dabigatran trough values taken at separate visits (r² = 0.002, n = 7). Furthermore, there was no correlation found between the drug concentrations and patients’ renal function determined by both creatinine and cystatin-C based equations. None of the patients enrolled in the study were in the proposed on-therapy trough range during at least one visit.

Conclusion

The chromogenic anti-factor IIa assay demonstrated similar performance in quantifying dabigatran plasma trough concentrations to HPLC-MS/MS. Single measurement of dabigatran concentration by either of two methods during routine visits may not be reliable in identifying patients at consistently low or high dabigatran concentrations.

Electronic supplementary material

The online version of this article (doi:10.1186/s12959-016-0084-2) contains supplementary material, which is available to authorized users.

Emergent Bleeding in Patients Receiving Direct Oral Anticoagulants

Direct oral anticoagulants (DOACs) offer clinical advantages over warfarin, such as minimal medication and food interactions and fixed dosing without the need for routine monitoring of coagulation status. As with all anticoagulants, bleeding, either spontaneous or provoked, is the most common complication. The long-term use of these drugs is increasing, and there is a crucial need for emergency medicine service professionals to understand the optimal management of associated bleeding. This review aims to describe the indications and pharmacokinetics of available DOACs; to discuss the risk of bleeding; to provide a treatment algorithm to manage DOAC-associated emergency bleeding; and to discuss future directions in bleeding management, including the role of specific reversal agents, such as the recently approved idarucizumab for reversal of the direct thrombin inhibitor dabigatran. Because air medical personnel are increasingly likely to encounter patients receiving DOACs, it is important that they have an understanding of how to manage patients with emergent bleeding.

Efficacy of prothrombin complex concentrates for the emergency reversal of dabigatran-induced anticoagulation

Dabigatran is effective in decreasing the risk of ischaemic stroke in patients with atrial fibrillation. However, like all anticoagulants, it is associated with a risk of bleeding. In cases of trauma or emergency surgery, emergency reversal of dabigatran-induced anticoagulation may be required. A specific reversal agent for dabigatran, idarucizumab, has been approved by the US Food and Drug Administration. Alternative reversal agents are available, such as prothrombin complex concentrates (PCCs) and activated PCCs (aPCCs). In this review we evaluate the role of PCCs and aPCCs in the reversal of dabigatran anticoagulation and consider which tests are appropriate for monitoring coagulation in this setting. Pre-clinical studies, small clinical studies and case reports indicate that PCCs and aPCCs may be able to reverse dabigatran-induced anticoagulation in a dose-dependent manner. However, dosing based on coagulation parameters can be difficult because available assays may not provide adequate sensitivity and specificity for measuring anticoagulation induced by dabigatran or the countering effects of PCCs/aPCCs. In addition, PCCs or aPCCs can potentially provoke thromboembolic complications. Despite these limitations and the fact that PCCs and aPCCs are not yet licensed for dabigatran reversal, their use appears to be warranted in patients with life-threatening haemorrhage if idarucizumab is not available.

A New Generation of Antiplatelet, and Anticoagulant Medication and the Implications for the Dental Surgeon

The management of dental patients taking either antiplatelet medication, anticoagulant medication or both has been well established in the previous literature. Recently, new generations of drugs have emerged which are becoming increasingly common, including direct thrombin inhibitors, factor X inhibitors and a new class of oral thienopyridines. The implications of these drugs for the dental surgeon are not yet fully known. Awareness remains low and there is very little information available within the literature on safe use during surgery. This review paper aims to provide some guidance for dental practitioners performing invasive procedures. CPD/CLINICAL RELEVANCE: A new generation of anticoagulant and antiplatelet drugs have serious implications for patients undergoing surgery and their use is increasing.

Current and developing strategies for monitoring and reversing direct oral anticoagulants in patients with non-valvular atrial fibrillation

OBJECTIVE

In light of the increasing clinical utilization of the direct oral anticoagulants (DOACs) among patients with non-valvular atrial fibrillation, this review evaluates strategies for monitoring and reversing the anticoagulant effect of these agents.

METHODS

We summarize the data currently available for laboratory monitoring and reversal of DOACs. Relevant literature was identified using search terms pertaining to oral anticoagulants, reversal agents, and laboratory monitoring using Pubmed, clinicaltrials.gov, and abstracts from recent major cardiovascular meetings.

RESULTS

Significant user appeal for the DOACs stems from the reliable pharmacokinetics of these agents, which render routine laboratory monitoring unnecessary for general use, as well as lower rates of bleeding as compared to warfarin. However, readily available laboratory tests have not been clinically validated for use with these agents. The ability to measure the anticoagulant effect of a DOAC in selected situations (e.g. serious bleeding, overanticoagulation, emergent procedures, and compliance monitoring) remains an unmet clinical need. Further, there is a paucity of data to guide treatment in patients receiving DOACs who experience a serious hemorrhage.

CONCLUSION

While evidence-based recommendations cannot be definitively provided for management of DOAC-related bleeding events at present, several targeted reversal agents are currently in development, and hold promise for solving this important clinical problem.

Impact of dabigatran on platelet function and fibrinolysis

BACKGROUND

We sought to evaluate the potential enhanced fibrinolytic and antiplatelet activity of dabigatran etexilate (DE) due to decreased thrombin levels in patients with stroke or transient ischemic attack and non-valvular atrial fibrillation (NVAF).

METHODS

Consecutive patients with cerebrovascular diseases and NVAF that were treated with DE in a tertiary university hospital. Fibrinolysis and platelet function were assessed by thromboelastometry (ROTEM) and platelet function analyzer (PFA)-100, respectively, before and after treatment with DE. Conventional coagulation tests, endogenous thrombin potential (ETP) and hemoclot thrombin inhibitors (HTI), were also performed in order to detect any possible correlation between dabigatran plasma levels, its anticoagulant activity and the intensity of platelet dysfunction or fibrinolysis.

RESULTS

A total of nineteen patients fulfilled our inclusion criteria (mean age 62.3±7.2years; 47% males; median CHADS2-score: 3; interquartile range: 2-4). DE treatment was associated with a significant reduction of the lysis index (LI60) at 60min (p=0.036), and prolongation of the PFA-100 CEPI closure time (p=0.024). After dabigatran treatment, abnormal PFA-100 results were obtained in two patients (11%, 95% CI: 2%-33%). DE levels (determined by HTI) were strongly inversely correlated (rho=-0.85; p<0.001) with the area under the curve (AUC) values in ETP assay. Νo association was found between HTI and PFA-100 CEPI CT (p=0.64), or LI60 measurements (p=0.60).

CONCLUSIONS

Our findings indicate that DE might affect platelet function and fibrinolysis and highlight the potential role of ETP as an alternative option in DE monitoring. The intensity and clinical relevance of DE antiplatelet and fibrinolytic effects require further investigation.

What neurosurgeons need to know about dabigatran etexilate (pradax(®)/pradaxa(®)/prazaxa(®))

Dabigatran etexaliate is a novel oral anticoagulant that directly inhibits thrombin. It offers a number of substantial medical benefits over other oral and parenteral anticoagulants but its advent raises important neurosurgical considerations. Dabigatran has important potential benefits. Unlike warfarin, it does not require routine blood tests to monitor its anticoagulative effect and there is no need for dose titration. Drug interactions are greatly simplified when compared to warfarin as dabigatran is not metabolized by cytochrome p450 isoenzymes. As a result, dabigatran has been approved in many jurisdictions for DVT prophylaxis after orthopaedic surgery and also for the prevention of embolic events associated with non-valvular atrial fibrillation. There are, however, important neurosurgical challenges associated with regular dabigatran use. Unlike current anti-coagulants, there is no specific reversal agent for dabigatran. Known reversal options include activated charcoal (within one to two hours of intake) and renal dialysis. Protamine sulfate and vitamin K are unlikely to affect the activity of dabigatran. Platelet concentrates will not inactivate dabigatran's anti-thrombin properties. Assessing the degree of anticoagulation is difficult as conventional markers of serum coagulability are typically normal in patients taking dabigatran. The potential neurosurgical challenges of dabigatran were cast in sharp relief by a recent case report from the United States that is considered in this note. In the absence of a clear reversal pathway, we propose a treatment algorithm for chronic dabigatran use based on the replacement of any deficient factors and rapid access to renal dialysis.

Use of Thromboelastography (TEG) for Detection of New Oral Anticoagulants

CONTEXT

The clinical introduction of new oral anticoagulants (NOACs) has stimulated the development of tests to quantify the effects of these drugs and manage complications associated with their use. Until recently, the only treatment choices for the prevention of venous thromboembolism in orthopedic surgical patients, as well as for stroke and systemic embolism in patients with atrial fibrillation, were vitamin K antagonists, antiplatelet drugs, and unfractionated and low-molecular-weight heparins. With the approval of NOACs, treatment options and consequent diagnostic challenges have expanded.

OBJECTIVE

To study the utility of thromboelastography (TEG) in monitoring and differentiating between 2 currently approved classes of NOACs, direct thrombin inhibitors (dabigatran) and factor Xa inhibitors (rivaroxaban and apixaban).

DESIGN

Blood samples from healthy volunteers were spiked with each NOAC in both the presence and absence of ecarin, and the effects on TEG were evaluated.

RESULTS

Both the kaolin test reaction time (R time) and the time to maximum rate of thrombus generation were prolonged versus control samples and demonstrated a dose response for apixaban (R time within the normal range) and dabigatran. The RapidTEG activated clotting time test allowed the creation of a dose-response curve for all 3 NOACs. In the presence of anti-Xa inhibitors, the ecarin test promoted significant shortening of kaolin R times to the hypercoagulable range, while in the presence of the direct thrombin inhibitor only small and dose-proportional R time shortening was observed.

CONCLUSIONS

The RapidTEG activated clotting time test and the kaolin test appear to be capable of detecting and monitoring NOACs. The ecarin test may be used to differentiate between Xa inhibitors and direct thrombin inhibitors. Therefore, TEG may be a valuable tool to investigate hemostasis and the effectiveness of reversal strategies for patients receiving NOACs.

Mechanisms of trauma-induced coagulopathy

PURPOSE OF REVIEW

Hemorrhage is the leading cause of potentially preventable death following injury. Excessive and uncontrolled bleeding, commonly referred to as trauma-induced coagulopathy (TIC), affects a quarter of all trauma patients and is associated with substantial injuries, increased transfusion requirements, and poor outcomes. Recent data have contributed to our current understanding of the molecular mechanisms driving TIC.

RECENT FINDINGS

The current literature offers evidence supporting proposed mechanisms that induce TIC, such as platelet dysfunction, endogenous anticoagulation, endothelial activation, fibrinogen modifications, and hyperfibrinolysis. However, the majority of these data are mere associations; causative data are slowly unfolding through the utilization of animal models of hemorrhagic shock coupled with prospective observational clinical studies.

SUMMARY

As both clinical and basic science research expands our understanding of TIC, trauma patient care is improving substantially. Future studies should focus on the interplay between the coagulation pathways whose simultaneous or codependent dysregulation could offer the most advantageous points for intervention.

Traumatic fatal cerebral hemorrhage in an old patient with a history of multiple sclerosis under dabigatran: a case report and review of the literature

One disadvantage of direct anticoagulant drug is the lack of an antidote, which may become relevant in patients with traumatic brain injury. A 77-years old man with atrial fibrillation and syncope received dabigatran despite recurrent falls. Due to a ground-level-fall, he suffered from subarachnoidal and intraparenchymal hemorrhages, subdural hematoma and brain edema with a midline shift. Despite osteoclastic trepanation and hematoma-evacuation he remained comatose and died seven days later without regaining consciousness. Most probably, decreased dabigatran clearance due to increased age might have contributed to the fatal course. We suggest withholding anticoagulant therapy in patients with unexplained falls. If anticoagulant therapy is deemed necessary, vitamin-K-antagonists with their potential for laboratory monitoring and reversal of anticoagulant activity should be preferred.

Laboratory assessment of the anticoagulant activity of dabigatran

BACKGROUND

Our aim was to identify laboratory assays in order to assess the anticoagulant effects of dabigatran etexilate (DE).

METHODS

Twenty patients with nonvalvular atrial fibrillation treated on DE (110 mg per os twice daily) and 20 on acenocoumarol were studied. Conventional coagulation tests, endogenous thrombin potential (ETP), thromboelastometry (ROTEM), epinephrine-induced light transmission aggregometry (LTA), and Hemoclot Thrombin Inhibitors (HTI) were performed in all patients.

RESULTS

In ROTEM analysis, the lysis index at 60 minutes was significantly lower in patients receiving DE (P = .011). In LTA, patients on DE showed decreased aggregation compared to those on acenocoumarol, marginally insignificant (P = .068). Regarding ETP, acenocoumarol affected thrombin generation more than dabigatran (area under the curve [AUC], P < .001), while statistically significant associations were detected between dabigatran levels, as determined by the HTI assay, and almost all parameters of ETP assay (AUC, P < .001).

CONCLUSION

The role of ETP in estimating anticoagulant activity of dabigatran possibly requires further research.

Reversing targeted oral anticoagulants

Dabigatran, rivaroxaban, and apixaban are orally active anticoagulants that are approved in many countries. Dabigatran inhibits thrombin, whereas rivaroxaban and apixaban are factor Xa inhibitors. In clinical trials, these novel oral anticoagulants were at least as effective as warfarin for preventing stroke in patients with atrial fibrillation, but with a lower rate of serious bleeding. However, the lack of true antidotes for these agents has caused concern when patients suffer life-threatening bleeding or trauma or require emergent invasive procedures. True antidotes are under development for all of these agents. In the meantime, activated and nonactivated prothrombin complex concentrates have been used as reversal agents. Factor VIIa may also be effective for reversal of the factor Xa inhibitors. Reversal of novel oral anticoagulants by these hemostatic agents has not been studied in bleeding human patients, so their true efficacy and appropriate dosing are not known.

Role of prothrombin complex concentrate in perioperative coagulation therapy

Prothrombin complex concentrate (PCC) is a term to describe pharmacological products that contain lyophilized, human plasma-derived vitamin K-dependent factors (F), FII, FVII, FIX, FX, and various amounts of proteins C and S. PCCs can be rapidly reconstituted in a small volume (20 ml for about 500 international units (IU)) at bedside and administered regardless of the patient's blood type. PCCs are categorized as 4-factor PCC if they contain therapeutic amounts of FVII, and 3-factor PCC when FVII content is low. In addition, activated PCC which contains activated FVII and FX with prothrombin is available for factor VIII bypassing therapy in hemophilia patients with inhibitors. Currently, 4-factor PCC is approved for the management of bleeding in patients taking warfarin, but there has been increasing use of various PCCs in the treatment of acquired perioperative coagulopathy unrelated to warfarin therapy and in the management of bleeding due to novel oral anticoagulants. There is also an ongoing controversy about plasma transfusion and its potential hazards including transfusion-related lung injury (TRALI). Early fixed ratio plasma transfusion has been implemented in many trauma centers in the USA, whereas fibrinogen concentrate and PCC are preferred over plasma transfusion in some European centers. In this review, the rationales for including PCCs in the perioperative hemostatic management will be discussed in conjunction with plasma transfusion.

Dabigatran-associated subdural hemorrhage: using thromboelastography (TEG(®)) to guide decision-making

Novel oral anticoagulants present challenges and uncertainties in the management of hemorrhagic emergencies. An 84-year-old man taking dabigatran presented with a subdural hematoma requiring neurosurgical intervention. Routine coagulation assays were prolonged at admission and following administration of Factor VIII Inhibitor Bypassing Activity (FEIBA). Thromboelastography (TEG(®)) was utilized to assess clot dynamics prior to placement of a subdural drain, which was safely inserted despite a prolonged thrombin time (TT). Exclusive reliance on the TT may delay necessary interventions. TEG(®) may be a valuable tool to investigate hemostasis in patients on dabigatran requiring emergent procedures.