Trauma patients with lower extremity and pelvic fractures: Should anti-factor Xa trough level guide prophylactic enoxaparin dose?

Thrombosis prophylaxis following trauma

PURPOSE OF REVIEW

This review explores the persistent occurrence of venous thromboembolic events (VTE) in major trauma patients despite standard thrombosis prophylaxis with low-molecular-weight heparin (LMWH) or unfractionated heparin (UFH). It investigates the inadequacies of standard pharmacologic prophylaxis and proposes alternative approaches not covered in current trauma guidelines.

RECENT FINDINGS

Recent studies highlight the effectiveness of monitoring and adjusting subcutaneous LMWH doses based on anti-Xa levels for the purpose of reducing VTE in trauma patients. The need for dose adaptation arises due to factors like fluctuating organ function, varying antithrombin levels, interaction with plasma proteins, and altered bioavailability influenced by oedema or vasopressor use. Additionally, promising alternatives such as intravenous LMWH, UFH, and argatroban have shown success in intensive care settings.

SUMMARY

The standard dosing of subcutaneous LMWH is often insufficient for effective thrombosis prophylaxis in trauma patients. A more personalised approach, adjusting doses based on specific effect levels like anti-Xa or choosing an alternative mode of anticoagulation, could reduce the risk of insufficient prophylaxis and subsequent VTE.

Creatinine clearance predicts the goal enoxaparin dose in traumatic brain injury

BACKGROUND

Patients with traumatic brain injury (TBI) are at high risk of venous thromboembolism (VTE). Recent guidelines recommend starting TBI patients on enoxaparin 30 mg twice daily and then considering weight-based dosing. Creatinine clearance may be better than weight for patients when considering high and low enoxaparin dose requirements. We hypothesize that creatinine clearance (CrCl) predicts goal enoxaparin dose better than weight-based dosing.

METHODS

A retrospective review was conducted on patients admitted to an urban, academic Level I trauma center from August 2017 to February 2020. Patients were included if greater than 18 years, admitted longer than 48 hours, and head and neck AIS ≥ 3. Patients were excluded if they did not have TBI, if they received deep vein thrombosis prophylaxis other than enoxaparin 12-hour dosing, if no anti-Xa levels were drawn, or if the goal anti-Xa level was not reached. Patients were grouped into dosing cohorts based on dose of enoxaparin required to reach goal. Pearson's correlation was used to compare mean CrCl and mean weight across dosing cohorts.

RESULTS

A total of 120 patients met inclusion and exclusion criteria, mean age was 47 years and 68% of patients were male. The mean hospital length of stay was 24 days. There were 5 (4.2%) deep vein thrombosis, no pulmonary embolism, and 5 (4.2%) patients died. Mean CrCl increased significantly with increased dosing of enoxaparin, Pearson's correlation coefficient of 0.484 ( p < 0.001). Weight on admission also increased with increasing enoxaparin dose requirements, with Pearson's correlation coefficient of 0.411 ( p < 0.001).

CONCLUSION

Creatine clearance predicts goal enoxaparin dose in TBI better than a weight-based dosing strategy. Further research with a larger patient population is required to validate CrCl values to guide enoxaparin dosing.

LEVEL OF EVIDENCE

Prognostic and Epidemiological; Level IV.

Is There a Role for Anti-factor Xa Activity Assay in Venous Thromboembolism Prophylaxis Management Among Orthopaedic Trauma Patients? Systematic Review and Meta-analysis

OBJECTIVES

To determine the effect of anti-factor Xa assay dosing of low-molecular-weight heparin (LMWH) on rates of venous thromboembolism (VTE), deep vein thrombosis (DVT), pulmonary embolism (PE), bleeding, and mortality among orthopaedic trauma patients.

DATA SOURCES

PubMed/MEDLINE, Embase, Ovid, Cochrane Central Register of Controlled Trials (CENTRAL), clinicaltrials.gov , and Scopus were systematically searched from inception of the database to 2021.

STUDY SELECTION

Prospective, retrospective, and randomized controlled trial studies were included if they compared rates of VTE, DVT, PE, bleeding, and/or mortality between orthopaedic trauma patients receiving anti-factor Xa-based LMWH dosing and those receiving standard dosing.

DATA EXTRACTION

Two independent reviewers screened titles and abstracts for eligibility. Study characteristics including study design, inclusion criteria, and intervention were extracted.

DATA SYNTHESIS

Meta-analysis was performed using pooled proportion of events (effect size) with 95% confidence intervals. A random-effects model was used. Heterogeneity was quantified by Higgins I 2 . Heterogeneity and variability between subgroups indicated differences in the pooled estimate represented by a P -value.

RESULTS

Six hundred eighty-five studies were identified, and 10 studies including 2870 patients were included. In total, 30.3% and 69.7% received an adjusted and nonadjusted dose of LMWH, respectively. The rate of VTE and DVT were significantly lower in the anti-factor Xa-adjusted cohort, whereas there was no statistically significant difference in rates of PE, bleeding, or mortality between the cohorts.

CONCLUSIONS

This systematic review and meta-analysis demonstrates that anti-factor Xa activity assay dosing of LMWH among orthopaedic trauma patients leads to a reduction in overall DVT rates, although not PE rates, without an increased risk of bleeding events.

LEVEL OF EVIDENCE

Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

Obesity classification predicts early complications and mortality after acetabular fracture

INTRODUCTION

Obesity remains a global epidemic. The effect of obesity on the risk of complications after acetabular fracture is unknown. Here, we evaluate the effect of BMI on early complications and mortality after acetabular fracture. We hypothesize that the risk of inpatient complications and mortality will be greater in patients with high BMI when compared to those with normal BMI.

METHODS

Adult patients with acetabular fracture were identified via the Trauma Quality Improvement Program data from 2015 to 2019. The primary outcome was overall complication rate with reference to normal-weight patients (BMI = 25-30 kg/m²). The secondary outcome was rates of death. The association of obesity class on the primary and secondary outcomes was assessed using Bonferroni-corrected multiple logistic regression models considering patient, injury, and treatment covariates.

RESULTS

A total of 99,721 patients with acetabular fracture were identified. Class I obesity (BMI = 30-35 kg/m²) was associated with 1.2 greater adjusted relative risk (aRR; 95% confidence interval (CI) 1.1-1.3) of any adverse event, without significant increases in adjusted risk of death. Class II obesity (BMI = 35-40 kg/m²) was associated with aRR = 1.2 (95% CI 1.1-1.3) of any adverse event and aRR = 1.5 (95% CI 1.2-2.0) of death. Class III obesity (BMI ≥ 40 kg/m²) was associated with aRR = 1.3 (95% CI 1.2-1.4) of any adverse event and aRR = 2.3 (95% CI 1.8-2.9) of death.

CONCLUSION

Obesity is associated greater risk of adverse events and death following acetabular fracture. Obesity severity classification scales with these risks.

Creatinine Clearance May Predict Goal Enoxaparin Dose in Trauma

BACKGROUND

Guidelines for enoxaparin dosing after trauma recommend an initial dose of 40 mg twice daily for most patients and then adjusting by anti-Xa levels. Previous studies indicated higher enoxaparin doses are necessary with higher levels of creatinine clearance (CrCl). We sought to determine if the goal enoxaparin dose correlates with the admission CrCl to reduce the reliance on measuring anti-Xa levels.

STUDY DESIGN

A retrospective review was conducted of patients admitted to an urban, academic Level 1 trauma center from April 2017 to February 2020. Patients started on enoxaparin who reached goal anti-Xa trough levels were included, and patients were excluded if they did not reach goal anti-Xa levels. Data collection included patient demographics, injury characteristics, admission CrCl, and final enoxaparin dose. CrCl was then correlated with the final enoxaparin dose.

RESULTS

Of 421 patients included, the mean age was 46.6 years and 73% were male. The median goal enoxaparin dose was 40 mg twice daily. The mean CrCl significantly increased with increasing twice-daily doses of enoxaparin (20 mg: 69.2 mL/min; 30 mg: 89 mL/min; 40 mg: 112.8 mL/min; 50 mg: 140.5mL/min; 60 mg: 147.4 mL/min; and 70 mg: 140 mL/min; p < 0.01).

CONCLUSIONS

Admission CrCl may predict the enoxaparin dose required to achieve adequate anti-Xa levels. Our data indicate that CrCls of approximately 70, 90, 110, 140, and 150 mL/min may predict the twice-daily enoxaparin doses of 20, 30, 40, 50, and 60 mg, respectively. CrCl dosing guidance may reduce the time to goal anti-Xa levels and the frequency of anti-Xa measurements. Further research is necessary, and enoxaparin dosing should continue to be monitored by anti-Xa levels.

Efficacy and Safety of Anti-Xa-Guided Versus Fixed Dosing of Low Molecular Weight Heparin for Prevention of Venous Thromboembolism in Trauma Patients: A Systematic Review and Meta-Analysis

PURPOSE

Trauma patients are at high risk of venous thromboembolism (VTE). We summarize the comparative efficacy and safety of anti-Xa-guided versus fixed dosing for low molecular weight heparin (LMWH) for the prevention of VTE in adult trauma patients.

METHODS

We searched Medline and Embase from inception through June 1, 2022. We included randomized controlled trials or observational studies comparing anti-Xa-guided versus fixed dosing of LMWH for thromboprophylaxis in adult trauma patients. We incorporated primary data from 2 large observational cohorts. We pooled effect estimates using a random-effects model. We assessed risk of bias using the ROBINS-I tool for observational studies and assessed certainty of findings using GRADE methodology.

RESULTS

We included 15 observational studies involving 10,348 patients. No randomized controlled trials were identified. determined that, compared to fixed LMWH dosing, anti-Xa-guided dosing may reduce deep vein thrombosis [adjusted odds ratio (aOR); 0.52, 95% CI: 0.40-0.69], pulmonary embolism (aOR: 0.48, 95% CI: 0.30-0.78) or any VTE (aOR: 0.54, 95% CI: 0.42-0.69), though all estimates are based on low certainty evidence. There was an uncertain effect on mortality (aOR: 1.06, 95% CI: 0.85-1.32) and bleeding events (aOR: 0.84, 95% CI: 0.50-1.39), limited by serious imprecision. We used several sensitivity and subgroup analyses to confirm the validity of our assumptions.

CONCLUSION

Anti-Xa-guided dosing may be more effective than fixed dosing for prevention of deep vein thrombosis, pulmonary embolism, and VTE for adult trauma patients. These promising findings justify the need for a high-quality randomized study with the potential to deliver practice changing results.

Cirrhosis is independently associated with complications and mortality following operative treatment of acetabular fractures

INTRODUCTION

Patients with cirrhosis are at higher risk for morbidity after injury. Acetabular fractures represent a highly morbid injury pattern. Few studies have specifically examined an effect of cirrhosis on risk of complications after acetabular fracture. We hypothesized that cirrhosis is independently associated with increased risk of inpatient complications following operative treatment of acetabular fractures.

METHODS

Adults patients with acetabular fracture who underwent operative treatment were identified from Trauma Quality Improvement Program data from 2015 to 2019. Patients with and without cirrhosis were matched on a propensity score predicting cirrhotic status and inpatient complications based on patient, injury, and treatment characteristics. The primary outcome was overall complication rate. Secondary outcomes included serious adverse event rate, overall infection rate, and mortality.

RESULTS

After propensity score matching, 137 cirrhosis+ and 274 cirrhosis- remained. No significant differences existed in observed characteristics after matching. Compared to cirrhosis- patients, cirrhosis+ patients experienced 43.4% (83.9 vs 40.5%, p < 0.001) greater absolute risk difference of any inpatient complication, 29.9% (51.8 vs 21.9%, p < 0.001) greater absolute risk difference of serious adverse events, 28.5% (41.6 vs 13.1%, p < 0.001) greater absolute risk difference of any infection, and 2.9% (2.9% vs 0.0%, p = 0.02) greater absolute risk difference of inpatient mortality.

CONCLUSION

Cirrhosis is associated with higher rates of inpatient complications, serious adverse events, infection, and mortality among patients undergoing operative repair of acetabular fracture.

LEVEL OF EVIDENCE

Prognostic Level III.

Preperitoneal Pelvic Packing for Hypotension Has a Greater Risk of Venous Thromboembolism Than Angioembolization: Management of Refractory Hypotension in Closed Pelvic Ring Injury

BACKGROUND

Patients with traumatic pelvic ring injury may present with hypotension secondary to hemorrhage. Preperitoneal pelvic packing (PPP) and angioembolization (AE) are alternative interventions for management of hypotension associated with pelvic ring injury refractory to resuscitation and circumferential compression. We hypothesized that PPP may be independently associated with increased risk of venous thromboembolism (VTE) compared with AE in patients with hypotension and pelvic ring injury.

METHODS

Adult patients with pelvic ring injury and hypotension managed with PPP or AE were retrospectively identified in the Trauma Quality Improvement Program (TQIP) database from 2015 to 2019. Patients were matched on a propensity score for receiving PPP based on patient, injury, and treatment factors. The primary outcome was the risk of VTE after matching on the propensity score for treatment. The secondary outcomes included inpatient clinically important deep vein thrombosis, pulmonary embolism, respiratory failure, mortality, unplanned reoperation, sepsis, surgical site infection, hospital length of stay, and intensive care unit (ICU) length of stay.

RESULTS

In this study, 502 patients treated with PPP and 2,439 patients treated with AE met inclusion criteria. After propensity score matching on age, smoking status, Injury Severity Score, Tile B or C pelvic ring injury, bilateral femoral fracture, serious head injury, units of plasma and platelets given within 4 hours of admission, laparotomy, and level-I trauma center facility designation, 183 patients treated with PPP and 183 patients treated with AE remained. PPP, compared with AE, was associated with a 9.8% greater absolute risk of VTE, 6.5% greater risk of clinically important deep vein thrombosis, and 4.9% greater risk of respiratory failure after propensity score matching.

CONCLUSIONS

PPP for the management of hypotension associated with pelvic ring injury is associated with higher rates of inpatient VTE events and sequelae compared with AE.

LEVEL OF EVIDENCE

Prognostic Level III . See Instructions for Authors for a complete description of levels of evidence.

Adjusted versus fixed doses of LMWHs in trauma patients: A systematic review and meta-analysis

PURPOSE

Venous thromboembolism (VTE) causes significant morbidity and mortality in patients with traumatic injuries, despite thromboprophylaxis. To decrease both thrombotic and bleeding risks, some authors suggest adjusting the thromboprophylactic doses of low-molecular-weight heparins (LMWH), in particular according to body weight at treatment initiation or to changes in anti-factor Xa level during treatment. Our objective was to estimate in trauma patients the efficacy and safety of such adjustments, compared with the conventional strategy of fixed-dose LMWH thromboprophylaxis.

SOURCE

A systematic review and a meta-analysis were conducted to identify and assess randomised control trials and observational studies with prospective enrolment that included trauma patients and compared adjustment of LMWH thromboprophylaxis versus no adjustment. The primary and secondary endpoints were VTE and bleeding, respectively. The Odds Ratio (OR) and 95% Confidence Interval (95% CI) were calculated using the Mantel-Haenszel method.

PRINCIPAL FINDINGS

Nine studies were included in the meta-analysis. No significant reduction in the risk of VTE was observed with adjusted doses of LMWH compared with fixed doses when considering only randomised control trials (OR 1.02 [95% CI, 0.09 to 11.6]) or all trials (OR 0.70 [95% CI, 0.34 to 1.42]). Similarly, there was no significant difference in bleeding risk (OR 1.36, 95% CI 0.59 to 3.10).

CONCLUSION

This meta-analysis shows that, to date, there is no evidence to justify adjusting LMWH doses, in agreement with the recommendations of the American College of Chest Physicians.

Chemoprophylaxis for venous thromboembolism in pelvic and/or acetabular fractures: A systematic review

BACKGROUND

It is unclear which pharmacological agents, and at what dosage and timing, are most effective for venous thromboembolism (VTE) prophylaxis in patients with pelvic/acetabular fractures.

METHODS

We searched the Cochrane Database of Systematic Reviews, Embase, Web of Science, EBSCO, and PubMed on October 3, 2020, for English-language studies of VTE prophylaxis in patients with pelvic/acetabular fractures. We applied no date limits. We included studies that compared efficacy of pharmacological agents for VTE prophylaxis, timing of administration of such agents, and/or dosage of such agents. We recorded interventions, sample sizes, and VTE incidence, including deep vein thrombosis (DVT) and pulmonary embolism.

RESULTS

Two studies (3604 patients) compared pharmacological agents, reporting that patients who received direct oral anticoagulants (DOACs) were less likely to develop DVT than those who received low molecular weight heparin (LMWH) (p < 0.01). Compared with unfractionated heparin (UH), LMWH was associated with lower odds of VTE (odds ratio [OR] = 0.37, 95% confidence interval [CI]: 0.22-0.63) and death (OR = 0.27, 95% CI: 0.10-0.72). Three studies (3107 patients) compared timing of VTE prophylaxis, reporting that late prophylaxis was associated with higher odds of VTE (OR = 1.9, 95% CI: 1.2-3.2) and death (OR = 4.0, 95% CI: 1.5-11) and higher rates of symptomatic DVT (9.2% vs. 2.5%, p = 0.03; and 22% vs. 3.1%, p = 0.01). One study (31 patients) investigated dosage of VTE prophylaxis, reporting that a higher proportion of patients with acetabular fractures were underdosed (23% of patients below range of anti-Factor Xa [aFXa] had acetabular fractures vs. 4.8% of patients within adequate range of aFXa, p<0.01).

CONCLUSIONS

Early VTE chemoprophylaxis (within 24 or 48 h after injury) was better than late administration in terms of VTE and death. Many patients with acetabular fractures are underdosed with LMWH, with inadequate aFXa levels. Compared with UH, LMWH was associated with lower odds of VTE and death. DOACs were associated with lower risk of DVT compared with LMWH.

LEVEL OF EVIDENCE

III, systematic review of retrospective cohort studies.

Enoxaparin titrated by anti-Xa levels reduces venous thromboembolism in trauma patients

BACKGROUND

Trauma is a major risk factor for the development of a venous thromboembolism (VTE). After observing higher than expected VTE rates within our center's Trauma Quality Improvement Program data, we instituted a change in our VTE prophylaxis protocol, moving to enoxaparin dosing titrated by anti-Xa levels. We hypothesized that this intervention would lower our symptomatic VTE rates.

METHODS

Adult trauma patients at a single institution meeting National Trauma Data Standard criteria from April 2015 to September 2019 were examined with regards to VTE chemoprophylaxis regimen and VTE incidence. Two groups of patients were identified based on VTE protocol-those who received enoxaparin 30 mg twice daily without routine anti-Xa levels ("pre") versus those who received enoxaparin 40 mg twice daily with dose titrated by serial anti-Xa levels ("post"). Univariate and multivariate analyses were performed to define statistically significant differences in VTE incidence between the two cohorts.

RESULTS

There were 1698 patients within the "pre" group and 1406 patients within the "post" group. The two groups were essentially the same in terms of demographics and risk factors for bleeding or thrombosis. There was a statistically significant reduction in VTE rate (p = 0.01) and deep vein thrombosis rate (p = 0.01) but no significant reduction in pulmonary embolism rate (p = 0.21) after implementation of the anti-Xa titration protocol. Risk-adjusted Trauma Quality Improvement Program data showed an improvement in rate of symptomatic pulmonary embolism from fifth decile to first decile.

CONCLUSION

A protocol titrating prophylactic enoxaparin dose based on anti-Xa levels reduced VTE rates. Implementation of this type of protocol requires diligence from the physician and pharmacist team. Further research will investigate the impact of protocol compliance and time to appropriate anti-Xa level on incidence of VTE.

LEVEL OF EVIDENCE

Therapeutic/care management, Level IV.

What Do We Know about Thromboprophylaxis and Its Monitoring in Critically Ill Patients?

Venous thromboembolism (VTE), including deep vein thrombosis and pulmonary embolism, is an important complication in patients hospitalized in intensive care units (ICU). Thromboprophylaxis is mainly performed with Low Molecular Weight Heparin (LMWH) and, in some specific patients, with Unfractionated Heparin (UFH). These intensive units are an environment where individual patient variability is extreme and where traditional antithrombotic protocols are frequently ineffective. This was known for a long time, but the hospitalization of many patients with COVID-19 inflammatory storms suddenly highlighted this knowledge. It is therefore reasonable to propose variable antithrombotic prevention protocols based initially on a series of individual criteria (weight, BMI, and thrombotic risks). Secondly, they should be adjusted by the monitoring of anticoagulant activity, preferably by measuring the anti-Xa activity. However, we still face unresolved questions, such as once- or twice-daily LMWH injections, monitoring at the peak and/or trough, and poorly defined therapeutic targets. Equally surprisingly, we observed a lack of standardization of the anti-Xa activity kits.

Pharmacokinetics of enoxaparin in COVID-19 critically ill patients

Background

In intensive-care unit (ICU) patients, pathophysiological changes may affect the pharmacokinetics of enoxaparin and result in underdosing.

Objectives

To develop a pharmacokinetic model of enoxaparin to predict the time-exposure profiles of various thromboprophylactic regimens in COVID-19 ICU-patients.

Methods

This was a retrospective study in ICUs of two French hospitals. Anti-Xa activities from consecutive patients with laboratory-confirmed SARS-CoV-2 infection treated with enoxaparin for the prevention or the treatment of venous thrombosis were used to develop a population pharmacokinetic model using non-linear mixed effects techniques. Monte Carlo simulations were then performed to predict enoxaparin exposure at steady-state after three days of administration.

Results

A total of 391 anti-Xa samples were measured in 95 patients. A one-compartment model with first-order kinetics best fitted the data. The covariate analysis showed that enoxaparin clearance (typical value 1.1 L.h-1) was related to renal function estimated by the CKD-EPI formula and volume of distribution (typical value 17.9 L) to actual body weight.

Simulation of anti-Xa activities with enoxaparin 40 mg qd indicated that 64% of the patients had peak levels within the range 0.2 to 0.5 IU.mL-1 and 75% had 12-hour levels above 0.1 IU.mL-1. Administration of a total daily dose of at least 60 mg per day improved the probability of target attainment.

Conclusion

In ICU COVID-19 patients, exposure to enoxaparin is reduced due to an increase in the volume of distribution and clearance. Consequently, enoxaparin 40 mg qd is suboptimal to attain thromboprophylactic anti-Xa levels.

Impact of antithrombin III and enoxaparin dosage adjustment on prophylactic anti-Xa concentrations in trauma patients at high risk for venous thromboembolism: a randomized pilot trial

The impact of antithrombin III activity (AT-III) on prophylactic enoxaparin anti-factor Xa concentration (anti-Xa) is unknown in high-risk trauma patients. So too is the optimal anti-Xa-adjusted enoxaparin dosage. This prospective, randomized, pilot study sought to explore the association between AT-III and anti-Xa goal attainment and to preliminarily evaluate two enoxaparin dosage adjustment strategies in patients with subprophylactic anti-Xa. Adult trauma patients with Risk Assessment Profile (RAP) ≥ 5 prescribed enoxaparin 30 mg subcutaneously every 12 h were eligible. AT-III and anti-Xa were drawn 8 h after the third enoxaparin dose and compared between patients with anti-Xa ≥ 0.1 IU/mL (goal; control group) or anti-Xa < 0.1 IU/mL (subprophylactic; intervention group). The primary outcome was difference in baseline AT-III. Subsequently, intervention group patients underwent 1:1 randomization to either enoxaparin 40 mg every 12 h (up to 50 mg every 12 h if repeat anti-Xa < 0.1 IU/mL) (enox12) or enoxaparin 30 mg every 8 h (enox8) with repeat anti-Xa assessments. The proportion of patients achieving goal anti-Xa after dosage adjustment were compared. A total of 103 patients were included. Anti-Xa was subprophylactic in 50.5%. Baseline AT-III (median [IQR]) was 87% [80-98%] in control patients versus 82% [71-96%] in intervention patients (p = 0.092). Goal trough anti-Xa was achieved on first assessment in 38.1% enox12 versus 50% enox8 patients (p = 0.67), 84.6% versus 53.3% on second assessment (p = 0.11), and 100% vs. 54.5% on third trough assessment (p = 0.045). AT-III activity did not differ between high-risk trauma patients with goal and subprophylactic enoxaparin anti-Xa concentrations, although future investigation is warranted. Enoxaparin dose adjustment rather than frequency adjustment may be associated with a higher proportion of patients achieving goal anti-Xa over time.

Characterizing the delays in adequate thromboprophylaxis after TBI

Background

We sought to compare enoxaparin dosing for venous thromboembolism (VTE) prophylaxis in trauma patients with and without traumatic brain injury (TBI) to better understand the time and dose required to reach target anti-Xa levels. Our hypothesis was that patients with TBI have significant delays in the initiation of adequate pharmacological prophylaxis and require a higher enoxaparin dose than currently recommended.

Methods

The medical records of trauma patients who received enoxaparin dosing based on anti-Xa trough levels between August 2014 and October 2016 were reviewed. Patients were included if their anti-Xa trough level reached the target range (0.1 IU/mL to 0.2 IU/mL).

Results

A total of 163 patients had anti-Xa levels within the target range of which 41 (25.2%) had TBI. Patients with TBI had longer delays before initiating enoxaparin (7.5 days vs. 1.5 days after admission, p<0.01) and were more likely to receive unfractionated heparin prior to enoxaparin (46.3% vs. 11.5%, p<0.01). Anti-Xa levels reached the target range later in patients with TBI (11 days vs. 5 days after admission, p<0.01). Enoxaparin 40 mg two times per day was the median dose required to reach the target anti-Xa levels for both cohorts. VTE rates were higher among patients with TBI (22.0% vs. 9.0%, p=0.03). Four patients (9.8%) had progression of their intracranial hemorrhage prior to receiving enoxaparin, although none progressed during enoxaparin administration.

Conclusion

Among patients with TBI who reached target anti-Xa levels, 11 days after admission were required to reach a median enoxaparin dose of 40 mg two times per day. Unfractionated heparin was used as pharmacological prophylaxis in about half of these patients. The delay in reaching the target anti-Xa levels and the use of unfractionated heparin likely contribute to the higher VTE rate in patients with TBI.

Level of evidence

Level III, therapeutic.

Impact of Weight on Anti-Xa Attainment in High-Risk Trauma Patients on Enoxaparin Chemoprophylaxis

BACKGROUND

Serum anti-factor Xa (anti-Xa) concentration may guide low molecular weight heparin chemoprophylaxis in trauma patients. Higher total body weight (TBW) is a risk factor for subprophylactic anti-Xa and venous thromboembolism (VTE). The purpose of this study was to evaluate TBW differences in patients with subprophylactic versus prophylactic trough anti-Xa.

METHODS

This retrospective study included adults admitted to the trauma service who received enoxaparin chemoprophylaxis, trough anti-Xa assessment, and screening duplex ultrasound. Initial enoxaparin dose was determined per trauma team weight-tiered protocol with subsequent 10 mg increase if anti-Xa was subprophylactic. Patients were stratified into subprophylactic (anti-Xa <0.1 IU/ml) and prophylactic (anti-Xa ≥0.1 IU/mL) groups. The primary outcome was difference in TBW. Secondary outcomes were weight-adjusted enoxaparin dose (mg/kg), VTE, red blood cell (pRBC) transfusions.

RESULTS

A total of 887 patients were included with 681 (76.8%) having subprophylactic anti-Xa. The subprophylactic group had significantly younger age, higher proportion male sex, higher Injury Severity Score (ISS), higher BMI, and longer length of hospital stay. The subprophylactic group had higher TBW (median [IQR], 87.8 [74-102] kg vs. 78.9 [68-91.8] kg; P < 0.001) which equated to a lower weight-adjusted dose (0.34 [0.3-0.41] mg/kg vs. 0.38 (0.33-0.44) mg/kg; P < 0.001). There were no differences in VTE (10.4% vs. 9.2%; P = 0.71) or pRBC administration (17.0% vs. 16.0%; P = 0.81).

CONCLUSIONS

TBW is higher and weight-adjusted enoxaparin dose is lower in high-risk trauma patients with subprophylactic anti-Xa concentrations. These data suggest TBW should be considered when determining the optimal prophylactic enoxaparin dose in high-risk trauma patients.

Venous thromboembolism in burns patients: Are we underestimating the risk and underdosing our prophylaxis?

BACKGROUND

Burns patients exhibit all factors of Virchow's triad and are thus at high theoretical risk of venous thromboembolism (VTE). At our tertiary referral burns unit, a standard dose of low molecular weight heparin, which acts primarily by inhibiting Factor Xa, is given for thromboprophylaxis. However, the pharmacokinetics of enoxaparin are altered following a burn injury, and thus burns patients are likely underdosed on their thromboprophylaxis. The objectives of this study were to determine the incidence and risk factors for VTE among burns patients at the Victorian Adult Burns Service (VABS) and to determine the adequacy of the current enoxaparin thromboprophylaxis regimen through measurement of anti-factor Xa (AFXa) levels and comparison with established reference ranges.

METHODS

This study consisted of two parts. In part 1, the Burns Registry of Australia and New Zealand (BRANZ) was reviewed for cases of VTE in burns patients admitted to the VABS from 2013 - 2018. Part 2 was a prospective study that determined peak and trough AFXa levels in patients admitted to the VABS with >10% total body surface area (TBSA) burns.

RESULTS

Part 1. Totally, 1,475 patients were admitted to the VABS between 2013 - 2018. There were 20 cases of VTE (1.36%). Percent TBSA of burn (OR = 1.04, 95% CI: 1.03 - 1.06), full thickness burns (OR = 2.78, 95% CI: 1.15 - 6.73), ICU admission (OR = 15.08, 95% CI: 5.01 - 45.44), mechanical ventilation (OR = 10.62, 95% CI: 4.05 - 27.91), operative procedures (OR = 1.43, 95% CI: 1.29 - 1.59), and a longer hospital stay (OR = 1.05, 95% CI: 1.04 - 1.07) were all associated with an increased VTE risk. Part 2. A total of 20 participants with >10% TBSA burns were recruited to the prospective study. Peak anti Factor Xa (AFXa) levels were measured for all 20 participants with 15% recording an initial prophylactic peak AFXa level within reference range. Upon subsequent measurements, 50% of participants reached a prophylactic peak AFXa level. Trough AFXa levels were measured for 17 participants with no participant recording an initial or subsequent trough AFXa level at or above the prophylactic threshold.

CONCLUSION

Our study demonstrates a high incidence of VTE among burns patients at the VABS, especially among the major burns patients, and a thromboprophylaxis protocol that is ineffective in achieving prophylactic levels of AFXa level. The evidence suggests a need to evaluate different dosing protocols among burns patients in order to improve AFXa levels, with the aim of decreasing incidence of VTE in high-risk patients.

When Is It Safe to Start Pharmacologic Venous Thromboembolism Prophylaxis After Pelvic Fractures? A Prospective Study From a Level I Trauma Center

BACKGROUND

The ideal time for pharmacologic venous thromboembolism (VTE) prophylaxis initiation after pelvic fracture is controversial. This prospective study evaluated the safety and efficacy of early VTE prophylaxis after blunt pelvic trauma.

METHODS

Patients presenting to our American College of Surgeons-verified level I trauma center (between December 1, 2016 and November 30, 2017) with blunt pelvic fracture were prospectively screened. Exclusion criteria were emergency department death, immediate operative intervention, transfers, home anticoagulation, pregnancy, and patients receiving no pharmacologic VTE prophylaxis during hospitalization. Patients were dichotomized into study groups based on VTE prophylaxis initiation time ≤48 h (early prophylaxis [EP]) versus >48 h (late prophylaxis [LP]) after emergency department arrival. Demographics, injury data, clinical data, VTE prophylaxis agent and initiation time, and outcomes were compared.

RESULTS

After exclusions, 146 patients were identified: 74 (51%) patients in EP group and 72 (49%) patients in LP group. Pelvic fracture severity was comparable between groups (Abbreviated Injury Scale extremity score 2 [2-3] versus 2 [2-3]; P = 0.610). On univariate analysis, deep vein thrombosis rates were higher after LP (n = 5, 7% versus 0, 0%; P = 0.027). Pulmonary embolism rates were similar (n = 2, 3% versus n = 3, 4%; P = 1.000). No patient required delayed intervention for bleeding, and postprophylaxis blood transfusion was comparable between groups (P > 0.05). On multivariate analysis, timing of pharmacologic VTE prophylaxis initiation was not associated with VTE development (odds ratio, 0.647; P = 0.999). Pelvic angioembolization was independently associated with VTE (odds ratio, 1.296; P = 0.044).

CONCLUSIONS

Early initiation of pharmacologic VTE prophylaxis after blunt pelvic fracture is safe. Although EP initiation did not reduce the rate of VTE, these data identify angioembolization as an independent risk factor for VTE. Patients with blunt pelvic fracture who undergo angioembolization may therefore represent a high-risk population who may especially benefit from EP.

Assessment of Anti-Factor Xa Levels of Patients Undergoing Colorectal Surgery Given Once-Daily Enoxaparin Prophylaxis: A Clinical Study Examining Enoxaparin Pharmacokinetics

Importance

Between 4% and 12% of patients undergoing colorectal surgery and receiving enoxaparin, 40 mg per day, have a postoperative venous thromboembolism (VTE) event. An improved understanding of why "breakthrough" VTE events occur despite guideline-compliant prophylaxis is an important patient safety question.

Objective

To determine the proportion of patients undergoing colorectal surgery who received adequate anticoagulation based on peak anti-factor Xa (aFXa) levels while receiving enoxaparin at 40 mg per day.

Design, Setting, and Participants

This prospective, nonrandomized clinical trial was conducted between February 2017 and July 2018 with 90-day follow-up at a quaternary academic medical center in the Intermountain West and included patients undergoing colorectal surgery who had surgery after receiving general anesthesia, were admitted for at least 3 days, and received enoxaparin, 40 mg once daily.

Interventions

All patients had aFXa levels measured after receiving enoxaparin 40 mg per day. Patients whose aFXa level was out of range entered the trial's interventional arm where real-time enoxaparin dose adjustment and repeated aFXa measurement were performed.

Main Outcomes and Measures

Primary outcome: in-range peak aFXa levels (goal range, 0.3-0.5 IU/mL) with enoxaparin, 40 mg per day. Secondary outcomes: (1) in-range trough aFXa levels (goal range, 0.1-0.2 IU/mL) and (2) the proportion of patients with in-range peak aFXa levels from enoxaparin, 40 mg once daily, vs the real-time enoxaparin dose adjustment protocol.

Results

Over 16 months, 116 patients undergoing colorectal surgery (65 women [56.0%]; 99 white individuals [85.3%], 13 Hispanic or Latino individuals [11.2%], and 4 Pacific Islander individuals [3.5%]; mean [range] age, 52.1 [18-85] years) were enrolled. Among 106 patients (91.4%) whose peak aFXa level was appropriately drawn, 72 (67.9%) received inadequate anticoagulation (aFXa < 0.3 IU/mL) with enoxaparin, 40 mg per day. Weight and peak aFXa levels were inversely correlated (r2 = 0.38). Forty-seven patients (77%) had a trough aFXa level that was not detectable (ie, most patients had no detectable level of anticoagulation for at least 12 hours per day). Real-time enoxaparin dose adjustment was effective. Patients were significantly more likely to achieve an in-range peak aFXa with real-time dose adjustment as opposed to fixed dosing alone (85.4% vs 29.2%, P < .001).

Conclusions and Relevance

This study supports the finding that most patients undergoing colorectal surgery receive inadequate prophylaxis from enoxaparin, 40 mg once daily. These findings may explain the high rate of "breakthrough" VTE observed in many clinical trials.

Trial Registration

ClinicalTrials.gov identifier: NCT02704052.

Efficacy and safety of the injection of the traditional Chinese medicine salviae miltiorrhizae and ligustrazine hydrochloride for the treatment of perioperative period of fracture: A meta-analysis of randomized controlled trials

BACKGROUND

The injection of the traditional Chinese patent medicine salviae miltiorrhizae and ligustrazine hydrochloride injection (SMLHI) has been widely used in treatment of various diseases such as angina pectoris or ischemic stroke in China. We aim to evaluate the efficacy and safety of SMLHI for the treatment of perioperative period of fracture.

METHODS

A systematic literature search was performed in seven medical databases from their inception until February 2019. 16 studies with randomized controlled trials, totaling 1589 patients, were included in this meta-analysis. The included studies were assessed by the cochrane risk of bias and analyzed by Review Manager 5.3 software.

RESULTS

The meta-analysis showed that SMLHI for the treatment of perioperative period of fracture was significantly better compared with the control group in terms of the total effective rate. The result showed that SMLHI could significantly reduce the risk of deep vein thrombosis and inflammatory cytokines. Furthermore, the result showed that SMLHI could significantly improve the coagulation function indexes such as prothrombin time, plasma fibrinogen and D-Dimer (P < .0001).

CONCLUSIONS

This meta-analysis demonstrated that SMLHI may be more effective and safe for the treatment of perioperative period of fracture. However, further and higher quality randomized controlled trials are required to prove treatment outcome.

Underdosing of Prophylactic Enoxaparin Is Common in Orthopaedic Trauma and Predicts 90-Day Venous Thromboembolism

OBJECTIVES

To determine the feasibility and impact of real-time anti-factor Xa (aFXa) level monitoring and enoxaparin dose adjustment in orthopaedic trauma. To examine the adequacy of standard fixed-dose enoxaparin chemoprophylaxis and to examine whether patient-specific factors influence enoxaparin metabolism.

DESIGN

Prospective cohort.

SETTING

Academic Level-I trauma center.

PATIENTS

Postoperative adult orthopaedic trauma patients undergoing acute fracture or nonunion surgery of the pelvis, acetabulum, or lower extremity placed on 30 mg of enoxaparin twice daily.

INTERVENTION

Peak steady-state aFXa levels were drawn with a goal range of 0.2-0.4 IU/mL. Patients with out-of-range levels underwent a 10-mg dose adjustment followed by repeat aFXa draws.

MAIN OUTCOME MEASURES

Peak and trough aFXa levels, 90-day venous thromboembolism, and bleed events.

RESULTS

Of 109 enrolled patients, 43% had inadequate initial peak aFXa levels (aFXa < 0.2 IU/mL) with standard dosing. Higher gross weight, acetabular surgery, and operation length predicted low aFXa levels (P < 0.001, 0.006, 0.004, respectively). Dose adjustment increased the proportion of patients with in-range aFXa levels from 53.2% to 87.8% (P < 0.001). Patients with low aFXa levels during hospitalization or at discharge had significantly higher 90-day deep vein thrombosis and pulmonary embolism rates compared to those with adequate aFXa levels (deep vein thrombosis 12% vs. 1.36%; P = 0.023, pulmonary embolism 8% vs. 0%; P = 0.027). There were no major bleed events.

CONCLUSIONS

Patients receiving inadequate enoxaparin chemoprophylaxis were at significantly increased risk of 90-day venous thromboembolism. Standard fixed-dose enoxaparin provided inadequate chemoprophylaxis in 43% of postoperative orthopaedic trauma patients, which significantly improved with dose adjustment. Weight, acetabular surgery, and operation length predicted inadequate enoxaparin prophylaxis.

LEVEL OF EVIDENCE

Therapeutic Level II. See Instructions for Authors for a complete description of levels of evidence.

Pharmacist recommendations for prophylactic enoxaparin monitoring and dose adjustment in trauma patients admitted to a surgical intensive care unit

Background:

There is limited information describing pharmacist participation in prophylactic enoxaparin monitoring in the surgical intensive care unit (SICU).

Objective:

Our study sought to: 1) characterize pharmacist recommendations for enoxaparin monitoring in trauma patients admitted to the SICU, 2) describe the frequency that medical providers accept pharmacist recommendations for enoxaparin monitoring in trauma patients admitted to the SICU, and 3) illustrate the frequency that trauma patients admitted to our SICU service achieve anti-factor Xa trough concentrations (AFXa-TRs) of 0.11 - 0.20 IU/mL following pharmacist recommendation to adjust prophylactic enoxaparin dosing.

Methods:

Adult patients who had an AFXa-TR drawn after at least three consecutive prophylactic enoxaparin doses between June 1, 2017 and March 1, 2018 were identified through chart review and included in this study. Patients were excluded based on the following criteria: 1) age less than 18 years, 2) anti-factor Xa (AFXa) level not representative of a trough concentration, 3) AFXa-TR not representative of steady state concentration, and 4) non-trauma based prophylactic enoxaparin dosing. This study was exempt from IRB review.

Results:

The final analysis consisted of 42 patients. A pharmacist provided at least one recommendation in 97.6% (41/42) of trauma patients with enoxaparin monitoring during their SICU stay. In total, a pharmacist made 170 recommendations, mean of 4.2 (SD 1.8) recommendations per patient. Recommendations were: 1) obtain an AFXa-TR, n=90; 2) adjust enoxaparin dose based on AFXa-TR, n=58; and 3) maintain enoxaparin dose based on AFXa-TR, n=22. Medical providers accepted 89.4% (152/170) of pharmacist recommendations for enoxaparin monitoring. Dose adjustments were made in 33 patients following pharmacist recommendation; of these, 27 had a repeat AFXa-TR following at least one dose adjustment. Target AFXa-TRs were achieved in 19/27 patients, indicating 70.4% had recommended AFXa concentrations.

Conclusions:

Pharmacists provided recommendations for prophylactic enoxaparin monitoring and dose adjustment in trauma patients admitted to the SICU. Medical providers regularly accepted pharmacist recommendations and trauma patients commonly achieved target AFXa-TR following pharmacist recommendation for dose adjustment. Further research is required to identify the optimal enoxaparin dose for VTE prophylaxis in trauma patients.

Thromboprophylaxis in Intensive Care Unit Patients: A Literature Review

Thromboembolism is a major complication in hospitalized patients. Intensive care unit (ICU) patients have a greater risk of thrombotic events due to additional risk factors such as immobilization, mechanical ventilation, and central catheters. The diagnosis and management of deep vein thrombosis (DVT) and pulmonary embolism (PE) in critically ill patients are challenging and these conditions are associated with high mortality. Medical thromboprophylaxis with low molecular weight heparin (LMWH) as well as unfractionated heparin (UFH) has been shown to reduce the incidence of thromboembolic events in such patients. For patients with high risk of bleeding, mechanical thromboprophylaxis can be used. Literature database was conducted on Medline for articles published up to 2018 using particular search terms such as thromboprophylaxis and venous thromboembolism in ICU patients. The following review summarizes the existing data regarding thromboprophylaxis in ICU patients with special consideration to the use of mechanical prophylaxis and pharmacologic prophylaxis using heparin products.