Pulmonary embolism in major trauma patients

Multi-Modal Venous ThromboembolicProphylaxis Aids in Risk Reduction Following Splenectomy in Female and Male Mice

INTRODUCTION

Splenectomy (SPLN) is associated with elevated risk of venous thromboembolic (VTE) disease. Enoxaparin (ENX) is a low-molecular-weight heparin agent used in VTE chemoprophylaxis. Early aspirin administration ameliorates postSPLN platelet hyperaggregability in male mice. Previous literature has excluded female mice, citing potential effects of estrogen on platelet count and activation as a reason. We hypothesized that multimodal therapy using aspirin and ENX would mitigate postoperative platelet aggregability in mice across sexes.

METHODS

Murine models of SPLN included both male and female mice. Treatment groups included placebo gavage, sham laparotomy, SPLN alone, SPLN and aspirin, SPLN and ENX, and SPLN with aspirin and ENX (n = 5 per group). Chemoprophylaxis dosing was initiated before SPLN. Mice were euthanized on post-operative day (POD) 1 or 3; platelet counts were obtained and blood samples were analyzed via electrical impedance aggregometry.

RESULTS

Females on POD 3 following SPLN demonstrated increased platelet count compared to female mice with no treatment intervention. Male and female mice demonstrated increased adenosine diphosphate (ADP)-induced platelet aggregability on POD 3 following SPLN compared to the placebo group. Treatment with aspirin and ENX decreased this post-SPLN platelet hyperaggregability in both sexes. Females demonstrated significantly higher ADP-mediated platelet aggregability in placebo, SPLN, and SPLN with aspirin and ENX when compared to males of identical treatment groups on POD 3.

CONCLUSIONS

Platelet hyperaggregability following SPLN is mediated primarily by ADP in both males and females, but higher relative aggregability is demonstrated in females. Early administration of dual-agent VTE chemoprophylaxis utilizing aspirin and ENX mitigates this hyperaggregability and may aid in VTE risk reduction across sexes.

Venous thromboembolism testing practices after orthopaedic trauma: prophylaxis regimen does not influence testing patterns

Objectives

To determine venous thromboembolism (VTE) testing patterns in an orthopaedic trauma population and to evaluate for differences in VTE surveillance by prophylaxis regimen through a secondary analysis of the ADAPT trial.

Design

Prospective randomized trial.

Setting

Level I trauma center.

Patients

Three hundred twenty-nine adult (18 years and older) trauma patients presenting with an operative extremity fracture proximal to the metatarsals/carpals or any pelvic or acetabular fracture requiring VTE prophylaxis.

Intervention

VTE imaging studies recorded within 90 days post injury.

Main Outcome Measurements

Percentage of patients tested for VTE were compared between treatment groups using Fisher's exact test. Subsequently, multivariable regression was used to determine patient factors significantly associated with risk of receiving a VTE imaging study.

Results

Sixty-seven patients (20.4%) had VTE tests ordered during the study period. Twenty (29.9%) of these 67 patients with ordered VTE imaging tests had a positive finding. No difference in proportion of patients tested for VTE by prophylaxis regimen (18.8% on aspirin vs. 22.0% on LMWH, P = 0.50) was observed. Factors associated with increased likelihood of VTE testing included White race (adjusted odds ratio [aOR]: 2.61, 95% CI: 1.26-5.42), increased Injury Severity Score (aOR for every 1-point increase: 1.10, 95% CI: 1.05-1.15), and lower socioeconomic status based on the Area Deprivation Index (aOR for every 10-point increase: 1.14, 95% CI: 1.00-1.30).

Conclusions

VTE surveillance did not significantly differ by prophylaxis regimen. Patient demographic factors including race, injury severity, and socioeconomic status were associated with differences in VTE surveillance.

Level of Evidence

Level I, Therapeutic.

Factors Associated with Venous Thromboembolism Development in Patients with Traumatic Brain Injury

BACKGROUND

Venous thromboembolic (VTE) events are a major concern in trauma and intensive care, with the prothrombotic state caused by traumatic brain injury (TBI) increasing the risk in affected patients. We sought to identify critical demographic and clinical variables and determine their influence on subsequent VTE development in patients with TBI.

METHODS

This was a cross-sectional study with data retrospectively collected from 818 patients with TBI admitted to a level I trauma center in 2015-2020 and placed on VTE prophylaxis.

RESULTS

The overall VTE incidence was 9.1% (7.6% deep vein thrombosis, 3.2% pulmonary embolism, 1.7% both). The median time to diagnosis was 7 days (interquartile range 4-11) for deep vein thrombosis and 5 days (interquartile range 3-12) for pulmonary embolism. Compared with those who did not develop VTE, patients who developed VTE were younger (44 vs. 54 years, p = 0.02), had more severe injury (Glasgow Coma Scale 7.5 vs. 14, p = 0.002, Injury Severity Score 27 vs. 21, p < 0.001), were more likely to have experienced polytrauma (55.4% vs. 34.0%, p < 0.001), more often required neurosurgical intervention (45.9% vs. 30.5%, p = 0.007), more frequently missed ≥ 1 dose of VTE prophylaxis (39.2% vs. 28.4%, p = 0.04), and were more likely to have had a history of VTE (14.9% vs. 6.5%, p = 0.008). Univariate analysis demonstrated that 4-6 total missed doses predicted the highest VTE risk (odds ratio 4.08, 95% confidence interval 1.53-10.86, p = 0.005).

CONCLUSIONS

Our study highlights patient-specific factors that are associated with VTE development in a cohort of patients with TBI. Although many of these are unmodifiable patient characteristics, a threshold of four missed doses of chemoprophylaxis may be particularly important in this critical patient population because it can be controlled by the care team. Development of intrainstitutional protocols and tools within the electronic medical record to avoid missed doses, particularly among patients who require operative interventions, may result in decreasing the likelihood of future VTE formation.

The silent killer: Previously undetected pulmonary emboli that result in death after discharge

INTRODUCTION

Pulmonary embolism (PE) is a recognized cause of death in hospitalized trauma patients, yet less is known about PE after discharge.

PATIENTS & METHODS

All post-discharge, autopsy-demonstrated, fatal PE resulting from trauma within a large US county over six years were analyzed. Counts, percentages, mean values, SD, and IQR were calculated for all variables.

RESULTS

1848 trauma deaths were reviewed, of which 85% had an autopsy. Eighty-five patients died from PE after discharge from their initial injury. 53% were initially treated at non-trauma centers, and 9% did not seek medical assistance. 75% were injured by falling, and most injuries occurred in the lower extremities. 86% had an ISS <16, but 87% needed assistance or were bed-bound after injury, despite 75% having no mobility limitations before the injury. 53% died within one month of injury, and 91% within the first year. Before death, only 11% were prescribed chemical thromboprophylaxis or an antiplatelet agent, and only 8% were diagnosed with venous thromboembolism before death.

CONCLUSIONS

Fatal PE after discharge typically occurred following activity-limiting lower extremity injuries with an ISS<16.

Incidence, risk factors and potential timing of occurrence of pulmonary embolism in fatal trauma: An autopsy based case-control study on 2705 victims

BACKGROUND

Pulmonary embolism (PE) following trauma is a potentially preventable but highly lethal complication. We sought to investigate the incidence, risk factors and potential timing of occurrence of post-traumatic PE in a large cohort of trauma fatalities.

METHODS

A case-control study on 9266 consecutive trauma fatalities (between 1996 and 2005) from a regional autopsy-based trauma registry. Injuries were classified according to the Abbreviated Injury Scale-1990 edition (AIS-90) and the Injury Severity Score (ISS) was calculated. Hospitalized victims were categorized according to the presence or absence of PE on autopsy. Univariate comparisons and multivariate logistic regression analysis for probabilities of association (odds ratios-OR) were performed.

RESULTS

Out of 2705 subjects who met the inclusion criteria, 116 had autopsy findings of PE and constituted the PE group (incidence of 4,3%), while the remaining victims formed the control group. The survival time of the PE group ranged from 0.66 to 104.73 days. Victims in the PE group were older (median age 69.5 vs 59), had lower ISS values (median 16 vs 26) and longer post-injury survival times (median 13.6 vs 5.7 days). Positively associated risk factors were AIS2-5 pelvic ring injuries (OR:2.23) and secondary deaths following an uneventful hospital discharge (OR:3.97), while AIS2-5 head (OR:0.33) and abdominal injuries (OR:0.23) showed a reverse association.

CONCLUSIONS

Trauma fatalities with autopsy findings of PE were associated with less severe trauma indicating that PE was likely detrimental to the fatal outcome. Both the early and delayed occurrence of PE was reaffirmed. Prophylactic measures should be initiated promptly and extended post discharge for high risk patients to prevent secondary deaths.

Perioperative Management of Incidental Pulmonary Embolisms on Trauma CT Scans: A Narrative Review

Unsuspected pulmonary embolism (PE) may be identified on an initial trauma computed tomography (CT) scan. The clinical importance of these incidental PEs remains to be elucidated. In patients who require surgery, careful management is needed. We sought to investigate the optimal perioperative management of such patients, including the use of pharmacological and mechanical thromboprophylaxis, possible thrombolytic therapy, and inferior vena cava (IVC) filters. A literature search was conducted, and all relevant articles were identified, investigated, and included. Medical guidelines were also consulted where appropriate. Pharmacological thromboprophylaxis is the mainstay of preoperative treatment, and low-molecular-weight heparins, fondaparinux, and unfractionated heparin may all be used. It has been suggested that prophylaxis should be administered as soon as possible after trauma. Such agents may be contraindicated in patients with significant bleeding, and mechanical prophylaxis and inferior vena cava filters may be favoured in these patients. Therapeutic anticoagulation and thrombolytic therapies may be considered but are associated with an increased risk of haemorrhage. Delaying surgery might help to minimise the risk of recurrent venous thromboembolism, and any interruption of prophylaxis must be strategically planned. Recommendations for postoperative care include a continuation of prophylaxis and therapeutic anticoagulation, with follow-up clinical evaluation within six months. Incidental PE is a common finding on trauma CT scans. Although the clinical significance is unknown, careful management of the balance between anticoagulation and bleeding is needed, especially in trauma patients and even more so in trauma patients requiring surgery.

Timing of venous thromboembolism chemoprophylaxis using objective hemoglobin criteria in blunt solid organ injury

BACKGROUND

The purpose of this study was to evaluate the safety and efficacy of early venous thromboembolism (VTE) chemoprophylaxis following blunt solid organ injury.

METHODS

A retrospective review of patients was performed for patients with blunt solid organ injury between 2009-2019. Enoxaparin was initiated when patients had <1g/dl Hemoglobin decline over a 24 h period. These patients were then categorized by initiation: ≤48 h and >48 h.

RESULTS

There were 653 patients: 328 (50.2%) <48 h and 325 (49.8%) ≥48 h. Twenty-nine (4.4%) developed VTE. Patients in ≥48 h group suffered more frequent VTE events (6.5% vs 2.4%, p = 0.021). Non-operative failure occurred in 6 patients (1.9%) in ≥48 h group, and 5 patients (1.5%) < 48 h group. Blood transfusion following chemophrophylaxis initiation was required in 69 (21.3%) in ≥48 h group, and 46 (14.0%) in < 48 h group, occurring similarly between groups (p=0.021).

CONCLUSION

Stable hemoglobin in the first 24 h is an efficacious, objective measure that allows early initiation of VTE chemoprophylaxis in solid organ injury. This practice is associated with earlier initiation of and fewer VTE events.

Clinical Characteristics and Risk Factors for Early versus Late Pulmonary Embolism in Trauma Patients: A Retrospective, Observational Study

Background

We sought to evaluate the clinical characteristics and risk factors for early versus late pulmonary embolism (PE) in trauma patients.

Methods

This was a retrospective analysis of injured patients who presented with a confirmed PE between 2013 and 2019. Data were analysed and compared for patients with early PE (≤4 days) versus late PE (>4 days post-trauma).

Results

The study included 82 consecutive trauma patients with confirmed diagnosis of PE. The mean age of patients was 42.3 ± 16.2 years. The majority were males (79.3%) and the median time from injury to PE was 10 days. Of the PE cases, 24 (29.3%) had early PE, while 58 (70.7%) had late PE. The early PE group had higher rates of surgical intervention within 24 hours of admission than the late PE group (p = 0.001). Also, the rate of sub-segmental thrombi was significantly higher in the early PE group (p = 0.01). The late PE group sustained more moderate-to-severe injuries ie, GCS ED <13 (p = 0.03) and the median time from injury to PE diagnosis was 15 days (p = 0.001). After adjusting for the potential covariates, surgery within 24 hours of admission [adjusted odds ratio 37.58 (95% confidence interval 3.393-416.20), p = 0.003] was found to be significant independent predictor of early PE in trauma patients.

Conclusion

One-third of post-trauma PEs occurs early after trauma and the surgical intervention within the first 24 hours of admission is a major risk factor. A prospective study is needed to develop an objective risk assessment for the prevention and detection of early and late PE post-trauma.

Early start of thromboprophylaxis does not increase risk of intracranial hematoma progression in multiply injured patients with traumatic brain injury

BACKGROUND

Venous thromboembolism (VTE) in severely injured patients with severe traumatic brain injury (TBI) is a risk during the clinical course. Data on the safety of an early initiation of pharmacological VTE prophylaxis in severely injured patients with concomitant severe TBI is sparse.

METHODS

Admissions to our level-1-trauma center between January 2015 and December 2018 were screened. Patients suffering from severe TBI (Abbreviated Injury Scale (AIS) of the head ≥3) and at least one further AIS ≥ 3 in any other body region were included. Demographic data, thromboembolic events, and progression of the intracranial hemorrhage were extracted from the patient's charts. According to the first application of pharmacological thromboprophylaxis (VTEp), patients were categorized either to the early, the late (later than 24 h) or the no therapy group.

RESULTS

In 79 patients (early: n = 35, late: n = 29, no therapy: n = 15) the Injury Severity Score (ISS) was 36.7 ± 12.7 points (AIS_head 4.1 ± 0.8). No differences were found regarding the progression of the intracranial hemorrhage after initiation of the VTE prophylaxis (adj. p = 0.8). The VTE rate was low (n = 1, 1.6%).

CONCLUSION

In severely injured patients with severe TBI, the early administration of pharmacological thromboprophylaxis did not result in a higher rate of intracranial hematoma progression.

Inpatient compliance with venous thromboembolism prophylaxis after orthopaedic trauma: results from a randomized controlled trial of aspirin versus low molecular weight heparin

Objectives:

To compare inpatient compliance with venous thromboembolism prophylaxis regimens.

Design:

A secondary analysis of patients enrolled in the ADAPT (A Different Approach to Preventing Thrombosis) randomized controlled trial.

Setting:

Level I trauma center.

Patients/Participants:

Patients with operative extremity or any pelvic or acetabular fracture requiring venous thromboembolism prophylaxis.

Intervention:

We compared patients randomized to receive either low molecular weight heparin (LMWH) 30 mg or aspirin 81 mg BID during their inpatient admission.

Main Outcome Measurements:

The primary outcome measure was the number of doses missed compared with prescribed number of doses.

Results:

A total of 329 patients were randomized to receive either LMWH 30 mg BID (164 patients) or aspirin 81 mg BID (165 patients). No differences observed in percentage of patients who missed a dose (aspirin: 41.2% vs LMWH: 43.3%, P = .7) or mean number of missed doses (0.6 vs 0.7 doses, P = .4). The majority of patients (57.8%, n = 190) did not miss any doses. Missed doses were often associated with an operation.

Conclusions:

These data should reassure clinicians that inpatient compliance is similar for low molecular weight heparin and aspirin regimens.

A nested case-control study of risk for pulmonary embolism in the general trauma population using nationwide trauma registry data in Japan

Post-trauma patients are at great risk of pulmonary embolism (PE), however, data assessing specific risk factors for post-traumatic PE are scarce. This was a nested case–control study using the Japan Trauma Data Bank between 2004 and 2017. We enrolled patients aged ≥ 16 years, Injury Severity Score ≥ 9, and length of hospital stay ≥ 2 days, with PE and without PE, using propensity score matching. We conducted logistic regression analyses to examine risk factors for PE. We included 719 patients with PE and 3595 patients without PE. Of these patients, 1864 [43.2%] were male, and their median Interquartile Range (IQR) age was 73 [55–84] years. The major mechanism of injury was blunt (4282 [99.3%]). Median [IQR] Injury Severity Score (ISS) was 10 [9–18]. In the multivariate analysis, the variables spinal injury [odds ratio (OR), 1.40 (1.03–1.89)]; long bone open fracture in upper extremity and lower extremity [OR, 1.51 (1.06–2.15) and OR, 3.69 (2.89–4.71), respectively]; central vein catheter [OR, 2.17 (1.44–3.27)]; and any surgery [OR, 4.48 (3.46–5.81)] were independently associated with PE. Spinal injury, long bone open fracture in extremities, central vein catheter placement, and any surgery were risk factors for post-traumatic PE. Prompt initiation of prophylaxis is needed for patients with such trauma.

Retrievable inferior vena cava filter for primary prophylaxis of pulmonary embolism in at-risk trauma patients: A feasibility trial

OBJECTIVE

To determine if insertion of rIVCF for PE prophylaxis in high risk trauma patients could result in a clinically meaningful reduction (>24 h) in time that patients are left unprotected from PEs SUMMARY AND BACKGROUND DATA: Trauma patients are at high risk for the development of pulmonary embolism (PE). Early pharmacologic PE prophylaxis is ideal, however many patients are unable to receive prophylaxis due to concomitant injuries. Current guidelines are conflicting on the role of prophylactic retrievable inferior vena cava filters (rIVCF) for PE prevention in this patient population, and robust data to guide clinicians is lacking.

METHODS

In this single center, randomized control trial of adult (age > 18 years) trauma patients at high risk for PE by EAST criteria and unable to receive pharmacologic prophylaxis for at least 72 h, we randomized 42 patients to receive a rIVCF or to not have a rIVCF placed. Our primary endpoints were time left unprotected to PE development and feasibility.

RESULTS

The median patient age was 53 years, with a median Injury Severity Score of 33. Randomization to rIVCF reduced the time left unprotected to PE (Control: 78.2 h [53.6-104]; rIVCF: 25.5 h [9.8-44.6], p = 0.0001). Two pulmonary embolisms occurred in the control group, and one in the rIVCF group. Seven deaths occurred in the control group, and 8 in the rIVCF group.

CONCLUSION

This feasibility study demonstrates a clinically meaningful reduction in time left unprotected to PE. Further investigations powered to demonstrate a reduction in PE incidence are required.

LEVEL OF EVIDENCE

Level 1 Evidence randomized controlled trial.

Feasibility study of hand-carried ultrasound-guided retrievable inferior vena cava filter placement

Background

With the development of ultrasonic diagnostic techniques in recent years, ultrasound-guided placement of inferior vena cava (IVC) filters has been widely used in clinics, and satisfactory results have been achieved. Our study aims to observe the accuracy of hand-carried ultrasound-guided retrievable vena cava filter placement, evaluate the feasibility and safety of this new method, and provide a scientific and effective interventional method and clinical data to prevent acute pulmonary embolism (PE) after battle injury of limbs.

Methods

Two hundred patients with post-traumatic thrombosis of the extremities were enrolled. The renal vein was located under the guidance of hand-carried ultrasound. The retrievable filter was fixed 1–2 cm below the opening of the renal vein. The self-expanding filter was used after the filter’s position was confirmed by injecting the contrast agent under the digital subtraction angiography (DSA) fluoroscopy.

Results

All the 200 patients underwent the operation successfully. The position of the hand-carried ultrasound localizer was consistent with the DSA localizer. All the filters were expanded smoothly. No complications related to the operation occurred.

Conclusions

The study concluded that the hand-carried ultrasound-guided retrievable vena cava filter placement has a high success rate and can prevent acute PE after limbs’ battle injury.

Traumatic Splenic Infarction and Pulmonary Embolism: A Case Report of Rare Radiological Finding

Focused abdominal sonography in trauma (FAST) and contrast-enhanced computed tomography (CECT) abdomen are important radiological tests for evaluating the abdomen in polytrauma cases. When vitals are stable, they help to reach a diagnosis in the majority of patients. However, in a small number of cases they fail to explain the clinical scenario. A continued serial clinical assessment may be helpful in these circumstances. A polytrauma patient was found to be FAST positive. The CT scan revealed pulmonary embolism, splenic infarction, perisplenic and perihepatic hematoma. The patient was complaining of pain abdomen and it worsened on day three of the injury. An exploratory laparotomy was performed. A circumferential intestinal wall hematoma with a tear in mesentery was found. This is a rare case of traumatic splenic infarction with evidence of pulmonary embolism. The serial clinical assessment was helpful as it indicated the need for intervention.

Aspirin versus low-molecular-weight heparin for venous thromboembolism prophylaxis in orthopaedic trauma patients: A patient-centered randomized controlled trial

Background

Emerging evidence suggests aspirin may be an effective venous thromboembolism (VTE) prophylaxis for orthopaedic trauma patients, with fewer bleeding complications. We used a patient-centered weighted composite outcome to globally evaluate aspirin versus low-molecular-weight heparin (LMWH) for VTE prevention in fracture patients.

Methods

We conducted an open-label randomized clinical trial of adult patients admitted to an academic trauma center with an operative extremity fracture, or a pelvis or acetabular fracture. Patients were randomized to receive LMWH (enoxaparin 30-mg) twice daily (n = 164) or aspirin 81-mg twice daily (n = 165). The primary outcome was a composite endpoint of bleeding complications, deep surgical site infection, deep vein thrombosis, pulmonary embolism, and death within 90 days of injury. A Global Rank test and weighted time to event analysis were used to determine the probability of treatment superiority for LMWH, given a 9% patient preference margin for oral administration over skin injections.

Results

Overall, 18 different combinations of outcomes were experienced by patients in the study. Ninety-nine patients in the aspirin group (59.9%) and 98 patients in the LMWH group (59.4%) were event-free within 90 days of injury. Using a Global Rank test, the LMWH had a 50.4% (95% CI, 47.7–53.2%, p = 0.73) probability of treatment superiority over aspirin. In the time to event analysis, LMWH had a 60.5% probability of treatment superiority over aspirin with considerable uncertainty (95% CI, 24.3–88.0%, p = 0.59).

Conclusion

The findings of the Global Rank test suggest no evidence of superiority between LMWH or aspirin for VTE prevention in fracture patients. LMWH demonstrated a 60.5% VTE prevention benefit in the weighted time to event analysis. However, this difference did not reach statistical significance and was similar to the elicited patient preferences for aspirin.

Venous thromboembolism in emergency general surgery patients: a single-centre retrospective cohort study

Background

There is limited literature on the risk of venous thromboembolism (VTE) in emergency general surgery (EGS) patients. We undertook this study to identify the rate of symptomatic VTE for patients undergoing EGS operations.

Methods

We conducted a retrospective cohort study evaluating EGS patients who underwent operative intervention between March and December 2014. Data collected included patient demographics, type of procedure, risk of VTE, VTE prophylaxis, development of symptomatic VTE, and mortality.

Results

We included 767 patients in our analysis. The mean age was 53 ± 19.7 years, and 52.2% of patients were female. Eighteen patients (2.3%) experienced VTE in hospital and 12 (1.6%) experienced VTE after discharge. Only 66% of patients received appropriate VTE prophylaxis. High-risk patients had a higher VTE rate (7.4% v. 2.3%, p < 0.001) and higher mortality (17.6% v. 4.0%, p < 0.001) than lowto moderate-risk patients.

Conclusion

The risk of VTE in patients requiring EGS is significant and persists after hospital discharge. Further studies on quality improvement with VTE prophylaxis are warranted.

Modern Management of Bleeding, Clotting, and Coagulopathy in Trauma Patients: What Is the Role of Viscoelastic Assays?

Purpose of Review

The purpose of this review is to briefly outline the current state of hemorrhage control and resuscitation in trauma patients with a specific focus on the role viscoelastic assays have in this complex management, to include indications for use across all phases of care in the injured patient.

Recent Findings

Viscoelastic assay use to guide blood-product resuscitation in bleeding trauma patients can reduce mortality by up to 50%. Viscoelastic assays also reduce total blood products transfused, reduce ICU length of stay, and reduce costs. There are a large number of observational and retrospective studies evaluating viscoelastic assay use in the initial trauma resuscitation, but only one randomized control trial. There is a paucity of data evaluating use of viscoelastic assays in the operating room, post-operatively, and during ICU management in trauma patients, rendering their use in these settings extrapolative/speculative based on theory and data from other surgical disciplines and settings.

Summary

Both hypocoagulable and hypercoagulable states exist in trauma patients, and better indicate what therapy may be most appropriate. Further study is needed, particularly in the operating room and post-operative/ICU settings in trauma patients.

Venous thromboembolism (VTE) prophylaxis in severely injured patients: an international comparative assessment

PURPOSE

Venous thromboembolisms (VTE) are a major concern after acute survival from trauma. Variations in treatment protocols for trauma patients exist worldwide. This study analyzes the differences in the number of VTE events and the associated complications of thromboprophylaxis between two level I trauma populations utilizing varying treatment protocols.

METHODS

International multicenter trauma registry-based study was performed at the University Medical Center Utrecht (UMCU) in The Netherlands (early commencement chemical prophylaxis), and Harborview Medical Center (HMC) in the United States (restrictive early chemical prophylaxis). All severely injured patients (ISS ≥ 16), aged ≥ 18 years, and admitted in 2013 were included. Primary outcomes were VTE [deep venous thrombosis (DVT) (no screening), pulmonary embolism (PE)], and hemorrhagic complications.

RESULTS

In UMCU, 279 patients were included and in HMC, 974 patients. Overall, 75% of the admitted trauma patients in UMCU and 81% in HMC (p < 0.001) received thromboprophylaxis, of which 100% in and 75% at, respectively, UMCU and HMC consisted of chemical prophylaxis. From these patients, 72% at UMCU and 47% at HMC (p < 0.001) were treated within 48 h after arrival. At UMCU, 4 patients (1.4%) (PE = 3, DVT = 1) and HMC 37 patients (3.8%) (PE = 22, DVT = 16; p = 0.06) developed a VTE. At UMCU, a greater percent of patients with VTE had traumatic brain injuries (TBI). Most VTE occurred despite adequate prophylaxis being given (75% UMCU and 81% HMC). Hemorrhagic complications occurred in, respectively, 4 (1.4%) and 10 (1%) patients in UMCU and HMC (p = 0.570). After adjustment for age, ISS, HLOS, and injury type, no significant difference was demonstrated in UMCU compared to HMC for the development of VTE, OR 2.397, p = 0.102 and hemorrhagic complications, OR 0. 586, p = 0.383.

CONCLUSIONS

A more early commencement protocol resulted in almost twice as much chemical prophylaxis being started within the first 48 h in comparison with a more delayed initiation of treatment. Interestingly, most episodes of VTE developed while receiving recommended prophylaxis. Early chemical thromboprophylaxis did not significantly increase the bleeding complications and it appears to be safe to start early.

Post-discharge adherence with venous thromboembolism prophylaxis after orthopedic trauma: Results from a randomized controlled trial of aspirin versus low molecular weight heparin

BACKGROUND

Orthopedic trauma patients are often treated with venous thromboembolism (VTE) chemoprophylaxis with aspirin or low molecular weight heparin (LMWH) after discharge from their index admission, but adherence patterns are not known. We hypothesized that overall adherence would be moderate and greater with aspirin compared to LMWH.

METHODS

We conducted a randomized controlled trial of adult trauma patients with an operative extremity fracture or any pelvic/acetabular fracture requiring VTE prophylaxis. Patients were randomized to receive either LMWH 30 mg BID or aspirin 81 mg BID. Patients prescribed outpatient prophylaxis were contacted between 10 and 21 days after discharge to assess adherence measured by the validated Morisky Medication Adherence Scale (MMAS-8). Adherence scores were compared between the two treatment arms with similar results for intention-to-treat and as-treated analyses. As-treated multivariable logistic regression was performed to determine factors associated with low-medium adherence scores.

RESULTS

One hundred fifty patients (64 on LMWH, 86 on aspirin) on chemoprophylaxis at time of follow-up completed the questionnaire. As-treated analysis showed that adherence was high overall (mean MMAS 7.2 out of 8, SD 1.5) and similar for the two regimens (LMWH: 7.4 vs. aspirin: 7.0, p = 0.13). However, patients on LMWH were more likely to feel hassled by their regimen (23% vs. 9%, p = 0.02). In a multivariable model, low-medium adherence was associated with taking LMWH as the prophylaxis medication (aOR 2.34, CI 1.06-5.18, p = 0.04), having to self-administer the prophylaxis (aOR 4.44, CI 1.45-13.61, p < 0.01), being of male sex (aOR 2.46, CI 1.10-5.49, p = 0.03), and of younger age (aOR 0.72 per additional 10 years of age, CI 0.57-0.91, p < 0.01).

CONCLUSIONS

Overall post-discharge adherence with VTE prophylaxis was high. Several factors, including prophylaxis by LMWH, were associated with decreased adherence. These factors should be considered when managing patients and designing efficacy trials.

LEVEL OF EVIDENCE

Therapeutic, level II.

Contemporary thromboprophylaxis of trauma patients

PURPOSE OF REVIEW

The traumatically injured patient is at high risk for developing venous thromboembolism. Clinical practice guidelines developed by the American College of Chest Physicians and the Eastern Association for the Surgery of Trauma recognize the importance of initiating thromboprophylaxis, but the guidelines lack specific recommendations regarding the timing and dose of pharmacologic thromboprophylaxis. We review the literature regarding initiation of thromboprophylaxis in different injuries, the use of inferior vena cava filters, laboratory monitoring, dosing regimens, and the use of antiplatelet therapy.

RECENT FINDINGS

Use of pharmacologic thromboprophylaxis with invasive intracranial monitors is not associated with increased bleeding complications. The initiation of low-molecular-weight heparin (LMWH) prophylaxis 48 h postinjury in blunt solid organ injury is not associated with an increase in the rate of failed nonoperative management. Antiplatelet therapy in conjunction with LMWH may help to prevent venous thromboembolism.

SUMMARY

In the setting of blunt traumatic brain and solid organ injury, initiation of pharmacologic thromboprophylaxis 48 h after injury is not associated with increased bleeding complications. There is no consensus or clear data showing which dosing regimen of LMWH is most effective or whether routine laboratory measurements are beneficial for determining effective thromboprophylaxis.

Variables associated with pulmonary thromboembolism in injured patients: A systematic review

BACKGROUND

Pulmonary thromboembolism (PTE) is a dangerous complication of traumatic injury, with varied risk profiles and treatment options. This review aims to describe reported incidence and variables associated with PTE among severely injured patients.

METHODS

Searches were conducted using PubMed, Cochrane and MEDLINE. Relevant studies were identified by two independent reviewers based on predetermined inclusion criteria. Incidence of PTE was the primary outcome measure. Variables associated with PTE was the secondary outcome measure. The Newcastle-Ottawa Scale was used to assess quality of included studies.

RESULTS

There were eight studies that satisfied inclusion criteria. The diagnosed incidence of PTE in these populations ranged from 0.35 to 24%. The most common variables associated with PTE were pelvic or lower limb injury, chest injury, higher total Injury Severity Score, male sex and age. Variables that were less commonly associated with PTE were previous warfarin use, head injury, high serum lactate, soft tissue injury, more than one operation, more than three days on a ventilator, presence of a subclavian central venous catheter, need for a blood transfusion, systolic blood pressure <90mmHg, abdominal injury, presence of a deep venous thrombosis, inferior vena cava filter placement and isolated liver spleen or spinal injuries.

CONCLUSIONS

The reported incidence of PTE after major trauma is variable and dependent on inclusion criteria, diagnostic criteria and study design. Identified variables differed to those reported for venous thromboembolism in other populations. It is difficult to predict populations at risk of clinically significant PTE following injury using available evidence. Further studies linked to patient-specific variables will assist in more precise risk-stratification and interventions.

Epidemiology and pathophysiology of venous thromboembolism: similarities with atherothrombosis and the role of inflammation

Venous thromboembolism (VTE) is a multifactorial disease. Major provoking factors (e. g. surgery, cancer, major trauma, and immobilisation) are identified in 50–60 % of patients, while the remaining cases are classified as unprovoked. However, minor predisposing conditions may be detectable in these patients, possibly concurring to the pathophysiology of the disease, especially when co-existing. In recent years, the role of chronic inflammatory disorders, infectious diseases and traditional cardiovascular risk factors has been extensively investigated. Inflammation, with its underlying prothrombotic state, could be the potential link between these risk factors, as well as the explanation for the reported association between arterial and venous thromboembolic events.

Descriptive Analysis of Venous Thromboembolism in Georgia Trauma Centers Compared with National Trauma Centers Participating in the Trauma Quality Improvement Program

This study was designed to compare the incidence of venous thromboembolism (VTE) in Georgia trauma centers with other national trauma centers participating in the Trauma Quality Improvement Program (TQIP). The use of chemoprophylaxis and characteristics of patients who developed VTE were also examined. We conducted a retrospective observational study of 325,703 trauma admissions to 245 trauma centers from 2013 to 2014. Patient demographics, rate of VTE, as well as the use, type, and timing of chemoprophylaxis were compared between patients admitted to Georgia and non-Georgia trauma centers. The rate of VTE in Georgia trauma centers was 1.9 per cent compared with 2.1 per cent in other national trauma centers. Overall, 49.6 per cent of Georgia patients and 45.5 per cent of patients in other trauma centers had documented chemoprophylaxis. Low molecular weight heparin was the most commonly used medication. Most patients who developed VTE did so despite receiving prophylaxis. The rate of VTE despite prophylaxis was 3.2 per cent in Georgia and 3.1 per cent in non-Georgia trauma centers. Mortality associated with VTE was higher in Georgia trauma centers compared with national TQIP benchmarks. The incidence of VTE and use of chemoprophylaxis within Georgia trauma centers were similar to national TQIP data. Interestingly, most patients who developed VTE in both populations received VTE prophylaxis. Further research is needed to develop best-practice guidelines for prevention, early detection, and treatment in high-risk populations.

Patient preferences for venous thromboembolism prophylaxis after injury: a discrete choice experiment

OBJECTIVE

Limited evidence for the optimal venous thromboembolism (VTE) prophylaxis regimen in orthopaedic trauma leads to variability in regimens. We sought to delineate patient preferences towards cost, complication profile, and administration route (oral tablet vs. subcutaneous injection).

DESIGN

Discrete choice experiment (DCE).

SETTING

Level 1 trauma center in Baltimore, USA.

PARTICIPANTS

232 adult trauma patients (mean age 47.9 years) with pelvic or acetabular fractures or operative extremity fractures.

PRIMARY AND SECONDARY OUTCOME MEASURES

Relative preferences and trade-off estimates for a 1% reduction in complications were estimated using multinomial logit modelling. Interaction terms were added to the model to assess heterogeneity in preferences.

RESULTS

Patients preferred oral tablets over subcutaneous injections (marginal utility, 0.16; 95% CI: 0.11 - 0.21, P<0.0001). Preferences changed in favor of subcutaneous injections with an absolute risk reduction of 6.98% in bleeding, 4.53% in wound complications requiring reoperation, 1.27% in VTE, and 0.07% in death from pulmonary embolism (PE). Patient characteristics (sex, race, type of injury, time since injury) affected patient preferences (P<0.01).

CONCLUSIONS

Patients preferred oral prophylaxis and were most concerned about risk of death from PE. Furthermore, the findings estimated the trade-offs acceptable to patients and heterogeneity in preferences for VTE prophylaxis.

Prevalence and main determinants of early post-traumatic thromboembolism in patients requiring ICU admission

BACKGROUND

Post-traumatic thromboembolism (PE) is now a common challenging particularly in critically ill patients referred to emergency wards. We aimed to identify main factors associated with PE within 72 h of admission after trauma among patients referred to emergency ward.

METHODS

In this retrospective study, the database records of 240 patients, with the primary diagnosis of trauma requiring ICU admission and with a final diagnosis of pulmonary embolism, were reviewed. The patients were categorized as the subjects with early pulmonary embolism (≤3 days) and those with late pulmonary embolism (>3 days).

RESULTS

According to our analysis, 48.5% of the patients suffered PE faced this event within 72 h of trauma events. The patients in early PE group were older than those who suffered late PE. The prevalence rate of long bone fractures in lower extremities was significantly higher in those with early PE compared with the other patients. The group with early PE had more severe injury when compared to those with later PE. The severe and very severe injuries were indicated in 49.5 and 15.4% in early PE group, and 14.0 and 6.9% in late PE group, respectively. Using the multivariable logistic regression model, older age, presence of long bone fractures, and more severe injury could predict occurrence of early PE in trauma patients referred to emergency ward.

CONCLUSION

Occurring early PE is predicted in majority of traumatic patients requiring ICU admission especially in older ones, patients with long bone fractures and those with more severe injury.

Lethal Trauma Pulmonary Embolism is a Black Swan Event in Patients at Risk for Deep Vein Thrombosis: An Evidence-Based Review

We delineated the incidence of trauma patient pulmonary embolism (PE) and risk conditions by performing a systematic literature review of those at risk for deep vein thrombosis (DVT). The PE proportion was 1.4 per cent (95% confidence interval = 1.2–1.6) in at-risk patients. Of 10 conditions, PE was only associated with increased age (P < 0.01) or leg injury (P < 0.01; risk ratio = 1.6). As lower extremity DVT (LEDVT) proportions increased, mortality proportions (P = 0.02) and hospital stay (P = 0.0002) increased, but PE proportions did not (P = 0.13). LEDVT was lower with chemoprophylaxis (CP) (4.9%) than without CP (19.1%; P < 0.01). PEwas lower withCP (1.0%) than without CP (2.2%; P = 0.0004). Mortality was lower with CP (6.6%) than without CP (11.6%; P = 0.002). PE was similar with (1.2%) and without (1.9%; P = 0.19) mechanical prophylaxis (MP). LEDVT was lower with MP (8.5%) than without MP (12.2%; P = 0.0005). PE proportions were similar with (1.3%) and without (1.5%; P = 0.24) LEDVTsurveillance. Mortality was higher with LEDVTsurveillance (7.9%) than without (4.8%; P < 0.01). A PE mortality of 19.7 per cent (95% confidence interval = 18–22) 3 a 1.4 per cent PE proportion yielded a 0.28 per cent lethal PE proportion. As PE proportions increased, mortality (P = 0.52) and hospital stay (P = 0.13) did not. Of 176 patients with PE, 76 per cent had no LEDVT. In trauma patients at risk for DVT, PE is infrequent, has a minimal impact on outcomes, and death is a black swan event. LEDVTsurveillance did not improve outcomes. Because PE was not associated with LEDVT and most patients with PE had no LEDVT, preventing, diagnosing, and treating LEDVT may be ineffective PE prophylaxis.

Increased Enoxaparin Dosing for Venous Thromboembolism Prophylaxis in General Trauma Patients

Objective: To review the evidence regarding increased enoxaparin dosing for venous thromboembolism (VTE) prophylaxis in the general trauma patient population. Data Sources: A search of MEDLINE databases (1946 to October 2016) was conducted using the search terms enoxaparin, thromboembolism prophylaxis, venous thromboembolism, trauma, anti-factor Xa, and weight-based dosing. Additional references were identified from a review of literature citations. Study Selection and Data Extraction: Search results were limited to English-language studies conducted in humans. Trials that included only obese patients or nontrauma patients were excluded. Data Synthesis: A total of 7 trials (958 patients) explored the use of increased dosing of enoxaparin for VTE prophylaxis in trauma patients. Patients were divided by enoxaparin dosing strategies: standard dosing of 30 mg twice daily (BID; n = 509), higher initial dosing regimen (n = 216), or dosing based on anti-FXa level adjustments (n = 233). The majority of the 42 total VTE events (64.3%) occurred in the standard dosing regimen. Within each group, VTE was reported in 5.3% of patients in the standard dosing group, 3.2% in the higher initial dosing group, and 4% in the anti-FXa adjustment group. Initial subtherapeutic anti-FXa levels occurred in 33% to 92% of standard dose patients and 9% to 39% of higher initial dose patients. The average weight-based dose required to achieve a therapeutic level ranged between 0.43 and 0.54 mg/kg/dose BID. The overall rate of bleeding was low, with 3 incidents (0.37%) reported. Conclusion: Standard-dose enoxaparin prophylaxis may not be optimal for the general trauma patient population. Weight-based enoxaparin dosing (0.5 mg/kg/dose BID) is an option in trauma patients considered to be at a lower risk of bleeding complications.

Elevated risk of venous thromboembolic events in patients with inflammatory myopathies

Venous thromboembolism (VTE) is a multifactorial disease manifesting as either deep vein thrombosis or pulmonary embolism. Its prevalence makes VTE a significant issue for both the individual – as a negative factor influencing the quality of life and prognosis – and the society due to economic burden. VTE is the third most common vascular disorder in Western countries, after myocardial infarction and stroke, making it a major cause of in-hospital mortality, responsible for 5%–10% of hospital deaths. Despite many studies conducted, only 50%–60% provoking factors have been identified, while the remaining 40%–50% have been classified as idiopathic or unprovoked. Chronic inflammatory disorders, with their underlying prothrombotic state, reveal an increased risk of VTE (six to eight times) compared with the general population. Among the inflammatory disorders, we can identify inflammatory myopathies – a group of rare, chronic diseases featuring weakness and inflammation of muscles with periods of exacerbation and remission; their main classes are polymyositis and dermatomyositis. The objective of this review is to emphasize the need of VTE prophylaxis in individuals with inflammatory myopathies in order to reduce morbidity and mortality rates among those patients and improve their quality of life and prognosis.

Risk Factors for Deep Venous Thrombosis Following Orthopaedic Trauma Surgery: An Analysis of 56,000 patients

Background:

Deep venous thrombosis (DVT) and pulmonary embolism (PE) are recognized as major causes of morbidity and mortality in orthopaedic trauma patients. Despite the high incidence of these complications following orthopaedic trauma, there is a paucity of literature investigating the clinical risk factors for DVT in this specific population. As our healthcare system increasingly emphasizes quality measures, it is critical for orthopaedic surgeons to understand the clinical factors that increase the risk of DVT following orthopaedic trauma.

Objectives:

Utilizing the ACS-NSQIP database, we sought to determine the incidence and identify independent risk factors for DVT following orthopaedic trauma.

Patients and Methods:

Using current procedural terminology (CPT) codes for orthopaedic trauma procedures, we identified a prospective cohort of patients from the 2006 to 2013 ACS-NSQIP database. Using Wilcoxon-Mann-Whitney and chi-square tests where appropriate, patient demographics, comorbidities, and operative factors were compared between patients who developed a DVT within 30 days of surgery and those who did not. A multivariate logistic regression analysis was conducted to calculate odds ratios (ORs) and identify independent risk factors for DVT. Significance was set at P < 0.05.

Results:

56,299 orthopaedic trauma patients were included in the analysis, of which 473 (0.84%) developed a DVT within 30 days. In univariate analysis, twenty-five variables were significantly associated with the development of a DVT, including age (P < 0.0001), BMI (P = 0.037), diabetes (P = 0.01), ASA score (P < 0.0001) and anatomic region injured (P < 0.0001). Multivariate analysis identified several independent risk factors for development of a DVT including use of a ventilator (OR = 43.67, P = 0.039), ascites (OR = 41.61, P = 0.0038), steroid use (OR = 4.00, P < 0.001), and alcohol use (OR = 2.98, P = 0.0370). Compared to patients with upper extremity trauma, those with lower extremity injuries had significantly increased odds of developing a DVT (OR = 7.55, P = 0.006). The trend toward increased odds of DVT among patients with injuries to the hip/pelvis did not reach statistical significance (OR = 4.51, P = 0.22). Smoking was not found to be an independent risk factor for developing a DVT (P = 0.1217).

Conclusions:

This is the largest study to date using the NSQIP database to identify risk factors for DVT in orthopaedic trauma patients. Although the incidence of DVT was low in our cohort, the presence of certain risk factors significantly increased the odds of developing a DVT following orthopaedic trauma. These findings will enable orthopaedic surgeons to target at-risk patients and implement post-operative care protocols aimed at reducing the morbidity and mortality associated with DVT in orthopaedic trauma patients.

Splenectomy is associated with a higher risk for venous thromboembolism: A prospective cohort study

BACKGROUND

Thrombocytosis following splenectomy is a common occurrence. Whether this thrombocytosis leads to a higher risk for venous thromboembolism (VTE) remains unclear. This investigation aimed to determine if splenectomy increases the risk for VTE.

METHODS

This was a prospective study conducted in the SICU between 1/2011 and 11/2013 investigating the VTE risk in patients undergoing a splenectomy compared with those undergoing any other abdominal procedure.

RESULTS

In total 2503 patients were admitted to the SICU: 37 (2%) after a splenectomy and 638 (26%) after any other abdominal surgery. Splenectomy patients had a higher incidence of VTE compared to patients undergoing any other abdominal procedure (29.7% vs. 12.1%, p < 0.01). After adjustment, splenectomy was associated with a higher adjusted risk for VTE compared to the no-splenectomy group (AOR [95% CI]: 2.6 [1.2, 5.9], p = 0.02). Reactive thrombocytosis did not predict the development of VTE.

CONCLUSION

Splenectomy increases the risk for VTE, however reactive thrombocytosis is not associated with this higher incidence. Further investigations are required to characterize the pathophysiologic mechanisms of VTE development following splenectomy.

Coagulation Profile Changes Due to Thromboprophylaxis and Platelets in Trauma Patients at High-Risk for Venous Thromboembolism

We hypothesize there are coagulation profile changes associated both with initiation of thromboporphylaxis (TPX) and with change in platelet levels in trauma patients at high-risk for venous thromboembolism (VTE). A total of 1203 trauma intensive care unit patients were screened with a VTE risk assessment profile. In all, 302 high-risk patients (risk assessment profile score ≥ 10) were consented for weekly thromboelastography. TPX was initiated between initial and follow-up thromboelastography. Seventy-four patients were analyzed. Upon admission, 87 per cent were hypercoagulable, and 81 per cent remained hypercoagulable by Day 7 ( P = 0.504). TPX was initiated 3.4 ± 1.4 days after admission; 68 per cent received unfractionated heparin and 32 per cent received low-molecular-weight heparin. The VTE rate was 18 per cent, length of stay 38 (25–37) days, and mortality of 17.6 per cent. In all, 76 per cent had a rapid clotting time at admission versus 39 per cent at Day 7 ( P < 0.001); correcting from 7.75 (6.45–8.90) minutes to 10.45 (7.90–15.25) minutes ( P < 0.001). At admission, 41 per cent had an elevated maximum clot formation (MCF) and 85 per cent had at Day 7 ( P < 0.001); increasing from 61(55–65) mm to 75(69–80) mm ( P < 0.001). Platelets positively correlated with MCF at admission (r = 0.308, R2 = 0.095, P = 0.008) and at Day 7 (r = 0.516, R2 = 0.266, P < 0.001). Change in platelet levels correlated with change in MCF (r = 0.332, R2 = 0.110, P = 0.005). In conclusion, hypercoagulability persists despite the use of TPX. Although clotting time normalizes, MCF increases in correlation with platelet levels. As platelet function is a dominant contributor to sustained trauma-evoked hypercoagulability, antiplatelet therapy may be indicated in the management of severely injured trauma patients.

Computed tomography pulmonary angiography: more than a screening tool for pulmonary embolus

BACKGROUND

Traumatically injured patients have multiple causes for acute respiratory decompensation. We reviewed the use of computed tomography pulmonary angiography (CTPA) in critically injured patients to evaluate the results and impact on patient care.

METHODS

The charts of trauma patients (age >16 years) admitted to our intensive care unit for greater than 48 hours, who underwent CTPA for acute respiratory decompensation, were reviewed to determine the results of these studies and the effect on patient care.

RESULTS

We identified 188 patients who underwent CTPA for acute physiologic changes. Pertinent clinical finding were identified in 95% of studies and included atelectasis/collapse (56%), pleural effusion (18%), pneumonia (15%), and pulmonary embolus (18%). These results prompted interventions designed to improve patient outcome. The most frequent interventions were modifications of ventilator therapy (52%), antibiotic therapy (28%), mini-bronchoalveolar lavage (15%), or bronchoscopy (15%). Diagnostic agreement between chest x-ray and CTPA was poor to moderate (κ = 0.013-0.512).

CONCLUSIONS

Computed tomography pulmonary angiography is valuable in the evaluation of cardiopulmonary deterioration in critically ill traumatically injured patients. Computed tomography pulmonary angiography offers the ability to identify causes of acute physiologic changes not detected using standard chest x-ray. The results of these studies provide insight into the underlying pathophysiology and offer an opportunity to direct subsequent patient care.

Sustained release of tissue factor following thrombosis of lower limb trauma

This study was undertaken to provide evidence for the mechanism of venous thromboembolism (VTE) in healthy patients with minor lower limb injury (fracture; Achilles tendon rupture) that was medically managed with plaster cast/brace immobilization. The Plaster Cast clinical trial provided a unique opportunity to identify the natural history of VTE using placebo-controlled patients (n = 183) with validation of the mechanism using the low-molecular-weight heparin (LMWH; reviparin)-treated patients (n = 182). Confirmed VTE in this population was associated with a burst of tissue factor release (and a minor fibrinolytic deficit) leading to thrombin generation that was sustained at least 5 weeks, greater with fractures than with soft-tissue injuries and greater with surgery than with conservative treatment. The root cause likely involves platelet/leukocyte activation (inflammation) rather than endothelial cell injury. Thromboprophylaxis with a low dose of LMWH reduced thrombin generation, with patients undergoing surgery benefitting the most.

Multiple lower-extremity and pelvic fractures increase pulmonary embolus risk

The incidence of venous thromboembolism after major trauma has been estimated to be as high as 60%, despite appropriate prophylaxis. Pulmonary embolism is associated with deep venous thrombosis and also with significant rates of morbidity and mortality. This study examined risk factors for pulmonary embolism among patients with pelvic and lower-extremity fractures in the National Trauma Data Bank. Univariate analysis and multiple logistic regression were used to assess potential risk factors for pulmonary embolism during the index hospitalization period. A total of 199,952 patients with pelvic and lower-extremity fracture were identified. Of these patients, 918 (0.46%) had a pulmonary embolism and 117 (12%) of them died during hospitalization. The risk of pulmonary embolism was significantly increased in patients with multiple fractures (odds ratio, 1.89; P<.001) only. No significant relationship was found with fracture location (pelvis, femur, tibia). Other factors that were associated with increased rates of pulmonary embolism were obesity (body mass index >40 odds ratio, 3.38; P<.001), history of warfarin use (P=.009), hospital disposition (surgery odds ratio, 1.68; P<.001; intensive care unit odds ratio, 2.4; P<.001), and hospital setting (university odds ratio, 1.36; P<.001). Multiple pelvic or lower-extremity fractures, but not their anatomic locations, were associated with pulmonary embolism in the National Trauma Data Bank. As expected, obese patients and those with a history of warfarin therapy have higher rates of pulmonary embolism. This study offers guidance in identifying patients with musculoskeletal trauma who are at elevated risk for pulmonary embolism.

The incidence and the risk factors of venous thromboembolism in Korean patients with pelvic or acetabular fractures

BACKGROUND

Pelvic ring and acetabular fractures are the results of high energy trauma, but there is a paucity of information available regarding the incidence and risk factors of venous thromboembolism (VTE) after these injuries in Asians. This study was undertaken to evaluate the incidence of VTE after a pelvic or an acetabular fracture and to identify predictive factors.

METHODS

A prospective evaluation was performed by indirect computed tomography (CT) venography in patients with pelvic or acetabular fractures. Ninety-five patients were examined by indirect CT venography. Fifty-five patients suffered from a pelvic ring injury (anteroposterior compression 5, lateral compression 25, vertical shear 25), and the remaining 40 from acetabular fractures (simple 18, complex 22). Indirect CT venography was performed within 1-2 weeks of initial trauma. Relationships between VTE and sex, age, fracture pattern, body mass index, injury severity score, period of immobilization, and need for surgical treatment were analyzed. Deep vein thrombosis (DVT) in a more proximal to popliteal vein and the existence of PE were considered clinically significant.

RESULTS

Thirty-two patients (33.7 %) were found to have VTE at an average of 11 days after initial injury. Clinically significant DVT was found 20 cases (21.1 %). No statistical difference was found between pelvic ring injuries and acetabular fractures with respect to the development of VTE. For those with pelvic ring injury, the incidence of VTE in those with a vertical shear injury (52 %) was significantly greater than in others with a pelvic ring injury (p = 0.014). Patients with an age >50 were found to be at greater risk of VTE (p = 0.032).

CONCLUSION

Our findings demonstrate that Korean patients with pelvic or acetabular fractures have a higher risk of VTE than is generally believed, and caution should be taken to prevent and treat VTE, especially in high energy pelvic ring injury and elderly patients.

Venous thromboembolism during combat operations: a 10-y review

BACKGROUND

This article examines the incidence of venous thromboembolism (VTE) in combat wounded, identifies risk factors for pulmonary embolism (PE), and compares the rate of PE in combat with previously reported civilian data.

METHODS

A retrospective review was performed of all U.S. military combat casualties in Operation Enduring Freedom and Operation Iraqi Freedom with a VTE recorded in the Department of Defense Trauma Registry from September 2001 to July 2011. The Military Amputation Database of all U.S. military amputations during the same 10-y period was also reviewed. Demographic data, injury characteristics, and outcomes were evaluated.

RESULTS

Among 26,634 subjects, 587 (2.2%) had a VTE. This number included 270 subjects (1.0%) with deep venous thrombosis (DVT), 223 (0.8%) with PE, and 94 (0.4%) with both DVT and PE. Lower extremity amputation was independently associated with PE (odds ratio [OR], 1.70; 95% confidence interval [CI], 1.07-2.69). A total of 1003 subjects suffered a lower extremity amputation, with 174 (17%) having a VTE. Of these, 75 subjects (7.5%) were having DVT, 70 (7.0%) were having PE, and 29 (2.9%) were found to have both a DVT and a PE. Risk factors found to be independently associated with VTE in amputees were multiple amputations (OR, 2; 95% CI, 1.35-3.42) and above the knee amputation (OR, 2.11; 95% CI, 1.3-3.32).

CONCLUSIONS

Combat wounded are at a high risk for thromboembolic complications with the highest risk associated with multiple or above the knee amputations.

Frequency and relevance of acute peritraumatic pulmonary thrombus diagnosed by computed tomographic imaging in combat casualties

BACKGROUND

Posttraumatic pulmonary embolism is historically diagnosed after clinical deterioration within the first week after injury. An increasing prevalence of immediate and asymptomatic pulmonary embolism have been reported in civilian and military trauma, termed hereafter as acute peritraumatic pulmonary thrombus (APPT). The objective of this study was to define the frequency of APPT diagnosed by computed tomographic (CT) imaging in wartime casualties. An additional objective was to identify factors, which may be associated with this radiographic finding

METHODS

A 1-year retrospective cohort analysis conducted using the US and UK Joint Theater Trauma Registries performed to determine the prevalence of and risk factors for the diagnosis of APPT in casualties admitted to Bastion Hospital, Afghanistan. APPT imaging characteristics were collected, and demographics, injury severity and mechanism, and risk factors were included in the analysis. Logistic regression was used to identify factors independently associated with APPT.

RESULTS

APPT was found in 66 (9.3%) of 708 consecutive trauma admissions, which received a CT chest with intravenous contrast as part of their initial evaluation. Diagnosis of APPT at the time of injury was made in 23 patients (3.2%), while thrombus was detected in 43 additional patients (6.1%) at the time of reexamination of CT images. Of the APPTs, 47% (n = 31) were central, 38% (n = 25) were segmental, and 15% (n = 10) were subsegmental. Forty-seven percent (n = 31) had bilateral APPT. Logistic regression found presence of deep venous thrombosis on admission (odds ratio, 5.75; 95% confidence interval, 2.44-13.58; p < 0.0001) and traumatic amputation (odds ratio, 2.53; 95% confidence interval, 1.10-5.85; p = 0.030) to be independently associated with APPT. All APPTs were felt to be incidental and likely would not have required interventions such as anticoagulation or vena caval interruption.

CONCLUSION

This report is the first to characterize acute, peritraumatic pulmonary thrombus in combat injured. Nearly 1 in 10 patients with severe wartime injury has findings of pulmonary thrombus on CT imaging, although many instances require repeat examination of initial images to identify the clot. APPT is a phenomenon of severe injury and associated with deep venous thrombosis and lower-extremity traumatic amputation. Additional study is needed to characterize the natural history of peritraumatic pulmonary thrombus and the indications for anticoagulation or vena cava filter devices.

Hypercoagulability following blunt solid abdominal organ injury: when to initiate anticoagulation

BACKGROUND

The optimal time to initiate venous thromboembolism pharmacoprophylaxis after blunt abdominal solid organ injury is unknown.

METHODS

Postinjury coagulation status was characterized using thromboelastography (TEG) in trauma patients with blunt abdominal solid organ injuries; TEG was divided into 12-hour intervals up to 72 hours.

RESULTS

Forty-two of 304 patients (13.8%) identified underwent multiple postinjury thromboelastographic studies. Age (P = .45), gender (P = .45), and solid organ injury grade (P = .71) were similar between TEG and non-TEG patients. TEG patients had higher Injury Severity Scores compared with non-TEG patients (33.2 vs 18.3, respectively, P < .01). Among the TEG patients, the shear elastic modulus strength and maximum amplitude values began in the normal range within the first 12-hour interval after injury, increased linearly, and crossed into the hypercoagulable range at 48 hours (15.1 ± 1.9 Kd/cs and 57.6 ± 1.6 mm, respectively; P < .01, analysis of variance).

CONCLUSIONS

Patients sustaining blunt abdominal solid organ injuries transition to a hypercoagulable state approximately 48 hours after injury. In the absence of contraindications, pharmacoprophylaxis should be considered before this time for effective venous thromboembolism prevention.

The effects of location and low-molecular-weight heparin administration on deep vein thrombosis outcomes in trauma patients

BACKGROUND

Deep vein thrombosis (DVT) is common after trauma. Pulmonary embolism (PE) is a feared complication of DVT. Standard doses of low-molecular-weight heparin (LMWH) are commonly used to prevent and treat DVT and PE. There is variable bioavailability of LMWH with standard therapy. The traditional concept that below-knee DVT is associated with a lower risk of subsequent PE may result in less aggressive therapy. The purposes of this study were to assess the rates of PE in above-knee versus below-knee DVT and longitudinally evaluate outcomes of DVT treated with LMWH therapy.

METHODS

This was a retrospective review of patients at a university Level I trauma center during the years 2005 through 2010. Patients diagnosed with lower-extremity DVT were included in this study. Patients were classified by location of lower-extremity DVT and type of LMWH therapy received. All high-risk trauma patients were evaluated with weekly duplex Doppler ultrasonography. All duplex studies were reviewed for DVT resolution or improvement. Symptomatic patients were evaluated with computed tomographic angiography to rule out PE. Demographics, total length of hospital stay, length of intensive care unit stay, and Injury Severity Score (ISS) were collected.

RESULTS

Three-hundred eight trauma patients with lower-extremity DVT were included. More patients developed below-knee DVT (65.6%) compared with above-knee DVT (34.4%). Increased length of hospital stay, intensive care unit stay, and higher ISS were noted in patients with above-knee DVT. More patients had below-knee DVT in the prophylactic dosing group. With LMWH therapy, three PEs occurred in patients in the prophylactic dosing group with below-knee DVT, and no PEs occurred in the therapeutic treatment group. The incidence of PE between patients with below-knee DVT compared with above-knee DVT overall was not different (3.3% and 4.7%, p = 0.59). To assess DVT outcomes, 157 of the 308 patients had serial duplex studies following diagnosis of lower-extremity DVT. The number of patients receiving either therapeutic or prophylactic LMWH was similar (51% and 49%). There was no difference in rates of resolution or improvement between LMWH dosing groups or location of DVT.

CONCLUSION

In screened trauma patients, below-knee DVT is more common than above-knee DVT. There was no difference in the incidence of PE between groups. Standard prophylactic and therapeutic dosing of LMWH does not affect the rates of resolution or improvement of lower-extremity DVT. Rates of resolution and improvement of DVT is not dependent of location of lower-extremity DVT.

LEVEL OF EVIDENCE

Therapeutic study, level IV; epidemiologic study, level III.

Investigation of multiligamentous knee injury patterns with associated injuries presenting at a level I trauma center

OBJECTIVES

To characterize multiligamentous knee injury patterns and describe associated morbidities.

DESIGN

Retrospective.

SETTING

Level I trauma center.

PATIENTS

One hundred two patients (106 knees) with multiligamentous knee injuries and/or dislocations from 2000 through 2008. Subgroup of 82 knees with appropriate magnetic resonance images available assessed for ligamentous injury patterns.

INTERVENTION

Data obtained from medical records for 106 knees.

MAIN OUTCOME MEASUREMENTS

Presence of arterial injuries, nerve injuries, associated fracture patterns, and whole-body morbidities.

RESULTS

The most common (43%) injury pattern was a combined disruption of the anterior cruciate ligament, posterior cruciate ligament, and posterolateral corner. Twenty-five percent of knees had associated ipsilateral tibial plateau fractures, and 19% had associated ipsilateral femoral fractures. Peroneal nerve injury occurred in 25% of knees, arterial injury in 21%, and compartment syndrome in 16%. An intra-abdominal injury was present in 13% of patients, a severe closed head injury in 10%, and a symptomatic pulmonary embolism in 5%.

CONCLUSIONS

Nearly half the multiligamentous knee injuries involved the anterior cruciate ligament, posterior cruciate ligament, and posterolateral corner; one-fourth had associated ipsilateral tibial plateau fractures. The incidence of peroneal nerve injury (25%) was higher than previously reported (20%), whereas the incidence of arterial injury (21%) was comparable to previous reports (19%). Posterolateral corner injuries were more prevalent than previously reported and were highly associated with peroneal nerve injury. We found a substantial incidence of associated morbidities of the whole body. Multiligamentous knee injuries are a marker of concomitant trauma and should be closely evaluated at presentation and during the hospital course to allow for early intervention for life- or limb-threatening comorbidities.

Thromboprophylaxis for trauma patients

BACKGROUND

Trauma is a leading causes of death and disability in young people. Venous thromboembolism (VTE) is a principal cause of death. Trauma patients are at high risk of deep vein thrombosis (DVT). The incidence varies according to the method used to measure the DVT and the location of the thrombosis. Due to prolonged rest and coagulation abnormalities, trauma patients are at increased risk of thrombus formation. Thromboprohylaxis, either mechanical or pharmacological, may decrease mortality and morbidity in trauma patients who survive beyond the first day in hospital, by decreasing the risk of VTE in this population.A previous systematic review did not find evidence of effectiveness for either pharmacological or mechanical interventions. However, this systematic review was conducted 10 years ago and most of the included studies were of poor quality. Since then new trials have been conducted. Although current guidelines recommend the use of thromboprophylaxis in trauma patients, there has not been a comprehensive and updated systematic review since the one published.

OBJECTIVES

To assess the effects of thromboprophylaxis in trauma patients on mortality and incidence of deep vein thrombosis and pulmonary embolism. To compare the effects of different thromboprophylaxis interventions and their effects according to the type of trauma.

SEARCH METHODS

We searched The Cochrane Injuries Group Specialised Register (searched April 30 2009), Cochrane Central Register of Controlled Trials 2009, issue 2 (The Cochrane Library), MEDLINE (Ovid) 1950 to April (week 3) 2009, EMBASE (Ovid) 1980 to (week 17) April 2009, PubMed (searched 29 April 2009), ISI Web of Science: Science Citation Index Expanded (SCI-EXPANDED) (1970 to April 2009), ISI Web of Science: Conference Proceedings Citation Index-Science (CPCI-S) (1990 to April 2009).

SELECTION CRITERIA

Randomized controlled clinical trials involving people of any age with major trauma defined by one or more of the following criteria: physiological: penetrating or blunt trauma with more than two organs and unstable vital signs, anatomical: people with an Injury Severity Score (ISS) higher than 9, mechanism: people who are involved in a 'high energy' event with a risk for severe injury despite stable or normal vital signs. We excluded trials that only recruited outpatients, trials that recruited people with hip fractures only, or people with acute spinal injuries.

DATA COLLECTION AND ANALYSIS

Four authors, in pairs (LB and CM, EF and RC), independently examined the titles and the abstracts, extracted data, assessed the risk of bias of the trials and analysed the data. PP resolved any disagreement between the authors.

MAIN RESULTS

Sixteen studies were included (n=3005). Four trials compared the effect of any type (mechanical and/or pharmacological) of prophylaxis versus no prophylaxis. Prophylaxis reduced the risk of DVT in people with trauma (RR 0.52; 95% CI 0.32 to 0.84). Mechanical prophylaxis reduced the risk of DVT (RR = 0.43; 95% CI 0.25 to 0.73). Pharmacological prophylaxis was more effective than mechanical methods at reducing the risk of DVT (RR 0.48; 95% CI 0.25 to 0.95). LMWH appeared to reduce the risk of DVT compared to UH (RR 0.68; 95% CI 0.50 to 0.94). People who received both mechanical and pharmacological prophylaxis had a lower risk of DVT (RR 0.34; 95% CI 0.19 to 0.60)

AUTHORS' CONCLUSIONS

We did not find evidence that thromboprophylaxis reduces mortality or PE in any of the comparisons assessed. However, we found some evidence that thromboprophylaxis prevents DVT. Although the strength of the evidence was not high, taking into account existing information from other related conditions such as surgery, we recommend the use of any DVT prophylactic method for people with severe trauma.

Inferior vena cava filters for primary prophylaxis: when are they indicated?

Over the past several years there has been a rapid increase in the number of inferior vena cava (IVC) filters placed for primary thromboprophylaxis. Increased use has occurred in settings where other methods of thromboprophylaxis are viewed to be inadequate, technically challenging, or that place patients at an unacceptably high bleeding risk. These clinical services include trauma, bariatric surgery, neurosurgery, cancer, intensive care unit populations, and patients with a relative contraindication to anticoagulation. We review the studies to date addressing filter placement for these indications. Although preliminary data are promising, the patient populations most likely to benefit from prophylactic IVC filter placement have not been well defined, and randomized studies demonstrating efficacy have not been conducted. Moving forward, it will be critical to accomplish these two tasks if IVC filters are to continue to have a role in primary thromboprophylaxis.

Risk factors for vascular occlusive events and death due to bleeding in trauma patients; an analysis of the CRASH-2 cohort

BACKGROUND

Vascular occlusive events can complicate recovery following trauma. We examined risk factors for venous and arterial vascular occlusive events in trauma patients and the extent to which the risk of vascular occlusive events varies with the severity of bleeding.

METHODS AND FINDINGS

We conducted a cohort analysis using data from a large international, double-blind, randomised, placebo-controlled trial (The CRASH-2 trial) [1]. We studied the association between patient demographic and physiological parameters at hospital admission and the risk of vascular occlusive events. To assess the extent to which risk of vascular occlusive events varies with severity of bleeding, we constructed a prognostic model for the risk of death due to bleeding and assessed the relationship between risk of death due to bleeding and risk of vascular occlusive events. There were 20,127 trauma patients with outcome data including 204 (1.01%) patients with a venous event (pulmonary embolism or deep vein thrombosis) and 200 (0.99%) with an arterial event (myocardial infarction or stroke). There were 81 deaths due to vascular occlusive events. Increasing age, decreasing systolic blood pressure, increased respiratory rates, longer central capillary refill times, higher heart rates and lower Glasgow Coma Scores (all p<0.02) were strong risk factors for venous and arterial vascular occlusive events. Patients with more severe bleeding as assessed by predicted risk of haemorrhage death had a greatly increased risk for all types of vascular occlusive event (all p<0.001).

CONCLUSIONS

Patients with severe traumatic bleeding are at greatly increased risk of venous and arterial vascular occlusive events. Older age and blunt trauma are also risk factors for vascular occlusive events. Effective treatment of bleeding may reduce venous and arterial vascular occlusive complications in trauma patients.

Pulmonary emboli after blunt trauma: timing, clinical characteristics and natural history

BACKGROUND

Venous thromboembolism (VTE) frequently complicates the recovery of trauma patients, and contributes to morbidity and mortality. Recent studies showed an increase in diagnosis of pulmonary embolism (PE) mainly in the early or immediate period after trauma. The clinical significance of those incidental PEs is unclear.

METHODS

The study cohort included all blunt trauma patients who had a contrast-enhanced CT of the chest performed as part of their initial trauma assessment from January 1, 2005 to January 31, 2007 in a large academic Canadian trauma centre. Patients diagnosed with PE at any point during admission were identified using our institutional trauma registry. All chest CT scans and electronic charts were reviewed. Patients were classified according to time of PE detection (immediate, early or late) and symptoms (asymptomatic or symptomatic). The clinical characteristics and hospital course of the patients who were diagnosed with immediate PE were described.

RESULTS

1259 blunt trauma patients were reviewed. Six patients presented with immediate PE (0.5%); nine patients were found to have early PE (0.7%) and 13 had late PE (1.0%). All six of the patients with immediate PE were classified as asymptomatic. Five of the nine patients with early PE were symptomatic and all 13 patients who developed late PE were symptomatic. Amongst the six patients with immediate PE, five survived 24h hospitalisation. Four of them were managed with prophylactic low molecular weight heparin and no other thromboembolic events were observed during admission or after discharge.

CONCLUSIONS

The increased use of advanced CT technology in trauma patients has resulted in an increased diagnosis of incidental PEs that are asymptomatic. The clinical significance and management of these small, incidental PE are uncertain and further studies are needed to clarify the natural history of this controversial finding.

Post-traumatic pulmonary embolism in the intensive care unit

OBJECTIVE:

To determine the predictive factors, clinical manifestations, and the outcome of patients with post-traumatic pulmonary embolism (PE) admitted in the intensive care unit (ICU).

METHODS:

During a four-year prospective study, a medical committee of six ICU physicians prospectively examined all available data for each trauma patient in order to classify patients according to the level of clinical suspicion of pulmonary thromboembolism. During the study period, all trauma patients admitted to our ICU were classified into two groups. The first group included all patients with confirmed PE; the second group included patients without clinical manifestations of PE. The diagnosis of PE was confirmed either by a high-probability ventilation/perfusion (V/Q) scan or by a spiral computed tomography (CT) scan showing one or more filling defects in the pulmonary artery or its branches.

RESULTS:

During the study period, 1067 trauma patients were admitted in our ICU. The diagnosis of PE was confirmed in 34 patients (3.2%). The mean delay of development of PE was 11.3 ± 9.3 days. Eight patients (24%) developed this complication within five days of ICU admission. On the day of PE diagnosis, the clinical examination showed that 13 patients (38.2%) were hypotensive, 23 (67.7%) had systemic inflammatory response syndrome (SIRS), three (8.8%) had clinical manifestations of deep venous thrombosis (DVT), and 32 (94%) had respiratory distress requiring mechanical ventilation. In our study, intravenous unfractionated heparin was used in 32 cases (94%) and low molecular weight heparin was used in two cases (4%). The mean ICU stay was 31.6 ± 35.7 days and the mean hospital stay was 32.7 ± 35.3 days. The mortality rate in the ICU was 38.2% and the in-hospital mortality rate was 41%. The multivariate analysis showed that factors associated with poor prognosis in the ICU were the presence of circulatory failure (Shock) (Odds ratio (OR) = 9.96) and thrombocytopenia (OR = 32.5).Moreover, comparison between patients with and without PE showed that the predictive factors of PE were: Age > 40 years, a SAPS II score > 25, hypoxemia with PaO₂/FiO₂ < 200 mmHg, the presence of spine fracture, and the presence of meningeal hemorrhage.

CONCLUSION:

Despite the high frequency of DVT in post-traumatic critically ill patients, symptomatic PE remains, although not frequently observed, because systematic screening is not performed. Factors associated with poor prognosis in the ICU are the presence of circulatory failure (shock) and thrombocytopenia. Predictive factors of PE are: Age > 40 years, a SAPS II score > 25, hypoxemia with PaO₂/FiO₂ < 200, the presence of a spine fracture, and the presence of meningeal hemorrhage. Prevention is highly warranted.

Venous thromboembolic events in isolated severe traumatic brain injury

OBJECTIVE

The purpose of this study was to investigate the effect of prophylactic anticoagulation on the incidence of venous thromboembolic events (VTE) in patients suffering from isolated severe traumatic brain injury (TBI).

MATERIALS AND METHODS

Retrospective matched case-control study in adult patients sustaining isolated severe TBI (head AIS ≥3, with extracranial AIS ≤2) receiving VTE prophylaxis while in the surgical intensive care unit from 1/2007 through 12/2009. Patients subjected to VTE prophylaxis were matched 1:1 by age, gender, glasgow coma scale (GCS) score at admission, presence of hypotension on admission, injury severity score, and head abbreviated injury scale (AIS) score, with patients who did not receive chemical VTE prophylaxis. The primary outcome measure was VTE. Secondary outcomes were SICU and hospital length of stay (HLOS), adverse effects of anticoagulation, and mortality.

RESULTS

After propensity matching, 37 matched pairs were analysed. Cases and controls had similar demographics, injury characteristics, rate of craniotomies/craniectomies, SICU LOS, and HLOS. The median time of commencement of VTE prophylaxis was 10 days. The incidence of VTE was increased 3.5-fold in the controls compared to the cases (95% CI 1.0-12.1, P=0.002). The mortality was higher in patients who did not receive anticoagulation (19% vs. 5%, P=0.001). No adverse outcomes were detected in the anticoagulated patients.

CONCLUSION

Prophylactic anticoagulation decreases the overall risk for clinically significant VTE in patients with severe isolated TBI. Prospective validation of the timing and safety of chemical VTE prophylaxis in these instances is warranted.

The effects of direct factor Xa inhibitor (Rivaroxaban) on the human osteoblastic cell line SaOS2

Thromboprophylaxis reduces the risk of surgery-related deep vein thrombosis, but anticoagulants were associated with systemic osteoporosis, a known risk factor for poor fracture healing. Rivaroxaban (XARELTO(®)) is a novel anticoagulant with specific ability to inhibit factor Xa, a serine endopeptidase, which plays a key role in coagulation. This study investigated the direct effects of rivaroxaban on bone biology using an in vitro cell culture model from the human female osteoblastic cell line SaOS2. Cells at subconfluence were treated for 24 hr with different concentrations of rivaroxaban and analyzed for DNA synthesis and creatine kinase- and alkaline phosphatase-specific activities, and were treated 21 days for analyzing mineralization. Rivaroxaban (0.01-50 μg/ml) dose-dependently inhibited up to 60% DNA synthesis of the cells. Creatine kinase-specific activity was also inhibited dose-dependently to a similar extent by the same concentrations. Alkaline phosphatase-specific activity was dose-dependently inhibited but only up to 30%. Cell mineralization was unaffected by 10 μg/ml rivaroxaban. This model demonstrated a significant rivaroxaban-induced reduction in osteoblastic cell growth and energy metabolism, and slight inhibition of the osteoblastic marker, alkaline phosphatase, while osteoblastic mineralization was unaffected. These findings might indicate that rivaroxaban inhibits the first stage of bone formation but does not affect later stages (i.e., bone mineralization).