Venous thromboembolism chemoprophylaxis regimens in trauma and surgery patients with obesity: A systematic review

Weight-based enoxaparin thromboprophylaxis in young trauma patients: analysis of the CLOTT-1 registry

Introduction

Optimal venous thromboembolism (VTE) enoxaparin prophylaxis dosing remains elusive. Weight-based (WB) dosing safely increases anti-factor Xa levels without the need for routine monitoring but it is unclear if it leads to lower VTE risk. We hypothesized that WB dosing would decrease VTE risk compared with standard fixed dosing (SFD).

Methods

Patients from the prospective, observational CLOTT-1 registry receiving prophylactic enoxaparin (n=5539) were categorized as WB (0.45-0.55 mg/kg two times per day) or SFD (30 mg two times per day, 40 mg once a day). Multivariate logistic regression was used to generate a predicted probability of VTE for WB and SFD patients.

Results

Of 4360 patients analyzed, 1065 (24.4%) were WB and 3295 (75.6%) were SFD. WB patients were younger, female, more severely injured, and underwent major operation or major venous repair at a higher rate than individuals in the SFD group. Obesity was more common among the SFD group. Unadjusted VTE rates were comparable (WB 3.1% vs. SFD 3.9%; p=0.221). Early prophylaxis was associated with lower VTE rate (1.4% vs. 5.0%; p=0.001) and deep vein thrombosis (0.9% vs. 4.4%; p<0.001), but not pulmonary embolism (0.7% vs. 1.4%; p=0.259). After adjustment, VTE incidence did not differ by dosing strategy (adjusted OR (aOR) 0.75, 95% CI 0.38 to 1.48); however, early administration was associated with a significant reduction in VTE (aOR 0.47, 95% CI 0.30 to 0.74).

Conclusion

In young trauma patients, WB prophylaxis is not associated with reduced VTE rate when compared with SFD. The timing of the initiation of chemoprophylaxis may be more important than the dosing strategy. Further studies need to evaluate these findings across a wider age and comorbidity spectrum.

Level of evidence

Level IV, therapeutic/care management.

The association between obesity and postoperative outcomes in a broad surgical population: A 7-year American College of Surgeons National Surgical Quality Improvement analysis

BACKGROUND

The number of obese surgical patients continues to grow, and yet obesity's association with surgical outcomes is not totally clear. This study examined the association between obesity and surgical outcomes across a broad surgical population using a very large sample size.

METHODS

This was an analysis of the 2012 to 2018 American College of Surgeons National Surgical Quality Improvement database, including all patients from 9 surgical specialties (general, gynecology, neurosurgery, orthopedics, otolaryngology, plastics, thoracic, urology, and vascular). Preoperative characteristics and postoperative outcomes were compared by body mass index class (normal weight 18.5-24.9 kg/m², overweight 25.0-29.9, obese class I 30.0-34.9, obese II 35.0-39.9, obese III ≥40). Adjusted odds ratios were computed for adverse outcomes by body mass index class.

RESULTS

A total of 5,572,019 patients were included; 44.6% were obese. Median operative times were marginally higher for obese patients (89 vs 83 minutes, P < .001). Compared to normal weight patients, overweight and obese patients in classes I, II, and III all had higher adjusted odds of developing infection, venous thromboembolism, and renal complications, but they did not exhibit elevated odds of other postoperative complications (mortality, overall morbidity, pulmonary, urinary tract infection, cardiac, bleeding, stroke, unplanned readmission, or discharge not home (except for class III patients).

CONCLUSION

Obesity was associated with increased odds of postoperative infection, venous thromboembolism, and renal but not the other American College of Surgeons National Surgical Quality Improvement complications. Obese patients need to be carefully managed for these complications.

Weight-adjusted dosing of tinzaparin for thromboprophylaxis in obese medical patients

Background

The optimal dose of tinzaparin for prophylaxis in obese medical patients is not well defined.

Objectives

To evaluate the anti-Xa activity in obese medical patients on tinzaparin prophylaxis adjusted for actual bodyweight.

Methods

Patients with a body mass index of ≥30 kg/m² treated with 50 IU/kg tinzaparin once daily were prospectively included. Anti-Xa and anti-IIa activity; von Willebrand factor antigen and von Willebrand activity; factor VIII activity; D-dimer, prothrombin fragments; and thrombin generation were measured 4 hours after subcutaneous injection between days 1 and 14 after the initiation of tinzaparin prophylaxis.

Results

We included 121 plasma samples from 66 patients (48.5% women), with a median weight of 125 kg (range, 82-300 kg) and a median body mass index of 41.9 kg/m² (range, 30.1-88.6 kg/m²). The target anti-Xa activity of 0.2 to 0.4 IU/mL was achieved in 80 plasma samples (66.1%); 39 samples (32.2%) were below and 2 samples (1.7%) above the target range. The median anti-Xa activity was 0.25 IU/mL (IQR, 0.19-0.31 IU/mL), 0.23 IU/mL (IQR, 0.17-0.28 IU/mL), and 0.21 IU/mL (IQR, 0.17-0.25 IU/mL) on days 1 to 3, days 4 to 6, and days 7 to 14, respectively. The anti-Xa activity did not differ among the weight groups (P = .19). Injection into the upper arm compared to the abdomen resulted in a lower endogenous thrombin potential, a lower peak thrombin, and a trend to a higher anti-Xa activity.

Conclusion

Dosing of tinzaparin adjusted for actual bodyweight in obese patients achieved anti-Xa activity in the target range for most patients, without accumulation or overdosing. In addition, there is a significant difference in thrombin generation depending on the injection site.

Effectiveness and Safety of High-Dose Thromboprophylaxis in Morbidly Obese Major Trauma Patients

BACKGROUND

Trauma increases risk for venous thromboembolism (VTE) and obesity is a known independent risk factor for VTE development. Currently, no consensus on an optimal prophylactic dosing strategy for morbidly obese trauma patients exists. The objective of this study is to evaluate the effectiveness and safety of a BMI-stratified dosing strategy for VTE prophylaxis in morbidly obese trauma patients.

METHODS

This was a single center, retrospective cohort study of adult major trauma patients with a body mass index (BMI) of ≥40 kg/m2 admitted to the surgical-trauma intensive care unit from April 2014 to July 2020. Patients included were those who received enoxaparin 40 mg subcutaneously (SQ) every 12 hours (Q12H) for BMI of 40 to 49.9 kg/m2 or 60 mg SQ Q12H BMI ≥ 50 kg/m2 (per protocol), or enoxaparin 40 mg SQ Q12H for BMI of 40 to 49.9 kg/m2 (non-protocol). The primary endpoint was confirmed incidence of VTE. Secondary endpoints included occurrence of deep vein thrombosis (DVT) or pulmonary embolism (PE) during hospitalization, bleeding events, intensive care unit (ICU) and hospital length of stay (LOS) and hospital mortality.

RESULTS

One hundred forty-five morbidly obese major trauma patients were included, with 123 patients (84.8%) in the per-protocol group. The primary outcome of in-hospital VTE did not occur in any patients in this group. Bleeding events occurred in 3 patients (2.7%) with a BMI of 40 to 49.9 kg/m2 and in 2 patients (16.7%) with a BMI of ≥50 kg/m2 (P = .064). Twenty-two patients in the non-protocol group were reviewed. One VTE event (4.5%) and no bleeding events occurred in this group. Median ICU LOS was 5 days, and hospital LOS was 11 days for the entire study group.

CONCLUSIONS

Administration of enoxaparin 40 mg SQ Q12H to morbidly obese major trauma patients with a BMI of 40 to 49.9 kg/m2 and enoxaparin 60 mg SQ Q12H in those with a BMI of ≥50 kg/m2 resulted in low rates of VTE and bleeding events in the current study. However, future larger studies using this BMI-stratified dosing strategy are necessary to confirm these findings.

Assessment of BMI and Venous Thromboembolism Rates in Patients on Standard Chemoprophylaxis Regimens After Undergoing Free Tissue Transfer to the Head and Neck

Importance

Venous thromboembolism (VTE) is a severe complication after free tissue transfer to the head and neck (H&N). Enoxaparin 30 mg twice daily (BID) is a common regimen for chemoprophylaxis. However, differences in enoxaparin metabolism based on body weight may influence its efficacy and safety profile.

Objective

To assess the association between BMI and postoperative VTE and hematoma rates in patients treated with prophylactic enoxaparin 30 mg BID.

Design, Setting, and Participants

This was a retrospective review of a prospectively collected cohort from 2012 to 2022. Postoperative VTE, hematoma, and free flap pedicle thrombosis were recorded within 30 days of index surgery. The setting was a tertiary academic referral center. Participants included patients undergoing H&N reconstruction with free flaps that received fixed-dose subcutaneous enoxaparin 30 mg BID postoperatively. Statistical analysis was conducted from April to May 2022.

Main Outcomes and Measures

Outcomes include incidence of VTE, hematoma, and flap pedicle thrombosis events within 30 days of the surgery. Univariate and multivariable regression models were used to evaluate associations between BMI and other patient factors with these outcomes.

Results

Among the 765 patients included, 262 (34.24%) were female; mean (SD) age was 60.85 (12.64) years; and mean (SD) BMI was 26.36 (6.29). The rates of VTE and hematoma in the cohort were 3.92% (30 patients) and 5.09% (39 patients), respectively. After adjusting for patient factors, BMI was the only factor associated with VTE (OR, 1.07; 95% CI, 1.015-1.129). Obesity (BMI >30) was associated with increased odds of VTE (OR, 2.782; 95% CI, 1.197-6.564). Hematoma was not associated with BMI (OR, 0.988; 95% CI, 0.937-1.041). Caprini score of at least 9 was not associated with VTE (OR, 1.259; 95% CI, 0.428-3.701).

Conclusions and Relevance

This cohort study found that obesity was associated with an increased risk of VTE in patients after microvascular H&N reconstruction and while on standard postoperative chemoprophylaxis regimens. This association may suggest insufficient VTE prophylaxis in this group and a potential indication for weight-based dosing.

Standard Fixed Enoxaparin Dosing for Venous Thromboembolism Prophylaxis Leads to Low Peak Anti-Factor Xa Levels in Both Head and Neck and Breast Free Flap Patients

INTRODUCTION

 Venous thromboembolism (VTE) is a serious complication, particularly in cancer patients undergoing free flap reconstruction. Subcutaneous enoxaparin is the conventional prophylaxis for VTE prevention, and serum anti-factor Xa (afXa) levels are being increasingly used to monitor enoxaparin activity. In this study, free flap patients receiving standard enoxaparin prophylaxis were prospectively followed to investigate postoperative afXa levels and 90-day VTE and bleeding-related complications.

METHODS

 Patients undergoing free tissue transfer during an 8-month period were identified and prospectively followed. Patients received standard fixed enoxaparin dosing at 30 mg twice daily in head and neck (H&N) and 40 mg daily in breast reconstructions. Target peak prophylactic afXa range was 0.2 to 0.5 IU/mL. The primary outcome was the occurrence of 90-day postoperative VTE- and bleeding-related events. Independent predictors of afXa level and VTE incidence were analyzed for patients that met the inclusion criteria.

RESULTS

 Seventy-eight patients were prospectively followed. Four (5.1%) were diagnosed with VTE, and six (7.7%) experienced bleeding-related complications. The mean afXa levels in both VTE patients and bleeding patients were subprophylactic (0.13 ± 0.09 and 0.11 ± 0.07 IU/mL, respectively). Forty-six patients (21 breast, 25 H&N) had valid postoperative peak steady-state afXa levels. Among these, 15 (33%) patients achieved the target prophylactic range: 5 (33%) H&N and 10 (67%) breast patients. The mean afXa level for H&N patients was significantly lower than for breast patients (p = 0.0021). Patient total body weight was the sole negative predictor of afXa level (R ² = 0.47, p < 0.0001).

CONCLUSION

 Standard fixed enoxaparin dosing for postoperative VTE prophylaxis does not achieve target afXa levels for the majority of our free flap patients. H&N patients appear to be a particularly high-risk group that may require a more personalized and aggressive approach. Total body weight is the sole negative predictor of afXa level, supporting a role for weight-based enoxaparin dosing.

American Association for the Surgery of Trauma/American College of Surgeons-Committee on Trauma Clinical Protocol for inpatient venous thromboembolism prophylaxis after trauma

ABSTRACT

Trauma patients are at increased risk of venous thromboembolism (VTE), which includes both deep vein thrombosis and pulmonary embolism. Pharmacologic VTE prophylaxis is a critical component of optimal trauma care that significantly decreases VTE risk. Optimal VTE prophylaxis protocols must manage the risk of VTE with the competing risk of hemorrhage in patients following significant trauma. Currently, there is variability in VTE prophylaxis protocols across trauma centers. In an attempt to optimize VTE prophylaxis for the injured patient, stakeholders from the American Association for the Surgery of Trauma and the American College of Surgeons-Committee on Trauma collaborated to develop a group of consensus recommendations as a resource for trauma centers. The primary goal of these recommendations is to help standardize VTE prophylaxis strategies for adult trauma patients (age ≥15 years) across all trauma centers. This clinical protocol has been developed to (1) provide standardized medication dosing for VTE prophylaxis in the injured patient; and (2) promote evidence-based, prompt VTE prophylaxis in common, high-risk traumatic injuries.

LEVEL OF EVIDENCE

Therapeutic/Care Management; Level V.

Emergencies in obese patients: a narrative review

Obesity is associated to an increased risk of morbidity and mortality due to respiratory, cardiovascular, metabolic, and neoplastic diseases. The aim of this narrative review is to assess the physio-pathological characteristics of obese patients and how they influence the clinical approach during different emergency settings, including cardiopulmonary resuscitation. A literature search for published manuscripts regarding emergency and obesity across MEDLINE, EMBASE, and Cochrane Central was performed including records till January 1, 2021. Increasing incidence of obesity causes growth in emergency maneuvers dealing with airway management, vascular accesses, and drug treatment due to both pharmacokinetic and pharmacodynamic alterations. Furthermore, instrumental diagnostics and in/out-hospital transport may represent further pitfalls. Therefore, people with severe obesity may be seriously disadvantaged in emergency health care settings, and this condition is enhanced during the COVID-19 pandemic, when obesity was stated as one of the most frequent comorbidity. Emergency in critical obese patients turns out to be an intellectual, procedural, and technical challenge. Organization and anticipation based on the understanding of the physiopathology related to obesity are very important for the physician to be mentally and physically ready to face the associated issues.

Venous Thromboembolism Chemoprophylaxis in Trauma and Emergency General Surgery Patients: A Systematic Review

BACKGROUND

Appropriate venous thromboembolism (VTE) chemoprophylaxis in trauma and emergency general surgery (EGS) patients is crucial.

OBJECTIVE

The purpose of this study is to review the recent literature and offer recommendations for VTE chemoprophylaxis in trauma and EGS patients.

METHODS

We conducted a literature search from 2000 to 2021 for articles investigating VTE chemoprophylaxis in adult trauma and EGS patients. This study was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines.

RESULTS

Our search resulted in 34 articles. Most studies showed low-molecular-weight heparin (LMWH) is similar to unfractionated heparin (UFH) for VTE prevention; however, LMWH was more commonly used. Adjusted chemoprophylaxis dosing did not change the VTE rate but the timing did. Direct oral anticoagulants (DOACs) have been shown to be safe and effective in trauma and traumatic brain injury (TBI)/spinal cord injury (SCI). Studies showed VTE prophylaxis in EGS can be inconsistent and improves with guidelines that lower VTE events.

CONCLUSIONS

There may be no benefit to receiving LMWH over UFH in trauma patients. In addition, different drugs under the class of LMWH do not change the incidence of VTE. Adjusted dosing of enoxaparin does not seem to affect VTE incidence. The use of DOACs in the trauma TBI and SCI setting has been shown to be safe and effective in reducing VTE. One important consideration with VTE prophylaxis may be the timing of prophylaxis initiation, specifically as it relates to TBI, with a higher likelihood of developing VTE as time progresses. EGS patients are at a high risk of VTE. Improved compliance with clinical guidelines in this population is correlated with decreased thrombotic events.

Venous Thromboembolism in Trauma: The Role of Anticoagulation and Inferior Vena Cava Filters

Venous thromboembolism (VTE) is a significant contributor to morbidity and mortality among patients with severe trauma. Historically, prophylactic inferior vena cava filters (IVCFs) were used in high-risk trauma patients with suspected risk factors for VTE, including prolonged immobilization, and concurrent contraindication to anticoagulation. Mounting data regarding the efficacy of IVCF in this cohort, as well as concerns regarding morbidity of an in situ IVCF, have challenged this practice paradigm. In this review, we discuss the comanagement of VTE and trauma, including anticoagulation and the use of IVCF.

Association of the Risk of a Venous Thromboembolic Event in Emergency vs Elective General Surgery

Importance

Trauma patients have an increased risk of venous thromboembolism (VTE), partly because of greater inflammation. However, it is unknown if this association is present in patients who undergo emergency general surgery (EGS).

Objectives

To investigate whether emergency case status is independently associated with VTE compared with elective case status and to test the hypothesis that emergency cases would have a higher risk of VTE.

Design, Setting, and Participants

This retrospective cohort study used the American College of Surgeons National Surgical Quality Improvement Program database from January 1, 2005, to December 31, 2016, for all cholecystectomies, ventral hernia repairs (VHRs), and partial colectomies (PCs) to obtain a sample of commonly encountered emergency procedures that have elective counterparts. Emergency surgeries were then compared with elective surgeries. The dates of analysis were January 1 to 31, 2019.

Main Outcomes and Measures

The primary outcome was VTE at 30 days. A multivariable analysis controlling for age, sex, body mass index, bleeding disorder, disseminated cancer, laparoscopy approach, and surgery type was performed.

Results

There were 604 537 adults undergoing surgical procedures over 12 years (mean [SD] age, 55.3 [16.6] years; 61.4% women), including 285 847 cholecystectomies, 158 500 VHRs, and 160 190 PCs. The rate of VTE within 30 days was 1.9% for EGS and 0.8% for elective surgery, a statistically significant difference. Overall, 4607 patients (0.8%) had deep vein thrombosis, and 2648 patients (0.4%) had pulmonary embolism. A total of 6624 VTEs (1.1%) occurred in the cohort. As expected, when VTE risk was examined by surgery type, the risk increased with invasiveness (0.5% for cholecystectomy, 0.8% for VHR, and 2.4% for PC; P < .001). On multivariable analysis, EGS was independently associated with VTE (odds ratio [OR], 1.70; 95% CI, 1.61-1.79). Also associated with VTE were open surgery (OR, 3.38; 95% CI, 3.15-3.63) and PC (OR, 1.86; 95% CI, 1.73-1.99).

Conclusions and Relevance

In this cohort study, emergency surgery and increased invasiveness appeared to be independently associated with VTE compared with elective surgery. Further study on methods to improve VTE chemoprophylaxis is highly recommended for emergency and more extensive operations to reduce the risk of potentially lethal VTE.