Prevention of Venous Thromboembolism in Microvascular Surgery Patients Using Weight-Based Unfractionated Heparin Infusions

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.

Section: Discussionmentioning

confidence: 99%

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

Ambani

Bengür

Varelas

et al. 2022

“…With the majority of patients still requiring dose adjustments after weight-based infusions, this study highlighted variations in individual pharmacodynamics and therefore the need for individualized chemoprophylaxis regimens. 34 Clinically, VTE prevention has also been trending toward individualization in plastic surgery. In 2016, the consensus conference hosted by the American Association of Plastic Surgeons recommended consideration of chemoprophylaxis on a case-by-case basis in patients with a Caprini score greater than 8.…”

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Prolonged Venous Thromboembolism Prophylaxis May Not Be Necessary for DIEP Flap Breast Reconstruction: A Tertiary Center's 10-Year Experience

Huang

Bernstein

Otterburn

2022

Background Based on the 2005 Caprini Risk Assessment Model for venous thromboembolism, the American Society of Plastic Surgeons prevention guidelines would result in prolonged chemoprophylaxis (1 week or more) for the majority of patients undergoing deep inferior epigastric perforator flap breast reconstruction. We aim to assess the necessity of prolonged prophylaxis by describing our institutional experience in thromboembolism prevention and evaluating the incidence of symptomatic VTE in our patient cohort. Methods Women who underwent DIEP flap reconstruction from August 2011 to March 2020 at a tertiary care center were included. Charts were retrospectively reviewed for patient characteristics, VTE prophylaxis regimens, and development of deep vein thrombosis and pulmonary embolism within 60 days of surgery. Caprini scores were calculated for all patients. Results Out of the 249 patients included in the study, 245 patients received chemoprophylaxis only during hospitalization, while four patients additionally received anticoagulant for at least 2 weeks after discharge for prophylactic or therapeutic indications. The cohort's average Caprini score was 6.0, with 72.7% of scores between 3 and 6 and 26.5% at 7 or higher. One patient (0.4%), who scored a 7 and received prophylaxis only while hospitalized, developed deep vein thrombosis. There were no cases of pulmonary embolism. There was no significant difference in VTE rate between patients who received chemoprophylaxis consistent with ASPS guidelines and those who did not (p = 1.000). Conclusion Despite our limited chemoprophylaxis use in DIEP flap patients, our VTE incidence is low. This current work suggests that the blanket application of prolonged prophylaxis is not warranted, and it further serves as impetus to re-evaluate the 2005 Caprini RAM in this patient population.

“…Although limited by a small sample size, this study does suggest a need for further investigation regarding the ideal course for anticoagulation in microsurgical patients. 11…”

Section: Discussionmentioning

confidence: 99%

Genomic Analysis of Thrombophilia Variants in the General Population for the Creation of an Effective Preoperative Screening Tool

Azar

Menezes

2022

Background The loss of a free flap in reconstructive microsurgery is a devastating complication in both the intraoperative and postoperative setting. Previous research has identified a variety of genetic polymorphisms that induce a hypercoagulable state and predispose patients to clot formation and subsequent free flap loss. We aim to review the risks of performing microsurgery on patients who are genetically predisposed to hypercoagulability, as well as identify options, for preoperative screening of inherited thrombophilia. Methods A thorough literature review was conducted with an online database. A total of 30 studies were reviewed to identify genetic polymorphisms that cause inherited thrombophilia. Through manual review of the literature, a table was created that included thrombotic risk factors and their associated genetic polymorphisms. If the information was available, prevalence for each thrombotic risk was also reported. Results Overall, 18 thrombotic risk factors that contribute to hereditary thrombophilia were identified and linked with specific genes and/or genetic polymorphisms. In studies that did not look at particular ethnic groups, 13 unique thrombotic risk factors were identified. In studies that examined specific ethnic groups exclusively, 12 thrombotic risk factors were identified and related to their respective gene or group of genes. Five of the 18 thrombotic risk factors identified were associated with increased risks of both venous and arterial thrombosis. The remainder of the thrombotic risk factors was associated with increased risk of venous thrombosis exclusively. Conclusion The use of genetic screening tests for hereditary thrombophilia in the preoperative setting can serve as an effective preventative measure against postoperative thrombosis. Further exploration of thrombotic risk factors and their related genetic polymorphisms are important steps in reducing postoperative free flap loss.