Clinical Issues Committee of the American Society for Metabolic and Bariatric Surgery. Prophylactic measures to reduce the risk of venous thromboembolism in bariatric surgery patients

Venous thromboembolism (VTE) prophylaxis after bariatric surgery: a national survey of MBSAQIP director practices

BACKGROUND

Venous thromboembolism (VTE) is the most common cause of death following metabolic/bariatric surgery (MBS), with most events occurring after discharge. The available evidence on ideal prophylaxis type, dosage, and duration after discharge is limited.

OBJECTIVES

Assess metabolic/bariatric surgeon VTE prophylaxis practices and define existing variability.

SETTING

Metabolic and Bariatric Surgery Accreditation and Quality Improvement Program (MBSAQIP)-accredited centers.

METHODS

The members of the ASMBS Research Committee developed and administered a web-based survey to MBSAQIP medical directors and ASMBS members to examine the differences in clinical practice regarding the administration of VTE prophylaxis after MBS.

RESULTS

Overall, 264 metabolic/bariatric surgeons (136 medical directors and 128 ASMBS members) participated in the survey. Both mechanical and chemical VTE prophylaxis was used by 97.1% of the participants, knee-high compression devices by 84.7%, enoxaparin (32.4% 40 mg every 24 hours, 22.7% 40 mg every 12 hours, 24.4% adjusted the dose based on body mass index) by 56.5%, and heparin (46.1% 5000 units every 8 hours, 22.6% 5000 units every 12 hours, 20.9% 5000 units once preoperatively) by 38.1%. Most surgeons (81.6%) administered the first dose preoperatively, while the first postoperative dose was given on the evening of surgery by 44% or the next morning by 42.2%. Extended VTE prophylaxis was prescribed for 2 weeks by 38.7% and 4 weeks by 28.9%.

CONCLUSIONS

VTE prophylaxis practices vary widely among metabolic/bariatric surgeons. Variability may be related to limited available comparative evidence. Large prospective clinical trials are needed to define optimal practices for VTE risk stratification and prophylaxis in bariatric surgery patients.

Extended postoperative venous thromboembolism prophylaxis after bariatric surgery: a comparison of existing risk-stratification tools and 5-year MBSAQIP analysis

BACKGROUND

Venous thromboembolism (VTE) is a leading cause of 30-day mortality after metabolic and bariatric surgery (MBS). Multiple predictive tools exist for VTE risk assessment and extended VTE chemoprophylaxis determination.

OBJECTIVE

To review existing risk-stratification tools and compare their predictive abilities.

SETTING

MBSAQIP database.

METHODS

Retrospective analysis of the Metabolic and Bariatric Surgery Accreditation and Quality Improvement Program (MBSAQIP) database was performed (2015-2019) for primary minimally invasive MBS cases. VTE clinical factors and risk-assessment tools were evaluated: body mass index threshold of 50 kg/m2, Caprini risk-assessment model, and 3 bariatric-specific tools: the Cleveland Clinic VTE risk tool, the Michigan Bariatric Surgery Collaborative tool, and BariClot. MBS patients were deemed high risk based on criteria from each tool and further assessed for sensitivity, specificity, and positive predictive value.

RESULTS

Overall, 709,304 patients were identified with a .37% VTE rate. Bariatric-specific tools included multiple predictors: procedure, age, race, gender, operative time, length of stay, heart failure, and dyspnea at rest; operative time was the only variable common to all. The body mass index cutoff and Caprini risk-assessment model had higher sensitivity but lower specificity when compared with the Michigan Bariatric Surgery Collaborative and BariClot tools. While the sensitivity of the tools varied widely and was overall low, the Cleveland Clinic tool had the highest sensitivity. The bariatric-specific tools would have recommended extended prophylaxis for 1.1%-15.6% of patients.

CONCLUSIONS

Existing MBS VTE risk-assessment tools differ widely for inclusion variables, high-risk definition, and predictive performance. Further research and registry inclusion of all significant risk factors are needed to determine the optimal risk-stratified approach for predicting VTE events and determining the need for extended prophylaxis.

Assessment of empiric body mass index-based thromboprophylactic dosing of enoxaparin after bariatric surgery: evidence for dosage adjustment using anti-factor Xa in high-risk patients

BACKGROUND

Despite thromboprophylaxis, postoperative deep vein thrombosis and pulmonary embolism occur after bariatric surgery, perhaps because of failure to achieve optimal prophylactic levels in the obese population.

OBJECTIVES

The aim of this study was to evaluate the adequacy of prophylactic dosing of enoxaparin in patients with severe obesity by performing an antifactor Xa (AFXa) assay.

SETTING

An academic medical center METHODS: In this observational study, all bariatric surgery cases at an academic center between December 2016 and April 2017 who empirically received prophylactic enoxaparin (adjusted by body mass index [BMI] threshold of 50 kg/m²) were studied. The AFXa was measured 3-5 hours after the second dose of enoxaparin.

RESULTS

A total of 105 patients were included; 85% were female with a median age of 47 years. In total, 16 patients (15.2%) had AFXa levels outside the prophylactic range: 4 (3.8%) cases were in the subprophylactic and 12 (11.4%) cases were in the supraprophylactic range. Seventy patients had a BMI <50 kg/m² and empirically received enoxaparin 40 mg every 12 hours; AFXa was subprophylactic in 4 (5.7%) and supraprophylactic in 6 (8.6%) of these patients. Of the 35 patients with a BMI ≥50 who empirically received enoxaparin 60 mg q12h, no AFXa was subprophylactic and 6 (17.1%) were supraprophylactic. Five patients (4.8%) had major bleeding complications. One patient developed pulmonary embolism on postoperative day 35.

CONCLUSION

BMI-based thromboprophylactic dosing of enoxaparin after bariatric surgery could be suboptimal in 15% of patients with obesity. Overdosing of prophylactic enoxaparin can occur more commonly than underdosing. AFXa testing can be a practical way to measure adequacy of pharmacologic thromboprophylaxis, especially in patients who are at higher risk for venous thromboembolism or bleeding.

Portomesenteric venous thrombosis complicated by a haemorrhagic shock: a rare complication of laparoscopic gastrectomy

Portomesenteric venous thrombosis is a rare complication reported in only a few cases involving laparoscopic bariatric surgery. We report a case of a 44-year-old woman who presented 14 days after recent laparoscopic sleeve gastrectomy with the chief complaint of abdominal pain and associated nausea. Abdominal CT demonstrated thrombi in her superior mesenteric, portal and splenic veins. She was initiated on therapeutic heparin but developed haemorrhagic shock shortly afterwards. Subsequent CT angiogram failed to localise the source of her haemorrhage. Her haemodynamic instability improved following a 6-day intensive care unit stay requiring vasopressive agents and blood transfusions. Further hypercoagulable workup revealed that she was a heterozygous carrier of the prothrombin gene mutation, and thus started on lifelong oral anticoagulation.

Splanchnic Vein Thrombosis - an Uncommon Complication after Laparoscopic Sleeve Gastrectomy

BACKGROUND

Laparoscopic sleeve gastrectomy (LSG) is an innovative and relatively safe surgical approach for weight reduction in morbidly obese people. Splanchnic vein thrombosis (SVT) is an extremely rare complication of LSG and, if not recognized, carries a high mortality rate. This paper highlights a potentially lethal condition of SVT after LSG.

CASE REPORT

A 37-year-old morbidly obese woman was referred to our institution for LSG. Three weeks after the intervention, she was readmitted with abdominal pain, vomiting, nausea, diarrhea, and fever with positive family anamnesis to viral disease. Abdominal X-ray as well as utrasonography were both normal, and no X-ray contrast medium leakage was observed. One week later, she was readmitted with septic condition. An abdominal computed tomography scan diagnosed lienal vein thrombosis along its whole length and partial thrombosis of the superior mesenteric vein.

CONCLUSION

SVT presents very heterogeneously, which makes it extremely challenging to diagnose and to make an appropriate treatment decision. With regard to the high prevalence of obesity and the increasing frequency of LSG, prompt diagnosis and management are crucial.

Clinical markers of the hypercoagulable state by rotational thrombelastometry in obese patients submitted to bariatric surgery

BACKGROUND

Metabolic and inflammatory disturbances associated with obesity are considered important trigger factors for venous thromboembolism (VTE). Identification of clinical markers indicating a hypercoagulability state could define a group of high-risk patients in the surgical setting. This study aimed to identify these markers using rotational thrombelastometry (ROTEM) analysis, an established method for hemostasis testing that can detect hyperfunctional stages of the clotting process.

METHODS

From June to December 2010, this study investigated 109 consecutive obese patients (28 women and 22 men, mean age 46 years, body mass index 46.6 ± 7 kg/m(2)) with no history of VTE who were candidates for bariatric surgery. Preoperative clinical and metabolic characteristics and ROTEM analysis were recorded. Hypercoagulable risk was defined when patients showed a clot strength (G) of ≥11 dynes/cm(2).

RESULTS

Of the 109 patients, 20 (18%) were hypercoagulable according to ROTEM analysis. Metabolic/inflammatory biomarkers such as leptin, C-reactive protein, fibrinogen levels, and platelet count were significantly higher in the high-risk patients. In the multivariate analysis, fibrinogen was an independent predictor of G ≥ 11 dynes/cm(2) [odds ratio (OR) 2.92, 95 % confidence interval (CI) 1.80-5.21, p = 0.023]. After adjustment to other data, only waist circumference affected the prediction [OR 4.42, 95 % CI 2.27-6.71, p = 0.009]. Receiver operating characteristic curve analysis showed that 3.95 g/l was the best cutoff point for fibrinogen predictability (sensitivity 100 %, specificity 41%).

CONCLUSION

A hypercoagulability state in obese patients is associated with central obesity and high fibrinogen levels, which should be considered clinical hallmarks of this state. More aggressive perioperative prophylaxis for VTE should be recommended when these hallmarks are present in obese patients.

Pulmonary embolism and fatal stroke in a patient with severe factor XI deficiency after bariatric surgery

We report the case of a 40-year-old woman with a severe factor XI (FXI) deficiency who died from a stroke due to bilateral internal carotid arteries occlusion after a laparoscopic gastric bypass (bariatric surgery). This stroke was probably secondary to a pulmonary embolism with a paradoxical embolism through a previously unknown foramen ovale. This woman who had one severe episode of bleeding before the bypass received for the intervention a single infusion of 27 U/kg of FXI concentrate. A careful evaluation of the bleeding and thrombotic risk was performed before surgery, and despite all preventive measures, this tragic event occurred. The aim of this report is to alert medical teams to carefully balance the benefit-risk of such an intervention in a patient with a severe FXI deficiency.

Portal vein thrombosis following laparoscopic sleeve gastrectomy for morbid obesity

A high index of suspicion is necessary to diagnose portal vein thrombosis following laparoscopic bariatric procedures.

Introduction:

Portal vein thrombosis has been documented after laparoscopic general surgery and has been uncommonly observed after laparoscopic bariatric surgery. Among bariatric operations, the sleeve gastrectomy is being performed with ever-increasing frequency. Here we report the case of a man who presented with portal vein thrombosis after laparoscopic sleeve gastrectomy.

Case Description:

A 41-y-old man underwent an uneventful laparoscopic sleeve gastrectomy for the treatment of morbid obesity, and presented on postoperative day 10 with nonfocal abdominal pain, nausea, vomiting, and leukocytosis. Computed tomography revealed portal vein thrombosis, which was found in the setting of Clostridium difficile colitis.

Discussion:

Portal vein thrombosis may be identified with increasing frequency as the number of laparoscopic bariatric operations continues to increase. A high index of suspicion is necessary to diagnose this rare, but potentially lethal, complication.

Actual situation of thromboembolic prophylaxis in obesity surgery: data of quality assurance in bariatric surgery in Germany

Background. Evidence-based data on optimal approach for prophylaxis of deep venous thrombosis (VTE) and pulmonary embolism (PE) in bariatric operations is discussed. Using antithrombotic prophylaxis weight adjusted the risk of VTE and its complications have to be balanced with the increased bleeding risk. Methods. Since 2005 the current situation for bariatric surgery has been examined by quality assurance study in Germany. As a prospective multicenter observational study, data on the type, regimen, and time course of VTE prophylaxis were documented. The incidences of clinically diagnosed VTE or PE were derived during the in-hospital course and follow up. Results. Overall, 11,835 bariatric procedures were performed between January 2005 and December 2010. Most performed procedures were 2730 gastric banding (GB); 4901 Roux-en-Y-gastric bypass (RYGBP) procedures, and 3026 sleeve gastrectomies (SG). Study collective includes 72.5% (mean BMI 48.1 kg/m(2)) female and 27.5% (mean BMI 50.5 kg/m(2)) male patients. Incidence of VTE was 0.06% and of PE 0.08%. Conclusion. VTE prophylaxis regimen depends on BMI and the type of procedure. Despite the low incidence of VTE and PE there is a lack of evidence. Therefore, prospective randomized studies are necessary to determine the optimal VTE prophylaxis for bariatric surgical patients.

Preoperative placement of inferior vena cava filters and outcomes after gastric bypass surgery

OBJECTIVE

To assess relationships between inferior vena cava (IVC) filter placement and complications within 30 days of gastric bypass surgery.

SUMMARY OF BACKGROUND DATA

IVC filters are increasingly being used as prophylaxis against postoperative pulmonary embolism in patients undergoing bariatric surgery, despite a lack of evidence of effectiveness.

METHODS

On the basis of data from a prospective clinical registry involving 20 Michigan hospitals, we identified 6376 patients undergoing gastric bypass surgery between 2006 and 2008. We then assessed relationships between IVC filter placement and complications within 30 days of surgery. We used propensity scores and fixed effects logistic regression to control for potential selection bias.

RESULTS

A total of 542 gastric bypass patients (8.5%) underwent preoperative IVC filter placement, most of whom (65%) had no history of venous thromboembolism. The use of IVC filters for gastric bypass patients varied widely across hospitals (range, 0%-34%). IVC filter patients did not have reduced rates of postoperative venous thromboembolism (adjusted odds ratio [OR], = 1.28; 95% confidence interval [CI], 0.51-3.21), serious complications (adjusted OR, = 1.40; 95% CI, 0.91-2.16), or death/permanent disability (adjusted OR, = 2.49; 95% CI, 0.99-6.26). More than half (57%) of the IVC filter patients in the latter group had a fatal pulmonary embolism or complications directly related to the IVC filter itself, including filter migration or thrombosis of the vena cava. In subgroup analyses, we were unable to identify any patient group for whom IVC filters were associated with improved outcomes.

CONCLUSIONS

Prophylactic IVC filters for gastric bypass surgery do not reduce the risk of pulmonary embolism and may lead to additional complications.

Evidence of thromboembolism prophylaxis in bariatric surgery-results of a quality assurance trial in bariatric surgery in Germany from 2005 to 2007 and review of the literature

BACKGROUND

Since January 1st, 2005, the current situation for bariatric surgery has been examined by means of a voluntary quality assurance study in Germany with a multicenter design in which 38 hospitals and surgical departments participated. The data are registered in cooperation with the Institute of Quality Assurance in Surgery at the Otto-von-Guericke University of Magdeburg (Germany).

METHODS

Data describing peri-interventional characteristics were prospectively documented in an internet online data registry. All primary bariatric procedures performed since January 1st, 2005, were registered. In addition, reoperations in patients who had previously undergone primary surgical intervention were included. As a representative excerpt from the overall prospective multicenter observational study on obesity surgery, data on the type, regimen, and time course of deep venous thrombosis (DVT) prophylaxis were documented. From the number and spectrum of complications, the incidences of clinically manifest DVT or pulmonary embolism (PE) were derived during the in-hospital course and follow-up in conjunction with the type of surgical procedure and body mass index (BMI).

RESULTS

Overall, 3,122 bariatric procedures were performed at 38 German hospitals between January 2005 and December 2007. These procedures were subdivided into 2,869 primary operations and 253 revisions (sex ratio, male to female = 25.6:74.4%). The average BMI of all patients was 48.5 kg/m(2) in 2005, 48.4 kg/m(2) in 2006, and 48.0 kg/m(2) in 2007. In 2005 and 2006, gastric banding (GB) was the most commonly performed operation, followed by Roux-en-Y gastric bypass (RYGBP). In 2007, RYGBP was carried out in 42.1% of all bariatric procedures. Interestingly, the incidence of deep venous thrombosis (DVT) was only 0.06%, whereas PE occurred in 0.06% of patients only after hospital discharge. The DVT prophylaxis protocol used has been changed for the last 2 years: the majority of patients with a BMI above 50 kg/m(2) received low-molecular-weight heparin twice a day.

CONCLUSION

In Germany, a trend from GB to sleeve gastrectomy (SG) and malabsorptive approach has been evaluated. This trend is associated with differences of the DVT prophylaxis regimen in the profile of bariatric surgical patients depending on BMI and the type of bariatric procedure. Despite the low incidence of DVT and pulmonary embolism (PE) detected, there is a lack of evidence on a reasonable regimen for sufficient DVT prophylaxis in bariatric surgery; instead, there are only recommendations from the guidelines and statements of a specific medical society. Therefore, prospective studies are necessary to determine the optimal DVT prophylaxis for bariatric surgical patients as well as obese patients undergoing surgery.

Status of venous thromboembolism prophylaxis among bariatric surgeons: have we changed our practice during the past decade?

BACKGROUND

Venous thromboembolism (VTE) is considered one of the principal causes of morbidity and mortality in patients requiring bariatric surgery. A survey to all members of the American Society for Metabolic and Bariatric Surgery was conducted in 1998 and published in 2000 in the journal "Obesity Surgery."

METHODS

A survey was repeated to all physician members of the American Society for Metabolic and Bariatric Surgery to determine the current practices for VTE prophylaxis. The results were compared with those of the previous study.

RESULTS

Of the members, 35% completed the survey for a total of 332 responses. The number of cases annually per surgeon almost doubled since 1998 (145 versus 85). Laparoscopic gastric bypass has replaced open gastric bypass as the most common procedure performed, followed by laparoscopic gastric banding as the second most common procedure. Most surgeons (95%) use chemical prophylaxis to prevent VTE, but almost 60% preferred low-molecular-weight heparin compared with 13% in 1998. More than 60% of bariatric surgeons discharged their patients with chemical prophylaxis compared with 12% in 1998. Inferior vena cava filters for prophylaxis are considered by 55% compared with only 7% in 1998. The incidence of reported deep vein thrombosis was significantly lower in 2007 (2.635 versus .93), as was the incidence of pulmonary embolism (.95% versus .75%). Almost 50% of surgeons still reported > or =1 fatality because of VTE complications.

CONCLUSION

Chemical prophylaxis for VTE with some type of heparin is the standard of care for patients undergoing bariatric surgery. Low-molecular-weight heparin is now used by two thirds of the respondents to this survey. Most surgeons who responded to the survey discharged their patients home with heparin, and many consider the use of inferior vena cava filters for VTE prophylaxis. Our findings support the American Society for Metabolic Bariatric Surgery position statement regarding VTE prophylaxis in this patient population. Research is necessary to establish the role of inferior vena cava filters, discharging patients with chemoprophylaxis and to determine the adequate dosage and duration of prophylaxis.

The effect of extended post-discharge chemical thromboprophylaxis on venous thromboembolism rates after bariatric surgery: a prospective comparison trial

BACKGROUND

The effect of extended post-discharge thromboprophylaxis (ETP) on venous thromboembolism (VTE) rates following bariatric surgery (BS) is unknown.

METHODS

308 consecutive patients who underwent BS between 2003 and 2007 and who had > 1 month of follow-up were included. In-hospital-only VTE prophylaxis (group A), or extended 10-day ETP (group B) was used in 132 and 176 patients, respectively. All patients underwent bilateral lower extremity venous Doppler studies (BLEVDS) prior to discharge. Primary endpoint was the incidence of VTE within 30 days postoperatively. VTE was defined as a clinically evident deep vein thrombosis or pulmonary embolism documented by positive BLEVDS, or computed chest tomography. The primary safety endpoint was bleeding associated with > or = 2 g/dL decrease in hemoglobin compared with baseline, transfusion or reoperation.

RESULTS

The incidence of VTE was 1.9% (6/308); 66.6% (4/6) of cases occurred after cessation of thromboprophylaxis. There were no deaths in either group. With the exception of percentage open surgical approach (A: 3% versus B: 0%, p = 0.03), percentage conversions (A: 0 versus B: 3.8%, p = 0.01), and hospital stay (A: 3 versus B: 2.2 days, p < 0.0001), the two groups were comparable in relation to age, sex, body mass index, percentage revision surgery, operative time, and history of VTE. VTE rate was significantly higher in group A (A: 4.5% versus B: 0%, p = 0.006). Although morbidity was higher in group A (A: 12.1% versus B: 1.1%, p < 0.0001), no VTE event occurred in patients who had other complications. The incidence of significant bleeding was lower in group B (A: 5.3% versus B: 0.56%, p = 0.02).

CONCLUSIONS

ETP is safe and effective in reducing the incidence of VTE as compared with in-hospital thromboprophylaxis only.