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Safety and efficacy of intravascular ultrasound-guided inferior vena cava filter in super obese bariatric patients
Surgery for Obesity and Related Diseases 4 (2008) 50 –54
Original article
Safety and efficacy of intravascular ultrasound-guided inferior vena cava filter in super obese bariatric patients Clark M. Kardys, M.D., Michael C. Stoner, M.D.*, Mark L. Manwaring, M.D., Michael Barker, M.D., Kenneth G. MacDonald, M.D., John R. Pender, M.D., William H. Chapman, III, M.D. Department of Surgery, Section of Bariatric and Minimally Invasive Surgery and Section of Vascular Surgery, East Carolina University Brody School of Medicine, Greenville, North Carolina Received May 11, 2007; revised September 5, 2007; accepted September 11, 2007
Abstract
Background: The morbidly obese (body mass index ⬎40 kg/m2) are at significant risk of postoperative venous thromboembolism (VTE). Pulmonary embolism is the leading cause of death after Roux-en-Y gastric bypass, approximating .5%. Because of the technical limitations with fluoroscopy and table weight limits, it has been our practice at our university-based bariatric center to offer intravascular ultrasound (IVUS)-guided inferior vena cava filter (IVCF) placement at Roux-en-Y gastric bypass to patients with a history of VTE, hypercoagulable state, or profound immobility. Methods: The hospital and outpatient records of all 594 patients who underwent Roux-en-Y gastric bypass from January 1, 2004 to October 31, 2006 were reviewed. The patients who had undergone concurrent IVUS-guided IVCF placement were selected. The co-morbidities, outcomes, and complications were recorded. Results: Of the 594 patients, 31 (mean body mass index 71.2 ⫾ 2.96 kg/m2) had undergone concurrent IVUS-guided IVCF placement. The indications included a history of VTE (n ⫽ 5), a known hypercoagulable state (n ⫽ 2), and profound immobility (n ⫽ 25). The technical success rate was 96.8%. One filter was malpositioned in the iliac vein. No catheter site complications occurred. A ventilation/perfusion scan and computed tomography scan each detected pulmonary embolism in 2 surviving patients within 2 months postoperatively. Two patients died, 1 on postoperative day 8 and 1 on postoperative day 15 (6.4%). The mean follow-up time was 262.8 ⫾ 37.3 days. Autopsy excluded VTE or IVCF-related issues as the cause of death in both patients. Conclusion: These results suggest the efficacy of IVUS-guided IVCF placement in preventing mortality from pulmonary embolism in high-risk bariatric patients. IVUS-guided IVCF placement can be safely performed with an excellent success rate in high-risk patients who would not otherwise be candidates for intervention because of the technical limitations of fluoroscopy. (Surg Obes Relat Dis 2008;4:50 –54.) © 2008 American Society for Metabolic and Bariatric Surgery. All rights reserved.
Keywords:
Bariatric surgery; Pulmonary embolism; Inferior vena cava filter; Intravascular ultrasound; IVUS
Presented at the American Society of Bariatric Surgeons 24th Annual Meeting, San Diego, California, June 11–16, 2007 *Reprint requests: Michael C. Stoner, M.D., Division of Vascular and Endovascular Surgery, East Carolina University, 600 Moye Boulevard, Greenville, NC 27834. E-mail: [email protected]
Postoperative pulmonary embolism (PE) is the leading cause of death after bariatric surgery, with an incidence as low as .5% to as great as 4% [1–7]. The super obese (body mass index [BMI] ⬎50 kg/m2) are at increased risk of venous thromboembolism (VTE) owing to multiple physical and physiologic factors, with PE rates as great as 28% [1,2,5,6,8 –12]. The mortality from PE in the super obese is reported to be 27–75% [4,6]. Current techniques for deep
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C. M. Kardys et al. / Surgery for Obesity and Related Diseases 4 (2008) 50 –54
venous thrombosis (DVT) prophylaxis include sequential compression devises, early ambulation, and medical prophylaxis with heparin or low-molecular-weight heparin (LMWH) [4,5,13–15]. The success of these protocols in PE prevention in bariatric populations continues to be mixed [4,6,9,16 –18]. Inferior vena cava filters (IVCFs) have previously been shown to decrease the incidence of, and mortality from, PE in bariatric surgery patients [1,4,6,9,13– 15,19 –24]. IVCFs are recommended for those patients with super obesity, decreased mobility, venous insufficiency, a previous thromboembolic event, or known hypercoagulability [4 – 6,13,19]. Some super obese patients are excluded from IVCF placement using fluoroscopy because of table weight limits and inadequate fluoroscopic penetration [25,26]. Transabdominal ultrasonography has been used for IVCF placement; however, its use is limited in all patients by an increased abdominal girth and overlying bowel gas [27–29]. Intravascular ultrasound (IVUS) offers a technique for IVCF placement for bariatric patients, including the super obese [3,9,20,27–34]. The purpose of this study was to examine a contemporary series of IVUS-guided IVCF placement in a high-risk population of bariatric patients. Methods Patient selection A retrospective review of all bariatric patients who underwent IVUS-guided IVCF placement at Roux-en-Y gastric bypass was performed. The recorded data included a history of DVT, PE, hypercoagulable disorder, arthritis, pain in weight-bearing joints, chronic obstructive pulmonary disorder, asthma, obstructive sleep apnea, lower extremity edema, venous insufficiency, age, BMI, complications, occurrence of postoperative PE or DVT, and follow-up duration. The results are reported as the mean ⫾ standard error. Perioperative care Super obese patients and patients with a history of venous insufficiency, hypercoagulable disorder, profound immobility, or a history of VTE were considered for IVCF placement. No specific BMI threshold was used at which all patients underwent IVCF placement; however, those with a BMI ⬎50 kg/m2 were given consideration. Adjunctive DVT prophylaxis at this facility included sequential compression devices or foot pumps placed before surgery and 5000 U of heparin given subcutaneously preoperatively. Patients ambulated the day of surgery if they were not in the intensive care unit. All patients received Enoxaparin 40 mg twice daily on postoperative day 1, and sequential compression devices were used when the patients were in bed. Patients with a BMI ⬎60 kg/m2 were treated with Enoxaparin for 2 weeks postoperatively.
51
Filter insertion technique The patients were placed in the supine position under general anesthesia. Both groins were prepared. The femoral vein, most frequently the right, was cannulated with an 18-gauge needle. The Seldinger technique was used to place an 8F sheath. A second percutaneous access was obtained immediately cephalad to the first, and a 12F sheath was placed. Imaging was performed with a Galaxy 1 scanner (Boston Scientific, Natick, MA). The 8F, 12.5-MHz IVUS probe was passed through the femoral vein cephalad to the IVC and to the right atrium. The catheter was pulled back, visualizing in sequence the hepatic veins, right renal artery, renal veins, and, finally, the iliac confluence before being returned to the level of the renal veins. The IVC was measured at the level of the renal veins to ensure its size was 20 –28 mm in the greatest diameter. With concurrent IVUS imaging, a Stainless Steel Over-the-Wire Greenfield Vena Cava Filter (Boston Scientific) was inserted by way of the 12F sheath and placed so that the filter’s tip rested at or below the mid portion of the renal veins. The filter was deployed, and IVUS was used to view the struts of the filter to ensure appropriate strut spacing and apposition to the vena cava. The sheaths were removed, and pressure was held for 5 minutes. Abdominal radiography was performed postoperatively to verify the location of the filter [28]. Results From January 2004 through October 2006, 31 patients underwent IVUS-guided IVCF placement at Roux-en-Y gastric bypass. Their mean age was 42 ⫾ 1.7 years (range 20 –59). The mean BMI was 71 ⫾ 3.0 kg/m2 (range 38 – 107; Table 1). Of these 31 patients, 29 were super obese with a BMI ⬎50 kg/m2. Of the 2 non–super obese patients, 1 had a history of DVT and the second had obstructive sleep apnea and venous insufficiency. All patients underwent Roux-en-Y gastric bypass performed by either the open (n ⫽ 23) or laparoscopic (n ⫽ 8) technique. The co-morbidities and risk factors included obstructive sleep apnea (n ⫽ 19), pain in weight-bearing joints (n ⫽ 16), lower exTable 1 Patient demographics Age (y) Mean ⫾ SE Range Gender (n) Male Female BMI (kg/m2) Mean ⫾ SE Range Surgical technique (n) Open Laparoscopic BMI ⫽ body mass index.
43 ⫾ 1.8 20–59 12 19 71 ⫾ 3 38–107 22 5
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C. M. Kardys et al. / Surgery for Obesity and Related Diseases 4 (2008) 50 –54
tremity edema (n ⫽ 12), venous insufficiency (n ⫽ 5), previous VTE (n ⫽ 5), and factor V Leiden mutation (n ⫽ 2; Table 2). All patients underwent postoperative abdominal radiography to verify filter position. IVCF placement was unable to be verified owing to inadequate x-ray penetration in 6 patients (19%). The difference in the mean operative time, intensive care unit stay, and hospital length of stay between those with VTE and those without VTE was not statistically significant (Table 3). The mean follow-up time was 262 ⫾ 38 days. One patient was lost to follow-up after 79 days. Two patients died, 1 on postoperative day 8 and 1 on postoperative day 15 (6.4%). The first death was due to bowel necrosis and the second to tracheostomy site hemorrhage. Of these 2 patients, 1 had undergone filter placement in the right iliac vein and had not had an opportunity for filter repositioning. Of the surviving patients, 1 developed an upper extremity DVT (3.1%), and 2 (6.4%) developed PE. One PE was discovered by spiral computed tomography 41 days postoperatively. Another PE was seen on a ventilation/perfusion scan 10 days postoperatively. Of these 2 patients, 1 had undergone laparoscopic Roux-en-Y gastric bypass and 1 open surgery. No IVCF site infections or clinical signs of DVT developed. Discussion Several metabolic and mechanical factors contribute to the hypercoagulable state of the obese. High levels of leptin, C-reactive protein, tumor necrosis factor-alpha, serum amyloid A, plasminogen activator inhibitor-1, adipsin (complement D), adipocyte complement-related protein, and interleukin-6 are all elevated in the obese and contribute to inflammation and hypercoagulability [35,36]. Obesity has been shown to increase intra-abdominal pressure. This creates a chronic abdominal hypertension that is transmitted to the femoral venous system, contributing to obesity-associated venous insufficiency. These mechanical and physical factors lead to an increased incidence of VTE [4,36,37]. Table 2 Co-morbidities Co-morbidity
n
%
History of PE History of VTE Factor V Leiden COPD Asthma Obstructive sleep apnea Venous insufficiency Lower extremity edema Pain in weight-bearing joints Arthritis BMI ⬎50 kg/m2
4 5 2 1 4 19 5 12 16 6 29
13 16 6 3 13 62 16 38 52 19 94
PE ⫽ pulmonary embolism; VTE ⫽ venous thromboembolism; COPD ⫽ chronic obstructive pulmonary disease; BMI ⫽ body mass index.
Table 3 Complications Complication
n
%
Insertion site PE DVT Total VTE Malposition
0 2 1 3 2
0 6.4 3.1 9.5 6.4
Abbreviations as in Table 2.
Super obesity (BMI ⬎50 kg/m2) has been found to be an independent risk factor for perioperative mortality in bariatric patients [4,9]. Carmody et al. [4] demonstrated in a 24-year review of ⬎3800 bariatric patients that a BMI ⬎50 kg/m2, venous stasis disease, and obesity hypoperfusion syndrome were all independent risk factors for PE. Despite prophylaxis recommendations for many patient populations, a national consensus for specific regimens of PE prophylaxis in bariatric patients is lacking [5,13,14]. The widespread use of DVT prophylaxis and the increased frequency of laparoscopic gastric bypass have not decreased the rate of PE. The inadequacy of non–weight-based regiments of heparin and LMWH might have contributed to this limited success [1,4,6,9,17–19,38]. Our patients were given 40 mg of LMWH twice daily for 2 weeks, rather than the standard 40 mg once-daily dose [16,18,38]. It would seem logical that a higher dose of anticoagulant would lead to lower PE rates, despite a lack of conclusive evidence supporting this idea. Several studies have demonstrated that the increased risks of bleeding from weight-based heparin and LMWH regimens are minimal [17,18,38]. Given the low risk and potential for benefit, we have chosen to use a greater than standard dose of LMWH. In 1 study by Gargiulo et al. [6], patients with a BMI ⬎55 kg/m2 who underwent open gastric bypass demonstrated a 10-fold increase in the relative risk of PE. PEs were fatal in 75% of those with a BMI ⬎55 kg/m2. By changing their practice and placing IVCFs in all patients with a BMI ⬎55 kg/m2, they decreased their overall PE rate from 2.1% to 0 and their PE-related mortality from 1.6% to 0. In patients with a BMI ⬎55 kg/m2 who refused IVCF placement, the incidence of PE was 22.5%, with 56% of those patients dying of their PE [6]. The PE rate (6.4%) in our study was greater than the published PE rates (range .5– 4%) across bariatric populations with no stratification by BMI [5,6,8 –12]. The mean BMI in the present study of ⬎71 kg/m2 was 40% greater than the previously stated threshold of 50 kg/m2 for an increased risk of PE. This greater complication rate likely resulted, at least in part, from a selection bias for IVCF placement in patients at very high risk because of super obesity and other co-morbidities. Patients experiencing VTE did have longer operative times and longer intensive care unit and hospital lengths of stay. Our series was inad-
C. M. Kardys et al. / Surgery for Obesity and Related Diseases 4 (2008) 50 –54
equately powered to show a statistically significant difference. Future studies with a larger case series might be able to demonstrate whether these variables are independent risk factors. The 2 PEs that did occur in our study were not fatal. One patient had a BMI of 69 kg/m2, in addition to factor V Leiden mutation. The other patient with a BMI of 64 kg/m2 had a history of VTE, limited mobility, asthma, obstructive sleep apnea, and venous insufficiency. Several techniques are available for IVCF placement in the bariatric population. Traditionally, the IVCF has been placed under fluoroscopic guidance. The fluoroscopy table weight limits (225 kg in our facility) preclude the use of the fixed equipment within the fluoroscopy suite in super obese patients. Within the operating room, portable C-arms might not allow adequate visualization for IVCF placement in the super obese. IVCF placement guided by transabdominal ultrasonography is very difficult in bariatric patients, particularly the super obese. In contrast, the IVUS-guided technique is unaffected by body habitus once the femoral vein has been cannulated [3,28 –31,33,34]. IVUS-guided IVCFs can be placed through either the femoral or the jugular vein. In our study, the femoral vein was used in all cases. IVCFs are not without complications. Complications include strut fracture, filter migration, caval wall erosion, insertion site thrombosis, the risk of DVT, and postphlebitic syndrome. Postphlebitic syndrome is a serious, but rare, complication of IVCF placement. Given the exceptionally high mortality of PE in the super obese and the limited effectiveness of pharmacologic PE prophylaxis in the bariatric patient, we believe that the benefits of PE prophylaxis from IVCF placement outweigh the risks in this population [21,23,24]. In our series, no insertion sight or filter-related complications occurred. Routine ultrasound surveillance for lower extremity DVT was not performed. No patients returned with symptoms of postphlebitic syndrome during a mean follow-up time of 263 days. Another option for PE prophylaxis is placement of removable IVCFs. These filters offer the opportunity for removal under fluoroscopy, generally within the first 6 months of placement [20,22,39]. Many studies of nonbariatric patients have noted that most of these filters are never removed. In some cases, this has resulted from a lack of follow-up. Other factors leading to removal failure have included the inability to collapse the filter, incorporation of the filter into the vessel wall, wall erosion, or clot trapped within the filter [20,39]. In the bariatric population, many of the patients would not have lost adequate weight to be eligible for fluoroscopic removal and would have still been susceptible to the VTE risk factors associated with morbid obesity. A jugular route for removal is also required. Conclusion The super obese and otherwise high-risk bariatric patient is at the greater risk of VTE because of many factors,
53
including venous insufficiency, immobility, obesity hypoventilation syndrome, and metabolic factors. This risk increases as the BMI increases, requiring additional strategies for VTE prophylaxis. As the BMI increases, IVCF placement using fluoroscopic techniques ceases to be feasible because of the patient’s size. Complications of IVCF placement, although significant, are far less catastrophic than the potential complications of PE. The results of this study have demonstrated that IVCFs can be safely placed at surgery, regardless of patient size. These data suggest that IVCF placement is safe and effective in preventing fatal PE. More data are needed to determine IVCF efficacy and the statistical relationship between the morbidity of IVCF and the prevention of PE-related morbidity and mortality in this population. Disclosures The authors have no commercial associations that might be a conflict of interest in relation to this article. References [1] Sapala J. Fatal pulmonary embolism after bariatric operations for morbid obesity: a 24-year retrospective analysis. Obes Surg 2003;13: 819 –25. [2] Livingston E, Huerta S, Arthur D, Lee S, De Shileds S, Herber D. Male gender is a predictor of morbidity and age a predictor of mortality for patients undergoing gastric bypass surgery. Ann Surg 2005;236:576 – 82. [3] Oppat WF, Chiou AC, Matsumura JS. Intravascular ultrasound guided vena cava filter placement. J Endovasc Surg 1999;6:285–7. [4] Carmody BJ, Sugerman HJ, Kellum JM, et al. Pulmonary embolism complicating bariatric surgery: detailed analysis of a single institution’s 24-year experience. J Am Coll Surg 2006;203:831–7. [5] Kaboli P. DVT prophylaxis and anticoagulation in the surgical patient. Med Clin North Am 2003;87:77–110. [6] Gargiulo NJ, Veith FJ, Lipsitz EC, Suggs WD, Ohki T, Goodman E. Experience with inferior vena cava filter placement in patients undergoing open gastric bypass procedures. J Vas Surg 2006;44: 1301–5. [7] Sugerman HJ, Kellum JM, Engle KM, et al. Gastric bypass for treating severe obesity. Am J Clin Nutr 1992;55:560 – 6. [8] Livingston E. Complication of bariatric surgery. Surg Clin North Am 2005;85:853– 68. [9] Ferrell A. Placement of inferior vena cava filters in bariatric surgical patients—possible indications and technical consideration. Obes Surg 2004;14:738 – 43. [10] Livingston E. Procedure, incidence and complication rates of bariatric surgery in the United States. Am J Surg 2004;188:105–10. [11] Yale C. Gastric surgery for morbid obesity: complications and longterm weight control. Arch Surg 1989;124:941– 6. [12] Buchwald H. Bariatric surgery for morbid obesity: health implications for patients, health professionals, and third-party payers. J Am Coll Surg 2005;200:593– 604. [13] Geerts WH, Pineo GF, Heit JA, et al. The seventh ACCP conference on antithrombotic and thrombolytic therapy: evidence-based guidelines. Chest 2004;126:338 – 400. [14] Pieracci F, Barie P, Pomp A. Critical care of the bariatric patient. Crit Care Med 2006;34:1796 –1804.
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[15] Wu E, Barba C. Current practices in the prophylaxis of venous thromboembolism in bariatric surgery. Obes Surg 2000;10:7–13. [16] Shepherd MF, Rosborough TK, Schwartz ML. Heparin thromboprophylaxis in gastric bypass surgery. Obes Surg 2003;13:249 –53. [17] Scholten DJ, Hoedema RM, Scholten SE. A comparison of two different prophylactic dose regimens of low molecular weight heparin in bariatric surgery. Obes Surg 2002;12:19 –24. [18] Shepard MF, Rosborough TK, Schwartz ML. Unfractionated heparin infusion for thromboprophylaxis in highest risk gastric bypass surgery. Obes Surg 2004;14:601–5. [19] Keeling W, Stone P, Armstrong P, Murr M, Shames M. Current indications for preoperative inferior vena cava filter insertion in patients undergoing surgery for morbid obesity. Obes Surg 2005;15: 1009 –12. [20] Rosenthal D, Wellons E, Levitt A, Shuler F, O’Conner R, Henderson V. Role of prophylactic temporary inferior vena cava filters placed at the ICU bedside under intravascular ultrasound guidance in patients with multiple trauma. J Vasc Surg 2004;40:958 – 64. [21] von Bary S, Kühn J, Krieger S, Sobala K. Vena cava filter—prevention of pulmonary embolism: report of clinical experiences. Zentralblatt Chir 1999;124:27–31. [22] Stein P, Alnas M, Skaf E, et al. Outcome and complications of retrievable inferior vena cava filters. Am J Cardiol 2004;94:1090 –3. [23] Becker D, Philbrick J, Selby J. Inferior vena cava filters: indications, safety, effectiveness. Arch Intern Med 1992;152:1985–94. [24] Poletti P, Becker C, Prina L, et al. Long-term results of the Simon nitinol inferior vena cava filter. Eur Radiol 1998;8:289 –94. [25] Ignotus P, Wetton C. CT fluoroscopic guided insertion of inferior vena cava filters. Br J Radiol 2006;79:258 – 60. [26] Brown D, Labuski M, Cardella J, Singh H, Waybill P. Determination of inferior vena cava diameter in the angiography suite: comparison of three common methods. J Vasc Interv Radiol 1999;10:143–7. [27] Garrett J. Expanding options for bedside placement of inferior vena cava filters with intravascular ultrasound when transabdominal duplex ultrasound imaging is inadequate. Ann Vasc Surg 2004;18: 329 –34.
[28] Passman MA, Dattilo JB, Guzman RJ, Naslund TC. Bedside placement of inferior vena cava filters by using transabdominal duplex ultrasonography and intravascular ultrasound imaging. J Vasc Surg 2005;42:1027–32. [29] Neuzil DF, Garrard CL, Berkman RA, Pierce R, Naslund TC. Duplex-directed vena caval filter placement: report of initial experience. Surgery 1998;123:470 – 4. [30] Gamblin T. A prospective evaluation of a bedside technique for placement of inferior vena cava filters: accuracy and limitations of intravascular ultrasound. Am Surg 2003;69:382– 6. [31] Bonn J, Liu J, Eschelman D, Sullivan K, Pinheiro L, Gardiner G. Intravascular ultrasound as an alternative to positive-contrast vena cavography prior to filter placement. J Vasc Interv Radiol 1999;10: 843–9. [32] Ebaugh J, Chiou A, Morasch M, Matsumura J, Pearce W. Bedside vena cava filter placement guided with intravascular ultrasound. J Vasc Surg 2001;24:21– 6. [33] Chiou A. Intravascular ultrasound-guided bedside placement of inferior vena cava filters. Semin Vasc Surg 2006;19:150 – 4. [34] Oppat W, Chiou A, Matsumura J. Bedside vena cava filter placement guided with intravascular ultrasound. J Vasc Surg 1999;34:21– 6. [35] Ahima R, Flier J. Adipose tissue as an endocrine organ. Trends Endocrinol Metab 2000;11:327–32. [36] Kougias P, Chai H, Lin P, Yao Q, Lumsden A, Chen C. Effects of adipocyte-derived cytokines on endothelial functions: implication of vascular disease. J Surg Res 2005;126:121–9. [37] Sugerman H, Sugerman E, Wolfe L, Kellum J, Schweitzer M, DeMaria E. Risks and benefits of gastric bypass in morbidly obese patients with severe venous stasis disease. Ann Surg 2001;234:41– 6. [38] Kalfarentzos F, Yarmenitis S, Kehagias I, et al. Prophylaxis of venous thromboembolism using two different doses of low-molecular-weight heparin (nadroparin) in bariatric surgery: a prospective randomized trial. Obes Surg 2001;11:670 –7. [39] Kirilcuk N, Herget E, Dicker R, Spain D, Hellinger J, Brundage S. Are temporary inferior vena cava filters really temporary. Am J Surg 2005;190:858 – 63.
Original article
Safety and efficacy of intravascular ultrasound-guided inferior vena cava filter in super obese bariatric patients Clark M. Kardys, M.D., Michael C. Stoner, M.D.*, Mark L. Manwaring, M.D., Michael Barker, M.D., Kenneth G. MacDonald, M.D., John R. Pender, M.D., William H. Chapman, III, M.D. Department of Surgery, Section of Bariatric and Minimally Invasive Surgery and Section of Vascular Surgery, East Carolina University Brody School of Medicine, Greenville, North Carolina Received May 11, 2007; revised September 5, 2007; accepted September 11, 2007
Abstract
Background: The morbidly obese (body mass index ⬎40 kg/m2) are at significant risk of postoperative venous thromboembolism (VTE). Pulmonary embolism is the leading cause of death after Roux-en-Y gastric bypass, approximating .5%. Because of the technical limitations with fluoroscopy and table weight limits, it has been our practice at our university-based bariatric center to offer intravascular ultrasound (IVUS)-guided inferior vena cava filter (IVCF) placement at Roux-en-Y gastric bypass to patients with a history of VTE, hypercoagulable state, or profound immobility. Methods: The hospital and outpatient records of all 594 patients who underwent Roux-en-Y gastric bypass from January 1, 2004 to October 31, 2006 were reviewed. The patients who had undergone concurrent IVUS-guided IVCF placement were selected. The co-morbidities, outcomes, and complications were recorded. Results: Of the 594 patients, 31 (mean body mass index 71.2 ⫾ 2.96 kg/m2) had undergone concurrent IVUS-guided IVCF placement. The indications included a history of VTE (n ⫽ 5), a known hypercoagulable state (n ⫽ 2), and profound immobility (n ⫽ 25). The technical success rate was 96.8%. One filter was malpositioned in the iliac vein. No catheter site complications occurred. A ventilation/perfusion scan and computed tomography scan each detected pulmonary embolism in 2 surviving patients within 2 months postoperatively. Two patients died, 1 on postoperative day 8 and 1 on postoperative day 15 (6.4%). The mean follow-up time was 262.8 ⫾ 37.3 days. Autopsy excluded VTE or IVCF-related issues as the cause of death in both patients. Conclusion: These results suggest the efficacy of IVUS-guided IVCF placement in preventing mortality from pulmonary embolism in high-risk bariatric patients. IVUS-guided IVCF placement can be safely performed with an excellent success rate in high-risk patients who would not otherwise be candidates for intervention because of the technical limitations of fluoroscopy. (Surg Obes Relat Dis 2008;4:50 –54.) © 2008 American Society for Metabolic and Bariatric Surgery. All rights reserved.
Keywords:
Bariatric surgery; Pulmonary embolism; Inferior vena cava filter; Intravascular ultrasound; IVUS
Presented at the American Society of Bariatric Surgeons 24th Annual Meeting, San Diego, California, June 11–16, 2007 *Reprint requests: Michael C. Stoner, M.D., Division of Vascular and Endovascular Surgery, East Carolina University, 600 Moye Boulevard, Greenville, NC 27834. E-mail: [email protected]
Postoperative pulmonary embolism (PE) is the leading cause of death after bariatric surgery, with an incidence as low as .5% to as great as 4% [1–7]. The super obese (body mass index [BMI] ⬎50 kg/m2) are at increased risk of venous thromboembolism (VTE) owing to multiple physical and physiologic factors, with PE rates as great as 28% [1,2,5,6,8 –12]. The mortality from PE in the super obese is reported to be 27–75% [4,6]. Current techniques for deep
1550-7289/08/$ – see front matter © 2008 American Society for Metabolic and Bariatric Surgery. All rights reserved. doi:10.1016/j.soard.2007.09.015
C. M. Kardys et al. / Surgery for Obesity and Related Diseases 4 (2008) 50 –54
venous thrombosis (DVT) prophylaxis include sequential compression devises, early ambulation, and medical prophylaxis with heparin or low-molecular-weight heparin (LMWH) [4,5,13–15]. The success of these protocols in PE prevention in bariatric populations continues to be mixed [4,6,9,16 –18]. Inferior vena cava filters (IVCFs) have previously been shown to decrease the incidence of, and mortality from, PE in bariatric surgery patients [1,4,6,9,13– 15,19 –24]. IVCFs are recommended for those patients with super obesity, decreased mobility, venous insufficiency, a previous thromboembolic event, or known hypercoagulability [4 – 6,13,19]. Some super obese patients are excluded from IVCF placement using fluoroscopy because of table weight limits and inadequate fluoroscopic penetration [25,26]. Transabdominal ultrasonography has been used for IVCF placement; however, its use is limited in all patients by an increased abdominal girth and overlying bowel gas [27–29]. Intravascular ultrasound (IVUS) offers a technique for IVCF placement for bariatric patients, including the super obese [3,9,20,27–34]. The purpose of this study was to examine a contemporary series of IVUS-guided IVCF placement in a high-risk population of bariatric patients. Methods Patient selection A retrospective review of all bariatric patients who underwent IVUS-guided IVCF placement at Roux-en-Y gastric bypass was performed. The recorded data included a history of DVT, PE, hypercoagulable disorder, arthritis, pain in weight-bearing joints, chronic obstructive pulmonary disorder, asthma, obstructive sleep apnea, lower extremity edema, venous insufficiency, age, BMI, complications, occurrence of postoperative PE or DVT, and follow-up duration. The results are reported as the mean ⫾ standard error. Perioperative care Super obese patients and patients with a history of venous insufficiency, hypercoagulable disorder, profound immobility, or a history of VTE were considered for IVCF placement. No specific BMI threshold was used at which all patients underwent IVCF placement; however, those with a BMI ⬎50 kg/m2 were given consideration. Adjunctive DVT prophylaxis at this facility included sequential compression devices or foot pumps placed before surgery and 5000 U of heparin given subcutaneously preoperatively. Patients ambulated the day of surgery if they were not in the intensive care unit. All patients received Enoxaparin 40 mg twice daily on postoperative day 1, and sequential compression devices were used when the patients were in bed. Patients with a BMI ⬎60 kg/m2 were treated with Enoxaparin for 2 weeks postoperatively.
51
Filter insertion technique The patients were placed in the supine position under general anesthesia. Both groins were prepared. The femoral vein, most frequently the right, was cannulated with an 18-gauge needle. The Seldinger technique was used to place an 8F sheath. A second percutaneous access was obtained immediately cephalad to the first, and a 12F sheath was placed. Imaging was performed with a Galaxy 1 scanner (Boston Scientific, Natick, MA). The 8F, 12.5-MHz IVUS probe was passed through the femoral vein cephalad to the IVC and to the right atrium. The catheter was pulled back, visualizing in sequence the hepatic veins, right renal artery, renal veins, and, finally, the iliac confluence before being returned to the level of the renal veins. The IVC was measured at the level of the renal veins to ensure its size was 20 –28 mm in the greatest diameter. With concurrent IVUS imaging, a Stainless Steel Over-the-Wire Greenfield Vena Cava Filter (Boston Scientific) was inserted by way of the 12F sheath and placed so that the filter’s tip rested at or below the mid portion of the renal veins. The filter was deployed, and IVUS was used to view the struts of the filter to ensure appropriate strut spacing and apposition to the vena cava. The sheaths were removed, and pressure was held for 5 minutes. Abdominal radiography was performed postoperatively to verify the location of the filter [28]. Results From January 2004 through October 2006, 31 patients underwent IVUS-guided IVCF placement at Roux-en-Y gastric bypass. Their mean age was 42 ⫾ 1.7 years (range 20 –59). The mean BMI was 71 ⫾ 3.0 kg/m2 (range 38 – 107; Table 1). Of these 31 patients, 29 were super obese with a BMI ⬎50 kg/m2. Of the 2 non–super obese patients, 1 had a history of DVT and the second had obstructive sleep apnea and venous insufficiency. All patients underwent Roux-en-Y gastric bypass performed by either the open (n ⫽ 23) or laparoscopic (n ⫽ 8) technique. The co-morbidities and risk factors included obstructive sleep apnea (n ⫽ 19), pain in weight-bearing joints (n ⫽ 16), lower exTable 1 Patient demographics Age (y) Mean ⫾ SE Range Gender (n) Male Female BMI (kg/m2) Mean ⫾ SE Range Surgical technique (n) Open Laparoscopic BMI ⫽ body mass index.
43 ⫾ 1.8 20–59 12 19 71 ⫾ 3 38–107 22 5
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tremity edema (n ⫽ 12), venous insufficiency (n ⫽ 5), previous VTE (n ⫽ 5), and factor V Leiden mutation (n ⫽ 2; Table 2). All patients underwent postoperative abdominal radiography to verify filter position. IVCF placement was unable to be verified owing to inadequate x-ray penetration in 6 patients (19%). The difference in the mean operative time, intensive care unit stay, and hospital length of stay between those with VTE and those without VTE was not statistically significant (Table 3). The mean follow-up time was 262 ⫾ 38 days. One patient was lost to follow-up after 79 days. Two patients died, 1 on postoperative day 8 and 1 on postoperative day 15 (6.4%). The first death was due to bowel necrosis and the second to tracheostomy site hemorrhage. Of these 2 patients, 1 had undergone filter placement in the right iliac vein and had not had an opportunity for filter repositioning. Of the surviving patients, 1 developed an upper extremity DVT (3.1%), and 2 (6.4%) developed PE. One PE was discovered by spiral computed tomography 41 days postoperatively. Another PE was seen on a ventilation/perfusion scan 10 days postoperatively. Of these 2 patients, 1 had undergone laparoscopic Roux-en-Y gastric bypass and 1 open surgery. No IVCF site infections or clinical signs of DVT developed. Discussion Several metabolic and mechanical factors contribute to the hypercoagulable state of the obese. High levels of leptin, C-reactive protein, tumor necrosis factor-alpha, serum amyloid A, plasminogen activator inhibitor-1, adipsin (complement D), adipocyte complement-related protein, and interleukin-6 are all elevated in the obese and contribute to inflammation and hypercoagulability [35,36]. Obesity has been shown to increase intra-abdominal pressure. This creates a chronic abdominal hypertension that is transmitted to the femoral venous system, contributing to obesity-associated venous insufficiency. These mechanical and physical factors lead to an increased incidence of VTE [4,36,37]. Table 2 Co-morbidities Co-morbidity
n
%
History of PE History of VTE Factor V Leiden COPD Asthma Obstructive sleep apnea Venous insufficiency Lower extremity edema Pain in weight-bearing joints Arthritis BMI ⬎50 kg/m2
4 5 2 1 4 19 5 12 16 6 29
13 16 6 3 13 62 16 38 52 19 94
PE ⫽ pulmonary embolism; VTE ⫽ venous thromboembolism; COPD ⫽ chronic obstructive pulmonary disease; BMI ⫽ body mass index.
Table 3 Complications Complication
n
%
Insertion site PE DVT Total VTE Malposition
0 2 1 3 2
0 6.4 3.1 9.5 6.4
Abbreviations as in Table 2.
Super obesity (BMI ⬎50 kg/m2) has been found to be an independent risk factor for perioperative mortality in bariatric patients [4,9]. Carmody et al. [4] demonstrated in a 24-year review of ⬎3800 bariatric patients that a BMI ⬎50 kg/m2, venous stasis disease, and obesity hypoperfusion syndrome were all independent risk factors for PE. Despite prophylaxis recommendations for many patient populations, a national consensus for specific regimens of PE prophylaxis in bariatric patients is lacking [5,13,14]. The widespread use of DVT prophylaxis and the increased frequency of laparoscopic gastric bypass have not decreased the rate of PE. The inadequacy of non–weight-based regiments of heparin and LMWH might have contributed to this limited success [1,4,6,9,17–19,38]. Our patients were given 40 mg of LMWH twice daily for 2 weeks, rather than the standard 40 mg once-daily dose [16,18,38]. It would seem logical that a higher dose of anticoagulant would lead to lower PE rates, despite a lack of conclusive evidence supporting this idea. Several studies have demonstrated that the increased risks of bleeding from weight-based heparin and LMWH regimens are minimal [17,18,38]. Given the low risk and potential for benefit, we have chosen to use a greater than standard dose of LMWH. In 1 study by Gargiulo et al. [6], patients with a BMI ⬎55 kg/m2 who underwent open gastric bypass demonstrated a 10-fold increase in the relative risk of PE. PEs were fatal in 75% of those with a BMI ⬎55 kg/m2. By changing their practice and placing IVCFs in all patients with a BMI ⬎55 kg/m2, they decreased their overall PE rate from 2.1% to 0 and their PE-related mortality from 1.6% to 0. In patients with a BMI ⬎55 kg/m2 who refused IVCF placement, the incidence of PE was 22.5%, with 56% of those patients dying of their PE [6]. The PE rate (6.4%) in our study was greater than the published PE rates (range .5– 4%) across bariatric populations with no stratification by BMI [5,6,8 –12]. The mean BMI in the present study of ⬎71 kg/m2 was 40% greater than the previously stated threshold of 50 kg/m2 for an increased risk of PE. This greater complication rate likely resulted, at least in part, from a selection bias for IVCF placement in patients at very high risk because of super obesity and other co-morbidities. Patients experiencing VTE did have longer operative times and longer intensive care unit and hospital lengths of stay. Our series was inad-
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equately powered to show a statistically significant difference. Future studies with a larger case series might be able to demonstrate whether these variables are independent risk factors. The 2 PEs that did occur in our study were not fatal. One patient had a BMI of 69 kg/m2, in addition to factor V Leiden mutation. The other patient with a BMI of 64 kg/m2 had a history of VTE, limited mobility, asthma, obstructive sleep apnea, and venous insufficiency. Several techniques are available for IVCF placement in the bariatric population. Traditionally, the IVCF has been placed under fluoroscopic guidance. The fluoroscopy table weight limits (225 kg in our facility) preclude the use of the fixed equipment within the fluoroscopy suite in super obese patients. Within the operating room, portable C-arms might not allow adequate visualization for IVCF placement in the super obese. IVCF placement guided by transabdominal ultrasonography is very difficult in bariatric patients, particularly the super obese. In contrast, the IVUS-guided technique is unaffected by body habitus once the femoral vein has been cannulated [3,28 –31,33,34]. IVUS-guided IVCFs can be placed through either the femoral or the jugular vein. In our study, the femoral vein was used in all cases. IVCFs are not without complications. Complications include strut fracture, filter migration, caval wall erosion, insertion site thrombosis, the risk of DVT, and postphlebitic syndrome. Postphlebitic syndrome is a serious, but rare, complication of IVCF placement. Given the exceptionally high mortality of PE in the super obese and the limited effectiveness of pharmacologic PE prophylaxis in the bariatric patient, we believe that the benefits of PE prophylaxis from IVCF placement outweigh the risks in this population [21,23,24]. In our series, no insertion sight or filter-related complications occurred. Routine ultrasound surveillance for lower extremity DVT was not performed. No patients returned with symptoms of postphlebitic syndrome during a mean follow-up time of 263 days. Another option for PE prophylaxis is placement of removable IVCFs. These filters offer the opportunity for removal under fluoroscopy, generally within the first 6 months of placement [20,22,39]. Many studies of nonbariatric patients have noted that most of these filters are never removed. In some cases, this has resulted from a lack of follow-up. Other factors leading to removal failure have included the inability to collapse the filter, incorporation of the filter into the vessel wall, wall erosion, or clot trapped within the filter [20,39]. In the bariatric population, many of the patients would not have lost adequate weight to be eligible for fluoroscopic removal and would have still been susceptible to the VTE risk factors associated with morbid obesity. A jugular route for removal is also required. Conclusion The super obese and otherwise high-risk bariatric patient is at the greater risk of VTE because of many factors,
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including venous insufficiency, immobility, obesity hypoventilation syndrome, and metabolic factors. This risk increases as the BMI increases, requiring additional strategies for VTE prophylaxis. As the BMI increases, IVCF placement using fluoroscopic techniques ceases to be feasible because of the patient’s size. Complications of IVCF placement, although significant, are far less catastrophic than the potential complications of PE. The results of this study have demonstrated that IVCFs can be safely placed at surgery, regardless of patient size. These data suggest that IVCF placement is safe and effective in preventing fatal PE. More data are needed to determine IVCF efficacy and the statistical relationship between the morbidity of IVCF and the prevention of PE-related morbidity and mortality in this population. Disclosures The authors have no commercial associations that might be a conflict of interest in relation to this article. References [1] Sapala J. Fatal pulmonary embolism after bariatric operations for morbid obesity: a 24-year retrospective analysis. Obes Surg 2003;13: 819 –25. [2] Livingston E, Huerta S, Arthur D, Lee S, De Shileds S, Herber D. Male gender is a predictor of morbidity and age a predictor of mortality for patients undergoing gastric bypass surgery. Ann Surg 2005;236:576 – 82. [3] Oppat WF, Chiou AC, Matsumura JS. Intravascular ultrasound guided vena cava filter placement. J Endovasc Surg 1999;6:285–7. [4] Carmody BJ, Sugerman HJ, Kellum JM, et al. Pulmonary embolism complicating bariatric surgery: detailed analysis of a single institution’s 24-year experience. J Am Coll Surg 2006;203:831–7. [5] Kaboli P. DVT prophylaxis and anticoagulation in the surgical patient. Med Clin North Am 2003;87:77–110. [6] Gargiulo NJ, Veith FJ, Lipsitz EC, Suggs WD, Ohki T, Goodman E. Experience with inferior vena cava filter placement in patients undergoing open gastric bypass procedures. J Vas Surg 2006;44: 1301–5. [7] Sugerman HJ, Kellum JM, Engle KM, et al. Gastric bypass for treating severe obesity. Am J Clin Nutr 1992;55:560 – 6. [8] Livingston E. Complication of bariatric surgery. Surg Clin North Am 2005;85:853– 68. [9] Ferrell A. Placement of inferior vena cava filters in bariatric surgical patients—possible indications and technical consideration. Obes Surg 2004;14:738 – 43. [10] Livingston E. Procedure, incidence and complication rates of bariatric surgery in the United States. Am J Surg 2004;188:105–10. [11] Yale C. Gastric surgery for morbid obesity: complications and longterm weight control. Arch Surg 1989;124:941– 6. [12] Buchwald H. Bariatric surgery for morbid obesity: health implications for patients, health professionals, and third-party payers. J Am Coll Surg 2005;200:593– 604. [13] Geerts WH, Pineo GF, Heit JA, et al. The seventh ACCP conference on antithrombotic and thrombolytic therapy: evidence-based guidelines. Chest 2004;126:338 – 400. [14] Pieracci F, Barie P, Pomp A. Critical care of the bariatric patient. Crit Care Med 2006;34:1796 –1804.
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