Question 2e from the first paper of 2000 presents the candidate with a pulmonary embolism scenario, and explores the possibility of IVC filter insertion. The college wanted a list of pros and cons. Since this early paper, the cons seem to have multiplied. The rushed exam candidate should probably limit their reading to the content of this  highly critical 2013 article from PulmCCM, as well as the excellent LITFL page on IVC filter placement. For the time-rich exam candidate, this issue of CHEST published all of the most recent (9th edition) ACCP guidelines. Whereas previously they had a specific set of guidelines for IVC filters, they have now split them all up between different indications, and one needs to hunt though the articles for the recommendations. PulmCCM link to a summary statement which describes them.  The British also have a set of discrete recommendations available (from 2006).

In the interest of future-proofing this topic against as-yet unwritten CICM SAQs, this question will be answered according to a "critically evaluate" template.

Rationale of IVC filter insertion

  • Pulmonary embolis is common, and carries with it a substantial mortality and morbidity.
  • Preventative measures such as mechanical thromboprophylaxis and prophylactic anticoagulation are not uniformly effective, and not always appropriate.
  • Certain at-risk groups will therefore be at increased risk of fatal pulmonary embolism.
  • A mechanical filter may prevent such fatal embolism at the cost of some filter-related complications
  • Therefore, there are certain groups in whom the risk of filter-related complications weighs favourably against the risk of massive PE.

Indications for insertion

  • Absolute contraindication to anticoagulation in a patient with high risk of DVT/PE
    • These might include unsecured aneurysm after SAH,  or recent major gastrointestinal haemorrhage eg. from varices.
  • Complication of anticoagulation which requires it to be reversed
    • eg. significant bleeding while anticoagulated, or HITTS
  • Inability to achieve full anticoagulation for whatever reason
  • Pulmonary emboli while fully anticoagulated
  • Previously, the indications also included pulmonary embolectomy and large free-floating iliofemoral venous thrombus.
  • The ACCP also lament the "extended indications" for placement;  people seem to have started inserting these things prophylactically into all sorts of people who have no evidence of DVT or PE, but who are at risk of it. These groups include trauma, burns, cancer patients, those with clot-induced pulmonary hypertension and those with predictably poor compliance with anticoagulation (eg. the demented elderly).

Advantages of the IVC filter

  • Can be inserted in patients with a contraindication to anticoagulation
  • May decrease the risk of fatal PE
  • Is retrievable, supposedly

Disadvantages of the IVC filter

  • These things do not prevent or treat DVT; they are not a replacement for anticoagulation
  • Venous stasis of lower limbs will occur
  • Though retrievable, in practice fewer than 60% are ever retrieved.
  • Filter related complications, eg malposition,  IVC damage, perforation, IVC thrombosis, and embolism of filter fragments. The filter may even migrate into the pulmonary artery.
  • It may offer no mortality benefit whatsoever.

Insertion of the IVC filter:

  • Interventional radiology procedure
  • Access via the femoral or IJ
  • venogram is performed to define the anatomy
  • Seldinger technique of insertion, with fluoroscopic guidance
  • Desired position is infrarenal

Evidence to support or refute the use of these devices

  • PREPIC trial (2005): 400 patients with proximal DVT, all anticoagulated for a minimum of 3 months, were randomised to either receive a filter or not. The IVC filter reduced the rate of PE from 15% to 6%. However, at 8-year follow-up there was no change in mortality, and the IVC filter group actually had more DVTs.
  • Lots of problems with this trial. For instance, all the patients were anticoagulated, and so did not meet the major indication for IVC filter insertion (i.e. contraindication to anticoagulation).
  • FILTER-PEVI trial (2012): a very specific group; 141 patients undergoing PEVI (percutaneous endovenous intervention) for DVT. The argument was that this clot retrieval procedure can dislodge emboli, and IVC filters should be deployed before you fiddle with the clot material. The trial confirmed that the IVC filters decrease this risk of iatrogenic PE eightfold.  However, the numbers were: 1 in 14 patients vs. 8 in 22 patients.
  • A more pragmatic study (White et al, 2000) looked prospectively at a large group of patients (n = 75,000) of whom 3632 had IVC filters inserted, presumably with conventional indications (i.e. many would have had contraindications for anticoagulation). Depressingly, there did not seem to be any difference in hospitalisation for PE recurrence.
  • A recent retrospective study of major trauma patients (Hemmila et al, 2015) also did not demonstrate any mortality benefit.

References

PulmCCM: April 12, 2013. "Inferior vena cava filters: debatable benefit; rarely removed"

ACCP: Radiologic management of IVC filters, 2012

Prasad, Vinay, Jason Rho, and Adam Cifu. "The inferior vena cava filter: how could a medical device be so well accepted without any evidence of efficacy?." JAMA internal medicine 173.7 (2013): 493-495.

You, John J., et al. "Antithrombotic therapy for atrial fibrillation: antithrombotic therapy and prevention of thrombosis: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines." CHEST Journal 141.2_suppl (2012): e531S-e575S.

Sarosiek, Shayna, Mark Crowther, and J. Mark Sloan. "Indications, complications, and management of inferior vena cava filters: the experience in 952 patients at an academic hospital with a level I trauma center." JAMA internal medicine 173.7 (2013): 513-517.

Linsenmaier, Ulrich, et al. "Indications, management, and complications of temporary inferior vena cava filters." Cardiovascular and interventional radiology21.6 (1998): 464-469.

Baglin, T. P., J. Brush, and M. Streiff. "Guidelines on use of vena cava filters."British journal of haematology 134.6 (2006): 590-595.

Young, Tim, Hangwi Tang, and Rodney Hughes. "Vena caval filters for the prevention of pulmonary embolism." Cochrane Database Syst Rev 2.2 (2010).

Tola, Juan C., Robert Holtzman, and Lawrence Lottenberg. "Bedside placement of inferior vena cava filters in the intensive care unit." The American Surgeon65.9 (1999): 833-7.

Rohrer, Michael J., et al. "Extended indications for placement of an inferior vena cava filter." Journal of vascular surgery 10.1 (1989): 44-50.

These are the papers quoted at the end of the college answer:

Arcasoy, Selim M., and John W. Kreit. "Thrombolytic therapy of pulmonary embolism: a comprehensive review of current evidence." CHEST Journal 115.6 (1999): 1695-1707.

Goldhaber, Samuel Z. "Pulmonary Embolism" NEJM 339(2); 1998  p93·104

Greenfield, Lazar J., and Robert B. Rutherford. "Recommended reporting standards for vena caval filter placement and patient follow-up." Journal of vascular and interventional radiology 10.8 (1999): 1013-1019.

PREPIC Study Group. "Eight-year follow-up of patients with permanent vena cava filters in the prevention of pulmonary embolism the PREPIC (prévention du risque d’embolie pulmonaire par interruption cave) randomized study." Circulation 112.3 (2005): 416-422.

White, Richard H., et al. "A population-based study of the effectiveness of inferior vena cava filter use among patients with venous thromboembolism." Archives of Internal Medicine 160.13 (2000): 2033-2041.

Hemmila, Mark R., et al. "Prophylactic Inferior Vena Cava Filter Placement Does Not Result in a Survival Benefit for Trauma Patients." Annals of surgery 262.4 (2015): 577-585.

Sharifi, Mohsen, et al. "Role of IVC filters in endovenous therapy for deep venous thrombosis: the FILTER-PEVI (filter implantation to lower thromboembolic risk in percutaneous endovenous intervention) trial." Cardiovascular and interventional radiology 35.6 (2012): 1408-1413.