The Role of the Vena Cava Filter in the Prophylaxis and Treatment of PE

I.   Statement of the Problem

Vena caval interruption is a form of PE prophylaxis that is being used more frequently in trauma patients. Patients with ongoing bleeding or those with recent brain, spinal cord or ocular injury will not tolerate even minor amounts of bleeding. Furthermore, multiply injured patients often have extremity injuries which preclude the use of sequential compression devices (SCDs). The decision to place a "prophylactic" vena cava filter in a trauma patient requires a fundamental understanding of the risk:benefit ratio. The data included in this review indicate the risk:benefit ratio is favorable in a high-risk trauma patient. Therefore, the problem becomes defining the "high-risk" patient and the short and long-term complication rates of vena caval interruption.

The literature is somewhat difficult to interpret because each author differs in their definition of a "prophylactic" vena cava filter. It is probably more accurate to use the terms "traditional" and "extended" indications for vena cava filter placement. This review is designed to examine the data available for the use of vena cava filters for "extended" indications in the trauma patient, that is, filter placement early after injury, before the patient has clinical or radiographic evidence of a DVT or PE.

II.   Process

A Medline search from 1980 to 1996 showed five articles when "vena cava filter" was cross-referenced with "trauma". An additional personal review of the literature revealed seven additional articles and two abstracts that address extended indications of vena cava filter placement in trauma patients. Also, there were four articles that specifically addressed complications and long-term follow up with vena cava filters which are included in this review.

III.   Recommendations

A.   Level I

There is a large body of evidence not reviewed in this section to support insertion of a vena cava filter for "traditional" indications in trauma patients. These indications include:

• Recurrent PE despite full anticoagulation,
• Proximal DVT and contraindications to full anticoagulation,
• Proximal DVT and major bleeding while on full anticoagulation,
• Progression of iliofemoral clot despite anticoagulation (rare).

B.   Level II

"Extended" indications for prophylactic vena cava filter placement in a patient with established DVT or PE include:

• Large free-floating thrombus in the iliac vein or IVC,
• Following massive PE in which recurrent emboli may prove fatal,
• During/after surgical embolectomy.

C.   Level III

Insertion of a "prophylactic" vena caval filter should be considered in patients without a DVT/PE:

1. Who cannot receive anticoagulation, and
2. Have one or more of the following injury patterns:
   1. Recent brain injury,
   2. Incomplete spinal cord injury with para or quadriplegia,
   3. Complex pelvic fractures with associated long-bone fractures,
   4. Multiple long-bone fractures,
   5. Major eye injury.

IV.   Scientific Foundation

The placement of a vena cava filter in a trauma patient who does not have an established DVT or PE is certainly controversial. There is no question that vena cava filters are efficacious. They prevent the occurrence of PE from lower extremity DVT with about a 98% success rate.¹ The real issue is defining who should receive these filters, and whether it is without significant complications and cost-effective. There is no data at this point to address the latter, and some recent papers do address the risk factor issue.

Several recent studies have reported on the use of vena caval filters for extended indications. Golueke and coworkers² reported on 21 filters placed prophylactically before total joint replacement. All patients also received low dose heparin, aspirin, and, when possible, graduated compression stockings. There were no filter-related complications or episodes of PE in this group. Likewise, Webb et al. in 1992 reported their results of using a "prophylactic" filter in 24 of 52 patients undergoing acetabular fracture repair with sufficient risk factors.³ They had no insertion complications. Four patients had leg edema, one with phlegmasia, and no PEs. In the 27 patients who did not receive a filter, there were 2 PEs, one of which was fatal. Rohrer and coworkers reported on the use of vena caval filters for "extended" indications in 66 patients (many of whom were trauma patients).⁴ There was only one fatal PE in this group, and 22 patients had no documented DVT before filter insertion. The recurrent nonfatal PE rate was 3%, and symptomatic occlusion of the IVC occurred 4.5% of the time in this study. Major limitations of this study include the retrospective design, inability to distinguish outcomes in the 21 patients with VCF used as prophylaxis from the 45 others, and unspecified follow-up duration.

Jarrell and coworkers⁵ reported a favorable experience with 21 Greenfield filters that were placed in spinal-cord-injured patients with documented DVT or PE and a "traditional" indication for filter insertion. There was only one PE death in this group and two instances of IVC thrombus, both of which were well tolerated.

There are now several reports in the literature of the use of "prophylactic" vena caval filters for extended indications in trauma patients. These studies reveal two PEís, one fatal, in 305 patients, and these studies and are all Class II and III evidence.^6-13 There have been minimal insertion and short-term complications reported; one-year patency rates ranged from 82% to 96%,^9,11 and two-year patency rates have been reported in 96%⁹ of prophylactic filters inserted in trauma patients. Moreover, there does not seem to be a higher DVT rate in prophylactic filter patients compared to non-filter patients.^7,8 The efficacy of vena cava filters preventing PEs is not an issue. The long-range complications and cost-effectiveness of this therapy does need to be studied.

The decision to place a prophylactic filter in a trauma patient requires a fundamental understanding of its risk-benefit ratio. The data would indicate that the risk-benefit ratio is favorable in the high-risk trauma patients. The problem is defining the high-risk patient. One trauma study¹⁴ identified four injury patterns that accounted for 92% of PEs: (1) spinal cord injury with paraplegia or quadriplegia, (2) severe closed head injury with a Glasgow Coma Score £ 8, (3) age > 55 years with isolated long bone fractures, and (4) complex pelvic fractures associated with long bone fractures. Another retrospective review including 9,721 patients¹² showed that the high risk categories include head injury plus spinal cord injury, head injury plus long bone fracture, severe pelvic fracture plus long bone fracture, and multiple long bone fractures. These authors estimate that if they would have utilized a prophylactic filter in these 2% of patients, there would have been a very dramatic reduction in PE. They suggested that patients with an estimated risk of PE of 2% to 5%, despite prophylaxis, are reasonable candidates for prophylactic vena caval filter placement, especially if conventional prophylactic measures cannot be used. Many years of experience with the Greenfield filter indicate that it has a patency rate of about 96%, a recurrent PE rate of 3% to 5%, and a caval penetration rate of about 2%. ⁷ These are reasonable complication rates, but multiplied over the lifetime of a young patient, these rates could become important. There is one study that indicates a significant amount of chronic venous insufficiency in long-term follow up of prophylactic filter patients.¹⁵ However, there was no non-filter group to compare to, so it is not clear if the filter was the cause of this chronic venous insufficiency in this very high risk group.

V.   Summary

There is no Class I literature to support insertion of a vena cava filter in a trauma patient without an established DVT or PE. There is starting to accumulate a fair amount of Class II and III data which may support its use in "high-risk" trauma patients without a documented occurrence of a DVT or PE. At this time, we recommend consideration of IVC filter insertion in patients without a documented DVT or PE who meet high-risk criteria and cannot be anticoagulated.

VI.   Future Investigation

There is an obvious need of Class I randomized, prospective controlled data to either support or refute the use of vena caval interruption in trauma patients. Such studies need to enroll only high risk patients with a sufficiently high enough PE rate to attempt to prove filter efficacy and improve outcome in the patients who receive a truly prophylactic vena cava filter. This study would need to be large and multicenter in nature. The pilot portion of such a study has been completed, and the large multicenter trial should involve many investigators from trauma associations. Other important unresolved issues include the following:

• Do vena cava filters significantly reduce the incidence of clinically important PE in patients who receive "optimal" prophylaxis?
• If so, can a group of patients be identified who have a high failure rate with "optimal" prophylaxis?
• What are the short-term and long-term complications of vena cava filter insertion used as primary prophylaxis in trauma patients?
• Is vena cava filter insertion cost-effective?

Reference Conclusions