Vena cava filtration involves inserting a mechanical filter into the inferior vena cava to prevent devastating pulmonary emboli from occurring.

Table: Prophylactic Greenfield Filter Placement in Selected High-Risk Trauma Patients

Table: Prophylactic Vena Cava Insertion in Patients with Traumatic SCI

Discussion

Four case control studies examined the effect of prophylactic IVC filter insertions on the incidence of DVT after SCI.  Gorman et al. (2009) conducted a retrospective chart review of individuals admitted to SCI rehabilitation receiving IVC filters compared to those that did not.  The study found individuals with IVC filters had a significantly lower incidence rate of DVT than those not on IVC, p=0.021.  The study found DVT was more likely to occur in patients who have experienced a motor vehicle crash than those that have not; furthermore IVC filters were more likely to be inserted in these patients. A 30 or greater Injury Severity Score was highly correlated with the development of DVT.

Khansarinia et al. (1995),in a case control study, compared 108 patients who sustained multiple trauma with known high risk of PE (including SCI patients) and received a prophylactic Greenfiled filter (PGF) to 216 historically matched control patients.  None of the patients in the PGF group had a pulmonary embolism while 13 patients in the control group had a PE (p<0.009), 9 of which were fatal (p<0.03).  The overall mortality rate was reduced in the PGF group (18 of 108, 16%) versus the control group (47 of 216, 22%) but this result was not deemed to be statistically significant.

A case control study compared the installation of Greenfield IVC filter placement in SCI individuals with acute cervical injury to those without cervical injury (Kinney et al. 1996).  The study found filters in cervical patients frequently migrated (45.5%) and the mean migration distance was significantly higher than those individuals with noncervical injury (p<0.05).  Duperier et al. (2001) in a case series involving high risk trauma patients, reported negligible complications and movement of Greenfield filter placement. Hence, it is an effective and safe prophylactic option for DVT.

Rogers et al. (1995)in a case control study, pre-post and comparison with historical controls studied 63 patients receiving a prophylactic vena cava filter – 15 of these patients had head injuries, 25 had SCIs and 23 had pelvic fractures.  Of 3151 admissions to a trauma service, 71 were considered to be in a high-risk category for PE of whom 63 received a prophylactic vena cava filter.  The mean time to insertion of the vena cava filter was 4.3 days post-admission.  Overall, there were 19 patients (30%) with prophylactic vena cava filters who developed a DVT.  When the incidence of pulmonary embolism in a high-risk patient population was compared before and after the prophylactic vena cava filter policy was instituted, there was a significant reduction (p<0.00072) in the incidence of PE in the group receiving the filters. 

In a case series, Roberts et al. (2011) found that the use of a retrievable inferior vena cava filter (IVCF) was effective in reducing incidence of DVT, without any related complications.  Jarrell et al. (1983)studied 21 acute SCI patients in whom a Kim-Ray Greenfield filter was inserted in the inferior vena cava.  One patient with a filter died of a PE.  On follow-up no other PEs were noted while there were two instances of thrombosis of the inferior vena cava.

Wilson et al. (1994)in a retrospective chart audit studied 22 acute traumatic SCI patients who were treated with a vena cava filter insertion.  No complications were associated with vena cava filter insertion.  No patients developed venous thrombosis during acute hospitalization (median 22 days) and no patients developed PE after filter insertion. 

Maxwell et al. (2002) in a retrospective chart audit studied 111 SCI patients to determine if they were different than other trauma patients in terms of the incidence of DVT and PE.  They concluded that inferior vena cava filters were not necessarily needed for SCI patients as the incidence of DVTs and PEs were not that much different than other trauma patients.  Maxwell et al. have noted, “there are high risk  patients with SCI …that probably deserve prophylactic IVC filter placement.  They include patients that have failed DVT prophylaxis or have contraindications to anticoagulation.  SCI patients with long bone fractures also appear to be at extreme risk for DVT and may also benefit from IVC filter placement” (p. 902).

Conclusion

• There is level 3 evidence that inferior vena cava filters significantly reduce the risk of pulmonary emboli in high-risk SCI patients.

• Inferior vena cava filters significantly reduce the risk of pulmonary emboli in high-risk SCI patients.