Although pharmacological measures have been generally the preferred treatment for venous thromboembolism prophylaxis post SCI, mechanical means of limiting venous stasis can also serve to reduce the incidence of DVT post SCI. Mechanical treatments are designed to limit stasis in the paralyzed lower extremities.  However, it should be noted that use of these devices should be accompanied by the twice daily inspection for skin discolourations or breakdown, or broken blood vessels.  As well, pneumatic compression devices are not suitable for patients with severe arterial insufficiency.

Table: Evaluating Physical Methods for the Prevention of DVT

Discussion

Winemiller et al. (1999)did chart audits to conduct a case-control study of 285 SCI patients.  Multivariate analysis suggested that sequential pneumatic compression devices (SCD) or gradient elastic stockings (GES) were associated with a reduced risk of venous thromboembolism.  Multivariate analysis also suggested a decreased risk of venous thromboembolism in patients with SCI treated with heparin within the first 14 days or anytime within 42 days.  Although the risk reduction was approximately twice that at of SCD/GES it was not statistically significant.  

A pre-post study by Chung et al. (2011) found a high incidence (43%) of DVT post SCI in individuals receiving prophylactic mechanical compression on their lower limbs.  The treatment involved the use of gradient elastic stockings, external sequential pneumatic compression and early ambulation.  In order to better examine the effectiveness of mechanical compression, individuals were not offered pharmacological prophylaxis.  This may account for the high rate of DVT incidence.

Becker et al. (1987)studied whether rotating treatment tables would prevent the development and progression of DVT in acute SCI patients.  The authors noted that rotating treatment tables had been used up to that time in acute SCI patients to maintain spinal cord alignment while facilitating nursing care, allowing even distribution of ventilation and preventing pressure sores.  It was hypothesized that because these appliances rotated continuously, they might serve to inhibit thrombosis formation by reducing venous stasis.  This randomized trial involved 15 patients with acute SCIs.  Four of the 5 control (nonrotated) patients developed distal and proximal thrombi, assessed by I¹²⁵ fibrinogen scanning and impedance plethysmography while only one of the 10 treated (rotated) SCI patients developed both distal and proximal venous thrombi (p=0.007).

Conclusion

• There was level 4 (limited) evidence that sequential pneumatic compression devices (SCD) or gradient elastic stockings (GES) were associated with a reduced risk of venous thromboembolism post SCI.
• There is level 1b evidence (based on one small RCT) that rotating treatment tables reduce the incidence of venous thrombi in acute SCI patients.

• Mechanical compression may reduce the incidence of venous thromboembolism post SCI.
• The use of rotating treatment tables reduces the incidence of venous thrombo-embolism post SCI.

Table 10 Combined Pharmacological and Physical Measures for the Prophylaxis of Venous Thromboembolism Post SCI

Discussion

Merli et al. (1992) studied 37 SCI patients who received 2 weeks of prophylaxis with external pneumatic compression plus gradient elastic stockings and low dose heparin 5,000 s/c q12h.  Of 19 patients treated, 17 had negative fibrinogen scanning upon completion of the study while the 2 remaining patients developed a positive fibrinogen scan on days 6 and 8 of the study.  In comparison, the control group developed positive I¹²⁵ fibrinogen scans in 6/17 patients and all were confirmed by venography.  The incidence of thrombosis was significantly different than that of the treated group (p=0.04).

Deep et al. (2001) reported the use of prophylactic DVT treatment involving anti-thromboembolic stockings and 40mg of exnoxaparin during their entire rehabilitation stay resulted in only 2.9% incidence rate of DVT or PE in individuals post SCI. 

Spinal Cord Injury Thromboprophylaxis Investigators conducted two studies (2003a; 2003b) which examined the effect of low-dose unfractionated heparin (UFH) (5000 U subcutaneously every 8 h) plus intermittent pneumatic compression (IPC) (to be used at least 22h/day) or enoxaparin (30 mg subcutaneously every 12 h).  The first study (2003a) found no significant difference between the two groups in the rate of DVT. While the second study found that over a longer term, individuals in the UFH and IPC group had a greater chance of VTE and DVT than those in the enoxaparin group.

Aito et al. (2000)studied 275 SCI patients, 99 of whom were treated within 72 hours of injury while 176 were treated after 8 days post SCI.  The treatment involved permanently dressed gradient elastic stockings, s/c LMWH 0.4 ml once a day, and external sequential pneumatic compression (ESPC) of the lower limbs 3 hrs per day given in 2 applications.  There was early mobilization of the lower limbs.  The complete prophylactic treatment lasted at least 30 days post SCI; LMWH and ESPC were continued for 2 more months depending on the patient’s progress.  For the earlier treated group, DVT incidence was 2% while the incidence in the later treated group was 26%.  Of those 60% were detected at the time of later admission, while the remaining 40% developed in a period not exceeding 6 weeks of hospitalization.  Sixty-five percent of detected DVT did not show any obvious clinical sign.  ASIA A patients were more likely to develop a DVT (36%) while only 7% of ASIA D patients did so on admission.

Green et al. (1982)randomized 28 SCI patients with complete injuries, were randomized to either external pneumatic calf compression (EPCC) alone, and EPCC combined with aspirin (ASA) 300 mg bid and dipyridamole 75 mg bid.  Twenty-seven subjects completed the study – DVT was detected in 9/27 patients, an incidence significantly less than the 78% previously recorded in the 37 patients not receiving prophylaxis (p<0.001).  Thrombi developed in 6/15 patients treated solely with EPCC and in 3/12 receiving ASA/Dipyridamole as well as EPCC (p<0.1).  The authors concluded that early application of pharmacological plus mechanical treatments markedly reduced the risk of DVT complications.

Although there was no moderate to strong evidence that combined measures to provide effective DVT prophylaxis this was a consequence of the quality of the studies. However, it makes sense intuitively, given Virchow’s trial that different measures designed to treat different risk factors would have an additive effect and hence be more effective than individual treatments.

Conclusions

• There is level 4 (limited) evidence that a comprehensive prophylactic treatment of external pneumatic compression, gradient pressure stockings and low dose heparin reduces venous thrombosis post SCI.
• There is level 4 (limited) evidence that a comprehensive prophylactic regimen of pharmacological and physical measures is more effective in preventing venous thrombosis post SCI when instituted early rather than later.
• There was a trend (supported by one RCT) that pneumatic compression plus antiplatelet agents (ASA and Dipyridamole) was more effective than pneumatic compression alone.  Although an RCT, the numbers were small thus the trend was non-significant (p<0.1).

• A combined regiment of pneumatic compression, pressure stockings and low-dose heparin given prophylactically may reduce the incidence of venous thrombosis and the effect is better in early post SCI.