Venous Thromboembolism, Adult Trauma Patients

Authors

Rogers, Frederick B. MD; Cipolle, Mark D. MD, PhD; Velmahos, George MD, PhD; Rozycki, Grace MD; Luchette, Fred A. MD

Author Information

From the University of Vermont, Department of Surgery, Fletcher Allen Health Care (F.B.R.), Burlington, Vermont, Department of Surgery, Lehigh Valley Hospital (M.D.C.), Allentown, Pennsylvania, Department of Surgery, Division of Trauma and Critical Care, University of Southern California (G.V.), Los Angeles, California, Department of Surgery, Emory University School of Medicine, Atlanta, Georgia, and Department of Surgery, Division of Trauma, Critical Care, and Burns, Loyola University Medical Center (F.A.L.), Maywood, Illinois.

Submitted for publication September 1, 2001.

Accepted for publication March 15, 2002.

Any reference in this guideline to a specific commercial product, process, or service by trade name, trademark, or manufacturer does not constitute or imply an endorsement, recommendation, or any favoritism by the authors or EAST. The views and opinions of the authors do not necessarily state or reflect those of EAST and shall not be used for advertising or product endorsement purposes.

Address for reprints: Frederick B. Rogers, MD, University of Vermont Department of Surgery, Fletcher Allen Health Care, 111 Colchester Avenue, Burlington, VT 05401; email: frederick.rogers@vtmednet.org.

Statement of the Problem

In 1983, Gardner and Fox^[23] discovered a venous pump on the sole of the foot that consists of a plexus of veins that fills by gravity and empties on weightbearing, thus increasing femoral blood flow without muscular assistance. A mechanical device, the arteriovenous (A-V) foot pump, has been developed to mimic this effect of weightbearing. The major advantage of this system is that it only requires access to the foot, which enables its use in patients with Jones dressings, casts, or externally fixed limbs that previously were unsuitable for a PCD. One study has shown that the pulsatile action of the A-V foot pump increased venous blood flow velocity in the popliteal vein by 250%.^[24]

Process

With the recent clinical introduction of the A-V foot pump, there is a paucity of relevant literature related to this subject. A MEDLINE review dating back to 1980 revealed 12 articles on A-V foot pumps, with 8 articles specifically related to the use of A-V foot pumps in the trauma patient. These eight studies were the basis for the recommendations below (Table 3).

Recommendations

A. Level I: A Level I recommendation for this topic cannot be supported because of insufficient data.

B. Level II: A Level II recommendation for this topic cannot be supported because of insufficient data.

C. Level III: A-V foot pumps may be used as a substitute for pneumatic compression devices in those high-risk trauma patients who cannot wear PCDs because of external fixators or casts and cannot be anticoagulated because of their injuries. It should be noted that in trauma patients, A-V foot pumps have not been shown to be as efficacious as PCDs and are associated with some significant complications.^[12][25][26]

Scientific Foundation

Most of the studies involving the use of A-V foot pumps are found in the orthopedic literature, and many of these series involve small numbers of patients. Although little has been documented on the effects of A-V footpumps on DVT in trauma patients, other beneficial effects have been observed. In 71 patients who had operations or casts for traumatic lower extremity injuries, Gardner and Fox^[27] showed a significant decrease in pain, swelling, and measurement of compartment pressures in the affected extremities with the use of the A-V foot pumps. In the discussion to this article, the authors hypothesized that the increased blood flow seen with the pumps was because of hyperemia mediated by endothelial-derived relaxing factor (now thought to be nitric oxide) that was liberated by the endothelium secondary to sudden pressure changes, which could have been caused by the A-V pumps. This endothelial-derived relaxing factor release could encourage the opening of critically closed capillaries, enabling reabsorption of fluid, hence the decrease in compartment pressures. In addition, reports have been documented of A-V foot pumps improving arterial blood flow with the relief of ischemic rest pain.^[28][29] In addition to preventing VTE, all of these proposed foot pump mechanisms of action may be potentially beneficial in healing extremity injuries.

In a recent prospective randomized study by Knudson et al.,^[12] A-V foot pumps were one arm of a number of prophylactic measures (LMWH and PCDs were the other arms) used to prevent DVT in high-risk trauma patients. Of 372 patients enrolled in the study, the DVT rate was 5.7% for the A-V foot pumps, 2.5% for the PCDs, and 0.8% for the low-molecular-weight heparin as determined on follow-up serial duplex ultrasound. Of note, in 8 of 53 patients who wore foot pumps, severe skin changes, including blistering and wound problems, occurred. This required three patients to be removed early from the study.

Spain et al.^[25] compared the use of A-V foot pumps to PCDs in 184 consecutively injured patients. In this nonrandomized study, patients who could not receive a PCD because of lower extremity injuries were placed in A-V foot pumps. Overall, no significant difference was seen in DVT rates between the two groups, with PCDs at 7% and A-V foot pumps at 3%. The authors of this study concluded that A-V foot pumps were a reasonable alternative to PCDs when lower extremity fractures preclude the use of PCDs. Anglen et al.^[26]performed a randomized prospective trial comparing A-V foot pumps with PCDs in high-risk orthopedic patients and followed them with serial ultrasound. In 124 patients, the overall incidence of DVT was 4% in those with A-V foot pumps and 0% in those with PCDs. Unfortunately, meaningful analysis of such a study was confounded by the heterogeneity of the two groups and the fact that a sizable number of patients received either aspirin or warfarin postoperatively. In another study by Anglen et al.^[30] in a trauma population of ICU and ward patients, the A-V foot pumps were found to be applied properly and functioning correctly only 59% of the time, a problem similar to that reported by Comerota et al.^[31] for PCDs.

Summary

Only one clinical series in trauma patients compares A-V foot pumps with other standard techniques of DVT prophylaxis. The results from this series were not definitive in terms of benefits of A-V foot pumps preventing DVT. However, a use of A-V foot pumps may exist in the high-risk trauma patient who has a contraindication to heparin because of injuries or who cannot have PCDs placed on lower extremities secondary to external fixators or large bulky dressings.

Future Investigations

Prospective randomized studies are needed comparing A-V foot pumps to standard prophylactic measures in trauma patients at high risk for the development of DVT.

Acknowledgment

We thank Jody Ciano for her help in the preparation of this article.

References

1. Pasquale M, Fabian TC, and the EAST Ad Hoc Committee on Guidelines Development. Practice management guidelines for trauma from the Eastern Association for the Surgery of Trauma. J Trauma. 1998; 44: 941-957.
2. Interim Manual for Clinical Practice Guideline Development. Rockville, MD: Agency for Health Care Policy and Research; May 1991.
3. Knudson MM, Lewis FR, Clinton A, et al. Prevention of venous thromboembolism in trauma patients. J Trauma. 1994; 37: 480-487.
4. Kudsk KA, Fabian T, Baum S, et al. Silent deep venous thrombosis in immobilized multiple trauma patients. Am J Surg. 1989; 158: 515-519.
5. Velmahos GC, Nigro J, Tatevossian R, et al. Inability of an aggressive policy of thromboprophylaxis to prevent deep venous thrombosis (DVT) in critically injured patients: are current methods of DVT prophylaxis insufficient? J Am Coll Surg. 1998; 187: 529-533.
6. Spain DA, Richardson JD, Polk JR, et al. Venous thromboembolism in the high-risk trauma patient: do risks justify aggressive screening and prophylaxis? J Trauma. 1997; 42: 463-469.
7. Dennis JW, Menawat S, Von Thron J, et al. Efficacy of deep venous thrombosis prophylaxis in trauma patients and identification of high-risk groups. J Trauma. 1993; 35: 132-139.
8. Meyer CS, Blebea J, Davis K Jr, Fowl R, Kempsczinski RF. Surveillance venous scans for deep venous thrombosis in multiple trauma patients. Ann Vasc Surg. 1995; 9: 109-114.
9. Piotrowski JJ, Alexander JJ, Brandt CP, et al. Is deep vein thrombosis surveillance warranted in high-risk patients? Am J Surg. 1996; 172: 210-213.
10. Napolitano LM, Garlapati VS, Heard SO, et al. Asymptomatic deep venous thrombosis in the trauma patient: is an aggressive screening protocol justified? J Trauma. 1995; 39: 651-659.
11. Geerts WH, Code KJ, Jay RM, et al. A prospective study of venous thromboembolism after major trauma. N Engl J Med. 1994; 331: 1601-1606.
12. Knudson MM, Morabito D, Paiement GD, et al. Use of low molecular weight heparin in preventing thromboembolism in trauma patients. J Trauma. 1996; 41: 446-459.
13. Abelseth G, Buckley RE, Pineo GE, et al. Incidence of deep vein thrombosis in patients with fractures of the lower extremity distal to the hip. J Orthop Trauma. 1996; 10: 230-235.
14. Upchurch GR Jr, Demling RH, Davies J, et al. Efficacy of subcutaneous heparin in prevention of venous thromboembolic events in trauma patients. Am Surg. 1995; 61: 749-755.
15. Knudson MM, Collins JA, Goodman SB, et al. Thromboembolism following multiple trauma. J Trauma. 1992; 32: 2-11.
16. Hill SL, Berry RE, Ruiz AJ. Deep venous thrombosis in the trauma patient. Am Surg. 1994; 60: 405-408.
17. Geerts WH, Jay RM, Code KI, et al. A comparison of low-dose heparin with low-molecular weight heparin as prophylaxis against venous thromboembolism after major trauma. N Engl J Med. 1996; 335: 701-707.
18. Waring WP, Karunas RS. Acute spinal cord injury and the incidence of clinically occurring thromboembolic disease. Paraplegia. 1991; 29: 8-16.
19. Spannagel U, Kujath P. Low molecular weight heparin for the prevention of thromboembolism in outpatients immobilized by plaster cast. Semin Thromb Hemost. 1993; 19 (suppl 1): 131-141.
20. Shackford SR, Davis JW, Hollingsworth-Fridlund P, et al. Venous thromboembolism in patients with major trauma. Am J Surg. 1990; 159: 365-369.
21. Ruiz AJ, Hill SL, Berry RE. Heparin, deep venous thrombosis, and trauma patients. Am J Surg. 1991; 162: 159-162.
22. Velmahos GC, Kern J, Chan L, et al. Prevention of venous thromboembolism after injury: an evidence-based report-part I: analysis of risk factors and evaluation of the role of vena cava filters. J Trauma. 2000; 49: 132-139.
23. Gardner AMN, Fox RH. The venous pump of the human foot: preliminary report. Bristol Med Chir J. 1983; 98: 109-112.
24. Laverick MD, McGivern RC, Crone MD, Mollan RAB. A comparison of the effects of electrical calf muscle stimulation and the venous foot pump on venous blood flow in the lower leg. Phlebology. 1990; 5: 285-290.
25. Spain DA, Bergamini, Hoffman JF, et al. Comparison of sequential compression devices and foot pumps for prophylaxis of deep venous thrombosis in high-risk trauma patients.Am Surg. 1998;64:522-526.
26. Anglen JO, Bagby C, George R. A randomized comparison of sequential-gradient calf compression with intermittent plantar compression for prevention of venous thrombosis in orthopedic trauma patients: preliminary results. Am J Orthop. 1998; 33: 53-57.
27. Gardner AM, Fox RH, Lawrence C, et al. Reduction of post-traumatic swelling and compartment pressure by impulse compression of the foot. J Bone Joint Surg Br. 1990; 72: 810-815.
28. Morgan RH, Carolan G, Psaila JV, et al. Arterial flow enhancement by impulse compression. Vasc Surg. 1991; 25: 8-15.
29. Abu-Own A, Cheatle T, Scurr JH, et al. Effects of intermittent pneumatic compression of the foot on microcirculatory function in arterial disease. Eur J Vasc Surg. 1993; 7: 488-492.
30. Anglen JO, Goss K, Edwards J, Heickfeldt RE. Foot pump prophylaxis for deep venous thrombosis: the rate of effective usage in trauma patients. Am J Orthop. 1998; 27: 580-582.
31. Comerota AJ, Katz ML, White JV. Why does prophylaxis with external pneumatic compression for deep vein thrombosis fail? Am J Surg. 1992; 164: 265-268.
32. Caprini JA, Arcelus JI, Hoffman K, et al. Prevention of venous thromboembolism in North America: results of a survey among general surgeons. J Vasc Surg. 1994; 20: 751-758.
33. Pidala MJ, Donovan DL, Kepley RF. A prospective study on intermittent pneumatic compression in the prevention of deep vein thrombosis in patients undergoing total hip or total knee replacement. Surg Gynecol Obstet. 1992; 175: 47-51.
34. Woolson ST, Watt JM. Intermittent pneumatic compression to prevent proximal deep venous thrombosis during and after total hip replacement: a prospective, randomized study of compression alone, compression and aspirin, and compression and low-dose warfarin. J Bone Joint Surg Am. 1991; 73: 507-512.
35. Gersin K, Grindlinger GA, Lee V, et al. The efficacy of sequential compression devices in multiple trauma patients with severe head injury. J Trauma. 1994; 37: 205-208.
36. Fisher CG, Blachut PA, Salvian AJ, et al. Effectiveness of pneumatic leg compression devices for the prevention of thromboembolic disease in orthopaedic trauma patients: a prospective, randomized study of compression alone versus no prophylaxis. J Orthop Trauma. 1995; 9: 1-7.
37. Keith SL, McLaughlin DJ, Anderson FA Jr, et al. Do graduated compression stockings and pneumatic boots have an additive effect on the peak velocity of venous blood flow? Arch Surg. 1992; 127: 727-730.
38. Inada K, Koike S, Shirai N, et al. Effects of intermittent pneumatic leg compression for prevention of postoperative deep venous thrombosis with special reference to fibrinolytic activity. Am J Surg. 1988; 155: 602-605.
39. Jacobs DG, Piotrowski JJ, Hoppensteadt DA, et al. Hemodynamic and fibrinolytic consequences of intermittent pneumatic compression: preliminary results. J Trauma. 1996; 40: 710-717.
40. Bradley JG, Krugener GH, Jager HJ. The effectiveness of intermittent plantar venous compression in prevention of deep venous thrombosis after total hip arthroplasty. J Arthroplasty. 1993; 8: 57-61.
41. Davidson JE, Willms DC, Hoffman MS. Effect of intermittent pneumatic leg compression on intracranial pressure in brain-injured patients. Crit Care Med. 1993; 21: 224-227.
42. Parra RO, Farber R, Feigl A. Pressure necrosis from intermittent-pneumatic-compression stockings [letter]. N Engl J Med. 1989; 321: 1615.
43. Lachmann EA, Rook JL, Tunkel R, et al. Complications associated with intermittent pneumatic compression. Arch Phys Med Rehabil. 1992; 73: 482-485.
44. Greenfield LJ, Proctor MC, Rodriguez JL, et al. Posttrauma thromboembolism prophylaxis. J Trauma. 1997; 42: 100-103.
45. Monreal M, Lafoz E, Navarro A, et al. A prospective double-blind trial of a low molecular weight heparin once daily compared with conventional low-dose heparin three times daily to prevent pulmonary embolism and venous thrombosis in patients with hip fracture. J Trauma. 1989; 29: 873-875.
46. Green D, Lee MY, Lim AC, et al. Prevention of thromboembolism after spinal cord injury using low-molecular-weight heparin. Ann Intern Med. 1990; 113: 571-574.
47. Litz RJ, Hubler M, Koch T, Albrecht DM. Spinal-epidural hematoma following epidural anesthesia in the presence of antiplatelet and heparin therapy. Anesthesiology. 2000; 95: 1031-1033.
48. Hirsh J, Warkentin TE, Shaughnessy SG, et al. Heparin and low molecular weight heparin: mechanism of action, pharmacokinetics, dosing, monitoring, safety. Chest. 2001; 119: 64S-94S.
49. Osler TM, Rogers FB. Prophylaxis against venous thromboembolism after major trauma. N Engl J Med. 1997; 336: 586.
50. Turpie AGG, Gallus AS, Hoek JA. A synthetic pentasaccharide for the prevention of deep-vein thrombosis after total hip replacement. N Engl J Med. 2001; 344: 619-625.
51. Bauer KA, Eriksson BI, Lassen MR, et al. Fondaparinux compared with enoxaparin for the prevention of venous thromboembolism after elective major knee surgery. N Engl J Med. 2001; 345: 1305-1310.
52. Webb LX, Rush PT, Fuller SB, et al. Greenfield filter prophylaxis of pulmonary embolism in patients undergoing surgery for acetabular fracture. J Orthop Trauma. 1992; 6: 139-145.
53. Jarrell BE, Posuniak E, Roberts J, et al. A new method of management using the Kim-Ray Greenfield filter for deep venous thrombosis and pulmonary embolism in spinal cord injury. Surg Gynecol Obstet. 1983; 157: 316-320.
54. Cipolle M, Marcinczyk M, Pasquale M, et al. Prophylactic vena caval filters reduce pulmonary embolism in trauma patients [abstract]. Crit Care Med. 1995; 23: A93.
55. Rodriguez JL, Lopez JM, Proctor MC, et al. Early placement of prophylactic vena caval filters in injured patients at high-risk for pulmonary embolism. J Trauma. 1996; 40: 797-804.
56. Rogers FB, Shackford SR, Ricci MA, et al. Routine prophylactic vena cava filter insertion in severely injured trauma patients decreases the incidence of pulmonary embolism. J Am Coll Surg. 1995; 180: 641-647.
57. Rosenthal D, McKinsey JF, Levy AM, et al. Use of the Greenfield filter in patients with major trauma. Cardiovasc Surg. 1994; 2: 52-55.
58. Wilson JT, Rogers FB, Wald SL, et al. Prophylactic vena cava filter insertion in patients with traumatic spinal cord injury: preliminary results. Neurosurgery. 1994; 35: 234-239.
59. Winchell RJ, Hoyt DB, Walsh JC, et al. Risk factors associated with pulmonary embolism despite routine prophylaxis: implications for improved protection. J Trauma. 1994; 37: 600-606.
60. Zolfaghari D, Johnson B, Weireter LJ, et al. Expanded use of inferior vena cava filters in the trauma population. Surg Annu. 1995; 27: 99-105.
61. Rogers FB, Shackford SR, Wilson J, et al. Prophylactic vena cava filter insertion in severely injured trauma patients: indications and preliminary results. J Trauma. 1993; 35: 637-642.
62. Patton JH Jr, Fabian TC, Croce MA, et al. Prophylactic Greenfield filter: acute complications and long-term follow up. J Trauma. 1996; 41: 231-237.
63. Leach TA, Pastena JA, Swan KG. Surgical prophylaxis for pulmonary embolism. Am Surg. 1994; 60: 292-295.
64. Khansarinia S, Dennis JW, Veldenz HC, Butcher JL, Hartland L. Prophylactic Greenfield filter placement in selected high-risk trauma patients. J Vasc Surg. 1995; 22: 235-236.
65. Gosin JS, Graham AM, Ciocca RG, Hammond JS. Efficacy of prophylactic vena cava filters in high-risk trauma patients. Ann Vasc Surg. 1997; 11: 100-105.
66. Sekharan J, Dennis JW, Miranda FE, et al. Long-term follow-up of prophylactic Greenfield filters in multisystem trauma patients. J Trauma. 2001; 51: 1087-1091.
67. Greenfield LJ, Proctor MC, Michaels AJ, Taheri PA. Prophylactic vena cava filters in trauma: the rest of the story. J Vasc Surg. 2000; 32: 490-495.
68. Van Natta TL, Morris JA Jr, Eddy VA, et al. Elective bedside surgery in critically injured patients is safe and cost effective. Ann Surg. 1998; 227: 618-624.
69. Langan EM III, Miller RS, Casey WJ, et al. Prophylactic inferior vena cava filters in trauma patients at high-risk: follow-up examination and risk/benefit assessment. J Vasc Surg. 1999; 30: 484-488.
70. Velmahos GC, Kern J, Chan L, et al. Prevention of venous thromboembolism after trauma: an evidence-based report-part II: analysis of risk factors and evaluation of the role of vena cava filters. J Trauma. 2000; 49: 140-144.
71. Greenfield LJ, Proctor MC. Recurrent thromboembolism in patients with vena cava filters. J Vasc Surg. 2001; 33: 510-514.
72. Golueke PJ, Garrett WV, Thompson JE, et al. Interruption of the vena cava by means of the Greenfield filter: expanding the indications. Surgery. 1988; 103: 111-117.
73. Rohrer MJ, Scheidler MG, Wheeler HB, et al. Extended indications for placement of inferior vena cava filter. J Vasc Surg. 1989; 10: 44-50.
74. Ferris EJ, McCowan TC, Carver DK, et al. Percutaneous inferior vena cava filters: follow-up of seven designs in 320 patients. Radiology. 1993; 188: 851-856.
75. Nunn CR, Neuzil D, Naslund T, et al. Cost-effective method for bedside insertion of vena cava filters in trauma patients. J Trauma. 1997; 45: 752-758.
76. Headrick JR, Barker DE, Pate LM, Horne K, Russell WL, Burns RP. The role of ultrasonography and inferior vena cava filter placement in high-risk trauma patients. Am Surg. 1997; 63: 1-8.
77. McMurtry AL, Owings JT, Anderson JT, Battistella FD, Gosselin R. Increase use of prophylactic vena cava filters in trauma patients failed to decrease overall incidence of pulmonary embolism. J Am Coll Surg. 1999; 189: 314-320.
78. Ashley DW, Gamblin TC, Burch ST, Solis MM. Accurate deployment of vena cava filters: comparison of intravascular ultrasound and contrast venography. J Trauma. 2001; 50: 975-981.
79. Greenfield LJ. Post trauma thromboembolism prophylaxis. Paper presented at: Eighth Annual Meeting of the American Venous Forum, February 1996; San Diego, CA.
80. Tola JC, Hotzman R, Lottenberg L. Bedside placement of inferior vena cava filters in the intensive care unit. Am Surg. 1999; 65: 833-837.
81. Lorch H, Welger D, Wagner V, et al. Current practice of temporary vena cava filter insertion: a multicenter registry. J Vasc Intervent Radiol. 2000; 11: 83-88.
82. Neuerburg JM, Gunther RW, Vorwerk D, et al. Results of a multicenter study of the retrievable tulip vena cava filter: early clinical experience. Cardiovasc Intervent Radiol. 1997; 20: 10-16.
83. Wheeler HB, Anderson FA Jr. Diagnostic methods for deep vein thrombosis. Haemostasis. 1995; 25: 6-26.
84. Wheeler HB, Anderson FA Jr. Use of noninvasive tests as the basis for treatment of deep vein thrombosis. In: Bernstein EF, ed. Vascular Diagnosis. 4th ed. St. Louis: Mosby; 1993: 1894-1912.
85. Burns GA, Cohn SM, Frumento RJ, et al. Prospective ultrasound evaluation of venous thrombosis in high-risk trauma patients. J Trauma. 1993; 35: 405-408.
86. Napolitano LM, Garlapati VS, Heard SO, et al. Asymptomatic deep venous thrombosis in the trauma patient: is an aggressive screening protocol justified? J Trauma. 1995; 39: 651-659.
87. Meythaler JM, DeVivo MJ, Hayne JB. Cost-effectiveness of routine screening for proximal deep venous thrombosis in acquired brain injury patients admitted to rehabilitation. Arch Phys Med Rehabil. 1996; 77: 1-5.
88. White RH, Goulet JA, Bray TJ, et al. Deep-vein thrombosis after fracture of the pelvis: assessment with serial duplex-ultrasound screening. J Bone Joint Surg Am. 1990; 72: 495-500.
89. Meredith JW, Young JS, O'Neil EA, et al. Femoral catheters and deep venous thrombosis: a prospective evaluation of venous duplex sonography. J Trauma. 1993; 35: 187-191.
90. Brasel KJ, Borgstrom DC, Weigelt JA. Cost effective prevention of pulmonary embolus in high-risk trauma patients. J Trauma. 1997; 42: 456-463.
91. Agnelli G, Radicchia S, Nenci GG. Diagnosis of deep vein thrombosis in asymptomatic high-risk patients. Haemostasis. 1995; 25: 40-48.
92. Wells PS, Lensing AW, Davidson BL, et al. Accuracy of ultrasound for the diagnosis of deep venous thrombosis in asymptomatic patients after orthopedic surgery: a meta-analysis. Ann Intern Med. 1995; 122: 47-54.
93. Prandoni P, Bernardi E. Upper extremity deep vein thrombosis. Curr Opin Pulm Med. 1999; 5: 222-226.
94. Chu DA, Ahn JH, Ragnarson KT, et al. Deep venous thrombosis: diagnosis in spinal cord injured patients. Arch Phys Med Rehabil. 1985; 66: L365-L368.
95. Myllynen P, Kammonen M, Rokkanen P, et al. Deep venous thrombosis and pulmonary embolism in patients with acute spinal cord injury: a comparison with nonparalyzed patients immobilized due to spinal fractures. J Trauma. 1985; 25: 541-543.
96. Brach BB, Moser KM, Cedar L, et al. Venous thrombosis in acute spinal cord paralysis. J Trauma. 1977; 17: 289-292.
97. Satiani B, Falcone R, Shook L, Price J. Screening for major deep venous thrombosis in seriously injured patients: a prospective study. Ann Vasc Surg. 1997; 11: 626-629.
98. Sandler DA, Martin JF, Duncan JS, et al. Diagnosis of deep-vein thrombosis: comparison of clinical evaluation, ultrasound, plethysmography and venoscan with x-ray venogram. Lancet. 1984; 2: 716-719.
99. Burke B, Sostman HD, Carroll BA, Witty LA. The diagnostic approach to deep venous thrombosis. Clin Chest Med. 1995; 16: 253-268.
100. Freeark RJ, Boswick J, Fardin R. Posttraumatic venous thrombosis. Arch Surg. 1967; 95: 567-575.
101. Montgomery KD, Potter HG, Helfet DL. Magnetic resonance venography to evaluate the deep venous system of the pelvis in patients who have an acetabular fracture. J Bone Joint Surg Am. 1995; 77: 1639-1649.
102. Rabinov K, Paulin S. Roentgen diagnosis of venous thrombosis in the leg. Arch Surg. 1972; 104: 134-144.
103. Bettmann MA, Robbins A, Braun SD, et al. Contrast venography of the leg: diagnostic efficacy, tolerance, and complication rates with ionic and nonionic contrast media. Radiology. 1987; 165: 113-116.
104. Kakkar VV, Howe CT, Nicolaides AN, et al. Deep vein thrombosis of the leg: is there a high-risk group? Am J Surg. 1970; 120: 527-530.
105. Brathwaite CE, Mure AJ, O'Malley K, et al. Complications of anticoagulation for pulmonary embolism in low risk trauma patients. Chest. 1993; 104: 718-720.

Table

A-V Foot Pumps