Prophylaxis for Deep Venous Thrombosis in Patients With Craniotomies: A Review

Shabbar F. Danish, MD; Mark G. Burnett, MD; Sherman C. Stein, MD

Disclosures

Neurosurg Focus. 2004;17(4) 

In This Article

Strategies for DVT Prophylaxis

The methods used for pericraniotomy DVT prophylaxis are mechanical, pharmacological, or a combination of both.

These techniques include the use of graduated compression stockings, electrical stimulation of the calf muscles, intermittent external pneumatic calf compression, and rotating tables. The main advantages of mechanical prophylaxis are that there is minimal risk associated with them, and they are relatively inexpensive and simple to use.[21]

Both local and systemic factors appear to be involved in the success of mechanical prophylaxis. Elastic support of 16 to 20 mm Hg decreases venous stasis and increases venous return. Leg wrappings and stockings with no pressure gradient are ineffective in the prevention of DVT.[10] The period of "fibrinolytic shutdown" after surgery appears to be reversed with intermittent calf compression.[11] In one comparison of mechanical devices, Vanek[67] suggested that pneumatic compression was superior to stockings in preventing DVT but not PE, but admitted that the data were "sparse and conflicting."

Although several medications, including aspirin, unfractionated heparin, low-molecular-weight heparin, and warfarin have been used for pharmacological prophylaxis, heparin is the only one used perioperatively in patients undergoing neurosurgery. Heparin is a naturally occurring anticoagulant that is synthesized and secreted by mast cells in the body. It binds to antithrombin III and inhibits thrombogenesis, primarily through inactivation of factors IIa and Xa. Larger heparin fragments can also bind to and inactivate thrombin.

The low-molecular-weight heparins are fragments of unfractionated heparin with a shorter glycosaminoglycan chain length. This prevents them from binding to protein, such as thrombin. Factor Xa is preferentially inhibited compared with unfractionated heparin, and because thrombin is unaffected the partial thromboplastin time is normal. Theoretical advantages of low-molecular-weight heparins are more predictable anticoagulant response, greater bioavailability and longer halflife when administered subcutaneously, lower incidence of heparin-induced thrombocytopenia, and less inhibition of platelet function.[40]

It is unclear when to start prophylaxis and how long to continue it. Some practitioners advocate 2 weeks of prophylaxis for all patients after surgery. They support this recommendation with studies indicating that the majority of acute clinically apparent DVTs are diagnosed during this time period, and it is also the time in which 75% of asymptomatic DVTs are believed to be formed.[24] Others propose a longer duration of prophylaxis, observing that patients who remained at risk for DVT after 1 or 2 weeks experienced this condition at the same rate as control patients after mechanical prophylaxis was stopped. Macdonald, et al.,[41] reported that in 50% of patients in whom DVT developed, it occurred between 1 and 2 months postsurgery.

Whether heparin should be started intraoperatively or at some early point postsurgery has not been determined. Given that bleeding after craniotomy may result in devastating complications, many practitioners wait at least 1 day after surgery to begin heparin administration.[21] Waiting to begin heparin treatment until the early postoperative period does not appear to increase the rate of DVT formation. Macdonald, et al., studied patients in the initial days after surgery and did not detect a single DVT in more than 100 patients examined using Doppler ultrasonography with in 2 or 3 days of the procedure.

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