Study: Early use of heparin reduces risk of DVT by 43%

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Most cases of deep vein thrombosis (DVT) in patients who undergo neurosurgical procedures occur within the first week after procedure, indicating a direct correlation between length of surgery and development of lower extremity DVT. Researchers found that use of subcutaneous heparin at either 24 hours or 48 hours after procedure reduced the risk of lower extremity DVT by 43 percent, according to a study in this month's Journal of Neurology.

Venous thromboembolism (VTE) is a major risk factor for mortality in neurosurgical patients, the authors wrote, and DVT goes untreated in 18 to 50 percent of all neurosurgery patients. “The adverse rates of surgical site hemorrhagic complication with pharmacologic prophylaxis versus the rates of VTE post-procedure are not well-studied and the optimal method of prophylaxis in neurosurgical patients (mechanical, pharmacological or both) remains controversial.”

To bulk up the sparse data, Ahmad Khaldi, MD, of the Loyola University Medical Center in Maywood, Ill., and colleagues set out to evaluate the risks of developing lower extremity DVT following a neurosurgical procedure, the timing of the initiation of pharmacological DVT on the occurrence of VTE and the relationship between DVT and pulmonary embolism related to VTE prophylaxis in neurosurgical patients.

The researchers enrolled 2,638 neurosurgical patients who were treated at Loyola between January 2006 and December 2008 and who were reviewed for clinical documentation of VTE.

Of the patients enrolled, 1,303 patients were male and 1,335 were female. Patients had an average age of 49.

Patients deemed as “high-risk” had surveillance lower extremity ultrasound (duplex) studies twice a week and patients at an increased risk for DVT were also screened. Thirty-four percent of patients (n=555) underwent at least one lower extremity duplex venous study and 84 percent showed positive results within the first week of admission—this rate increased an additional 8 percent by the second week.

The researchers reported that the risk of developing DVT post-neurosurgical procedure with use of only mechanical DVT prophylaxis was 16 percent. When a regimen of 5000 U twice daily of subcutaneous heparin was added to mechanical DVT prophylaxis, the rate of developing DVT was reduced to 9 percent. According to the researchers, there was a 43 percent reduction in the rate of developing DVT when pharmacological prophylaxis was utilized.

Patients received subcutaneous heparin within 48 hours, but this was advanced to within 24 hours of surgery because of the high risk of VTE; however, researchers found no significant difference in the rate of surgical site or hemorrhagic complications between the 24-hour or 48-hour group compared to the patient arm that had no pharmacological prophylaxis.

Of the 2,638 patients, 94 exhibited possible pulmonary embolism that led to a diagnostic radiologic study—22 percent of these studies were positive. Heparin use at either 24 or 48 hours did not reduce the rate of pulmonary embolism. But, the authors did find that six patients who underwent a radiologic study had positive pulmonary embolism while nine of 38 patients with a negative lower extremity duplex had a positive pulmonary embolism.

“Neurosurgical patients have an increased risk of developing VTE due to limb paralysis, stroke and immobility as well as hypercoaguable states induced by certain neoplasms, such as astsrocytoma,” the authors wrote.

“The reduction of VTE (deep vein thrombosis/pulmonary embolism) in all post-surgical patients is a major quality and safety target and continues to be a major complication following all surgical as well as neurosurgical procedures,” the authors wrote. “Understanding the incidence of DVT and pulmonary embolism as well as the effects of prophylactic therapies specifically in neurosurgical patients for whom there is ongoing concern about the hemorrhagic risks associated with pharmacologic VTE prophylaxis may serve as a baseline for future national quality improvement initiative.

“Our study validates that most VTE occurs early (within the first week) after a neurosurgical intervention with a positive correlation between length of surgery and development of lower extremity DVT,” the authors concluded. “The study questions if lower extremity duplex alone is an adequate screening tool for assessing the risk of pulmonary embolism development.”