Prophylaxis for Deep Venous Thrombosis in Neurosurgery
Prophylaxis for Deep Venous Thrombosis in Neurosurgery
The incidence of deep venous thrombosis (DVT) and subsequent pulmonary embolism (PE) in patients undergoing neurosurgery has been reported to be as high as 25%, with a mortality rate from PE between 9 and 50%. Even with the use of pneumatic compression devices, the incidence of DVT has been reported to be 32% in these patients, making prophylactic heparin therapy desirable. Both unfractionated and low-molecular-weight heparin have been shown to reduce the incidence of DVT consistently by 40 to 50% in neurosurgical patients. The baseline rate for major intracranial hemorrhage (ICH) following craniotomy has been reported to be between 1 and 3.9%, but after initiation of heparin therapy this rate has been found to be as high as 10.9%. Therefore, neurosurgeons must balance the risk of PE against the increased risk of postoperative ICH from prophylactic heparin for DVT. The authors review the literature on the incidence of DVT and PE in neurosurgical patients, focusing on the incidence of ICH related to the use of unfractionated and low-molecular-weight heparin in this patient population.
Deep venous thrombosis occurs in the deep draining veins of the extremities, with a propensity to appear in the large veins of the lower extremities. More recently, the term VTE has been used to refer to both DVT and PE. A variety of factors place the neurosurgery population at increased risk for DVT; these include intracranial surgery, malignant tumors, duration of surgery, decreased mobilization postoperatively, postoperative paralysis, and older age. The classic presenting symptom for DVT is a painful, swollen, erythematous limb. Propagation of the clot with in deep draining veins can result in dislodgment of an embolus to downstream organs, usually the lungs.
Symptoms of PE include shortness of breath, pleuritic chest pain, and tachycardia. In the US, fatal PE occurs in an estimated 50,000 to 200,000 people per year. In fact, 90% of patients in whom PE develops outside the hospital setting die within 1 hour. Although the actual incidence of a clinically significant PE is relatively rare in the general population, its occurrence increases dramatically in hospitalized neurosurgical patients.
In a review of the incidence of DVT and PE in neurosurgical patients treated in the early 1990s who were diagnosed using various techniques (for example, compression ultrasonography, venography, and ventilation/perfusion lung imaging) investigators demonstrated an incidence of 18 to 50% for DVT and 0 to 25% for PE. In one large prospective study of neurosurgical patients, the rate of VTE was 25% (33 of 130); of these 7% (nine of 130) were symptomatic, with two deaths occurring from PE. The highest risk for DVT is in patients with brain tumors (28-43%), followed by patients undergoing craniotomy (25%), and those with head injury (20%). Hamilton, et al., noted that the risk of a PE in the general neurosurgical population was 5%, with a mortality rate ranging from 9 to 50%. Altschuler, et al., reported an 8.4% rate of PE in patients with brain tumors and a mortality rate of 2% from PE in patients with spinal cord injury.
The 2001 ACCP consensus on DVT prophylaxis acknowledged a high incidence of this disorder in neurosurgical patients, noting that in 22% of patients fibrinogen uptake test results were consistent with evidence of DVT, and that the rate of proximal DVT found on duplex studies was 5%. Wen and Hall stated that "in neurosurgical patients if one assumes a conservative rate of clinically apparent PE at 0.5% with a 50% mortality rate, and that 700,000 neurosurgical cases (3500 surgeons, 200 cases/year) are performed annually in the United States, a halving of the rate of pulmonary embolism could save 875 lives each year." The primary prevention method for fatal PE is averting the formation of a DVT.
Definition and Incidence of DVT and PE in Neurosurgical Patients
The incidence of deep venous thrombosis (DVT) and subsequent pulmonary embolism (PE) in patients undergoing neurosurgery has been reported to be as high as 25%, with a mortality rate from PE between 9 and 50%. Even with the use of pneumatic compression devices, the incidence of DVT has been reported to be 32% in these patients, making prophylactic heparin therapy desirable. Both unfractionated and low-molecular-weight heparin have been shown to reduce the incidence of DVT consistently by 40 to 50% in neurosurgical patients. The baseline rate for major intracranial hemorrhage (ICH) following craniotomy has been reported to be between 1 and 3.9%, but after initiation of heparin therapy this rate has been found to be as high as 10.9%. Therefore, neurosurgeons must balance the risk of PE against the increased risk of postoperative ICH from prophylactic heparin for DVT. The authors review the literature on the incidence of DVT and PE in neurosurgical patients, focusing on the incidence of ICH related to the use of unfractionated and low-molecular-weight heparin in this patient population.
Deep venous thrombosis occurs in the deep draining veins of the extremities, with a propensity to appear in the large veins of the lower extremities. More recently, the term VTE has been used to refer to both DVT and PE. A variety of factors place the neurosurgery population at increased risk for DVT; these include intracranial surgery, malignant tumors, duration of surgery, decreased mobilization postoperatively, postoperative paralysis, and older age. The classic presenting symptom for DVT is a painful, swollen, erythematous limb. Propagation of the clot with in deep draining veins can result in dislodgment of an embolus to downstream organs, usually the lungs.
Symptoms of PE include shortness of breath, pleuritic chest pain, and tachycardia. In the US, fatal PE occurs in an estimated 50,000 to 200,000 people per year. In fact, 90% of patients in whom PE develops outside the hospital setting die within 1 hour. Although the actual incidence of a clinically significant PE is relatively rare in the general population, its occurrence increases dramatically in hospitalized neurosurgical patients.
In a review of the incidence of DVT and PE in neurosurgical patients treated in the early 1990s who were diagnosed using various techniques (for example, compression ultrasonography, venography, and ventilation/perfusion lung imaging) investigators demonstrated an incidence of 18 to 50% for DVT and 0 to 25% for PE. In one large prospective study of neurosurgical patients, the rate of VTE was 25% (33 of 130); of these 7% (nine of 130) were symptomatic, with two deaths occurring from PE. The highest risk for DVT is in patients with brain tumors (28-43%), followed by patients undergoing craniotomy (25%), and those with head injury (20%). Hamilton, et al., noted that the risk of a PE in the general neurosurgical population was 5%, with a mortality rate ranging from 9 to 50%. Altschuler, et al., reported an 8.4% rate of PE in patients with brain tumors and a mortality rate of 2% from PE in patients with spinal cord injury.
The 2001 ACCP consensus on DVT prophylaxis acknowledged a high incidence of this disorder in neurosurgical patients, noting that in 22% of patients fibrinogen uptake test results were consistent with evidence of DVT, and that the rate of proximal DVT found on duplex studies was 5%. Wen and Hall stated that "in neurosurgical patients if one assumes a conservative rate of clinically apparent PE at 0.5% with a 50% mortality rate, and that 700,000 neurosurgical cases (3500 surgeons, 200 cases/year) are performed annually in the United States, a halving of the rate of pulmonary embolism could save 875 lives each year." The primary prevention method for fatal PE is averting the formation of a DVT.
