Prevention of deep vein thrombosis in neurological surgery (pp. 35-58)
Authors: (Mario Ganau and Leonello Tacconi)
Abstract: Background: The mean incidence of deep vein thrombosis (DVT) in neurosurgical reports is variable and surprisingly approaches 25%, whereas the incidence of pulmonary embolism (PE) is thought to be between 1.5% and 3%, with a mortality rate between 9% and 50%. Although DVT is probably the single most important, preventable cause of morbidity and mortality in this domain, its pharmacologic prevention is still a controversial matter due to the concern associated with the possible increased risk of postoperative haemorrhaging. Prophylactic options against DVT/PE include elastic stockings, intermittent pneumatic compression devices, low-dose unfractionated heparin (UFH), and low molecular-weight heparin (LMWH). The aim of this chapter is to describe the prophylactic protocols for DVT currently in use in neurological surgery and share our experience on this topic.
Analysis of the prophylactic protocols in neurological surgery: Systematic reviews of the English literature concerning DVT prophylactic protocols in neurosurgery have been conducted by a PubMed search (back to 1986). at the latter aimed to analyze the risks and benefits associated with different prophylactic regimens: abstracts of all identified articles were reviewed, and detailed information from eligible articles was extracted.
Description of our own protocol: Herein, we describe the DVT prophylactic protocol currently in use at the Neurosurgical Department in Trieste (Italy) and report the related results obtained on more than 3,818 consecutive patients that have undergone neurosurgical cranial or spinal procedures at our institution since January 2004. All patients were screened with preoperative blood coagulation tests.According to the presence of risk factors in the anamnesis, the type of surgical procedure (minor or major cranial or spinal procedures) and expectations associated with their postoperative course (prolonged immobilization), the patients were then stratified into three classes of risk: low-, moderate- or high-risk subgroups. The protocol is associated with both pharmacological and mechanical prophylactic measures: administering LMWH (2,000 UI to 4,000 UI per day), elasting stockings and mechanical pneumatic sequential compression leg devices. The end points of this protocol are to keep the incidence of DVT, PE and postoperative haemorrhaging as low as possible. Over the years, they were assessed as follows: in the case of neurological deterioration, significant bleeding in the surgical site was promptly ruled out by a head or spinal CT scan, as well in the case of a clinical suspicion for DVT or PE, a duplex ultrasonography and a chest x-ray plus a perfusion CT scan were respectively performed.
Results: Although literature confirms that intermittent pneumatic compression devices provide an adequate reduction of DVT/PE in some cranial and combined cranial/spinal series, UFH or LMWH have proved to further reduce the incidence of PE, and partially reduce the incidence of DVT. Nevertheless, UFH-based prophylaxis showed a higher incidence of postoperative haemorrhaging (2% - 4% in cranial series, and 1% in spinal ones), whereas LMWH protocols present less bleeding drawbacks. Our prophylactic protocol was well tolerated in all patients; particularly the stratification of risk and subdivision into risk groups gave us the opportunity to avoid concerns regarding overtreatment. Clinical evidence of DVT occurred in 0.4% of our cohort; one patient died of fatal PE 2 months after surgery. Less than 1% of our patients presented significant postoperative haemorrhaging, mostly after major cranial surgery.
Conclusion: The results reported in literature confirm the need for a DVT prophylactic protocol in neurosurgical patients: a combined mechanical/pharmacological regimen seems to be the most appropriate and effective, but a prospective randomized trial to assess the best
dosage, molecule and timing of LMWH administration is still lacking. On the other hand, even if our database only allows for an observational analysis, the results obtained in such a large group of neurosurgical patients are encouraging, since they show the efficacy in terms of DVT and PE prevention, without significant incidence of postoperative complications such as surgical-site haemorrhaging. Certainly, this data gives enough evidence to support the DVT prophylactic protocol applied throughout the last 6 years at our institution.