Venous Thromboembolism in the ICU and Reversal of Bleeding on Anticoagulants

Evidence-based review of primary and secondary ischemic stroke prevention in adults: a neurosurgical perspective

In this paper, the authors' aim is to provide an evidence-based review of primary and secondary ischemic stroke prevention guidelines covering most of the common risk factors and stroke etiologies for the practicing neurosurgeon. The key to stroke prevention is in the identification and treatment of the major risk factors for stroke. These include hypertension, heart disease, diabetes mellitus, dyslipidemia, and tobacco smoking. An updated approach to secondary prevention of stroke in the setting of intracranial and extracranial large vessel atherosclerosis and cardioembolism is provided along with a brief overview of pertinent clinical trials. Novel pharmacological options for prevention of cardioembolic strokes, such as new alternatives to warfarin, are addressed with recommendations for interruption of therapy for elective surgical procedures. In addition, the authors have reviewed the anticoagulation guidelines and the risk of thromboembolic complications of such therapies in the perioperative period, which is an invaluable piece of information for neurosurgeons. Less common etiologies such as arterial dissections and patent foramen ovale are also briefly discussed. Finally, the authors have outlined the quality measures in the Medicare Physician Quality Reporting System and essential guidelines for Primary Stroke Center certification, which have implications for day-to-day neurosurgical practice.

Transesophageal echocardiography and vascular ultrasound in the diagnosis of catheter-related persistent left superior vena cava thrombosis

We refer to a very rare case of catheter-related thrombosis in a trauma patient with persistent left and absent right superior vena cava. The role of ultrasound examination in the early diagnosis and treatment of thrombosis in the setting of intensive care unit (ICU) is thoroughly discussed. A 30-year-old man was admitted to the ICU due to multiple trauma. Six days after right internal jugular vein (IJV) catheter insertion, and during a vascular ultrasound examination, an IJV catheter-related thrombosis was diagnosed. Hence, the catheter was removed, and a follow-up ultrasound examination revealed thrombus remnant in the IJV extended into brachiocephalic vein. Subsequently, to exclude a possible extension of the thrombus in the superior vena cava, a transesophageal echocardiography (TEE) examination was performed. The latter revealed a distended coronary sinus and the presence of persistent left superior vena cava (PLSVC). Additionally, TEE examination disclosed thrombus remnant within the PLSVC that was also confirmed with CT venography. Anticoagulant therapy was started thus preventing major complications such as coronary sinus obstruction. This case underlines the role of cardiovascular ultrasound examination as an important tool in performing variety of monitoring in the setting of the ICU.

The effect of a temporary inferior vena cava filter in the treatment of deep vein thrombosis in critically-ill patients

We studied the clinical courses of patients with deep vein thrombus (DVT) who underwent insertion of temporary inferior vena cava filters (tIVCF) and evaluated the effectiveness of the tIVCF. From January 2003 to March 2008, tIVCF were placed in 12 patients with a diagnosis of DVT in the Intensive Care Unit (ICU) of Gunma University Hospital. The mean age of the patients was 52 +/- 16 years (range, 18-82). Eight were medical patients who had not undergone any prior surgery, and 4 were postoperative patients, including 3 with a malignancy. The diagnosis of DVT was made using enhanced computed tomography. The Toray Neuhaus Protect catheter (6Fr, Toray Medical, Tokyo) was used as a tIVCF in all 12 patients. We evaluated the clinical course of the patients before and after placement of a tIVCF and studied their prognosis. DVT occurred on 15 +/- 9 days after surgery or admission to hospital. Pulmonary thromboembolism (PTE) was detected in 7 patients prior to the placement of a tIVCF, 3 of whom required cardiopulmonary resuscitation. The mean duration of tIVCF placement was 18 +/- 9 days; no episodes of PTE occurred after tIVCF placement. DVT completely or almost completely disappeared during the period of tIVCF placement; subsequently, tIVCFs were successfully removed in 10 patients (83%). A permanent IVCF was placed in only 1 patient, and the tIVCF was removed in the remaining patient because of suspected catheter infection. There were 2 complications related to tIVCF placement: infection at the insertion site and suspected catheter infection. tIVCF placement could prevent the occurrence of PTE without provoking life-threatening complications. The results suggest that tIVCF is useful in the prevention of PTE in patients with DVT.

Inhibition of extrinsic hemostasis activation by low-molecular-weight heparin

Low-molecular-weight heparins (LMWHs) are very important drugs; unfortunately, the routine global hemostasis assays activated partial thromboplastin time and prothrombin time are not sensitive to LMWHs. Here the 50% inhibitory concentration (IC(50)) values of heparin and LMWHs on extrinsic thrombin generation are determined. Pooled normal plasma was supplemented with 0-2 IU/ml unfractionated heparin, 0-2 IU/ml LMWH dalteparin, or 0-20 microg/ml pentosanpolysulfate in 5-ml polystyrole tubes (23 degrees C) and tested in the tissue-factor-triggered extrinsic coagulation activity assay (EXCA): 50 microl plasma + 5 microl tissue factor/CaCl(2), 1 and 2 min incubation time at 37 degrees C (coagulation reaction time for EXCA-1 and EXCA-2); + 100 microl of 2.5 mol/l arginine (pH 8.6), 20 min at room temperature; + 50 microl of 1 mmol/l CHG-Ala-Arg-pNA, 1.25 mol/l arginine; increase in absorbance/time at 23 degrees C; calibrator = 1 IU/ml bovine thrombin in 6.7% human albumin replacing the plasma sample; in EXCA-1, about 1 IU/ml thrombin is generated in pooled unfrozen normal citrated plasma. The IC(50) values in EXCA-1 are 0.1 IU/ml heparin, 0.02 IU/ml LMWH, and 4.7 microg/ml pentosanpolysulfate. In ECXA-2 the IC(50) values are 0.07 IU/ml, 0.01 IU/ml, and 4.6 microg/ml, respectively. The EXCA reflects the efficiency of anticoagulants on plasmatic coagulation. It is suggested to adjust the dosage of LMWH according to the EXCA value; about 30% of normal extrinsic thrombin generation might be the correct dose for prophylactic anticoagulation.

Prevention of Venous Thromboembolism in High-Risk Patients

The prevention of venous thromboembolism (VTE) in patients recovering from major trauma, spinal cord injury (SCI), or other critical illness is often challenging. These patient groups share a high risk for VTE, they often have at least a temporary high bleeding risk, and there are relatively few thromboprophylaxis trials specific to these populations. A systematic literature review has been conducted to summarize the risks and prevention of VTE in these three groups. It is concluded that routine thromboprophylaxis should be provided to major trauma, SCI and critical care patients based on an individual assessment of their thrombosis and bleeding risks. For patients at high risk for VTE, including those recovering from major trauma and SCI, prophylaxis with a low molecular weight heparin (LMWH) should commence as soon as hemostasis has been demonstrated. For critical care patients at lower thrombosis risk, either LMWH or low-dose heparin is recommended. For those with a very high risk of bleeding, mechanical prophylaxis should be instituted as early as possible and continued until pharmacologic prophylaxis can be initiated. The use of prophylactic inferior vena caval filters is strongly discouraged because their potential benefit has not been shown to outweigh the risks or substantial costs. Implementation of thromboprophylaxis in these patients requires a local commitment to this important patient safety priority as well as a highly functional delivery system, based on the use of pre-printed orders, computer prompts, regular audit and feedback, and ongoing quality improvement efforts.