Fibrinolysis and elastic compression: no fibrinolytic effect of elastic compression in healthy volunteers

The Effects of Intermittent Pneumatic Compression on Systemic and Local Fibrinolysis

Intermittent pneumatic compression (IPC) is effective in deep venous thrombosis prophylaxis. IPC prevents venous stasis by collapsing the peripheral venous plexus in an extremity leading to increased venous return. It has been suggested that IPC has an additional effect of enhancing fibrinolysis. This study was designed to evaluate the effect of IPC on both systemic and local fibrinolysis in normal volunteers by measuring the activity of tissue plasminogen activator (t-PA) and plasminogen activator inhibitor-type 1 (PAI-1). In addition, tissue factor pathway inhibitor (TFPI) was measured to assess changes in the extrinsic coagulation cascade. IPC was applied in the foot and calf of 10 healthy subjects and blood was drawn from the antecubital fossa to determine systemic fibrinolytic activity. Local fibrinolysis was assessed in 15 healthy subjects by placing an IPC cuff on the forearm and drawing blood 2 cm above the cuff The IPC maximum inflation pressure was 120 mm Hg lasting for 3 seconds at three cycles per minute. Blood samples were taken at rest, on the 10th minute of active IPC, and 5 minutes after cessation of IPC for both systemic and local measurements. The plasma was analyzed for TFPI, t-PA, and PAI-1 antigen by use of enzyme-linked immunosorbent assays. There were no significant changes in systemic or local fibrinolytic activity before, during, or after application of IPC. TFPI systemic activity before, during, and after was 111 ±24, 118 + 18, and 116 ±22, respectively. Local TFPI activity was 91 ±32, 93 +36, and 91 ± 24, respectively. The t-PA systemic activity before, during, and after was 4.1 ± 1.9, 4.7 ± 2.3, and 5 + 2.8, respectively. Local t-PA activity was 4.5 ± 1.3, 4.5 ± 1.4, and 4.2 ± 1.4, respectively. Systemic PAI-1 activity was 11 ± 9.2, 17 ± 19, and 17 ±31, respectively. Local PAI-I activity was 3.7 ± 3.1, 3 ± 1, and 2.8 + 1, respectively, p > 0.38 for all comparisons in both groups. No evidence was found that IPC enhances systemic and local fibrinolysis or TFPI release. Irrespective of the length of IPC application or the inflation pressure, several studies have reported increased fibrinolysis, whereas others have not found any changes. Although, according to the literature, there is a trend toward increased fibrinolytic activity, further controlled studies with adequate sample size should be performed to provide an answer to this controversial topic.

Intermittent Pneumatic Compression Devices – Physiological Mechanisms of Action

There are many reports of how IPC is used effectively in the clinical setting; including the prevention of deep venous thrombosis, improvement of circulation in patients with lower extremity arterial diseases, reduction of lymphoedema, and the healing of venous ulcers. However, despite the widely accepted use of IPC, it is still unclear how IPC actually exerts its beneficial effects. The exact physiological mechanisms of action are unknown. The clinical utility of IPC and the putative mechanisms by which IPC could exert its therapeutic effect will be reviewed. The paper will examine the mechanical effects of IPC exerted on the lower extremity, and the subsequent biochemical changes in the circulation. In vitro studies of the effects of mechanical stress such as compressive strain and shear on cultured endothelial cells, and their clinical relevance to IPC will also be reviewed.

Prevention and treatment of venous thromboembolism after major trauma

In prospective studies the incidence of deep venous thrombosis, documented by venography, is between 35% and 63% in patients with major trauma. Five independent risk factors for deep vein thrombosis have been identified in these patients: older age, fracture of the femur or tibia, surgery, spinal cord injury and blood transfusion. Mechanical antithrombotic methods and low-dose unfractionated heparin administered subcutaneously moderately decrease the risk of venous thromboembolism but are less effective than a fixed dose of subcutaneous unmonitored low molecular weight heparin. Prophylaxis with oral anticoagulants (International Normalized Ratio 2.0-3.0) is also effective but is much less used because of the bleeding risk. This is particularly the case in patients with intracranial neurosurgery and acute spinal cord injury. Only a few clinical studies have evaluated the treatment of venous thromboembolism in patients with major trauma. If the condition of a patient with major injury allows, the treatment of venous thromboembolism recommended after hip replacement is cautiously applied.