VTE: The Basics

Venous thromboembolic disease consists of both deep venous thrombosis (DVT) and pulmonary embolism (PE) and represents a serious risk to all ICU patients. Three key elements contribute to the development of DVT and PE:

  1. Venous stasis
  2. Hypercoagulability
  3. Venous Injury

Up to a third of ICU patients will develop DVT or PE without appropriate prophylaxis. The development of VTE has been shown to increase the duration of mechanical ventilation, ICU and hospital length of stay. Furthermore, the development of PE may cause cardiac or respiratory failure or even death.

For a comprehensive resource, check the guidelines published by the ACCP.

Predicting Risk

While there is much controversy regarding which hospitalized medical and surgical patients should receive pharmacologic prophylaxis for VTE, it is clear that critically-ill patients are at high-risk and should be considered for treatment with an anticoagulant unless there is a contraindication.

This is complicated further in surgical patients who may be at risk for developing hemorrhagic complications due to anticoagulation. The risks and benefits of anticoagulation must be carefully weighed.

A scoring system, the Padua Prediction Score, has been developed to predict the risk of developing VTE in hospitalized medical patients:

Baseline Feature Score
Active cancer a 3
Previous VTE (excluding superficial vein thrombosis) 3
Reduced mobility b 3
Already known thrombophilic condition c 3
Recent (≤ 1 month) trauma and/or surgery 2
Elderly age (≥ 70 years) 1
Heart and/or respiratory failure 1
Acute myocardial infarction or ischemic stroke 1
Acute infection and/or rheumatologic disorder 1
Obesity (BMI ≥ 30) 1
Ongoing hormonal treatment 1
a. Patients with local or distant metastases and/or in whom chemotherapy or radiotherapy had been performed in the previous 6 months.
b. Bedrest with bathroom privileges (either due to patient’s limitations or on physicians order) for at least 3 days.
c. Carriage of defects of anti- thrombin, protein C or S, factor V Leiden, G20210A prothrombin mutation, antiphospholipid syndrome.

At UCSF, we have developed risk stratification guidelines for  VTE prophylaxis in hospitalized patients using this scoring system.

VTE Risk Category or Population Patients Included Intervention
Very low
  • VTE score < 4 and is walking unassisted or will be discharged within 24 hours
  • Currently therapeutically anticoagulated
  • No VTE prophylaxis indicated
Low
  • VTE score < 4, not ambulating, and >24 hour stay anticipated
  •  Sequential Compression Devices (SCDs) except during ambulation
Intermediate
  • VTE risk ≥ 4 and without high-risk features (medical or surgical patients)
  • Enoxaparin 40 mg SC daily
  • If contraindications to enoxaparin (CrCl < 30 mL/min, epidural or neural catheter): Heparin 5000 units SC q12h
High
  • ICU admission
  • Hip fracture
  • Gynecologic oncology surgery
  • Enoxaparin 30 mg SC BID
  • If contraindications to enoxaparin (CrCl < 30 mL/min, epidural or neural catheter): Heparin 5000 units SC q8h
Orthopedic arthroplasty
  • Hip and knee arthroplasty
  • Enoxaparin 30 mg SC BID
  • Enoxaparin 40 mg SC daily
  • If epidural in place, renal insufficiency (CrCl <30 ml/min or sCr > 2.0 mg/dL), or weight > 150 kg: Heparin 5000 units SC q8h

 

It is clear, however, that all patients in the ICU should receive some form of prophylaxis, mechanical or pharmacologic, in addition to mobilization to minimize their risk of developing VTE.

Prophylaxis against VTE

Given the significant risk of developing VTE, all critically-ill patients should receive pharmacologic prophylaxis of some kind while in the ICU unless there is a contraindication to anticoagulation. The American College of Chest Physicians has published guidelines to assist in selecting appropriate prophylactic measures. The guidelines recommend the use of either low dose unfractionated heparin or low molecular weight heparin in critically-ill patients.

Mechanical prophylaxis is recommended for patients who are bleeding or who are at risk for major bleeding and recommend initiation of pharmacologic prophylaxis when bleeding risk subsides. Options for mechanical prophylaxis include intermittent pneumatic compression devices and graduated compression stockings (both are usually placed on the lower extremities). These interventions are aimed at decreasing venous stasis which is known to contribute to the development of VTE.

For patients with a history of heparin-induced thrombocytopenia, consideration should be given to the use of non-heparin anticoagluant agents such as fondaparinux or direct thrombin or factor Xa inhibitors.

The Importance of Mobilization

Another safe and effective way to prevent VTE is through mobilization. Frequent and consistent mobility can help prevent venous stasis by improving venous blood flow and velocity.

Multiple studies have also suggested that early mobilization and ambulation are safe and beneficial ways to manage patients with acute DVT with concurrent proper anticoagulation therapy with no increased risk of developing a PE. Early mobility can also reduce the incidence and severity of post-thrombotic syndrome – the symptoms of chronic venous insufficiency that can include pain, venous dilation, edema, abnormal pigmentation,skin changes, and venous ulcers secondary to DVT. Some studies also suggest that compared to bed rest, early ambulation does not cause progression of of the disease or increased mortality in patients with acute PE.

Early mobilization and ambulation should be considered for all patients to help prevent VTE and even in those who may have already developed it given that they are on approprate anticaogulation therapy.

Learn more about Early Mobilization.