DVT/PE

LEARNING OBJECTIVES :

KNOWLEDGE - Students should understand the:

1. Define and describe risk factors for developing DVT, including:
   1. Prior history of DVT/PE
   2. Immobility/hospitalization
   3. Increasing age
   4. Obesity
   5. Trauma
   6. Smoking
   7. Surgery
   8. Cancer
   9. Acute MI
   10. Stroke and neurologic trauma
   11. Coagulopathy
   12. Pregnancy
   13. Oral estrogens
2. Define and describe genetic considerations predisposing to venous thrombosis
3. Define and describe the symptoms and signs of DVT and PE.
4. Discuss the diagnostic evaluation of DVT and PE; apply the conclusions of the PIOPED study.
5. Generate a prioritized differential diagnosis of DVT/PE based on specific physical findings using pre-test probability tools.
6. Describe the indications for and utility of various diagnostic tests and describe their interpretation including but not limited to spiral CT, V/Q, lower extremity dopplers, d-dimer.
7. Define and describe the differential diagnosis of DVT including the many causes of unilateral leg pain and swelling:
   1. Venous stasis and the postphlebitic syndrome
   2. Lymphedema
   3. Cellulitis
   4. Superficial thrombophlebitis
   5. Ruptured popliteal cyst
   6. Musculoskeletal injury
   7. Arterial occlusive disorders
8. Define and describe the differential diagnosis of PE including the many causes of chest pain and dyspnea (overlap chest pain);
   1. MI/unstable angina
   2. Congestive heart failure
   3. Pericarditis
   4. Pneumonia/bronchitis/COPD exacerbation
   5. Asthma
   6. Pulmonary hypertension
   7. Pneumothorax
   8. Musculoskeletal pain (e.g. rib fracture, costochondritis)
9. Define and describe, and develop an appropriate management plan for DVT/PE including, but not limited to the following:
   1. Unfractionated heparin
   2. Low-molecular-weight heparin
   3. Warfarin
   4. Thrombolytics
10. Define and describe the risks, benefits, and indications for inferior vena cava filters
11. Define and describe the long-term sequelae of DVT and PE
12. Define and describe methods of DVT/PE prophylaxis, their indications and efficacy, including:
    1. Ambulation
    2. Graded compression stockings
    3. Pneumatic compression devices
    4. Unfractionated heparin
    5. Low-molecular-weight heparin
    6. Warfarin
13. Identify the appropriate duration of anticoagulation therapy in a patient with DVT and PE based on the clinical picture
14. Identify the appropriate thrombophilia work up in a patient with DVT and PE based on the clinical picture

SKILLS - Students should be able to:

1. History:   Identify the risk factors for DVT/PE.   In addition, students should be aware of the typical complaints of the patient with DVT/PE and recognize that the presentation may be atypical in many cases.
2. Differential Diagnoses: Identify at least 4 alternative diagnoses of DVT/PE.
3. Physical exam:   Understand that the some of the classic exam signs of DVT/PE are not highly specific or sensitive.   Vital signs may be one of the more important signs (tachycardia, tachypnea, hypotension), and monitoring these signs should be reinforced.
4.  

   Lab interpretation: interpret arterial blood gases and calculate the alveolar-arterial oxygen gradient; recognize CXR and EKG findings associated with PE.

5. Understand when to order certain diagnostic tests and how to interpret results.
6. Basic procedural skills: perform arterial blood sampling.
7. Communication skills: understand the importance of communicating the reason and rationale for the orderly progression of tests for DVT/PE; convey the significance of untreated DVT/PE and risks of therapy.  
8. Management skills:   provide acute anticoagulation therapy. Students must also understand indications, risks and benefits of anticoagulation as well as alternative therapites such as thrombolytics, catheter-directed thrombolysis and IVC filter.

ATTITUDES AND PROFESSIONAL BEHAVIORS:

• Students should recognize that some of the risk factors are preventable and that the therapy is long term, which is often a significant stress on the previously healthy ambulatory patient

REFERENCE SUMMARY - DVT AND PE :

Opinions regarding the diagnosis and management of venous thromboembolic disease.   ACCP Consensus Committee on Pulmonary Embolism, Chest 1998;113:499-504.

Clinically relevant questions related to the diagnosis and management of acute pulmonary embolism and deep venous thrombosis were addressed.   The data on which the opinions of the committee were based were sparse.   The consensus opinions were often based on experience or intuition rather than firm data.   Below are some of the questions that were addressed.

QUESTION: What is the utility of the D-dimer in combination with V/Q scans?

Background :
In a study of 10 patients who had a low probability interpretation of the lung scan and a plasma D-dimer level <500 ng/mL (a low value), the negative predictive value for acute PE was 100%.   Other studies used different cut-off values for D-dimer.

Consensus :
The ELISA for D-dimer has a high negative predictive value for PE.   Additional studies are needed to standardize the testing.

QUESTION: What is the role of contrast-enhanced helical (spiral) CT?

Background:
Pooled data from helical CT imaging compared to conventional pulmonary angiography or autopsy showed a sensitivity of 72% and a specificity of 95%.   For PE in central pulmonary arteries, pooled data show a sensitivity of 94% which fell to 13% for PE in subsegmental pulmonary arteries.

Consensus :
Helical CT is most useful for PE in the central arteries.   However, this diagnostic modality is still under investigation.   A normal contrast-enhanced CT scan does not exclude PE, particularly in subsegmental arteries.   If only a limited amount of contrast material can be given safely to a particular patient (e.g., a renal failure patient), then it may be wise to select the single most definitive test such as pulmonary angiography.

QUESTION: Can low molecular weight heparin (LMWH) be recommended for the outpatient treatment of deep venous thrombosis or PE at this time?

Background :
The home treatment of DVT with LMWH compared to inpatient administration of continuous IV heparin showed that there were no differences in recurrent thromboembolic events and bleeding complications.   No study has investigated the outpatient use of LMWH for the treatment of PE.

Consensus:
In the USA, LMWH has not been approved for the treatment of DVT and PE.   The outcome of studies now in progress will determine the safety and efficacy of LMWH in an outpatient setting.