January 11, 2016 - Pulmonary Embolism

Question 1

Why is PE Important?

Answer 1

1. Common
2. Life threatening
3. Can be challenging to diagnose
4. Treatable

Question 2

PE on CT

Answer 2

Large thrombus blocks blood supply. The IV contrast does not reach the parts of the tissue that is blocked off from the PE.

Question 3

Why do PE’s Have Different Clinical Presentations?

Answer 3

There is a huge variety of locations for a PE to occur, and a large variety of the size of PEs. Small PEs typically produce less symptoms than large ones.

The right side of the heart can act like a blender and mash up a clot into varying sized pieces, which may become stuck in the lungs.

Question 4

Origins of PE

Answer 4

90% originate from the deep veins in the legs.

The other 10% can occur from upper extremity veins, renal veins, pelvic veins, or the heart.

They do NOT come from superficial veins such as varicose veins or saphenous veins.

Question 5

Signs and Symptoms of a DVT

Answer 5

Red, swollen, warm, tender leg.

Many patients do not have symptoms. You need to investigate further by performing an ultrasound or looking for a D-Dimer.

Question 6

Pathophysiologic Response to a PE

Answer 6

Bilateral perfusion defects

Infarction (although the tissue is more resistant to infarction due to the dual blood supply of both the pulmonary circulation and bronchial artery)

Abnormal gas exchange

Cardiovascular compromise

Question 7

Diagnostic Evaluation of PE

Answer 7

History (HPI, PMHx, Risk Factors)

Physical Exam

Chest X-Rays, ECG

D-Dimer

V/Q Scans

Doppler U/S of Legs

Question 8

Risk Factors for PE

Answer 8

Immobilization

Surgery (within last 3 months)

Malignancy

Stroke

Previous DVT/PE

Smoking

Obesity

Hypertension

Coagulation abnormalities

Question 9

Hampton’s Hump

Answer 9

A radiologic sign which consists of a shallow wedge-shaped opacity in the periphery of the lung with its base against the pleural surface.

Can indicate a PE and may also be associated with pleural effusion.

Question 10

Westermark Sign

Answer 10

A radiographic sign seen in 2% of PE cases. It results as a combination of the dilation of the pulmonary arteries proximal to the embolus and the collapse of the distal vasculature creating the apparearance of a sharp cut off on chest radiography.

Question 11

Most Common Cause of False + D-Dimer

Answer 11

Pneumonia

Question 12

Estimating Clinical Probability of PE

Answer 12

Well’s Score

Question 13

Ventilation/Perfusion (V/Q) Scan

Answer 13

Patient breaths in radiolabelled particles and also has IV radiolabelled dye administered. You then look for unmatched defecits where areas are well-ventilated but there is no perfusion.

In the picture, A is the scan after inhalation of the particles. B is the scan after the radiolabelled dye is administered. You can see in A that the entire lung is well-coated, however in B there are areas where the blood is not well-perfused.

V/Q is useful if the Well’s Score is high or if it is low, but not intermediate.

Question 14

Signs of Massive PE

Answer 14

Severe dyspnea

Syncope

Tachycardia, tachypnea, hypotension, increased JVP, R-sided S3

Question 15

Treatment of PE

Answer 15

Initial and chronic anticoagulation

IVC filter for select indications

For massive PE… Systemic thrombolysis, catheter-directed thrombolysis, or surgical embelectomy.