Page 156 - Critical Care Nursing Demystified

Chapter 3 CARE OF THE PATIENT WITH CRITICAL CARDIAC AND VASCULAR NEEDS 141

Pulmonary Embolism (PE)

What Went Wrong?
A pulmonary embolism (PE) occurs when a clot originating in the venous cir-
culation, usually the deep veins of the legs or the pelvis, travels to the lungs and
lodges in a pulmonary artery. PE can also occur as a complication from the right
side of the heart when the cardiac rhythm is atrial fibrillation or atrial flutter.
The lack of complete emptying in atrial fibrillation/flutter can set up eddies
within the atria that allow the formation of clots. In these rhythms, the atria do
not contract uniformly, which leads to stagnation of blood flow and tendencies
to clot.
The hazards of PE can be summarized by Virchow’s triad. A patient at highest
risk is one who has (1) venous stasis, (2) injury to blood vessels, and (3) hemo-
concentrated blood. Venous stasis can be caused by immobility from bedrest and
riding in the same position in a car, train, or airplane. Blood vessels can be injured
through any instrumentation or surgery, especially of the pelvis and lower extrem-
ities such as total knee surgery and prostatectomy. Hypercoagulability or hemo-
concentrated blood can result from pregnancy or dehydration.
With the blockage of blood flow in the lungs, the circulation in front of the clot Downloaded by [ Faculty of Nursing, Chiangmai University 5.62.158.117] at [07/18/16]. Copyright © McGraw-Hill Global Education Holdings, LLC. Not to be redistributed or modified in any way without permission.
is affected. This blockage acts like a dam where only a trickle of blood (water)
gets through. The larger the clot, the more symptomatic the patient becomes. If
the clot is large enough, the alveoli do not get venous flow and therefore cannot
get rid of CO or absorb O . Hypercarbia and hypoxemia result. This is a true
2 2
perfusion or circulation problem but it affects oxygenation.
Also as with a dam, blood builds up behind the clot, increasing the pressure
in the lungs and resulting in pulmonary hypertension.

Hallmark Signs and Symptoms
The symptoms of PE depend upon the size, location, and how much of the
pulmonary circulation is blocked. In a small PE, the following symptoms can
occur:
• Dyspnea is the most common symptom.
• Tachycardia.
• Atrial fibrillation/flutter may be present.

• Pleuritic chest pain that often mimics an MI.
• Shortness of breath.
• Decreased breath sounds over the affected area.