Pulmonary Embolism Flashcards
Thrombus?
Blood clot
Embolism?
Blood clot (thrombus) or air/other things obstructing blood flow that mobilizes within vessels
Pulmonary embolism?
Thrombus in a pulmonary vessel (within he pulmonary circuit)
What is the mortality rate for PE?
> 30% mortality (if a large vessel is obstructed, death will occur very quickly)
Does pulmonary embolism go away after it is treateD?
Yes, but there is a high rate of recurrence
Etiology of pulmonary embolism
- Majority is d/t DVT
- Fat embolism from fracture
- Air embolism
- Amniotic fluid from ruptured amniotic sac
- saddle embolus
Which veins does a thrombus from a DVT typically occur in?
iliac, femoral, popliteal, great saphenous veins of the leg
Explain how DVT causes a PE
Thrombus within the iliac, femoral, popliteal, great saphenous veins of the leg that embolisms and reaches the pulmonary circuit.
Is a DVT life-threatening?
Not necessarily, it is only a major problem when the clot travels to a vital organ circulation
Explain the route of a thrombus if it were coming from the the lower body.
Into inferior vena cava -> R atrium -> R ventricle -> pulmonary artery -> pulmonary capillaries -> pulmonary vein (cloth gets caught in one of the smaller vessels of the pulmonary circuit)
Explain how a fracture causes pulmonary embolism
Fatty bone marrow is released during orthopaedic surgery or if a bone is fractured in trauma -> fat enters the circulation and moves as an emboli, reaching the pulmonary circuit
How does an Air embolism occur?
From syringe or tubing
How does amniotic fluid from a ruptured amniotic sac cause pulmonary embolism?
Amniotic fluid enters circulation during trauma or delivery through severed blood vessels.
Saddle embolus?
Named after the saddle-like appearance of an embolus created by a thrombus settling at the area where pulmonary vessels bifurcate, attracts platelets, causing the thrombus to increase in size
Explain the pathology of a pulmonary embolism. Assume that the P.E. was caused from a DVT.
DVT -> embolus -> R side of heart -> pulmonary circulation -> thrombus in arterial bed -> decreased perfusion ->. platelets attracted to the site of the thrombus d/t abnormality in vessel -> platelets degranulate to release mediators to attract more platelets but the degranulation also causes brachial and pulmonary artery constriction. There is hemodynamic instability d/t obstruction and further constriction of vessel and the nervous system reflexively causes bronchoconstriction. This results in a ventilation: perfusion imbalance (hypoxemia & systemic hypoxia). Decreased CO & decreased surfactant
Why do platelets degranulate?
To release mediators to attract more platelets (but here, the degranulation also causes bronchial and pulmonary artery constriction)
In a pulmonary embolism, why does the nervous system reflexively cause bronchoconstriction?
It is just a reflex, not beneficial
Why does the CO decrease in a pulmonary embolism?
There is an obstruction in the lungs -> decreased blood flow into the left side of the heart = less blood to pump out into the systemic circuit
What is the normal function of surfactant?
It decreases adhesion forces and prevents walls of alveoli from sticking together on exhalation
What is surfactant composed of?
Phospholipids, cholesterol, proteins and fluid (which is taken from the blood)
Why is there decreased surfactant during an pulmonary embolism?
With impeded circulation, there is decreased fluid available to form the surfactant. Also, the T2 alveolar cells that produce surfactant are ischemic and have decreased function, furthering the decrease in surfactant levels
What the decrease in surfactant in pulmonary embolism result in?
Atelectasis d/t walls sticking together
What is a complication of pulmonary embolism?
Right-sided HF
Why is right-sided HF a result of Pulmonary embolism?
Obstruction in the pulmonary circuit, which receives blood from the right side of the heart, so the right ventricle is pumping against increased resistance = increased workload on the right side of the heart = failure
