Mediscuss! Medical Forum

I don't know if it is obvious, but I cannot understand this:

Why is there pulmonary infarction in pulmonary embolism?

My confusion - Lungs have dual blood supply. Bronchial arteries supplying oxygenated blood (systemic circulation) and Pulmonary arterial system (pulmonary circulation) supplying deoxygenated blood. When there is pulmonary embolism, bronchial arteries are still intact. They are the ones that supply oxygenated blood!

So, back to the question: Why is there pulmonary infarction in pulmonary embolism?
Can someone please answer this?

Your doubt is valid.

Let me clear this first: Pulmonary infarction is NOT common in pulmonary embolism. It is seen in only 10% of patients with pulmonary embolism. The reason is that there is generally intact bronchial arterial and collateral arterial circulation.

In general, the effects of pulmonary embolism depend on:

• Size of embolus
• Size of occluded vessel
• Exent to which blood flow is obstructed
• Availabilty of alternative blood source - bronchial arteries
• Overall cardiovascular function of the person involved

Common effects of pulmonary embolism:

• Increased pulmonary vascular resistance, due to vascular obstruction
• Impaired gas exchange, due to increased alveloar dead space.
• Alveolar hyperventilation, due to reflex stimulation
• Increased airway resistance, due to bronchospasm
• Decreased pulmonary compliance, due to edema, hemorrhage and loss of surfactant.

As you can see, pulmonary infarction does not figure prominently here...

Conditions that favor the formation of pulmonary infarction in pulmonary embolism:

• Pulmonary infection - pneumonia/ consolidation
• Diminished ventilation
• Vascular congestion

These conditions can produce pulmonary infarction even in the ABSENCE of pulmonary embolism!

Shashikiran

A Pulmonary Embolism would cause immediate problems. Depending on the type of emboli. How about this:
1. Short of Breath
2. O2 Saturation Drops
3. Unable to get oxygen into the system
4. Hypoxiema
5. Tachycardia
6. Someone had better dial 911 or this person is going to be shaking hands with St. Peter.
7. Cardiac Arrest
All right sometimes it is not that dramatic. But on Sunday, I had a patient do just that. Lucky for us he was already on life support and we were able to treat. So sometimes it does go that fast and sometimes it depends on just a lot of other things like:
Is the person previously healthy with no lung disease? Then they have a better chance than someone who has extensive lung disease.
What is the person's age? Why did they throw the PE? All of these things come into play.