So now let's discuss pulmonary edema
that's caused by non cardiogenic causes.
This is slightly less common than cardiogenic pulmonary edema
but it's important to try and differentiate between the two when you do see it.
So as we know cardiogenic pulmonary edema is usually caused by CHF
and it's because of an increase pulmonary venous pressure.
Non cardiogenic edema is usually caused by increased capillary permeability
that may or may not be caused by alveolar damage
and it usually result in volume overload.
So there are multiple different causes of non cardiogenic pulmonary edema
just to list some of them,
it can be caused by ARDS or adult respiratory distress syndrome.
Neurogenic edema can cause it so in a patient
that has any kind of brain abnormality, high altitude edema.
So patients that are travelling to very high altitudes
all of a sudden can cause pulmonary edema.
Lymphangitic spread of malignancy can be a cause,
any kind of drug overdose especially heroin or cocaine.
Re-expansion edema in a patient that has atelectasis
that expands very quickly.
Any kind of allergic reaction and inhalational injury,
aspiration can cause it and patients that undergo near drowning experiences
can also have pulmonary edema. So again these are just the few
of the many different causes of pulmonary edema
that's cause by non cardiogenic origin.
So some of the radiographic features overlap with congestive heart failure
or cardiogenic edema. It includes bilateral, diffuse airspace disease
or the ground glass opacity that we saw with CHF.
Usually though with non cardiogenic edema
it has a more peripheral distribution rather than a central distribution
which is somewhat different than CHF.
One important thing to help you differentiate
is that the heart size is actually normal
and you'd normally don't see Kerley B lines,
peribonchial thickening or pleural effusions.
However again, there is considerable overlap with cardiogenic edema.
So this is an example of pulmonary edema.
So can you tell whether this is CHF or whether this is non cardiogenic?
It's a little bit difficult actually.
So this radiograph demonstrates a patient with the normal heart size
which is really the key difference but it does have bilateral,
central pulmonary edema and it's a distribution that's similar
to cardiogenic edema as we said non cardiogenic
is usually more peripheral in distribution.
But there are no pleural effusions.
So given the fact that the patient has a normal heart
and has no pleural effusions,
this actually represents non cardiogenic pulmonary edema.
This was obtain in a patient that had recent cracked, cocaine use.
So the clinical history should also help you.
So let's look at the differences between cardiogenic and non cardiogenic.
So in cardiogenic pulmonary edema
you normally would have cardiomegaly
but again you would not or it's very rare to find that in patients
that have non cardiogenic edema.
Interstitial thickening is seen really only in patients with cardiogenic edema
and that's represented as Kerley B lines.
You would see pleural effusion, rarely in patients with cardiogenic edema.
And consolidation, again is more central and perihilar
in patients with cardiogenic edema.
Again you would have that classic batwing appearance
in patients with cardiogenic edema but in non cardiogenic edema
usually the consolidation is seen more peripherally
but as we just saw the case that's not always true.
So let's take a loot at this case.
Do you think this is cardiogenic or non cardiogenic edema?
So here are some of the findings. Let's review some these.
So the patient does have an enlarged heart,
the patient has cephalization or prominence of the pulmonary vascular
in the upper lobe as you can see by the arrow
and the patient has perihilar haziness which we can see by the circle.
So this is actually an example of congestive heart failure
or cardiogenic edema and the key features here are the enlarged heart
and the cephalization which we really wouldn't expect to see
in a patient that has non cardiogenic edema.
So we've gone over some of the findings, similarities
and differences between cardiogenic and non cardiogenic edema.
Again, the clinical history is very important in these cases
but there are few imaging findings that you can use
to help you differentiate between the two.