Lung compliance

Factual Questions
1

I think this powerpoint I’m reading has conflicting information. Either that or being up and studying for 15 hours is taking its toll.

  • Compliance is how easily the elastic forces of the lungs accept a volume of inspired air.
    *Compliance is the ability of the lung to recoil (go back to its original shape)
    * It is what causes the lung to return to its resting state after an inhalation.
    * It is a measure of distendibility of an object; a measure of how easily it can be stretched.
    As someone who has a history of balloon twisting, the first and fourth points agree and the second and third disagree.

As I’m reading this, the first and last are saying that a more compliant lung is easier to fill with air. But, the second and third are saying that compliance is what causes the lung to recoil.

But, something elastic that easily accepts air doesn’t recoil well because it has lost its elasticity. The next page goes on to say that an example of high compliance is emphysema, where the patient can easily inhale but can’t get all the air out because their lungs don’t recoil as well as they should.
So, am I totally misreading the second and third points or is the powerpoint wrong?

2

As I understand it, compliance refers to the ability to stretch or distend, but not to recoil. So, you have it exactly right.

It is similar in the ventricles the heart - compliant ventricles can be readily filled and thus easily accept blood from the atria. On the other hand, stiff or non-compliant ventricles resist such filling since they can’t stretch to accommodate the incoming blood. The result can be pulmonary edema strictly on the basis of impaired cardiac filling and not at all due to poor ventricular contraction (i.e. diastolic, but not systolic, dysfunction).

3

Ok, good to know I’m not losing it. Thank you!