13 Oct 2023 • Are you preparing for the Wizards of Medicine: Pulmonology?🧙‍♂️

Well here's something that might just help?🙋‍♀️

Lets get down to the basics!

As far as pulmonology is concerned, the most common symptom a patient reports in clinical practice is breathing difficulty or SOB.

SOB is a vague complaint and needs to be analysed further before we reach a diagnosis and initiate treatment.

How do we analyse this symptom?🤷🏻

Spirometry!

You might see that the rate of breathing is faster, however the volume per breath is lower.

We need to analyse this 'volume'.

It might be evident that this is a lung disease🫁, but is it Obstructive or Restrictive?🩺

Well, we first need to understand some terms here:

TV: Tidal volume is the total amount of air inhaled or exhaled during regular respiration.

IRV: Inspiratory reserve volume is the additional volume over the TV.

ERV:Expiratory reserve volume refers to the additional volume that could be forcibly exhaled out after the expiration of a standard TV.

RV: Residual volume is the remaining volume of air in the lungs, after the reserve volume is expired. That's basically why our lungs don't deflate after forced expiration.

TLC: Total lung capacity applies to the total volume of air in the lungs after a forced inspiration.

TLC = TV + ERV + IRV + RV

What is VC?

Vital capacity is the total volume of air that can be expired after a maximum inhalation.

VC = TV + ERV + IRV

Well, then what is FVC?

Forced vital capacity is the total volume of air that is released out on forced expiration after a maximum inhalation.

So if the FVC is reduced, this indicates a restrictive lung disease.

Why?

Because there is an obvious restriction to the ability to exhale completely, a low FVC indicates a restrictive pattern.

Well, what about FEV1?

Think about it, if the airways are narrower than usual, the amount of air expired will definitely be low and prolonged.

Hence, FEV1 is the the volume of air expired on forced expiration in the 1st second.

While a low FVC indicates a restrictive lung disease, a low FEV1/ FVC indicates an obstructive lung disease.

Yes, the ratio is what determines if the lung disease has an obstructive pattern!

Did you know?

In obstructive lung diseases like COPD and Asthma, you can find out whether the bronchodilators are helping your patient.🧐

Don't wait....Tune in now to find out!🤗

🔗Click here to watch Lung Function Test: Basics & Interpretation by Dr. Salil Bendre right here on Medflix💛