• It is done to measure the functioning of the lungs
  • specifically the amount and speed of air that is exhaled
  • It is a pulmonary function test which determines how well your lungs are working
  • Lungs have multiple functions to do, Ventilation is one of the


  1. Volumes
    Tidal volume
    Inspiratory reserve volume
    Expiratory reserve volume
    Residual volume
  2. Capacities
    Inspiratory capacity
    Vital capacity
    Total lung capacity

Indications for spirometry
1.Evaluate dyspnea
2.Pulmonary disease
3.Monitor effects of therapies used to treat respiratory diseases
4.Pre and post-employment screening
5.Lung resection
6.Cardiac surgery

Places a clip on your nose to keep both nostrils closed.
Place a cup-like breathing mask around your mouth.
Take a deep breath in
Hold your breath for a few seconds
Exhale as hard as you can into the breathing mask

Some important terms:
Forced expiratory volume in First second FEV1
How much air is exhaled during forced breath in just first one second
Forced vital capacity FVC
how much air exhaled from lungs after deepest breath

FEV1/FVC ratio: This ratio helps to differentiate the lung disease whether it is obstructive or restrictive

Unexplained dyspnea: Patients having normal auscultation and x-ray finding but still have breathing problems.
COPD: chronically progressing disease
Asthma/COPD overlap: both features are observed

features similar in both COPD and Asthma

  • Difficulty in breathing
  • Coughing
  • Wheezing

Spirometry with reversibility:
It is done to differentiate asthma and COPD from which the patient is suffering
3.again Spirometry

After Bronchodilator the next spirometry shows improvement in the FEV1/FVC than the previous one
an increase of more than 12% indicates asthma
patients having less than 12% improvement are likely to have COPD.

Body Plethysmography:
it is a Pulmonary function test
it measures the air volume present in your lungs after forceful expiration.
It is tested for lung-volume measurement.

.You’ll sit or stand in a small, airtight chamber.
.Babies may have a special type of test that allows them to lay down.
.put clips on your nose to shut off air to your nostrils.
.breathe against a mouthpiece when it’s both opened and closed.

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