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Forced oscillation technique (FOT) in Coimbatore — an effort-free breathing test
15–20 minutes
Forced Oscillation Technique (FOT) is a modern, effort-independent way to assess airway resistance and reactance. Unlike spirometry, you only need to breathe normally — making it ideal for children, the elderly and patients with neuromuscular weakness.
FOT is especially valuable for detecting small-airway disease early in asthma and COPD, when spirometry can still look normal.
Who is this for?
- Children aged 3 and above
- Elderly patients who can't sustain forced exhalation
- Suspected small-airway disease with normal spirometry
- Monitoring response to inhaler therapy
What happens during your visit
- You sit and breathe quietly through a mouthpiece for 60–90 seconds.
- The machine sends gentle pressure oscillations to measure airway response.
- Tested before and after a bronchodilator if needed.
Why this test is performed
- To measure airway resistance and reactance in patients who cannot perform the forced blows that spirometry demands.
- To pick up small-airway disease in asthma and COPD at a stage when spirometry can still read as normal.
- To check objectively whether an inhaler is working, by testing before and after a bronchodilator.
How to prepare
- •Avoid a heavy meal in the hour before the test.
- •Bring your inhalers with you; we will tell you which ones to hold and for how long if reversibility is planned.
- •No sedation is used and there is nothing to recover from — you can drive home and go back to work.
What it feels like
- •You sit upright and breathe quietly through a mouthpiece while the cheeks are supported.
- •Gentle pressure oscillations are applied — most patients describe a faint vibration and nothing more.
- •Because normal tidal breathing is enough, children from about three years and frail elderly patients manage it easily.
15–20 minutes
Safety and limitations
- •There are no known risks. The test involves no radiation, no injection and no forced effort.
- •It complements spirometry rather than replacing it — where a full picture of lung volumes or gas transfer is needed, a complete PFT is still required.
Results and reporting
- •Resistance and reactance values are compared with predicted ranges for age and height, and with the post-bronchodilator reading.
- •Dr. Arun Gangadhar interprets the trace alongside your symptoms and any spirometry, and explains it at the same visit.
When to consult a pulmonologist
- Your child coughs or wheezes repeatedly but is too young for spirometry.
- You have breathlessness or cough with a normal spirometry report.
- You are elderly or have muscle weakness and cannot complete forced breathing manoeuvres.
How Lung Care helps
- •FOT is available alongside full pulmonary function testing at the RS Puram clinic, so the right test can be chosen on the day.
- •Where both are useful, the two are read together rather than in isolation.
Dr. Arun Gangadhar’s expertise
- •Dr. Arun Gangadhar reports lung function personally, which matters most in the borderline traces where FOT adds information.
Ready to book?
Reserve a consultation with Dr. Arun Gangadhar at our RS Puram clinic.