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Offered by Dr. Manish Aggarwal, Principal Director, Department of Chest Disease & Interventional Pulmonology, Max Hospital, with 24+ years of experience diagnosing and managing asthma and airway disease.
FeNO stands for fractional exhaled nitric oxide, a gas naturally produced in the airways that rises when there is inflammation present, particularly the type of inflammation seen in allergic asthma. The FeNO test measures the level of this gas in a single breath you exhale into a small handheld device.
Because it directly reflects airway inflammation rather than just airflow, it gives the doctor information that a standard breathing test like spirometry cannot provide on its own, helping to confirm a diagnosis and fine-tune treatment.
• 24+ years of clinical experience diagnosing and managing asthma and other airway conditions.
• Academic Foundations: MBBS, MD (Tuberculosis & Chest Diseases), FRCP (Glasgow), trained at premier Indian institutes.
• Hospital Affiliation: Principal Director, Department of Chest Disease & Interventional Pulmonology, Max Hospital, also practicing at his private clinic in Pitampura, Delhi.
• Holistic Approach: Results are interpreted directly by Dr. Aggarwal alongside your spirometry findings, symptoms, and treatment history, giving a fuller picture rather than a single isolated number.
• Therapeutic Precision: Frequently used to guide decisions on inhaled steroid therapy and to help distinguish asthma from other causes of cough or breathlessness.
• Global Fellowships: International clinical exposure across leading NHS hospitals in the UK, including Lister Hospital (Stevenage), Norfolk & Norwich University Hospital, The Queen Elizabeth Hospital (King's Lynn), The Great Western Hospital (Swindon), and Diana Princess of Wales Hospital (Grimsby).
• Professional Standings: Active member of respected global and national bodies, including the European Respiratory Society (ERS), American College of Physicians (ACP), Society of Critical Care Medicine (SCCM, USA), European Society of Intensive Care Medicine (ESICM), and Indian Chest Society.
• Patient Validation: Rated 4.9 on Google with 350+ verified patient reviews, known for a patient-first, clearly-explained approach to care.
Support the diagnosis of asthma, particularly when symptoms or spirometry results are unclear
Distinguish allergic, inflammation-driven asthma from other causes of cough, wheeze, or breathlessness
Help decide whether inhaled corticosteroid therapy is likely to be beneficial
Monitor whether a patient is responding to asthma treatment as expected
Check whether inhaler technique or adherence may be contributing to poor symptom control, since inflammation levels often reflect how well treatment is actually being used
Investigate a chronic cough where allergic airway inflammation is suspected
Especially allergic or eosinophilic asthma, where airway inflammation is a defining clinical feature.
Assessing cases where allergic airway inflammation is a highly suspected contributor.
Checking whether ongoing inflammation suggests a need for rapid treatment adjustment.
Helping reliably predict whether a patient is likely to benefit from specialized inhaled steroids.
Between asthma and other conditions like vocal cord dysfunction or non-allergic rhinitis, where FeNO adds needed clarity.
If you have symptoms that suggest asthma but the diagnosis isn't entirely clear, or if your current treatment doesn't seem to be working as expected, FeNO testing can add valuable information that guides the next step.
Wondering if inflammation is behind your symptoms?
Spirometry shows how well air moves through your airways, but it can appear completely normal even when deep tissue inflammation is active.
FeNO specifically measures airway inflammation, adding a reliable layer of molecular information that standard airflow sweeps cannot capture.
Used together, these tests give a more complete assessment, especially useful when baseline symptoms and spirometry results do not fully agree.
*Dr. Aggarwal will advise whether FeNO should be combined with spirometry or a full PFT based on your specific case.
• Avoid eating, drinking, or smoking for at least one hour before the test, as these can affect the baseline reading.
• Avoid vigorous exercise immediately before the test.
• If you are already using an inhaled steroid, let the clinic know, as this may influence your result and how it is interpreted.
• No special fasting or sedation is required, as this is a quick, completely non-invasive breath test.
Interface Setup: You will be shown how to breathe into a small, handheld FeNO device through a specialized disposable mouthpiece.
Controlled Pace: You take a normal breath in, then exhale slowly and steadily into the device at a controlled, even pace, usually guided by an interactive visual cue on the screen.
Readout Verification: The device measures the level of nitric oxide in your breath and displays a metric readout within a minute. The test may be repeated once or twice to confirm stability. The process takes roughly 5 to 10 minutes.
There is no clinical recovery time needed, and you can resume your normal day-to-day activities immediately. Results are available instantly, and Dr. Aggarwal reviews them the same day alongside your symptoms and history to make necessary modifications to your current asthma treatment plan.
FeNO testing is one of the safest and simplest tests used in modern respiratory medicine. It involves only normal, controlled breathing into a tracking device, with no needles, sedation, or forceful expiratory maneuvers required. It is highly suitable for children old enough to follow simple visual instructions.
You should contact our clinical care desk directly if you notice ongoing respiratory symptoms despite treatment adjustments made after your test, newly developed or worsening breathlessness, chronic deep cough, wheezing, or any acute concerns regarding how your current asthma therapies perform.
No. It simply involves breathing out slowly into a small handheld device. There is no needle, no sedation, and no discomfort involved.
Spirometry measures airflow through your airways, while FeNO measures the level of airway inflammation directly. The two tests give different, complementary information about your lung health.
FeNO testing supports an asthma diagnosis when used alongside your symptoms, history, and other tests such as spirometry. It is a strong piece of the puzzle rather than a standalone diagnostic test.
Yes, in many cases. A falling FeNO level over time on treatment often suggests that inflammation is being well controlled, while a persistently high level may suggest treatment needs to be adjusted.
Yes, FeNO testing is generally well tolerated by children old enough to follow simple breathing instructions, and it is commonly used to help diagnose and monitor asthma in younger patients as well.
We are available to answer queries, schedule urgent EBUS sessions or arrange Sleep diagnostic devices.
A quick FeNO test can uncover inflammation that other tests miss. Get tested and get clear answers from Dr. Manish Aggarwal, Delhi's leading pulmonologist with 24+ years of asthma and airway care experience.
📍 Clinic Address: JU-12A, Block G&JU, Ranikhet, Pitampura, Delhi, 110034
📞 Call Desk: +91 9899554095 | ✉️ Email: Aggarmanish@gmail.com