Using FeNO to Uncover the Answers to a Mystery Diagnosis

In this edition of FeNO stories, we speak to Amanda Babineau, a registered respiratory therapist and certified respiratory educator. She presents to us one of her clinical FeNO case studies, explaining how FeNO helped to get a young patient answers, and prioritized their asthma care.

A 13-year-old girl presented to the emergency room with symptoms of dyspnoea and allergy related coughing, of which she had been suffering with for one month. She had previously been treated on and off with a combination inhaled corticosteroid (ICS) and long-acting beta-agonist (LABA) inhaler and Montelukast but was no longer using these. The diagnosis at this time was unclear, so she was treated with antihistamines for one month.¹

A couple of weeks later the young patient returns to the ER, her symptoms had not improved despite taking antihistamines once daily, so she was prescribed an ICS preventer inhaler and a SABA inhaler as needed for three months.

The patient’s ER visits had been flagged by the Respiratory Health Clinic (RHC), and after the 2nd visit, the RHC performed a call back offering a consultation at the RHC, which was accepted. The respiratory health clinic performed spirometry on the patient, and suggested allergy testing, referral to paediatrician, and a change in the patients ICS and LABA inhaler to an ICS/LABA combination. On the one-week and one-month follow-up, the patient showed improvement with the treatment, fewer symptoms, and improved spirometry.¹

However, about six weeks later, the patient’s symptoms had returned. The clinic encouraged compliancy with the inhaler. Three months on, the patient’s symptoms had worsened, and the inhaler dose was increased. The patient had further spirometry which came back as normal, so they focused on a scent-free home and inhaler compliance.¹

At this time, the clinic did not have FeNO testing available to them. Amanda explains, “Now this is where FeNO and our NIOX® machine has become an integral part of our testing.”¹

“This is where FeNO comes in for us, and we cannot imagine working without it anymore.”¹

Two months later, the patient was requiring their SABA inhaler five times a day and her preventer inhaler was always taken as prescribed. In the household, they had reduced the perfume and other scents, and allergy tests came back negative. The plan was to continue the preventer treatment and suggest blood eosinophil count to the family doctor/paediatrician. Blood eosinophil count was performed shortly after, but the results were sent to the prescribing doctor and not to the RHC. The RHC was only aware of the abnormal results (eosinophils of 1000) during the next scheduled follow-up, five months later. Side note: the gap in receiving test results in a timely fashion has now been addressed. The clinic suggested a paediatric respirology referral for potential eosinophilic asthma.¹

The patient suffered another exacerbation and presented to the ER and was treated for a respiratory virus. Her eosinophils at this point were now at 1400. Shortly after, the patient was seen at the RHC with increased symptoms including dyspnoea and orange mucus.¹ The RHC performed a FeNO test on her for the first time which was at 182 ppb, indicating high levels of airway inflammation.¹

A few days later the patient’s symptoms had worsened, and she consulted the ER again. A chest X-ray was done and showed possible consolidation in the lungs, blood tests showed an eosinophil count of 1200 and IgE of over 2000. She was treated with a course of oral steroids for five days. Upon completing the prednisone, the patient returned (again) to the ER for the 3rd time in the span of 10 days; spirometry and a sinus and chest X-ray were done, and all came back normal. FeNO was measured again, this time in the ER.1 The FeNO came out as 243 ppb despite the course of oral steroids.¹

“When we saw this number, we took it seriously”

The patient was then prioritised much more quickly. She visited her paediatrician to rule out juvenile rheumatoid arthritis, possible cancers, and other co-morbidities, as they were looking at other reasons that her FeNO was high.¹

Outcomes

This is a case that is still in progress, she is now 15 years old. Her FeNO and spirometry are performed regularly, with FeNO generally between 75 – 90 ppb.¹ “For me what changed was that time she presented in the ER with symptoms, her spirometry was normal as well as her sinus/chest X-ray. Sometimes we tend to look at numbers and tests, but we don’t listen to the patient.”¹ “The FeNO test was able to confirm what we were suspecting but we weren’t able to confirm with other testing.”¹ It is suspected that more than just severe asthma is going on in this case, but the patient is in the care of specialists now.¹

Update

The patient has since been seen by an adult respirologist (she is now 15 and 6 months) and an ENT. The respirologist was leaning towards starting a biologic severe asthma treatment. The ENT discovered severe nasal polyps despite having a normal sinus Xray a few months prior. The patient underwent nasal polyp removal surgery in May 2024. The RHC followed up with the patient a month later; ICS/LABA reg, no asthma symptoms, normal spirometry and a FENO of 29!

Thank you, Amanda, for sharing this case study with us on how FeNO helped to provide answers that other tests were not giving. The respiratory health clinic now uses FeNO much earlier on in diagnosis, particularly when other tests are coming back normal or inconclusive. This is an example of where FeNO can give a clearer picture of what is going on in a patient’s airways, by quickly and accurately showing the level of inflammation in a patient’s lungs, something which other non-invasive tests could not show.^2-6

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