Niox vero

Potential predictors of compliance were obtained using a combination of questionnaires, daily diaries, and in-home assessments. Maternal age, body mass index (BMI), and asthma status were assessed using questionnaires at baseline visit. Symptoms and daily activities were assessed using the daily diaries. Peak expiratory flow was collected in the morning and afternoon during daily in-home assessment using the Pocket Peak^® Mechanical Peak Flow Meter (nSpire Health, Inc., Longmont, CO, USA). Exhaled nitrous oxide was collected during in-home assessment using the NIOX Vero (Aerocrine). Women were provided with proper training on how to use these devices during their clinical visits and were provided detailed instructions. In addition, daily diaries also assessed symptoms and various daily activities during the monitoring period.

F_ENO₅₀ was measured non-invasively using the hand-held NIOX Vero (Aerocrine AB, Sölna, Sweden) device expressed in parts per billion (ppb), with a measurement range of 5–300 ppb (16 (link)). The measurements were performed with the participant sitting without a nose clip following the recommendations from the European Respiratory Society and the American Thoracic Society (17 (link)). The participants were instructed to inhale to their full lung capacity through the mouthpiece that contained a protective filter to avoid environmental contamination. While exhaling, the participants were guided by an animation on the device to maintain a correct and constant expiratory flow rate of 50 mL/s, with 10% variation allowed. If the participant failed to perform the test correctly, the device automatically required a new measurement.
Elevated F_ENO₅₀ was defined as ≥25 ppb or ≥50 ppb, as recommended by the American Thoracic Society for the interpretation of F_ENO₅₀ in clinical practice (12 (link)). F_ENO₅₀ <25 ppb is used as an indication that eosinophilic airway inflammation is less likely, while F_ENO₅₀ ≥50 ppb indicates that eosinophilic airway inflammation is likely (12 (link)).

The Fraction of Exhaled Nitric Oxide (FENO) was measured at an expiratory flow of 50 mL/s with a chemiluminescence analyzer (NIOX VERO, Aerocrine AB, Stockholm, Sweden). Measurements were in accordance with American Thoracic Society (ATS) and European Respiratory Society (ERS) recommendations [26 (link)].

Baseline clinical parameters, including age, sex, body mass index (BMI), smoking status, allergic disease history (allergic rhinitis, pollinosis, infantile asthma, and atopic dermatitis), and other comorbidities, were collected from each patient’s medical records at the first FeNO measurement. Data on the total eosinophil count, serum immunoglobulin E (IgE), anti-glycopeptidolipid-core IgA antibody, FeNO, spirometry, chest radiography, and high-resolution computed tomography (HRCT) findings were also collected. FeNO was measured using a NO analyzer (NIOX MINO or NIOX VERO; Aerocrine, Solna, Sweden).