Diagnostic Accuracy of Tidal Breathing Patterns in Assessing Airflow Obstruction Compared with Spirometry

Spirometry is the standard for assessing airflow obstruction in COPD, but low-burden screening tools may support primary care in identifying patients needing referral, potentially enabling earlier diagnosis and timely disease management. A novel, easy-to-use device (AMES BV, the Netherlands) estimates obstruction from nasal pressure variation during tidal breathing and may support referral decisions. This study aimed to assess the ability of nasal pressure analysis to identify airflow obstruction compared with spirometry.

Cross-sectional study at a hospital pulmonary function laboratory. In a convenience sample of participants referred for routine spirometry, nasal pressure variation was measured via a nasal cannula and converted into an obstruction index, expressed as an estimated Forced Expiratory Volume in the first second/Forced Vital Capacity ratio (FEV₁/FVC). The ability to identify spirometry-derived obstruction (FEV₁/FVC<0.70) was assessed by sensitivity, specificity, and accuracy, with spirometry as reference standard. Bland-Altman plots were used to assess agreement between the estimated FEV₁/FVC ratio (derived from nasal pressure variation) and spirometry-defined FEV₁/FVC ratio.

Both procedures were performed in 192 participants (median age 66 (IQR 56-74) yrs; 39% male). Nasal pressure analysis showed moderate performance in detecting obstruction (sensitivity 66%, specificity 63%, accuracy 64%). The Bland-Altman plot showed variability between both measurements, consistent with moderate classification performance, with a mean difference of -0.016 and 95% limits of agreement ranging from -0.43 to 0.40.

Nasal pressure analysis showed moderate performance in detecting spirometry-defined airway obstruction, suggesting limited potential as a non-invasive tool. Further research is needed to establish its possible clinical utility.