RT Journal Article SR Electronic T1 Quantifying the magnitude of pharyngeal obstruction during sleep using airflow shape JF European Respiratory Journal JO Eur Respir J FD European Respiratory Society SP 1802262 DO 10.1183/13993003.02262-2018 VO 54 IS 1 A1 Dwayne L. Mann A1 Philip I. Terrill A1 Ali Azarbarzin A1 Sara Mariani A1 Angelo Franciosini A1 Alessandra Camassa A1 Thomas Georgeson A1 Melania Marques A1 Luigi Taranto-Montemurro A1 Ludovico Messineo A1 Susan Redline A1 Andrew Wellman A1 Scott A. Sands YR 2019 UL http://erj.ersjournals.com/content/54/1/1802262.abstract AB Rationale and objectives Non-invasive quantification of the severity of pharyngeal airflow obstruction would enable recognition of obstructive versus central manifestation of sleep apnoea, and identification of symptomatic individuals with severe airflow obstruction despite a low apnoea–hypopnoea index (AHI). Here we provide a novel method that uses simple airflow-versus-time (“shape”) features from individual breaths on an overnight sleep study to automatically and non-invasively quantify the severity of airflow obstruction without oesophageal catheterisation.Methods 41 individuals with suspected/diagnosed obstructive sleep apnoea (AHI range 0–91 events·h−1) underwent overnight polysomnography with gold-standard measures of airflow (oronasal pneumotach: “flow”) and ventilatory drive (calibrated intraoesophageal diaphragm electromyogram: “drive”). Obstruction severity was defined as a continuous variable (flow:drive ratio). Multivariable regression used airflow shape features (inspiratory/expiratory timing, flatness, scooping, fluttering) to estimate flow:drive ratio in 136 264 breaths (performance based on leave-one-patient-out cross-validation). Analysis was repeated using simultaneous nasal pressure recordings in a subset (n=17).Results Gold-standard obstruction severity (flow:drive ratio) varied widely across individuals independently of AHI. A multivariable model (25 features) estimated obstruction severity breath-by-breath (R2=0.58 versus gold-standard, p<0.00001; mean absolute error 22%) and the median obstruction severity across individual patients (R2=0.69, p<0.00001; error 10%). Similar performance was achieved using nasal pressure.Conclusions The severity of pharyngeal obstruction can be quantified non-invasively using readily available airflow shape information. Our work overcomes a major hurdle necessary for the recognition and phenotyping of patients with obstructive sleep disordered breathing.The degree of pharyngeal airflow obstruction varies widely for any given OSA severity (apnoea–hypopnoea index) and is challenging to measure. Here we combine information from automated flow shape to accurately estimate the severity of airflow obstruction. http://bit.ly/2uYD0rf