RT Journal Article SR Electronic T1 Apnoea characterisation using tracheal sounds spectral analysis JF ERJ Open Research JO erjor FD European Respiratory Society SP P18 DO 10.1183/23120541.sleepandbreathing-2017.P18 VO 3 IS suppl 1 A1 AbdelKebir SABIL A1 Guillaume Baffet A1 Cédric Freycenon A1 Jean Pinguet YR 2017 UL http://openres.ersjournals.com/content/3/suppl_1/P18.abstract AB Even if the airflow in the upper airway is insignificant, tracheal sounds emitted during apnea and just at the resumption of ventilation have their origin in the inspiratory depression created around the pharyngeal collapse. We aimed to establish a link between the characteristics of chocking sounds (CS) and the nature of the apnea characterized using polysomnography (PSG) with AASM 2012 criteria.Tracheal sounds were sampled at 4 kHz with 16 bits. The PSG recordings used for this study have a signal-to-noise ratio high enough to recognize the pulse signal. We studied the last 10 seconds of apneas and the resumption of ventilation. We characterize mixed or obstructive apneas by the presence of CS and central apnea by the absence of CS. The CS are characterized by their mid-inspiration snoring spectrum that can occur in any hyperventilation following an apnea. The detection of CS from the intermittent (during apnea) or permanent (at the end of apnea) clearing of the temporary obstacle is optimized using ROC curves.The study was conducted on 12 PSG recordings containing 342 obstructive, 240 mixed and 137 central apneas. The optimization criteria require a minimum CS above the background noise of 32 dB during apnea and 34 dB at the end of apnea. Mixed and obstructive sleep apneas are recognized with a sensitivity of 95.5% and a specificity of 95.5%.CS at the end of apneas correctly characterize obstructive events. Their absence indicates that the apneas are central. This study confirms the role of efforts that generate CS during arousal. Finally, compared to qualitative assessment of respiratory efforts using the thoracoabdominal movements, this method introduces a quantitative assessment of respiratory efforts.