PMC

A respiratory event with the criteria for hypopnoea without snoring sounds. Persistence of respiratory cycles in the flow sound signal but reduced in amplitude both at inspiration and expiration.

Detection of oral breathing using tracheal sounds. During expiration, the nasal pressure signal is null while the sound signal remains present. The oral expiration detected by the tracheal sound signal is confirmed by the thermistor signal, which shows respiratory variations.

Example of a mixed apnoea where respiratory efforts are absent at the beginning of the event and resume before the event finishes. The respiratory efforts evaluated with the SSP are confirmed by the RIP signals as well as by the oesophageal pressure.

Automatic breathing sound respiratory cycle delimitation using envelope detection techniques. The beginning and the end of inspiration and expiration are properly detected and correspond closely with the respiratory cycle delimitation on the nasal pressure signal as well as the RIP signals. Tho/Abd: thoracoabdominal.

Detection of three consecutive obstructive apnoeas using the PneaVoX tracheal sound sensor. 1) Absence of tracheal sound (absence of respiratory cycles on the flow sound intensity and the snoring intensity signals). 2) Absence of oronasal flow on the thermistor signal. 3) Absence of nasal pressure on the nasal pressure signal.

Presentation of a tracheal sound transducer. a) Diagram of the PneaVoX sensor that uses both an acoustic sensor and an SSP sensor. The sensors are inserted in a protective plastic housing to ensure an airtight acoustic chamber between the skin and the transducer. b) The sensor. c) Attachment of tracheal sound sensors to the skin using double-faced tape with an adhesive bandage over the sensor.