Breathing apparatus with monitored delivery device

摘要

A breathing apparatus is disclosed having a delivery device (30) for adding a volume of a substance to a gas flow, the delivery device having a gas inlet (31) and a gas outlet (33). The apparatus further comprises a first sensor unit (40) at the gas outlet (33) providing a first measurement value based on an acoustic property of a gas in a first conduit (41), and a second sensor unit (20) at the gas inlet (31) providing a second measurement value based on an acoustic property of a gas present in the second conduit (21). A control unit (50) determines the presence of the substance based on the first measurement value or based on a comparison of the first measurement value and the second measurement value, and provides for a regulatory loop for a gas composition including said substance added by said delivery device