A DEVICE FOR INDICATING THE PRESENCE OF CARBON DIOXIDE IN A PATIENT'S EXHALED AIR

摘要

A device for indicating the presence of CO2 in a patient's inhaled air comprises a CO2 detector including an indicator element (14) which undergoes a reversible colour change in response to exposure thereof to air containing CO2 in concentrations of the same order of magnitude as the CO2 concentration of air exhaled by a human being, and also comprises a heat-moisture exchanger (12) including a housing (13) with a first connecting port (15) adapted to be connected to the trachea of a patient, and a second connecting port (15) adapted for connection to a ventilator or an anaesthetic machine, for example. In a flow-through passage (P) extending between the connecting ports (15, 16) there is mounted an element (18) for the regenerative exchange of heat and moisture between, on the one hand, air flowing through the flow-through passage (P) in one direction and, on the other hand, air flowing through the flow-through passage (P) in the opposite direction. The indicator element (14) is disposed in the flow-through passage on the side of the heat-moisture exchanger element (18) remote from the first connecting port (15) and is viewable from outside the housing, and its response time for the colour change is sufficiently short to enable it to change colour upon each breath.