Patent ID: 7987849

Claim:
A method for determining the consumption of a CO 2 absorber in a respirator with a rebreathing system, the method comprising the steps of: providing the rebreathing system with a fresh gas mixer, with a computing and control unit, a respiration drive, a volume flow sensor located in an inspiratory branch, a CO 2 absorber located in an expiratory branch, the CO 2 absorber providing an output that is combined with an output of said fresh gas mixer and is sent to said inspiratory branch, a breathing gas escape valve and a breathing gas reservoir; connecting said computing and control unit to said fresh gas mixer, to said respiration drive and to said volume flow sensor to receive signals at said computing and control unit and to send control commands from said computing and control unit to said fresh gas mixer and to said respiration drive; determining a fresh gas volume (V FG ) discharged from said fresh gas mixer and inspiration volume flow (V I ) flowing into the inspiratory branch in said computing and control unit; determining a value for a purified rebreathing volume flow (V abs ) added from said CO 2 absorber from a difference of the values of the inspiration volume flow and the fresh gas volume (V I −V FG ) and determining a volume flow entering the CO 2 absorber from the value for the purified rebreathing volume flow and a preset or sensed CO 2 concentration value of gas flowing into the CO 2 absorber; determining a rate of CO 2 absorption from the volume flow entering the CO 2 absorber and from the preset or sensed CO 2 concentration value; integrating the determined rate of CO 2 absorption over time on the basis of the preset CO 2 concentration value or the sensed CO 2 concentration value measured with a gas sensor in the expiratory branch in order to determine the quantity of the CO 2 absorbed in said CO 2 absorber.