Patent ID: 8858457

Claim:
A method for the automatic evaluation and analysis of a capnogram in a test subject, the method comprising the steps of: providing a line unit supplying and receiving breathing gas; flowing breathing gas into and out of the test subject through the line unit; providing a first sensor connected to the line unit for detecting gas volume received from the patient; providing a second sensor connected to the line unit for detecting carbon dioxide concentration in the gas volume; recording measured values for an indicator of an expired volume and measured values for an indicator of a carbon dioxide concentration for the breathing gas of the test subject; forming, using a processor, a basis for an automatic analysis of the measured values recorded from the measured values for an indicator of the carbon dioxide concentration—concentration measured values—over the measured values for an indicator of the expired volume—volume measured values including an FCO 2 curve; performing, using the processor, an automatic approximation of at least part of the curve of the concentration measured values over the volume measured values; using three mutually adjacent straight lines for the approximation; performing, using the processor, an equal area determination to determine serial dead space (Vds) by means of a third of the three straight lines as a straight line through a plateau of phase 3 of the FCO 2 curve; determining, using the processor, a slope of the third straight line; determining and indicating, using the processor, a quality of a gas exchange in the lungs of the test subject on the basis of the slope of the third straight line; determining, using the processor, parameters of the curve of the concentration measured values over the volume measured values which indicate usability of the measured values for determining serial dead space; and automatically estimating, using the processor, usability of the measured values on the basis of the parameters determined.