Capnometer

 

A capnometer or capnograph  measures ‘end-tidal CO_2’ (the partial pressure of carbon dioxide in expired air at the end of expiration) exhaled through the nostril into a latex tube.

A narrow plastic tube is inserted into each nostril and the tubes are taped to the skin near the upper lip.  The machine then continuously monitors ‘end-tidal breath’.  The air from the tubes is analysed by an infrared gas analyser and the signal is then sent to a computer that feeds back the information to a videomonitor.  Most machines can provide hard copy output and also provide statistical analyses of the results.  It is also possible to place a ‘goal wave’ into the machine for comparative purposes.

It is thus a sensitive analyser of the type of breathing. Shallow, rapid, and effortful breathing lowers CO₂, while deep, slow, effortless breathing increases it.  You will know from this whether the person has achieved an increase in breathing rate or a decrease.

Biofeedback therapists use capnometric biofeedback to supplement respiratory strain gauge biofeedback with patients diagnosed with anxiety disorders, asthma, chronic pulmonary obstructive disorder (COPD), essential hypertension, panic attacks, and stress.