Perhaps Babione needs one of these for hyperventilation issues but hey I digress.
Air Force Tests New System to Monitor for Hypoxia Problems 18 Sep 2017
"...Cobham’s system has inhalation and exhalation monitors that fit in a flight vest pocket. The inhalation monitor is designed to measure oxygen pressure, temperature, pressure within the breathing hose, humidity and other factors. The exhalation monitor checks oxygen pressure, expired carbon dioxide, and pressure within the mask, among other variables...."
https://www.defensetech.org/2017/09/...oxia-problems/