Carbon dioxide concentration in extracellular fluids plays a critical and immediate role in pH regulation, electrolyte balance, hemoglobin chemistry, circulatory physiology, muscle function, and kidney physiology. Deregulation of extracellular CO2 precipitates major physical and psychological symptoms and deficits. Carbon dioxide concentration is precisely regulated by brainstem reflex mechanisms for maintaining proper homeostasis.

Using CO2 analyzers for medical purposes (capnography or capnometry) is for determining the concentration of CO2 gas in blood plasma and other extracellular fluids (Interstitial, lymph, cerebrospinal). They do so by measuring End-tidal CO2 (PetCO2), the CO2 concentration at the end of the breath (tide) which represents the average alveolar CO2 concentration. In healthy people, alveolar CO2 concentration is highly correlated with arterial CO2 concentration. Medical capnography is the use of CO2 analyzers in critical care, surgery, and medical emergency environments where life threatening shifts in blood gases must be continuously monitored and regulated.

Using CO2 analyzers for educational purposes is for identifying and unlearning dysfunctional breathing habits that compromise respiration based on the principles of behavior analysis and behavior modification. Dysfunctional breathing habits, where reflex-regulated CO2 has been compromised, may cause, trigger, exacerbate, and perpetuate a wide range of effects (symptoms and deficits) that are typically mistakenly attributed to other unrelated causes. In fact, the use of CO2 analyzer instrumentation is the only effective technological means to determining if, when, where, and how a learned habit is compromising respiration.

The CapnoTrainer® is a CO2 analyzer used for identifying breathing habits and then unlearning dysfunctional ones and learning new ones.