◄    HYPOCAPNIA ►

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Breathing behavior regulates pH through proper exhalation (ventilation) of carbon dioxide (CO₂). In fact, pH plays a major role in the distribution of oxygen itself. Proper exhalation of CO₂, at rest, is only about 12 to 15 percent of the total CO₂ arriving in the lungs. The remaining 85 to 88 percent of the CO₂ is retained in the blood, and is absolutely vital to pH regulation. Exhalation of more than this relatively small amount of CO₂, results in a CO₂ deficit in the blood and other body fluids, a deregulated respiratory chemistry known as hypocapnia. Traditional common sense has misguided us into believing that CO₂ is poisonous. This superstition needs to be replaced with the facts.

CO₂ regulates the pH level of extracellular body fluids, like blood and cerebrospinal fluid; electrolyte balance, like sodium and potassium; blood flow, like to the brain and to the heart; kidney physiology, like bicarbonate regeneration; and delivery of oxygen and nitric oxide (for vasodilation) by hemoglobin. Hypocapnia disrupts fundamental biochemistry.

Hypocapnia is the result of overbreathing behavior, the mismatch of breathing rate and depth. Its consequence is an increased level of pH, or respiratory alkalosis, which may have profound immediate and long-term effects that trigger, exacerbate, and/or cause a wide variety of emotional, perceptual, cognitive, attention, behavioral, and physical deficits that may seriously impact health and performance. Although the fundamental importance of CO₂ in body chemistry regulation, pH and electrolyte balance, is common knowledge to any pulmonary or acid-base physiologist, it remains virtually unknown by most healthcare practitioners, health educators, breathing trainers, and laypeople.

Hypocapnia may be the result of nervous system, cardiovascular (e.g., low blood pressure), respiratory (asthma), and metabolic disorders (e.g., diabetes), including challenges such as drugs, hormone changes (e.g., in pregnancy), altitude, heat, lung irritants, severe exercise, and others. In many of these cases, hypocapnia plays an adaptive role, where it serves to compensate for pH deregulation, such as in the cases of lactic acidosis during severe exercise and ketoacidosis in diabetes.

Hypocapnia is most frequently, however, the result of learned overbreathing behavior, behavior dictated by the biological principles of learning, which include motivation, emotion, perception, memory, and attention. Behavioral hypocapnia is hypocapnia as a consequence of learned behaviors. It points to the powerful role of breathing in self-regulated health and performance, where its effects are typically identified as “unexplained,” or simply go unrecognized altogether.

Click here to learn about the physiological changes associated with hypocapnia.

Click here to learn more about symptoms and deficits and acute effects associated with hypocapnia.

Copyrighted by Behavioral Physiology Institute, Boulder, Colorado USA