Definition
The term hyperventilation stands for the unphysiological phenomenon of accelerated and deepened breathing (hyper = too much, ventilation = aeration of the lungs).
Physiological regulation
Normally our respiratory drive is regulated by neurogenic and chemical stimuli. Especially the chemical stimulus is crucial in terms of hyperventilation. To understand hyperventilation, it is important to understand the physiological chemical respiratory drive.
The three main factors influencing hyperventilation are an increased carbon dioxide partial pressure (pCO2), an increase in protons (H+) and a decreased oxygen partial pressure (pO2). The strongest respiratory stimulus is set by a decrease in pCO2 and is also called hypercapnic respiratory stimulation. The value is measured by central chemoreceptors in the central nervous system.
If the value rises, regulatory mechanisms of the body intervene and stimulate breathing to exhale the excess CO2. Furthermore, hyperventilation with increased depth of breath occurs when the H+ count increases. However, the respiratory rate remains unchanged or increases if necessary.
The blood becomes “acidic” due to the increase in the H+ number and the pH value drops below its optimum value of 7.4. The increased exhalation of C02 is accompanied by a decrease in the proton number, so that the pH value rises again. The last regulatory mechanism is the one via peripheral chemoreceptors, which measure the pO2 in the blood of the aorta and the glomus caroticum. The condition of a decreased arterial pO2 is called hypoxia (hypo=too little, oxys = stands for oxygen) and stimulates the respiratory drive.
Psychogenic Hyperventilation
Hyperventilation, as defined above, describes the state of accelerated and deepened breathing beyond normal needs. The psychogenically triggered variant is completely detached from the regulatory mechanisms of the body. Through the increased respiration, a lot of CO2 is breathed out and therefore a reflex-induced decrease in respiration should actually occur.
However, this regulatory loop does not take effect in psychogenic hyperventilation, so that those affected continue to enter a state of deepened and accelerated breathing with a feeling of breathlessness. The consequence of psychogenic hyperventilation is a decrease in arterial and alveolar pCO2. This leads to respiratory alkalosis, i.e. a breath-dependent alkaline state of the blood in the form of an increase in pH, since the CO2 can no longer lower the pH by exhalation.
It can therefore be said that psychogenically induced hyperventilation is an inadequate reaction, detached from the normal pathophysiological mechanisms of the body. Triggers of psychogenic hyperventilation are manifold and individual. Accelerated breathing is often associated with psychologically stressful situations.
Anxiety, depression, aggression, pain and stress can also be the cause of psychogenic hyperventilation. Often affected persons are not aware that their emotional situation is about to provoke a hyperventilation trigger. Therefore this often happens unconsciously. According to current studies, women are more often affected than men. Furthermore, the risk of psychogenic hyperventilation increases in the second to third decade of life.
