Low CO2 (Hypocapnia): Definition, Causes, Symptoms and Treatment
Definition of Low CO2 (hypocapnia)
Hypocapnia (hypocapnea, also known as hypocarbia) is defined as a
deficiency of carbon dioxide in the arterial blood. This is
a major respiratory symptom. Most medical sources define hypocapnia
as less than 35 mm Hg for partial CO2 pressure in the arterial blood. The
arterial CO2 value for normal breathing at rest is 40 mm Hg (or about 5.3% CO2
partial pressure at sea level).
Another term "alveolar hypocapnia"
describes low CO2 levels in the alveoli of the lungs. Severe alveolar hypocapnia
generally leads arterial hypocapnia, which causes respiratory alkalosis.
(People with lung conditions often have arterial hypercapnia (elevated CO2)
caused by alveolar hypocapnia since alveolar hypocapnia immediately causes
bronchospasm.) These studies (see the Table below) show that alveolar hypocapnia is
very common for many chronic diseases. Most of these patients (with heart disease,
diabetes, cancer, and so forth) have arterial hypocarbia as well.
Furthermore, this Table also identifies the cause of hypocapnia.
What causes hypocapnia
Hypocarbia is caused by chronic
hyperventilation (or an automatic deep breathing pattern) leading to alveolar
hypocapnia (lack of CO2), and if there is no ventilation-perfusion mismatch, to
arterial CO2 deficiency. Normal breathing is imperceptible or unperceivable,
since it is small and light (10-12 breaths/min, 500 ml for tidal volume, and 6
L/min for minute ventilation at rest for a 70-kg person). In contrast,
hypocapnic patients and even most normal subjects breathe over 10 L/min and have
over 18 breaths/min for respiratory frequency.
Among lifestyle factors that cause hyperventilation and hypocarbia are
physical exercise with mouth breathing, meals (eating and especially
overeating), stress, anxiety, overheating, attempts to
breathe deeply, deep breathing exercises (except slow ones, like Pranayama),
supine sleep and being in the horizontal position, poor posture and many
other factors (see Causes of
Hyperventilation web page).
Respiratory and other symptoms of hypocarbia
hypocapnia is based on chronic hyperventilation, its symptoms are the same as
the symptoms of hyperventilation. They are very wide and range from chronic coughing
and nasal congestion, to constipation, coughing and muscle cramps. Among other
common symptoms of hypocapnia are bronchospasm, cold extremities, mouth
breathing, exacerbations of asthma, angina pain, and many others.
The key pathological effect of both, alveolar and arterial hypocapnia is
reduced levels of oxygen in body cells (tissue hypoxia), This promotes virtually
all chronic diseases. These and other physiological effects associated with low CO2
and low oxygen levels in body cells, with numerous medical studies, are provided
below (in CO2-related links). More information about symptoms of hypocapnia
can be found here: symptoms of
Severe hypocarbia: the most common cause/factor of mortality in the
The majority of terminally sick people die in conditions of severe hypocapnia due to
heavy and fast breathing. Separate web pages of this site have numerous studies
that show that terminally sick patients with cancer, cystic fibrosis, HIV, and
other conditions have up to 30-40 breaths per minute or more at rest.
Respiratory alkalosis, the result of heavy breathing in the sick, is the most common acid-base
abnormality observed in patients who are critically ill. It is common for
those with numerous diseases, including cancer, cardiovascular disease, diabetes,
HIV-AIDS, asthma, COPD, and many other conditions.
is based on overbreathing, successful treatment of hypocarbia
is based on addressing the cause: chronic hyperventilation. Therefore, treatment
of hypocapnia is the same as
treatment of hyperventilation. Note that based on impressive clinical evidence
(CO2 measurements in thousands of healthy and sick people),
leading Soviet physiologist Dr. KP Buteyko and about 150 medical
doctors (Buteyko breathing practitioners) suggested a different definition of
hypocapnia. These doctors tested nearly a half million people and found that great health (with a lot of energy, craving for physical exercise, joy of eating raw foods, naturally short sleep of no more than 4.5 hours and other amazing effects) is possible when people have even more carbon dioxide in alveoli of the lungs and arterial blood. Find out this number in your bonus content right below here.
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