Hypercapnia – Causes, Symptoms & Treatment


Hypercapnia occurs when the blood becomes too acidic with carbon dioxide. It ensures that the upper respiratory tract no longer functions properly. If the patient is not treated as soon as possible, the worst case scenario can be carbon dioxide anesthesia and death from respiratory arrest.

What is hypercapnia?

Symptoms of mild hypercapnia include flushing of the skin , headache , clearly visible blood vessels, muscle twitching, increased heart rate and mild confusion .

Medicine understands hypercapnia as an excessively high CO2 content in the (arterial) blood. In healthy people, the arterial partial pressure is a maximum of 40 mmHg. Patients with hypercapnia have a value above 45 mmHg. Hypercapnia is divided into an acute and a chronic form.

If, for some reason, a person cannot exhale the carbon dioxide that is produced as a metabolic by-product or that is inhaled, it accumulates in the blood. Then the CO2 partial pressure in the air sacs (alveoli) increases. The greater the acidosis (acidosis) of the blood with the gas, the more the breathing activity of the lungs is impeded.

Respiratory failure (shortness of breath) occurs . Hypercapnia can also occur as a symptom of another condition, such as Pickwick syndrome in patients with severe obesity . If respiratory failure is not treated in time, serious damage to the brain and heart occurs. In the worst case, CO2 anesthesia occurs with subsequent death from respiratory arrest .


Hypercapnia can have different causes. Adverse circumstances (accident), for example, can lead to the inhalation of extremely CO2-containing air. CO2 rebreathing, as in sudden infant death syndrome (SIDS), can also cause hypercapnia. Metabolic alkalosis, triggered by acute potassium deficiency , can also lead to the occurrence of excessive CO2 accumulation in the blood.

Inadequate respiratory function (respiratory insufficiency) due to damage to the alveoli (breastbone contusion due to an accident) or due to an obstruction in the airways are also the cause of blood acidification with CO2. Other triggers are: Damage to the respiratory center in the brain due to a cerebral infarction, impairment of the nerve pathways to the chest muscles due to paraplegia, pulmonary embolism , lung tumor , severe asthma attacks, shortness of breath due to a bad cold, severe pulmonary emphysema or even pneumonia .

Likewise, septic shock , certain neuromuscular disorders, ingestion of an inappropriate medication (steroids, diuretics, sedatives, anesthetics), and accidental administration of oxygen in patients with chronic obstructive pulmonary disease (COPD) .

Due to the permanent overloading of their airways, they already have a high level of acidity in their blood. However, the latter requires the activation of the breathing reflex. If oxygen is then accidentally supplied, the respiratory stimulus is inhibited and, in the worst case, respiratory arrest occurs.

Symptoms, Ailments & Signs

Symptoms of mild hypercapnia include flushing of the skin , headache , clearly visible blood vessels, muscle twitching, increased heart rate and mild confusion . As the partial CO2 pressure rises, there is shaking (tremor), increased breathing in an attempt to compensate for the shortness of breath, an increase in blood pressure and dizziness .

If the affected person then receives no help and the partial pressure rises to over 50 mmHg, seizures , sweating, palpitations, panic and hypoxia (insufficient supply of oxygen to the body) occur. The heartbeat slows down, the blood pressure drops sharply. This is followed by disturbances of consciousness with increasing drowsiness. The patient falls into a coma (CO2 anesthesia). If artificial respiration is not provided at this stage of hypercapnia, his lips will turn blue ( cyanosis ) and death from respiratory failure will occur.

Diagnosis & disease progression

Hypercapnia can be detected using an arterial blood gas analysis. The pH value and the oxygen saturation of the blood are also measured. If the pH falls below 7.35, respiratory acidosis is present. Acidification of the blood causes the blood vessels in the lungs to constrict, while at the same time those in the brain and the rest of the body widen. As a result, there is an increased potassium concentration in the blood, which impairs the heart function and can lead to cardiac arrhythmias. From a partial pressure of more than 60 mmHg, the patient falls into a coma.


If left untreated, hypercapnia can, in the worst case, lead to the death of the patient. The affected person usually dies from anesthesia caused by carbon dioxide, since the blood is extremely acidic. Eventually, respiratory arrest occurs, which in turn leads to cardiac arrest. In acute emergencies, urgent treatment by a doctor is therefore necessary.

Furthermore, the person concerned suffers from a high heartbeat and from an adeptness. Headaches also occur and the patient’s skin is usually red. The muscles twitch involuntarily and comes to a tremor. The quality of life is extremely reduced by the hypercapnia and the affected person also suffers from dizziness and nausea.

Not infrequently, there is also a loss of consciousness, in which the patients can also sustain injuries through a fall. Most sufferers also have a panic attack when the symptoms of hypercapnia appear. The treatment of the disease is acute in any case and must keep the affected person alive.

The underlying disease must also be treated. Whether further complications occur with this treatment depends strongly on the underlying disease and cannot generally be predicted universally. In most cases, however, life expectancy is reduced by hypercapnia.

When should you go to the doctor?

If symptoms such as skin flushing, headaches, and muscle twitching are noticed, hypercapnia may be the underlying cause. A doctor should be consulted if these symptoms appear for no apparent reason and persist for more than three to four days. If other symptoms appear, such as an increased heart rate or confusion, you must see a doctor on the same day.

If the hypercapnia remains untreated, seizures, tachycardia and sweating set in – at the latest then medical advice is needed. If the level of consciousness disorders increases, the emergency services must be alerted. External signs such as a blue discoloration of the lips, usually associated with a circulatory collapse, require immediate first aid measures. The person concerned must then be treated by an emergency doctor or taken to a hospital. Hypercapnia often occurs in connection with potassium deficiency, severe colds or pneumonia.

Septic shock and the use of certain medications can also be the cause. If the mentioned symptoms occur in connection with these diseases and risk factors, a doctor must be consulted immediately. In addition to the family doctor , a pneumologist or a specialist in internal medicine is the right contact person.

Treatment & Therapy

The first emergency medical treatment consists of removing the constricting clothing from the unconscious patient and elevating his chest. The legs should be lowered. Then the oxygen mask is put on. Fluids should only be given sparingly, if at all. In addition to further ventilation of the patient, the patient’s underlying disease can then be treated in the intensive care unit. He is ventilated by intubation or with the help of an oxygen mask.

It is connected to the BIPAP (Biphasic Positive Airway Pressure). The innovative ventilator enables the awakening patient to breathe at the lower and also at the upper pressure level. This stimulates diaphragm action, which in turn initiates activation of the respiratory pump. With stronger inhalation, the upper pressure level is lowered until both pressure levels correspond to each other. The hypercapnic patient is then extubated.

In the case of chronic ventilatory insufficiency, ventilation of the patient is more difficult because they are usually only slightly sedated and the physicians have to wait until their own breathing stops. Hypercapnia patients also receive beta sympathomimetics and theophylline . If an overdose of sedatives or opiates is the cause of the acidosis in the blood, anexates or naloxone are administered.

Outlook & Forecast

Hypercapnia has an unfavorable prognosis. In severe cases and without treatment, the disease leads to respiratory failure and death of the patient. In the event of an accident or sudden infant death, there is little chance of timely medical care to ensure the survival of the person concerned. If air with a high CO² content is inhaled, the person affected becomes acutely life-threatening and there are hardly any treatment options or the necessary help arrives too late.

If the hypercapnia occurs as a result of pronounced obesity or intense pneumonia , there is also little chance of a cure. In most cases, life-prolonging measures are initiated because the underlying disease is already so advanced that recovery can only be documented in very rare cases. Hypercapnia can lead to loss of consciousness in addition to death. This significantly increases the likelihood of sequelae or permanent impairments.

There is only a realistic chance of alleviating the symptoms if the underlying disease is treated early and if the patient cooperates sufficiently to improve their health. A complete freedom from symptoms is rarely given, but in principle it is quite possible under certain conditions. If no irreparable damage to the respiratory function has occurred, it can occur.


To prevent hypercapnia, it is best practice never to abuse steroids, laxatives , opiates , sedatives, and other drugs. This applies both to the duration of intake and to the dosage of the substances. Recreational divers should refrain from using economy breathing. If you suffer from COPD or take diuretics or steroids, you should definitely have your blood values ​​checked at short intervals. In addition, frequent ventilation of enclosed spaces can help prevent dangerous hypercapnia.


In the case of hypercapnia, the options for follow-up care are relatively severely limited in most cases. They are only available to those affected after successful treatment, so that the disease itself must be recognized and treated at an early stage. The earlier the hypercapnia is detected, the better the further course is, as a rule.

Complete healing is not always possible, so that in many cases the patient’s life expectancy is limited by this disease. In any case, those affected must protect their lungs with this disease. Smoking should be avoided. In general, a healthy lifestyle with a healthy diet also has a positive effect on the course of the disease.

Heavy loads on the body or strenuous and physical activities should be avoided. Taking medication can also have a positive effect on the course of the disease. The person concerned must pay attention to a correct dosage with regular use. Furthermore, the support and care of one’s own family and friends is very important in order to relieve the patient.

You can do that yourself

Hypercapnia usually requires immediate treatment by an emergency doctor . This can prevent the death of the patient. The condition itself can be prevented relatively easily if the sufferer does not abuse steroids or laxatives. Other medications that can lead to this disease should also not be taken in large quantities. Hypercapnia can also be avoided by regularly ventilating closed rooms, as this brings fresh, low-carbon air into the room from the outside.

If hypercapnia occurs, the first thing to do is call an ambulance. Until the arrival of the emergency doctor, the casualty’s clothing must be loosened if it constricts his body. Furthermore, the chest must be positioned high and the legs low to alleviate the discomfort. Liquids should also only be administered in very small amounts. The further treatment is then carried out by the emergency doctor with the help of a ventilation device.

During the course of treatment, it is important for those affected to pay attention to the intake of medication. Regular checking of blood values ​​can also prevent possible complications and symptoms.

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Hello! I am Lisa Newlon, and I am a medical writer and researcher with over 10 years of experience in the healthcare industry. I have a Master’s degree in Medicine, and my deep understanding of medical terminology, practices, and procedures has made me a trusted source of information in the medical world.