Hypercapnia - Causes and Symptoms

Definition

Hypercapnia is a condition characterized by the increase in the amount of carbon dioxide present in the blood.

The cause of this phenomenon is often to be found in anomalies affecting pulmonary or cardiac functioning, which lead to inadequate alveolar ventilation and are accompanied by alterations in the acid-base balance (such as respiratory acidosis). Hypercapnia is defined, in particular, by a partial pressure of carbon dioxide in the blood exceeding 45 millimeters of mercury (mmHg); normally, the pCO2 remains between 35 and 45 mmHg.

Depending on the severity of the condition, there are several symptoms that can occur in association with hypercapnia. These manifestations include dyspnea, vigorous use of accessory respiratory muscles, tachypnea, increased heart rate (tachycardia) or extrasystoles, sweating, muscle spasms, increased blood pressure and paradoxical abdominal movement.

Manifestations affecting the central nervous system range from confusion to loss of consciousness or coma. In some cases, the death of the patient may also occur. Chronic hypercapnia is usually tolerated better than acute, as well as having minor symptoms.

The main causes of hypercapnia are the same as hypoventilation and include chronic obstructive pulmonary disease, acute exacerbations of asthma and pulmonary emphysema. Even chronic bronchitis, pneumonia, drowning, edema and pulmonary embolism, states of respiratory failure and other obstructive airway diseases can cause hypercapnia.

An increase in carbon dioxide in the blood can also be observed in patients with heart problems (such as angina, myocardial infarction and pulmonary heart), stroke, head injury and rib fractures.

Furthermore, hypercapnia can be caused by breathing too much carbon dioxide air.

Other causes are drug intoxications that suppress the center of the breath and pathologies that cause weakness of respiratory muscles (eg Guillain-Barré syndrome, myasthenia gravis and botulism).

Even the conditions that increase the production of carbon dioxide, as occurs in the context of febrile states, sepsis, trauma, burns, hyperthyroidism and malignant hyperthermia, when combined with the inability to compensate for ventilation, can cause hypercapnia.