Respiratory acidosis occurs when the lungs cannot remove all of the carbon dioxide (a normal by-product of metabolism) produced by the body. This causes a disturbance of the acid-base balance in which body fluids become excessively acidic.

Respiratory acidosis can be a consequence of any lung disease that prevents removal of carbon dioxide. Common lung diseases that lead to respiratory acidosis include: chronic obstructive pulmonary disease (COPD), severe asthma, or airway obstruction.

Other diseases that may lead to respiratory acidosis include: the obesity hypoventilation syndrome, excessive fatigue of the diaphragm or muscles of the rib cage, or severe deformities of the spine and rib cage (for example, severe scoliosis).

In chronic respiratory acidosis, mild impairment of the lungs' ability to remove carbon dioxide occurs over a long period of time, leading to a stable situation. This is because the kidneys increase their retention of bicarbonate to maintain an acid-base balance in the blood that is almost normal.

In severe cases, the carbon dioxide builds up very quickly, leading to severe disturbances in the acid-base balance of the blood.

Symptoms of the disease that causes respiratory acidosis are usually noticeable, and may include shortness of breath, easy fatigue, chronic cough, or wheezing.

When respiratory acidosis becomes severe, confusion, irritability, or lethargy may be apparent.

• A chest X-ray or CAT scan may be done to diagnose possible lung disease
• Pulmonary function tests may help diagnose lung disease
• Arterial blood gases help assess the severity of the respiratory acidosis, and may detect abnormal oxygen levels

Treatment is aimed at the underlying lung disease.

• Smoking cessation is extremely important
• Bronchodilator drugs may reverse some airway obstruction
• Oxygen may be necessary if the blood oxygen level is low
• Mechanical ventilation may be necessary if the respiratory acidosis is severe

• Respiratory acidosis may be a sign of respiratory failure, with dangerously low blood oxygen levels.
• Excessive respiratory acidosis may lead to confusion, lethargy, or poor organ function. In extreme cases, low blood pressure and shock may result.

• Call your health care provider if you have symptoms of lung disease.
• Call 911 or get to an emergency room if you suspect you have severe respiratory acidosis, as this is a medical emergency.

Not smoking -- or quitting if you already smoke -- can prevent the development of many severe lung diseases that can lead to respiratory acidosis.