One of the conditions that can reduce the ability to adequately exhale carbon dioxide (CO2) is chronic obstructive pulmonary disease or COPD.
CO2 that is not exhaled can shift the normal balance of acids and bases in the body toward acidic. The CO2 mixes with water in the body to form carbonic acid.
With chronic respiratory acidosis, the body partially makes up for the retained CO2 and maintains acid-base balance near normal. The body's main response is an increase in excretion of carbonic acid and retention of bicarbonate base in the kidneys.
Medical treatment for chronic respiratory acidosis is mainly treatment of the underlying illness which has hindered breathing. Treatment may also be applied to improve breathing directly.
Respiratory acidosis can also be acute rather than chronic, developing suddenly from respiratory failure. Emergency medical treatment is required for acute respiratory acidosis to:
- Regain healthful respiration
- Restore acid-base balance
- Treat the causes of the respiratory failure
Here are some key points about respiratory acidosis. More detail and supporting information is in the main article.
- Respiratory acidosis develops when decreased breathing fails to get rid of CO2 formed in the body adequately
- The pH of blood, as a measure of acid-base balance, is maintained near normal in chronic respiratory acidosis by compensating responses in the body mainly in the kidney
- Acute respiratory acidosis requires emergency treatment
- Factors that could worsen respiratory acidosis include smoking, sedatives, and obesity
Acid-base balance and acidosis
When acid levels in the body are in balance with the base levels in the body, the pH measure of blood is 7.4. A lower pH number reflects higher levels of acid, and a higher pH number represents higher base levels.
Acidosis occurs when gas exchange in the lungs does not work as it should.
The narrow pH range for healthy functioning is between 7.35-7.45.
Acidemia is defined when pH of the blood is lower than 7.35. Alkalemia, or blood with high levels of base, is when blood pH is higher than 7.45.
Acidosis is excess acidity. It is classified as either metabolic or respiratory, depending on the main cause of the acid-base imbalance.
Metabolic acidosis does not arise from increased CO2, but from increased production of acids. It can occur in conditions such as diabetic ketoacidosis and kidney disease, as well as many other diseases.
Respiratory acidosis occurs when respiration does not adequately get rid of CO2. The increased CO2 results in an increase in acid and an acidic state.
The increased CO2 that occurs in respiratory acidosis is called hypercapnia when it rises above the normal range.
Hypercapnia in chronic respiratory acidosis can persist without dangerously acidic blood because of the body's responses to compensate. The kidneys get rid of more acid and reabsorb more base to try and create a balance.
Immediate medical attention is needed if this kidney function is no longer enough to maintain the balance of acids and bases. It is also needed in the event of acute respiratory acidosis from respiratory failure.
The symptoms of respiratory acidosis are generally the effects of raised CO2. In chronic respiratory acidosis, these symptoms are less noticeable than in acute respiratory acidosis. This is because compensating responses in the body keep blood pH near normal.
The acidifying effect of raised CO2 in chronic respiratory acidosis can be lessened in the blood. However, it is not lessened as effectively in the brain.
Symptoms of raised CO2 levels and acidity in the brain may be overlooked in long-term illness, but can include:
Sleep disturbance is one of the symptoms of raised CO2 levels.
In acute respiratory acidosis, or if chronic respiratory acidosis worsens, the effects of raised CO2 in the brain are more prominent. Symptoms can include:
- Muscle jerking
In acute respiratory acidosis and worsening chronic respiratory acidosis, blood pH is lowered and is linked with higher rates of death. Effects of the lowered pH include:
In acute respiratory acidosis, direct breathing assistance can be provided.
Medical treatment of chronic respiratory acidosis will focus on treating the underlying illness that hinders proper respiration.
Treatments may also be given to improve respiration, including drugs that help to open the passages to the lungs.
In acute respiratory acidosis, direct breathing assistance can be provided. Doctors may provide positive-pressure ventilation through a face mask.
In more severe conditions, breathing is mechanically assisted through a tube inserted into the airway.
Respiratory acidosis is avoided by maintaining healthy respiratory function. Long-term illness that affects respiration such as asthma and COPD should be well-monitored and medically managed.
If such illnesses are present, or if chronic respiratory acidosis develops from another condition, medications that can further reduce respiration should be avoided if possible. If patients do need to use them, they should be used in the smallest useful dose.
Behaviors such as smoking that reduce healthy respiration should be avoided. Since smoking has a strong association with developing COPD, quitting smoking is always encouraged.