Respiratory Acidosis: Symptoms, Causes, Diagnosis and Treatment

It refers to the condition in which bodily fluids, especially blood, become too acidic due to higher levels of carbon dioxide.

It is an indication that breathing (ventilation) is not adequately expelling carbon dioxide from the body.

There are a number of different causes of Respiratory Acidosis

It is a state that arises with certain diseases, and it is not a disease by itself. Without adequate intervention, respiratory acidosis can lead to a series of serious complications and even progress to death.

Types of respiratory acidosis

Acute respiratory acidosis

In acute respiratory acidosis, both PaCO2 and acidity are higher. Acute respiratory acidosis occurs when ventilation through the lungs suddenly fails.

PaCO2 : is the partial pressure of carbon dioxide (CO2) in the arterial blood.

The use of some medications or various medical conditions (such as brain or neuromuscular diseases) can cause acute respiratory acidosis.

Blocking the air due to asthma can also result in such a situation.

Chronic respiratory acidosis

In chronic respiratory acidosis, only PaCO2 is greater. Chronic respiratory acidosis can be the result of many disorders, such as the syndrome of hypoventilation due to obesity, neuromuscular disorders, and serious defects in ventilation.

The symptoms

Respiratory acidosis often presents with symptoms of the underlying disorders that cause respiratory acidosis.

Symptoms may vary depending on the severity of the diseases and the rate of PaCO2 increase. The mild to moderate increase in PaCO2 shows minimal symptoms.

The following non-specific symptoms can be seen in patients suffering from respiratory acidosis:

  • Anxiety.
  • The lack of air.
  • Sleep disorders.
  • Excessive daytime sleepiness.
  • Hallucinations
  • Confusion.
  • Wheezing
  • The increase of the thorax expansion.
  • The decrease in respiratory sounds.
  • Coloration of bluish skin.
  • Hippocratic fingers.
  • Depression.
  • Tremors in the hands.
  • Contractions
  • Convulsions

If left untreated, other symptoms may also become apparent as complications of respiratory acidosis occur.

The causes

Lungs and respiratory tract

These are considered as one of the main causes of respiratory acidosis.

The inability of the airways and lungs to carry out their normal functions hinders the normal exchange of gas, and therefore the acidity of the blood and bodily fluids.

These could be:

  • Chronic obstructive pulmonary disease (COPD), including chronic bronchitis and emphysema.
  • The narrowing of the airways, as seen with asthma, tracheal and laryngeal stenosis.
  • Obstructive sleep apnea.

Muscles and bones

The bones of the thoracic cavity, mainly the ribs and the sternum (chest bone), not only protect the lungs, but also serve as a binding site for the respiratory muscles.

These muscles can expand and contract in the chest cavity to draw air into the lungs or push it out.

Some diseases or disorders could be:

Neuromuscular diseases such as amyotrophic lateral sclerosis, Guillain-Barré syndrome, muscular dystrophy, myasthenia gravis, botulism, diaphragm dysfunction and paralysis.

Disorders of the thoracic wall, such as severe kyphoscoliosis, unstable thorax, ankylosing spondylitis, toraz in keel or pectus excavatum.

Nervous system

The nervous system plays an integral role in ventilation. Centers in the brain keep track of blood gas levels and ensure that ventilation is with the oxygen demands of the body.

Nerves carry signals from the brain to the muscles of respiration thus controlling the rate of respiration. These can be:

The central nervous system (CNS), central depression due to drug abuse (benzodiazepines, narcotics or barbiturates) and neurological disorders (encephalitis, trauma).

Neuropathy (injury or disease) of the phrenic or intercostal nerves.


Drug screening : a drug test can detect if some medications (such as barbiturates, opiates and benzodiazepines) are causing respiratory acidosis.

Imaging studies : X-ray, magnetic resonance or chest computed tomography may be useful to detect airway obstruction, weakness or paralysis of the diaphragm, and skeletal deformities.

CT or MRI can detect tumors or lesions in areas of the brain that control breathing.

Laboratory tests : blood samples are taken to assess the level of bicarbonate, the level of electrolytes, thyroid functions, and a complete blood cell count.

Pulmonary function tests : these tests can determine the severity of the disease.

Nerve and muscle tests : Electromyography (EMG) and nerve conduction velocity (NCV) tests can detect neuromuscular disorders.

Treatment of respiratory acidosis

The treatment depends on the underlying disorders. Supportive measures such as oxygen therapy or mechanical ventilation may sometimes be necessary regardless of the cause.

Lifestyle measures

Weight loss can help patients with hypoventilation syndrome due to obesity.

Muscle or nerve stimulation

In this technique, electric currents are administered. Rhythmic electrical stimulation of diaphragm or phrenic nerve gives positive results in breathing.

The drugs

Agents such as beta-agonist bronchodilators (salmeterol, albuterol), anticholinergic agents (tiotropium, ipratropium bromide), and methylxanthines (theophylline) help patients with severe bronchospasm (spasm of the pulmonary muscles) and obstructive pulmonary disease.

Anti-cholinergics also increase ventilation by decreasing the constriction of the bronchi and bronchioles of the lungs.

Theophylline also relaxes the lung muscles, but it is given with caution due to its toxic side effects.

Respiratory stimulants (medroxyprogesterone, acetazolamide) promote ventilation. Some of these are corticosteroids, which act by decreasing inflammation.

These medications help patients who developed respiratory acidosis due to asthma.

If respiratory acidosis is caused by an overdose of some sedative drugs, drug antagonists are used to reverse the effects.

Drugs such as flumazenil reverse the effects of benzodiazepines. Naloxone reverses the effects of narcotics.

Bicarbonate infusion therapy

Sodium bicarbonate occurs rarely, when patients show extremely low pH and cardiorespiratory arrest.

Oxygen therapy

Oxygen therapy can help patients with oxygen deficiency. It avoids the complications associated with prolonged oxygen deficiency.


Mechanical ventilation is done through the nose or through a tube in the windpipe.

This helps in the reduction of partial blood pressure of carbon dioxide (PaCO2) and the increase in partial blood pressure of oxygen (PaO2).