Respiratory acidosis

There are many causes of respiratory acidosis, including:

• Airway diseases, such as asthma and COPD
• Lung tissue diseases, such as pulmonary fibrosis, which causes scarring and thickening of the lungs
• Diseases that can affect the chest, such as scoliosis
• Diseases that affect the nerves and muscles that signal the lungs to inflate or deflate
• Medicines that suppress breathing, including narcotics (opioids), and "downers," such as benzodiazepines, often when combined with each other or alcohol
• Severe obesity, which restricts how much the lungs can expand
• Obstructive sleep apnea

Chronic respiratory acidosis occurs over a long time. This leads to a stable situation, because the kidneys increase body chemicals, such as bicarbonate, that help restore the body's acid-base balance.

Acute respiratory acidosis occurs when carbon dioxide builds up very quickly, before the kidneys can return the body to a state of balance.

Some people with chronic respiratory acidosis get acute respiratory acidosis when a serious illness worsens their condition and disrupts their body's acid-base balance.

Symptoms may include:

• Confusion
• Anxiety
• Easy fatigue
• Lethargy
• Shortness of breath
• Sleepiness
• Tremors (shaking)
• Warm and flushed skin
• Sweating

Your health care provider will perform a physical exam and ask about symptoms.

You may have certain tests, including:

• Arterial blood gas (measures oxygen and carbon dioxide levels in the blood)
• Basic metabolic panel
• Chest x-ray
• CT scan of the chest
• Pulmonary function test to measure breathing and how well the lungs are functioning
• Ultrasound of the heart (echocardiogram)

Treatment is aimed at the underlying disease, and may include:

• Bronchodilator medicines and corticosteroids to reverse some types of airway obstruction
• Noninvasive positive-pressure ventilation (called CPAP or BiPAP)
• Oxygen if your blood oxygen level is low
• Treatment to stop smoking.
• Changing medicines when appropriate

If your case is severe, you may need to be put on a breathing machine (ventilator).

How well you do depends on the disease causing the respiratory acidosis.

Complications may include:

• Poor organ function
• Respiratory failure
• Shock

Severe acute respiratory acidosis is a medical emergency. Seek medical help right away if you have symptoms of this condition.

Call your provider if you have symptoms of lung disease that suddenly get worse.

DO NOT smoke. Smoking can lead to many severe lung diseases that can cause respiratory acidosis.

Losing weight may help prevent respiratory acidosis due to obesity (obesity-hypoventilation syndrome).

Be careful about taking sedating medicines, and never combine these medicines with alcohol.

Use your CPAP device regularly if it has been prescribed for you.

Ventilatory failure; Respiratory failure; Acidosis - respiratory

McCoin NS, Self WH. Acid-base disorders. In: Walls RM, ed. Rosen's Emergency Medicine: Concepts and Clinical Practice. 10th ed. Philadelphia, PA: Elsevier; 2023:chap 113.

Sanghavi S, Albert TJ, Swenson ER. Acid-base balance. In: Broaddus VC, Ernst JD, King TE, et al, eds. Murray and Nadel's Textbook of Respiratory Medicine. 7th ed. Philadelphia, PA: Elsevier; 2022:chap 12.

Seifter JL. Acid-base disorders. In: Goldman L, Schafer AI, eds. Goldman-Cecil Medicine. 26th ed. Philadelphia, PA: Elsevier; 2020:chap 110.

Updated by: Denis Hadjiliadis, MD, MHS, Paul F. Harron Jr. Professor of Medicine, Pulmonary, Allergy, and Critical Care, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA. Also reviewed by David C. Dugdale, MD, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.