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What is Respiratory Acidosis?
Respiratory acidosis is a serious medical condition in which abnormally slow breathing (hypoventilation) increases the amount of carbon dioxide (CO2) in the blood, causing the pH (acid-base balance) of the blood, and other bodily fluids, to become too acidic.
How the Body Tries to Restore Balance
An important property of any solution, including blood, is its degree of acidity and alkalinity as measured on the pH scale. This essential scale ranges from 0 (very acidic) to 14 (very basic or alkaline). A pH of 7 is considered neutral. The pH of blood is usually slightly basic, ranging from 7.35 to 7.45.
Normally, the kidneys work in tandem with the lungs to keep the blood’s acid-base balance within normal limits. Breathing that’s too slow or too shallow leads to increased CO2, levels (hypercapnia) and consequentially, a decrease in pH.[1]
As blood pH drops, the breathing center in the brain tries to compensate by signaling the body to produce faster and deeper breathing in order to increase the amount of carbon dioxide exhaled. The kidneys also work to correct the imbalance by excreting more acid in the urine. If the body continues to produce too much acid, compensatory mechanisms such as these become overwhelmed and severe respiratory acidosis occurs, eventually causing respiratory failure, heart problems and coma.[2]
Causes of Respiratory Acidosis
There are a number of causes of respiratory acidosis; a few are listed below:1
- Asthma
- COPD, Emphysema, Chronic Bronchitis
- Neuromuscular diseases, such as amyotrophic lateral sclerosis (ALS or Lou Gehrig’s disease), myasthenia gravis or muscular dystrophy
- Chest wall disorders, such as severe kyphoscoliosis or flail chest
- Obesity hypoventilation syndrome
- Obstructive sleep apnea
- Central nervous system depression caused by drug overdose, neurological disorders or hypoventilation
- Other lung diseases including laryngeal and tracheal stenosis and interstitial lung disease
Symptoms of Respiratory Acidosis
Symptoms of respiratory acidosis vary, depending upon the severity of the underlying disorder and the speed at which CO2 levels rise. Initially, symptoms may be minimal, especially if the hypercapnia is mild and has developed over time. As the acidosis worsens, the following symptoms may occur:1
- Anxiety
- Shortness of breath
- Disruption of sleep
- Daytime sleepiness
- Confusion
- Lethargy
- Respiratory failure, coma and death (in severe cases)
Treatment of Respiratory Acidosis
Treatment of respiratory acidosis begins with focusing on the underlying disorder. If symptoms are severe enough – confusion, lethargy, respiratory muscle fatigue, and a low pH of <7.25 – the patient may have to be admitted to the intensive care unit.1
Medications
There are no drugs that specifically treat respiratory acidosis. Rather, medical therapies are directed towards treating the underlying health condition that’s causing the slow breathing and subsequent acidosis. Medications that may be used in treatment include:1
- Bronchodilators – relax and expand the airways
- Corticosteroids – reduce swelling and inflammation in the airways
- Benzodiazepine toxicity antidotes – reverses the effects of benzodiazepine overdose
- Opioid antagonists – reverses the effects of opioid overdose
Oxygen Therapy
Oxygen therapy plays a crucial role in the treatment of respiratory acidosis as many patients with high CO2 levels (hypercapnia) also have a decreased amount of oxygen in their blood (hypoxemia). In patients with COPD, long-term oxygen therapy used for more than 15 hours a day has been found to increase survival as well as reduce the risk of high blood pressure in the lungs (pulmonary hypertension).1
Because oxygen therapy has been known to worsen hypercapnia in some patients, caution should be employed when using it.1 To ensure you’re using supplemental oxygen according to your doctor’s prescription, talk to your primary care provider.
Breathing Support
Severe respiratory acidosis calls for life-saving measures that includes using either of the following to support breathing:1
- Non-invasive positive pressure ventilation (NIPPV) – including continuous positive airway pressure (CPAP) and bi-level positive airway pressure (BiPAP). Used as an alternative to intubation and mechanical ventilation to keep the airways open.
- Intubation and mechanical ventilation – inserting a special tube down the throat that’s connected to a machine that breathes for the patient until he or she can breathe on their own.
For more information about respiratory acidosis, talk to your pulmonologist or primary care provider.
[1] Byrd, Ryland Jr., MD, et. al. Respiratory Acidosis. Medscape. Last Updated 4/4/2017.
[2] Lewis, James III, MD. Acid-Base Disorders. Merck Manuals. Last reviewed 5/2016.
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