Respiratory depression (hypoventilation) is a breathing disorder characterized by slow and ineffective breathing.
During a normal breathing cycle, you inhale oxygen into your lungs. Your blood carries the oxygen around your body, delivering it to your tissues. Your blood then takes the carbon dioxide, a waste product, back to your lungs. The carbon dioxide exits your body when you exhale.
During hypoventilation, the body can’t adequately remove carbon dioxide. This can lead to poor use of oxygen by lungs. The result is a higher level of carbon dioxide and too little oxygen available to the body.
Hypoventilation is different from hyperventilation. Hyperventilation is when you breathe too quickly, lowering levels of carbon dioxide in the blood.
Symptoms of respiratory depression vary. Mild or moderate symptoms may include:
- daytime sleepiness
- shortness of breath
- slow and shallow breathing
As the condition progresses and your carbon dioxide level increases, you may develop:
- bluish-colored lips, fingers, or toes
Fast breathing isn’t typical with hypoventilation. However, some people experience faster breathing as their body attempts to blow out excess carbon dioxide.
Respiratory depression can occur for several reasons. Possible causes of hypoventilation include:
- neuromuscular diseases (cause weakening of muscles that control breathing)
- chest wall deformities (interfere with the ability to inhale and exhale)
- severe obesity (causes the body to work harder to breathe)
- brain injury (interferes with the brain’s ability to control basic functions like breathing)
- obstructive sleep apnea (collapses airway during sleep)
- chronic lung disease (describes conditions like COPD and cystic fibrosis that lead to blocked airways)
Hypoventilation can also occur as a side effect of certain medications. Large doses of central nervous system depressant drugs may slow down the respiratory system.
Medications that can have this effect on the body include:
See a doctor if you have symptoms of respiratory depression.
Your doctor will ask about your symptoms and medications. Then they will complete a physical examination and tests to make a diagnosis.
Your doctor may order a series of tests to determine the cause of respiratory depression. Tests include:
- chest X-ray: an imaging test that takes pictures of the chest area and checks for abnormalities.
- lung function test: a breathing test that determines how well your lungs work
- blood gas test: a blood test that measures the amount of carbon dioxide and oxygen, and the acid/base balance in your bloodstream
- pulse oximetry test: measures the oxygen level in your bloodstream through a painless monitor on your finger
- hematocrit and hemoglobin blood test: assesses the number of red blood cells available to carry oxygen through your body
- sleep study: used to diagnose sleep-related disorders, such as sleep apnea
Respiratory depression is a treatable condition. Treatments vary depending on the cause.
When medication triggers hypoventilation, stopping the medication may restore normal breathing.
Other possible treatments for hypoventilation include:
- oxygen therapy to support breathing
- weight loss
- CPAP or BiPAP machine to keep your airway open while sleeping
- surgery to correct a chest deformity
- inhaled medications to open airways and treat ongoing lung disease
If left untreated, hypoventilation can cause life-threatening complications, including death.
Respiratory depression occurring from a drug overdose can lead to respiratory arrest. This is when breathing completely stops, which is potentially fatal. Ongoing episodes of hypoventilation can also cause pulmonary hypertension, which can cause right-sided heart failure.
Following your treatment plan can prevent complications from developing.
Hypoventilation can interfere with your quality of life. Early identification and treatment may help your body maintain a healthy level of oxygen and carbon dioxide and prevent complications.