Respiratory depression, or hypoventilation, refers to a slow, shallow breathing rate. There are many causes, some of which are more serious than others.
The brain controls the respiratory drive. Therefore, anything that affects the function of the central nervous system, including the brain, can cause respiratory depression.
In mild cases, the person may not notice any symptoms. In other cases, they may have slow and shallow breathing.
Oxygen therapy and respiration machines may help treat respiratory depression, depending on its severity. Without treatment, respiratory depression can cause life threatening complications and even death.
This article provides an overview of respiratory depression, including its causes, symptoms, and treatments.
Respiratory depression happens when the lungs fail to exchange carbon dioxide and oxygen efficiently. This dysfunction leads to a buildup of carbon dioxide in the body, which can result in health complications.
A common symptom of respiratory depression is taking breaths that are slower and shallower than normal.
In most cases, breathing rates are as low as 8–10 breaths per minute. The normal breathing rate of a healthy adult is 12–20 breaths per minute.
Respiratory depression can cause acid to build up in the body and lead to respiratory acidosis, a life threatening condition associated with organ failure.
Certain medications and substances can cause respiratory depression or increase a person’s risk. These include sedative medication, narcotic pain medications, and other substances that depress brain function, such as alcohol and certain illegal drugs.
Some health conditions can also cause respiratory depression.
Common causes include:
- overdose of an opiate or opioid, such as morphine, tramadol, heroin, or fentanyl
- the use of opioids or anesthetics before, during, or after surgery
- stroke that affects the lower brain stem
- ethanol overdose or poisoning
- barbiturate overdose or poisoning
- sedative overdose or poisoning
- benzodiazepine overdose or poisoning
- congenital central hypoventilation syndrome (CCHS)
- central sleep apnea
- severely elevated blood ammonia, which can occur in liver failure and cirrhosis
- a brain tumor pressing on the brain stem at the respiratory center
The symptoms of respiratory depression depend on its severity. In more severe cases, the symptoms become more evident.
Symptoms of respiratory depression include:
Some people may also experience:
- shallow, slow breathing with little noticeable chest movement
- high or low blood pressure
- reduced or pinpoint pupils
- abnormal breath sounds, such as decreased breathing sounds or a distinct whistling or crackling sound while breathing
- apnea, which refers to an abnormally long pause between breaths that precedes a deep breath resembling a sigh
- bluish skin, especially in the toes and fingers
- rapid heart rate
If a person does not receive treatment, severe respiratory depression can lead to:
- respiratory arrest
- heart attack
- brain damage
- coma or death
- reduced heart rate
Anyone who suspects respiratory depression or notices several of the typical symptoms should seek medical attention immediately.
If a person is in the company of someone with these symptoms, it is vital to keep them alert and moving as much as possible.
A doctor will usually begin a diagnosis by asking questions about the person’s symptoms and reviewing their medical history and medication profile. They will then perform a physical exam to look for signs of abnormal breathing and heart rhythms.
After an initial visit, a doctor will usually order diagnostic tests to help confirm respiratory depression and evaluate its severity.
These tests may include:
- urine and serum drug screens
- alcohol level
- screening for other toxins
- serum ammonia level
- blood gas test, to calculate the ratio of acid to base and the amount of carbon dioxide and oxygen in the blood
- CT scans or MRI scans of the brain to check for stroke or tumors
- electroencephalogram (EEG)
Therapies and medications that doctors commonly use to treat respiratory depression include:
- oxygen therapy
- fluid therapy, either intravenous or oral
- continuous positive airway pressure (CPAP) machines
- bilevel positive airway pressure (BiPAP) machines
- mechanical ventilation
If overdose is the cause of respiratory depression, detoxification will be necessary. Doctors often use medications that work against the effects of opioids, such as naloxone (Narcan), methadone (Dolophine), and a combination of buprenorphine and naloxone (Suboxone).
It is not possible to prevent all cases of respiratory depression, such as those that are due to accidents or sudden disease. However, other cases are preventable.
Ways to reduce the chances of developing the condition include:
- avoiding sedative medications or taking extra precautions when using them
- monitoring children who are taking prescribed medications
- avoiding excessive alcohol use
- avoiding or taking extra precautions when using narcotic medications
Respiratory depression, or hypoventilation, happens when the lungs do not effectively exchange the gases oxygen and carbon dioxide. It can lead to complications, such as respiratory acidosis, and, without treatment, it can be fatal.
Causes include medical conditions that affect the brain, such as a stroke, and medications or recreational drugs that impair the function of the central nervous system.
If a person suspects respiratory depression, they should seek emergency medical attention.