Respiratory Depression (Hypoventilation)

Respiratory depression (hypoventilation) is when you breathe too slowly or too shallowly, leading to carbon dioxide building up in your blood (hypercapnia). Overdose of certain kinds of medications, like opioids, and certain brain, lung and muscle conditions can cause respiratory depression. It can lead to respiratory failure or cardiac arrest.

Overview

What is the respiratory depression (hypoventilation)?

Respiratory depression (hypoventilation) is when you breathe too slowly or shallowly, preventing proper gas exchange in your lungs. Gas exchange is when oxygen moves from the air sacs (alveoli) in your lungs to your blood, and carbon dioxide (CO2) moves from your blood to your lungs. The CO2 — which is a waste product that your body can’t use — then leaves your body when you breathe out.

Hypoventilation prevents carbon dioxide from leaving your blood, causing it to build up (hypercapnia). It can also sometimes prevent oxygen from getting to your lungs, which can lead to low oxygen levels in your blood (hypoxemia).

Symptoms and Causes

What are the symptoms of respiratory depression?

Symptoms of respiratory depression (hypoventilation) include: 

• Nausea and vomiting.
• Headache.
• Tiredness (fatigue) or lethargy.
• Disorientation, confusion or altered mental state.
• Fast heart rate.
• Dizziness.
• Slow, shallow or labored breathing.
• Bluish skin, lips or nails (cyanosis).

What causes respiratory depression?

A common cause of respiratory depression is misuse, overdose or an unexpected reaction to alcohol, prescription medications or other drugs, including:

• Opioids. Also called narcotics, common opioids include morphine, Vicodin®, oxycodone (OxyContin®) and fentanyl.
• Benzodiazepines. Some common benzodiazepines include lorazepam (Ativan®), alprazolam (Xanax®) and diazepam (Valium®).
• Barbiturates. Barbiturates are sometimes prescribed for seizures or migraines.
• Nonmedical drugs. This includes heroin and gamma hydroxybutyrate (GHB).
• Prescription sleep aids. This includes zolpidem (Ambien®). 
• Anesthesia.

Other conditions and diseases that can cause hypoventilation include:

• Having obesity (obesity hypoventilation syndrome/OHS).
• Conditions that obstruct your breathing. This includes chronic obstructive pulmonary disease (COPD) and obstructive sleep apnea.
• Conditions that reduce your ability to properly regulate your breathing (respiratory drive). Examples include stroke and hypothyroidism.
• Conditions that affect your spinal cord, nerves or muscle control. Examples include muscular dystrophy, nerve or spinal cord injuries, multiple sclerosis (MS) and amyotrophic lateral sclerosis (ALS). 
• Differences in chest or spine anatomy. Examples include scoliosis, ankylosing spondylitis and flail chest. 
• Toxins or poisoning. Examples include tetanus, ciguatera toxicity (poisoning from contaminated fish) and botulism.

What are the risk factors for respiratory depression?

Risk factors for respiratory depression include:

• Misuse of prescription or nonmedical drugs like opioids or benzodiazepines.
• Recent surgery.
• Certain lung, muscle and neurological (brain and spinal cord) conditions, like the ones listed above.

What are the complications of respiratory depression?

High carbon dioxide levels in your blood can lead to life-threatening complications, including:

• Respiratory acidosis. This is a condition where your blood is more acidic than it should be.
• Respiratory failure. This is a condition where you can’t get enough oxygen to the tissues in your body.
• Cardiac arrest.
• Coma.
• Pulmonary hypertension.

Diagnosis and Tests

How is respiratory depression (hypoventilation) diagnosed?

To diagnose respiratory depression, a provider will ask you about your symptoms, health history and any medications you take. They may use special blood tests to measure the carbon dioxide in your blood. They may also use other tests to help understand the cause of hypoventilation. 

What tests might be used?

Tests to diagnose respiratory depression and its underlying causes include:

• Arterial blood gas test.
• Pulmonary function tests.
• Pulse oximetry. Providers use a sensor that slips over your finger to measure the amount of oxygen in your blood.
• Blood tests. Many blood tests can help diagnose respiratory depression or its causes. These might include a complete blood count (CBC), basic metabolic panel (BMP), toxicology screen, CO2 blood test and thyroid function tests.
• Imaging. A provider may get chest X-rays or CT scans (computed tomography scans) of your chest or head to help diagnose any underlying conditions.
• Sleep study (polysomnography). A sleep study can diagnose sleep apnea and evaluate obesity hypoventilation syndrome, which can cause hypoventilation.

Management and Treatment

How is respiratory depression (hypoventilation) treated?

Treatment for respiratory depression depends on the cause and how severe it is. Healthcare providers may treat you with:

• Noninvasive ventilation. This is a machine that helps you breathe through a mask on your face. Examples include continuous positive airways pressure (CPAP) or bilevel positive airway pressure (often known under the trade name BiPAP®).
• Respiratory stimulant medications. A provider might be able to reverse respiratory depression with reversal agent medications if it’s caused by an overdose or side effect. Naloxone (Narcan®) is a reversal agent and can reverse the effects of opioids.
• Oxygen therapy.
• Mechanical ventilation.

Outlook / Prognosis

What’s the outlook for respiratory depression?

The outlook for respiratory depression depends on the cause. Emergency situations, like an opioid overdose, can be fatal if not treated immediately. Other causes, like sleep apnea, OHS or chronic illnesses, may make you feel sick over time and need ongoing treatment.

Prevention

Can respiratory depression be prevented?

The best way to prevent respiratory depression is to take medications as prescribed and manage any underlying conditions. Check with your provider or pharmacist before taking two or more medications — especially opioids, benzodiazepines or other sedative medications — together. Also, be aware of possible medication interactions with alcohol.

Living With

When should I see my healthcare provider?

Talk to your healthcare provider if:

• You have questions or concerns about a medical condition you have.
• You have questions or concerns about a medication they’ve prescribed.
• You have symptoms of respiratory depression, especially if you have another condition that puts you at risk.

When should I go to the ER?

Go to the nearest emergency room if you have any signs of serious illness, including:

• Seizures.
• Altered mental state or confusion.
• Inability to stay awake.
• Disorientation.
• Paranoia.
• Blue skin, nails or lips.

What questions should I ask my doctor?

It might be helpful to ask your healthcare provider:

• What caused this?
• How can I prevent it in the future?
• What are my treatment options?

A note from Wockr

Respiratory depression is a serious condition that allows carbon dioxide to build up in your blood. But in many cases, it’s preventable. If you take medications that put you at risk for respiratory depression, talk to your provider to make sure you’re taking them appropriately. If you have an ongoing condition that can cause respiratory depression, ask your provider what steps you can take to reduce your risk. They can talk to you about your concerns and make a plan to manage your condition or medications safely.