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What Are the Signs and Symptoms of Respiratory Failure?

The signs and symptoms of respiratory failure depend on its underlying cause and the levels of oxygen and carbon dioxide in the blood.

A low oxygen level in the blood can cause shortness of breath and air hunger (feeling like you can't breathe in enough air). If the level of oxygen is very low, it also can cause a bluish color on the skin, lips, and fingernails. A high carbon dioxide level can cause rapid breathing and confusion.

Some people who have respiratory failure may become very sleepy or lose consciousness. They also may develop arrhythmias (ah-RITH-me-ahs), or irregular heartbeats. These symptoms can occur if the brain and heart are not getting enough oxygen.

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Respiratory Failure Clinical Trials

Clinical trials are research studies that explore whether a medical strategy, treatment, or device is safe and effective for humans. To find clinical trials that are currently underway for Respiratory Failure, visit

December 19, 2011 Last Updated Icon

The NHLBI updates Health Topics articles on a biennial cycle based on a thorough review of research findings and new literature. The articles also are updated as needed if important new research is published. The date on each Health Topics article reflects when the content was originally posted or last revised.