Your health care provider will diagnose respiratory failure based on

• Your medical history

• A physical exam, which often includes

  • Listening to your lungs to check for abnormal sounds

  • Listening to your heart to check for arrhythmia

  • Looking for a bluish color on your skin, lips, and fingernails

• Diagnostic tests, such as

  • Pulse oximetry, a small sensor that uses a light to measure how much oxygen is in your blood. The sensor goes on the end of your finger or on your ear.

  • Arterial blood gas test, a test that measures the oxygen and carbon dioxide levels in your blood. The blood sample is taken from an artery, usually in your wrist.

Once you are diagnosed with respiratory failure, your provider will look for what is causing it. Tests for this often include a chest x-ray. If your provider thinks you may have arrhythmia because of the respiratory failure, you may have an EKG (electrocardiogram). This is simple, painless test that detects and records your heart's electrical activity.

https://medlineplus.gov/respiratoryfailure.html