There are a number of conditions that could be affecting your ability to breathe properly, either while you're asleep or awake. For example, if you have obesity hypoventilation syndrome (OHS), being overweight places a lot of pressure on the muscles around your lower airway, making it difficult for you to take in enough air. If you have a restrictive lung disease, the muscles and nerves used during breathing are affected, making it difficult to breathe properly on your own.
Generally, if your inability to breathe properly is part of a broader condition, then you will be diagnosed as part of the broader condition. Your doctor or care provider will determine the best diagnosis method for your condition and let you know the next steps to getting treated. Learn more about other respiratory conditions such as COPD, NMD, or OHS that affect your ability to breathe or about respiratory conditions in children.
If your inability to breathe at night is causing you to have apnoeas (you stop breathing while you're asleep), your care provider might request that you get a sleep study. Sleep studies are used to assess whether or not you have sleep apnoea, and if so, how severe it is. You can do a sleep study in a sleep clinic or in the comfort of your own home. Read more about sleep studies.
Blood Gas Analysis
The correct way to diagnose a respiratory insufficiency is via a blood gas analysis. A blood sample will be collected by your physician to determine your O2 and CO2 levels.
Transcutaneous CO2 measurement
If you already are using CPAP for treating your OSA, transcutaneous CO2 measurement can easily identify a respiratory insufficiency while you are sleeping.