Because certain lung conditions may have similar symptoms to heart failure, and because lung disease may coincide with heart failure, your doctor may ask you to undergo lung function tests. Lung function tests assess how well your lungs are working. The main test is called spirometry. It measures how much and how quickly you can move air in and out of your lungs.

For most of the lung function tests, you will wear a nose clip to make sure that no air passes in or out of your nose during the test. You then will be asked to breathe into a mouthpiece connected to a recording machine (spirometer). You will be given instructions on what to do, such as breathe in as deeply as possible and then breathe out as fast and hard as possible.

The accuracy of the tests depends on your ability to follow all the instructions. The respiratory therapist carrying out the test may strongly encourage you to breathe deeply during some of the tests to get the best results.

You may cough or feel light-headed after some of the tests but you will be given a chance to rest between tests. The testing may take from 5 to 15 minutes, depending on how many tests are done.

The results of the tests should help your doctor to:   

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