How to apply the recommended PFT algorithm
Learn about the currently recommended pulmonary function test (PFT) interpretation algorithm and how to use it.
In this case-based teaching video, from our Pulmonary Function Testing Essentials course, you'll learn how to apply the essentials of pulmonary function testing with the help of an algorithm.
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Take a deep dive into our Pulmonary Function Testing Essentials course and learn how to apply PFT interpretation guidelines to clinical cases. You'll learn when to use spirometry in your daily clinical practice, what tests to order, and how to interpret results. Complex concepts, like lung volume, spirometry, diffusing capacity, bronchodilator responsiveness, and obstructive and restrictive patterns, will become second nature to you once you’ve completed this course!
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[00:00:00] So, now you've learned the essentials of pulmonary function testing, let's try to apply what you've learned. Here is your first case: the patient is a 54-year-old man with a several month history of progressive dyspnea. He is 1.65 meters tall, weighs 66.2 kilograms, and is a lifelong non-smoker.
[00:00:30] Analysis begins with review of spirometry including forced vital capacity, forced inspiratory vital capacity, and slow vital capacity. As noted in the discussion regarding the current ATS / ERS approach to pulmonary function test interpretation, FEV1 is viewed in relationship to the largest of the aforementioned parameters. In this case,
[00:01:00] SVC is larger than FVC and FIVC. Therefore, the appropriate ratio to analyze is the FEV1 over SVC%. FEV1 over SVC% is 76%, which is greater than the lower limit of normal of 66%. We then look at the vital capacity once again in this case,
[00:01:30] SVC. SVC is 2.11, which is less than the lower limit of normal of 2.84. We then move on to review lung volumes, in particular TLC. TLC is 3.29, which is less than the lower limit of normal of 4.89; hence, we arrive at a diagnosis of restrictive lung disease. Finally,
[00:02:00] we look at the diffusing capacity and note that it is 14.85, which is less than the lower limit of normal of 22.17. This implies the existence of interstitial lung disease or another pulmonary parenchymal disorder. Note that application of the older PFT interpretation methodology would also have resulted in a diagnosis of restriction with reduced FVC,
[00:02:30] reduced FEV1, normal FEV1 over FVC%, and reduced TLC.