The tests are called Pulmonary Function Tests (PFT), and what I explain below is just the tests blowing into the tube of the smaller machine and not the ones inside the closet.
The machine is called a spirometer and it is used for the tests that take the volume measurements. The FEV1 is one of many tests done on this machine, but it is the one referred to most often. It is popular opinion that you should not only know what these tests mean but you should obtain copies of the results from your doctor for your own records, and it is unfortunate that many doctors don't interpret these results for you, so that you would better understand your condition.

Before I get to numbers, let me offer definition of the terms:

FEV1 - forced expiratory volume 1 = the volume of air that is forcefully exhaled in one second

FVC - forced vital capacity = the maximum volume of air that is forcefully exhaled %FEV1 - ratio of FEV1 to FVC expressed as a percentage

FEF25-75 -forced expiratory flow = the average air flow during the middle part of the exhalation

PEF - Peak expiratory flow rate = the peak air flow during exhalation

Normal values are based on four criteria: gender, race, age, and height. These criteria have all been determined to effect ones lung capacity, and conclude a normal value. The numbers to look at are the % of those predicted normal values. There will often be more that one result listed since it is protocol to give you three testings. Some of you may have a before and after test result, this means you were given a bronchiodilator between tests which helps determine your reaction to certain types of medication.

As I mentioned, and without going into a great deal more detail here, the most often used statistic to establish and track ones condition is the FEV1. These FEV1 values are most often used to describe your condition:
normal = above 80%
mild = 65-80%
moderate = 50-65%
severe = below 50%.

I hope this brief explanation will guide you gently toward a better understanding of your test results. Again this is simply my understanding of these numbers and not a medically qualified opinion. You should receive a more complete explanation of your condition from your doctor. In fact, insist on an explanation that you understand.
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Hope this helps
Slow and steady we go
Never alone

After I changed Pulmonary Dr's the new one sent me to the hospital and the lady that checked mine was awesome she explained everything she did and what the numbers meant and what was good and what was not and she made sure I had a copy of the test. My results are very low.
Stay safe and breath easy

Daniel's right in his analysis of the figures you gave. The one caveat I'd add is that there is increasing evidence that there are people who have COPD symptoms who test in the normal range. Best practice at this point is to treat them as if they do have COPD, but many docs won't do that. If that's the case, I'd really encourage them to quit polluting their lungs with stuff (if they are) and to begin a good exercise program, both aerobic and strengthening. Those to things could be the difference between living a nice long life and not.

Thanks guys..I know basically how to read PFT Results but this case baffled me as she is having pretty bad COPD type Lung Issues like us.....I found out yesterday they are treating her for ''Pleuritis''...maybe this is why her Lung Function Fev.1 percentage is really good.

I had my breathing test @ St Mary's Hospital The technician was very owledge any help me get thru y clostphobia !