BREATHLESS  WEBSITE: This site was founded by John Kirtley. Sadly he died in 2008.
It is now run by David Boswell and Terry Mackay
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DIAGNOSIS OF COPD

THE DIFFERENCE

What distinguishes Emphysema from Asthma? Both affect the airpipes called the bronchi that are the tubes which allow air to pass into and out from the lungs. Emphysema occurs due to the build up of mucus in the bulbous sacks that lie at the end of the air pipes - they are called the alveoli. Asthma occurs due to muscles causing constriction of the pipes themselves or when they become partially blocked with sticky mucus - sometimes both. These words are inspired by an article by Chris Le Roy.

DIAGNOSIS

OK so you've had a spirometer test (that machine you blow into) and it has measured two key volumes concerning your lungs.

The first is the absolute maximum total amount of air you can expel when breathing out. This is called your Forced Volume capacity - your FVC.

The next is the amount of air you can expel in the first second of a rapid breathing out. This is called your Forced Expiratory Volume - your FEV1.

NOTE.

Please note that the numbers and percentages associated with spirometry testing are not always correct as measures of your lung condition - they are just numbers and because they are generated by human beings they can vary according to how we feel from day to day and even from hour to hour. That said, they are still the best external indicators of your lung condition available.

Just to confuse us patients, there are two versions of the way these figures are used - A and B below.

In case you have read previous versions of the calculations made from tests mentioned here, note that the calculations given now are the correct ones for calculating the status of your lungs.

Method A. The calculation used by doctors for evaluating the relative condition of you lungs compared with those of a normal person is called the FEV1%. This is the ratio of your own FEV1 divided by the "expected" or "predicted" FEV1 for a normal fit person. So it is :  Patient FEV1 / FEV1 Predicted. 
This ratio is normally expressed as a percentage and is used by doctors to estimate the status of your lungs - and also in relation to life expectancy calculation when FEV1% falls below 30%. The method of arriving at the Predicted value of FEV1 is described below. 

Method B) The calculation used to check whether or not you have copd under the standard GOLD method, is also called the FEV1%. This is the ratio of your own FEV1 divided by your own FVC.
So it is : Patient FEV1 / Patient FVC. It is somewhat out of date these days, but can be used to classify the severity of your disease. See classifications below.

If you are comparing notes on FEV1% with a fellow patient, make sure you are using the same calculation. Method A is normally what the doctor will use to give you your FEV1%.

You may well also have had an X-Ray and normally a CT scan to confirm the diagnosis and maybe other tests. Note that the CT scan is the definitive method of diagnosis if you are suspected of having Emphysema or Bronchiectasis. If you have been diagnosed with either, make sure you get that CT scan. 

 What happens next ?
Well, in terms of your breathing capacity the FEV1 and FVC results are the ones that really matter at the present time and they are used to define whether or not you have COPD and in some cases also to define which stage or category your COPD has reached. Let's define again this FEV1 statistic. You blow into the tube, preferably sitting down and as hard as you can and for as long as you can, without coughing or pausing. If you are normal then most of the air in your lungs will be blown out in one second, like somebody who can blow out forty candles on a birthday cake all at once. But if you have COPD this doesn't happen and to empty your lungs you have to blow out for say fifteen seconds and in the first second, the hardest blow part may only blow out one or two candles. So, the F in FEV1 means Forced, or forcing the air out as hard as you can, the E in FEV1 means Expiratory or breathing out, not in, the V1 in FEV1 means Volume, or the most air you can breathe out in one second. Now the GP or respiratory nurse will read the computer print out and interpret the result. Better still,  before the machine is set up, ask if you can have a copy of the print out 


How does the computer or person calculate your Predicted value of FEV1 ?

Well your gender, age and height will be known and the average FEV1 that is 'predicted' or 'expected' at your age for a fit, lifelong non-smoker of your height will be known. Large numbers of people have been checked to get average figures.

Remember that everybody's FEV1 declines slowly after about aged 30. So it's a simple matter to put your FEV1 over the predicted/expected FEV1 and multiply by 100. And the result is given as a % - 

When John did it back in 2002, his FEV1 was 0.86 litres and his expected FEV1 at the age of 58 and a height of 5 feet 8 inches was 3.16 litres. So 0.86 over 3.16 times 100 equals 27%. "27%" !, he exclaimed, "27% of normal" !.  The consultant was hesitant and then said "You have Severe Emphysema", pointing at the X-rays and then added "Don't worry, it's not life threatening. "Oh great", John said, "Not now maybe, but how about later?" The consultant shrugged his shoulders "Nobody knows. You might be hit by a bus for all I know", 'Why do people always come up with that? thought John - and then he exclaimed " I'm now paranoid about buses"!


Since 2002, John's FEV1 declined to 0.5 litres by 2007, which is a larger drop than should be expected over 5 years. However, in 2002 it was probably on the verge of dropping anyway. Average annual decline is around 0.03 litres if you do not smoke, twice that if you do.

Different countries use diffrent classifications of severity. In the UK, NICE (National Institute for Clinical Excellence) states the following;


If your FEV1% (FEV1/FVC) x100 is between 50- 80 %, then you have MILD COPD
 If your FEV1% (FEV1/FVC) x100 is between 30-49%, then you have MODERATE COPD.

If your FEV1% (FEV1/FVC) x100 is below 30%, then you have SEVERE COPD .


If you don't understand this page, your GP or consultant will tell you whether you have mild, moderate or severe COPD or asthma or nothing at all !!


You can see now why John was so shocked. Unfortunately many of the symptoms of COPD only appear when you have reached the severe stage and that is when it is usually diagnosed. But all smokers over 40 beware; you may have the disease but don't know it, and if you are treated early enough and STOP SMOKING then you may never have the symptoms at all.  John kept wishing he'd known that and had a simple test.


30,000 people in the UK die of COPD and its complications every year and it is one of the fastest growing diseases. John gave up smoking two years before he was diagnosed but the damage to his lungs had already been done. And it is irreversible. But he knew he could slow down the progression of the disease and prolong his life, provided that he did not smoke again, took his medications and avoided extremes of cold and heat, ate sensibly and frequently, exercised and avoided people with infections. 


John held that he would encourage anyone who smokes and is worried that there may be something wrong, to answer the QUESTIONNAIRE and see if they might be affected by COPD or some  other ailment. If you have what you think is only smoker's cough, have it checked immediately. Don't forget it might not be serious, but on the other hand early diagnosis might save or prolong your life.