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Doing lung function tests

...any tips? Just done my fourth set, for reversibility testing. Lung function is not bad - though I still haven't worked out why PF is well above predicted and others are all below predicted - I know they're different but would have thought would be some continuity?

However I didn't really get proper readings - couldn't do the tests properly as no 3 results the same, took me 8 goes! I seem to have got worse at this - first time I did it was hard but managed to get similar results much more quickly. My PF technique isn't great either but this was really bad - feel like as a singer and wind player I shouldn't be this bad!

Have repeat tests in 6 weeks and would really like not to repeat this - it's knackering enough doing it 3 times. Does anyone have any suggestions on how to be less rubbish at these or do I just need to hope I can manage it properly on the day?

13 Replies

The fact that you sing and also play a wind instruement probably means that you have over a period of time used and excercised your lungs to get good breathing control (hope that makes sense... :) ) and at the same time increase your lung capacity which in turn gives you a good peak flow reading. Though not related I used to swim and found that because of the excercise and need to hold my breathe to complete sprint work my lung capacity was higher than normal and Ii had above average peak flows. Obviously with the asthma on a bad day this causes the lungs to be inflamed (you can also get mucus plus) and the airways to narrow which reduced your lung capacity and your peak flow drops.... Hence the variable peak flows depending on how well your lungs are doing...

Sorry, waffled loads, hope that this makes sense.


Thanks! Yes that does make sense - though my PFs often don't match up with symptoms which can be annoying. The variable blows are more within one set of readings - so I'll do it 3 times and they can all be quite different.

What I don't get is how my PF has improved, or at least stayed well above predicted, when the FEV1 and FVC/FEV1 ratio seems to have got worse - 1st time they were all above predicted I think and now the ratio and FEV1 are definitely lower than predicted. Figured the PF was from the singing etc but would have expected that to help the others too...hmmmm.

If I'd thought about this at the time I could have asked at my appt on Wed - he said 'any questions?' and that he could take all the time he wanted (and he would know all of this if anyone does) but I didn't think of it then, nor of asking again about the relievers being used in the test. I'm also confused now about how I seemed to have 'non-allergic' asthma - description fitted me well, but now I have high IgE which is a marker of allergy yet hadn't clocked actually being allergic to anything? wtf?? Maybe allergy tests will make me less confused.

Sorry for another ramble...kind of going off topic and not really expecting anyone to know answers. Am just kicking myself for not thinking of all this when I had the undivided attention of an asthma expert with plenty of time - RBH are prob going to have less time to answer random questions like this.


The FEV1/FVC ratio, also called Tiffeneau index, is a calculated ratio used in the diagnosis of obstructive and restrictive lung disease. It represents the proportion of the forced vital capacity exhaled in the first second. Normal values are approximately 80% or greater.

Basically this ratio is used to calculate the amount of airway obstruction in your lungs in asthma this is normally reversible. However, if the linning of you lungs remodel or becomes damaged e.g. from infecton/smoking etc and the changes becomes permanent your FEV1/FVC values will start to drop. Basicically anything less than 70% can give a diagnosis of COPD (the severity is scored on the GOLD scale). It is possible to be asthmatic and have COPD as well as there is a lot of cross over.


Thanks! Hmm weird - seems my predicted FEV1/FVC ratio is 84 and actual appears to be about 70/71. Can't say what it used to be as was never told specifically, just that the first time 2 yrs ago it was 'all normal, in fact better than normal', so conclude that unless someone was being very inefficient or loose in their definition of 'above predicted/normal' (not out of the question) it has in fact dropped for some reason.

Thankfully I am reasonably sure that the chances of my having COPD are very very low - I am 26, I have never smoked and never lived or worked anywhere massively polluted or full of coal dust etc. I think I am just strange lol


It could just be your asthma not being well controlled at the moment and with the right medication for you things may improve your spirometry results... Best to ask the question to the technition or your consultant when you go for your next spirometry....


The lovely lung function figures. Can vary depending on how ur lungs are even post flare up or infection . . Numbers can be down. So the dr takes this into account also when assessing the numbers ... Re copd my asthma nurse always said that poor control and airway remodelling could lead to.copd this was in the late 90's .... This was dismissed by a consultant many years ago but Seems to be in the loop of thought just now .... Never smoked never worked in heavy industry yet lung function is pants, but thankfully I respond to the good old atrovent, salbutamol , bricanyl and a good skelpling of prednisolone .... Best asking drs to exPlain the numbers i find its better than beating the brain up trying to Make sense out of it yourself ....


Thanks guys! Both your posts make sense - think control got worse, then slightly better on meds...hmmm, wonder what last set were like though when was bad but on no meds! Never told but would find it odd if they were worse than this lot - that cons wasn't great though.

Will definitely ask cons next time - best make use of seeing top asthma specialist, he should know! Not asking technician after the s*** she came out with about relievers though - making me feel crap for using a lot and telling me Atrovent is a LABA.


my lung function results can vary massively, although in one sitting they usually just get worse with each go! and i think that when lungs arent behaving, theyre harder to do so technique also isnt great so making results look even worse (thats what i blame it on anyway ;-)

as others have said, i would ask your cons to explain results as ive tried to interpret mine before and ended up in a bit of a tizz!

tips re doing them again, try not to think about it too much! i used to complicate them, in desperate attempts to produce a good result, but it just made me more frustrated!

also, in theory atrovent can be thought of as a LABA as its effects are designed to last 4-6 hours. its a kind of an inbetween as its relatively quick onset aswell. and because its an old drug (esp for asthma) people dont always understand its action.

hope your next lung function tests arent so frustrating and you get some answers!

B x


Thanks B - yeah that's kind of what I thought as it's got harder as my breathing got worse! I really hate LF tests - I would rather have almost anything else, and am crossing my fingers the RBH doesn't want to do a methacholine challenge as that sounds like the worst of all worlds!

I hope you're safely out and finished with exams btw?

Realised I should have qualified that statement about Atrovent - she didn't just say it was a LABA but that there was no possible way it could work in a shorter time period than hours which is obviously crap or they wouldn't use it for acute attacks!

I reckon she will be on holiday if she sees me coming lol - which suits me fine as she rather upset me by really laying into me about my reliever use and implying I was some kind of irresponsible drug addict who didn't realise it was medication and was just taking it for fun (has she ever actually tasted any of these drugs?!).


Sorry to jump on this thread philomela but.......

I had my lft today and the technitian said they were all normal except one which showed I had obstruction on expiration.

I'm seeing my cons on Thursday so will get a full breakdown of the results then but just wondered if anyone knew what this means?


No worries, hope you get some answers! I'm not really sure what they meant - even if I were an expert, which I'm not, they all seem to use different terms plus the technicians say one thing and dr/nurse says another - I once had the guy doing the tests, who was actually a respiratory physiologist so knew a lot about it, say that I did seem to have some obstruction there but then cons said 'variable but normal' so it can be a bit head-scratching I find!

Maybe - just a guess here - s/he meant your FEV1 was low as that's percentage of total exhaled volume in the first second? Esp. if it's relative to FVC which is total volume on maximum exhalation after maximum inhalation (sorry anyone if I've got this wrong, did look them up!) But sounds a bit vague really, you might have to wait for the cons unless someone who knows what they mean by this comes along.

Meanwhile this may help, or at least be interesting: en.wikipedia.org/wiki/Spiro...

(PS on a random note, I see above that I was hoping the RBH wouldn't do a challenge test...oops. Oh well, if it tells me something useful I won't mind. I just hope it does tell me something useful given my general crapness at doing these tests, but concerned it won't, especially now the Symbicort is - yay - helping my lungs to be a lot less twitchy in general.)


Ummm..... Fair point, that's all very confusing!

I'll wait to speak to my cons but thanks for the info.

Sounds like your lfts are even more confusing :-S


I had my lft today and the technitian said they were all normal except one which showed I had obstruction on expiration.

I'm seeing my cons on Thursday so will get a full breakdown of the results then but just wondered if anyone knew what this means?

With having asthma the obstruction could be caused by mucus plugs blocking or restricting your airways and/or chronic inflammation in your small airways causing airway narrowing and causing air trapping when breathing out. With asthma this is normally a reversible process.... It could be other things as well so best to ask your consultant when you see him/her.


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