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challenge testing

hi, could i pick your brains please. i did a challenge test today as my consultant needs to be 100% i have asthma as it is work related. i have to wait several months for the results which is awful, if i put what i saw on the graph on here could anyone who has an idea on how this works let me know their opinion please. I blew 3 times at the start which was a standard breath which was around 670 on the graph, i then steadily blew worse after being fed some awful powder which culminated in a final score of 450 ish when blowing for 1 second bursts. i then took my blue inhaler and after 20 minutes was back to normal ish. i felt awful , tight chested and wheezy/coughy during the test. could anyone shed light as to wether this is a normal rection or if it shows i have asthma? thanks for your time, chris

7 Replies

as far as my understanding goes that sounds like the response an asthmatic would show; significant but rversible reduction in peak flow. do you knowif you stopped the test part way through, my understanding of the metacholine challenge was that they stopped as soon as your fev1 (the air you blow in the first second) was significantly enough reduced. not 100% sure. did the lab tech say anything, i find they do tend to know what theyre talking about and often comment on what they see! hope youre feeling better soon!


Hi Chris, that doesnt sound like much fun ;) I can understand your frustration at having to wait for results, its horrible - but it wouldnt really be appropriate for people who are non medical (and over the internet) to interpret your results and say whether you have asthma, for lots of reasons.

I do hope your results come faster than anticipated, and youre no longer feeling the effects of the test

Lynda :)


I had a negative mannitol challenge (apparently) but I'd forgot to stop taking a few of my meds when I should have done - I threw up from coughing on the 4th level of it. my first lung function tests came back normal but I'd been on pred for a while before that varying from 50mg-20mg on the top of a LABA (200mg a day), high dosed inhaled steroids(2000mg a day), singulair(10mg) and regular salbutamol(6 puffs every 4 hours and when needed on hospital discharge advise). my cons didn't want me to do it again, because he got the results he needed once I'd managed to get off the pred and avoid the rest of my medication for a set amount of time with just the normal lung function tests.

I think but don't quote me on it, that the test is usually stopped if it's considered positive.


I have to have the same test in a few weeks and I think it's safe to say I'm terrified! Not looking forward to it at all!


Just thought I would add my experience in case it helps...

Chukkin - I think if you're not well at the time then they probably wouldn't go ahead - they do know it's a 'challenge' in many ways esp if you most likely do have asthma and it's bad already.

I had a negative histamine challenge as well but despite all the 'this is the gold standard' etc, the consultant didn't really seem bothered about it and didn't say it meant it wasn't asthma - I was almost wondering why he'd done it! There does seem to be a difference re stopping meds though in different places. I was talking to someone on the ward where I had mine and she said hers was negative there too but had been positive in her local where you were meant to stop things for much longer (a week I think, which seems a tall order for someone who is severe though I'm not (difficult/weird rather than severe) so probably could have managed it though it wouldn't have been fun).

Chris - like Lynda I agree we can't really comment, but seems like you had some reaction - wonder why the long wait though to hear?! If you need to know for work, have you also had reversibility testing? My challenge test was kind of a non-event, and I think the physiologist doing it thought I was really weird because I didn't like the fact nothing was happening (it was because I hated the whole diagnostic uncertainty thing and knew my meds did actually help but was worried they'd be taken away if the test was negative). When I explained what I meant though, I think she did understand and gave me a neb to counteract any effects, after which my lungs did feel a lot better and showed it - I generally have a response to reversibility even if the 'pre-test' results don't show much, because afterwards they tend to be a lot better, even better than predicted. But probably your consultant has done reversibility already?


The thing I think is most scary is that there is the (large?) possibility that the challenge could set off an attack - potentially life-threatening!!! Surely, since the meds are helping, it would be a better idea to treat for asthma rather than stressing the airways into an attack?

Just a thought!!!


Chukkin - dont worry too much (although i know i was when i was going to have the test done). they give you the trigger in tiny doses at first and then increase them, monitoring whats going on in your lungs, so as soon as they are reacting you will not be given any more trigger, so in theory, there is a limit as to how much they will 'allow' your airways to react before they stop you. Also, as far as i know its an automatic thing that you are given a neb afterwards to undo any reaction, but they deffo wouldnt let you go if you were really struggling. You are in the best possible place to have an asthma attack, you would be able to get immediate help (unlike at home where you are going to have to wait for an ambulance and stuff) you might feel pretty rubbish during the test, but its not going to do any long term damage, if it did then they wouldnt be allowed to do the test!

I personally had a normal reversibility spirometry before i was asked to do the mannitol challenge and as i showed so much reversibility they didnt bother with the mannitol challenge, and i know that if you have had a spiro before and your lungs are already restricted before the challenge starts then they wont do it (my lab tech said he had done this before when he had a woman who had had her meds stopped after showing no reversibility on the spiro - and the mannitol challenge had been booked for two weeks later, she was significantly lower that 50% of what she had been the first time - the tech said to her that he was just going to re-do the reversibility testing as now she clearly had something to reverse)


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