Hi All,
Been a long time since I posted, but still read regularly.
I am having a bit of a rough ride with my asthma at the moment and been undergoing various tests under my chest consultant.
The latest one that I have to go for (i can't remember the correct medical name) but its basically where they administer a histamine to breath in to induce bronchospasm.
Has anyone else had this test?? Would love to hear how you got on.
Thank you in advance.....a slightly anxious chickstar.
Hiya chickstar
Someone will correct me if im incorrect im sure-the test your referring to is called a bronchcial challenge and as you said you inhale a histamine which if your asthmatic would induce bronchospasm they then give you a brochodilator like ventolin and redo any spirometry tests. I have not had this done before but do very very vaguely remember studying it at university as part of my course.
Please dont get yourself to worked
up or anxious about it they will not let anything horrid happen to you it will all be carried out in controlled situation so if it does make you feel tight and wheezy etc they will give you medicines to relieve that.
Hopefully someone who has experienced the test first hand will come along soon and give you some reassurance but good luck and take care. Lotsa lv Xx
In addition to what Kit Kat has posted, the bronchial challenge test can also produce false positives and negatives. The test is used more I believe to rule out asthma as opposed to confirming it. Because of spirometry patterns etc it may help distinguish between different conditions like asthma and COPD.
Like Kit Kat said, it will be conducted in a controlled enviroment, so please don't worry.
Simi.
Grr- I must remember to copy my posts before clicking send...AUK had timed out, so I lost my response first time round! Here we go again! 
Hey chickstar.
I have had bronchial challenge testing performed a few years back as part of a clinical trial at the Brompton, when I was a skint med student wanting to earn a little cash!
It is used to detect hyperresponsiveness of the airways (which is a hallmark feature of asthma).
They use substances like methacholine, histamine or adenosine to induce a small reduction in your lung function, namely your FEV1 value on spirometry. They measure this by getting you to take a maximal breath in, and then breath out forcefully. The volume of air which you can exhale in the first second is your FEV1.
In the test, they will do initial measurement of your FEV1 so they have a baseline. They then ask you to take normal breaths for about 2 mins whilst you are given a a known concentration of the provoking substance by nebuliser.
After this time, they will get you to wait a few mins, and then repeat your FEV1 testing. They will then increase the concentration you are breathing and spriometry in a systematic fashion until they get the required decrease in FEV1. They usually look for a 20% drop, and different people will need a different concentration of the substance to induce this decrease. The substances will induce bronchospasm to all people, asthmatic or not- when at a high enough concentration. There's a certain concentration which is the cut-off for determining a 'hyperresponse' or normal response.
The concentration required for a 20% drop in your FEV1 is then plugged into some algebraic calculation, and this turns it into a values called your PC20. An asthmatic will have a lower PC20 than a non-asthmatic, and poorly controlled asthma results in a lower PC20 than well controlled asthma.
Once the FEV1 drop is acheived, the test is stopped and they will then get you to have some reliever medication, either by inhaler or nebuliser, and retest your FEV1. This demonstrates airway constriction reversibility, which is another feature of asthmatic lungs.
The test isn't at all scary. You might not even noticed any sensation of having any problems with your breathing associated with the 20% drop, but they like to get your FEV1 back to the baseline value.
I hope that this information is useful, and reassures you. Don't hesitate to ask if you have any other questions.
KSD
Thank you all for your replies. KSD your detailed response has made me feel less anxious.
Many thanks again and hope you are all as well as can be in this heat!
KSD, if you time out and loose your post, just click the browser back button, your post will still be there, and then you can either copy it or open a new tab/window depending on your browser and log-in again.
Woody-som, I've done what you said in the past...but this time the back button just took me to the sign in screen. 
It'll work in Firefox, but not in Internet Exploder, unfortunately
Just prooves Firefox is sooo much better than IE....
ooooo whats firefox and how do i get it , im fed up of losing my history and especially posts or personal messages when auk times out , as i have internet explorer ! thanks xx
( sorry i completely invaded your thread - )
Lil tinx, Firefox is a web browser - like Internet Explorer but nicer to use. It's okay to have both installed on your computer.
Firefox3 can be downloaded at:
mozilla-europe.org/en/firefox/
Hope you feel better soon chickstar! x
thanks ginny thats great ill give it a go
I've used firefox for years, was always way ahead of IE, but recently IE has been catching up. Firefox if you want has loads of plug-ins that can do some very wonderful things, one of my most used is session manager, just open several tabs, each with it;s own website, then save that as a session, and reload every time i use the browser, No Scripts is another worthwhile addition, it's block all those, well most of the annoying web redirections and popups.
Also from the same stable is Thunderbird, thats there email program, if you use outlook, or outlook express, then thunderbird will seem like a huge step up, or it did when i swapped ages ago.
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