What is Methacholine / Inhalation Bronchial test like?

[eaab08]

I have a conditional offer of appointment riding on this test, so I'm a little anxious about it. Any advice/tips to do well? I saw online that if the airway restricts by up to 20%, that means you may have asthma. I haven't had an asthma attack in years, and I've been active in sports without an inhaler, so I don't think I'd have a problem. However, I've also never breathed methacholine before, so I don't want to speak too soon.

 

[MullenLE]

If you have a conditional appointment, you are in all likelihood being considered for a medical waiver. The waiver authorities "may" ask for an MCCT or they may not. They will ask for what they need to render their waiver decisions. Not every waiver authorities use MCCT's and at this stage, the likelihood of one being able to obtain one is very low, due to restrictions on this test around the country.

 

[Usnavy2019]

I didn't have to take the MCT as an applicant as I had childhood exercise-induced asthma until I was 12. That met the DoDMERB standard. However, I did have to take one to get qualified to fly. I'm guessing you have taken a spirometry before. It is pretty much a series of spirometries given after increasing concentrations of methacholine, which is a bronchoconstrictor (a drug that makes your airways swell). The degree of broncoconstriction is measured by the decrease in FEV1 from the baseline measurement. FEV1 is Forced Expiratory Volume in 1 second. In layman's terms, it is the amount of air you exhale in one second.

As you alluded to earlier, a positive MCT (indicative of asthma) is a drop of greater than 20% in FEV1. A negative test (suggestive of not having asthma) is where the patient does not experience a drop greater than 20% FEV1 after receiving the highest concentrations. Doses are given in a stepwise manner (You start with no methacholine to get a baseline and then you are given a series of 4-5 doses of increasing concentration. I had 5 if I remember correctly). After the test, you are given albuterol and you take additional spirometries to ensure your airways are back to normal. Everyone will experience some drop in FEV1, but 20% is what is considered hyperresponsive.

My experience: I was pretty tired during in the latter part of the test since you are breathing out as hard as you can over and over. You most likely won't feel any chest tightness. My chest was actually kind of sore for a few days after, but I passed the test so I didn't mind. If you have been unrestricted asthma-wise, you shouldn't have any problems.

 

[hbtw2011]

DD had the MCCT as part of AMI for USNA waiver. She has an LOA contingent on medical so like you she felt a LOT of pressure going in to the test. She passed the MCCT but has yet to get word on being granted a waiver. She was granted one for USAFA without the MCCT.
Best advice- RELAX!!!! they are testing your breathing- you cannot fully breathe if you are uptight and worried. Also there is nothing you can do to prepare for the test. You will inhale methacholine from a nebulizer in increasing doses. after each dose you blow into a spirometer. If at any point you cannot blow at 80% percent of your baseline the test stops and you fail. If you stay above 80% you are considered to have passed. RELAX RELAX RELAX. Air flows much better when you are not stressed. Relax and breathe! Good luck with the test!
DD did not feel a thing in her chest during or after the test at all. We are really hoping to hear soon about a waiver. OH THE WAIT!!!

 

[eaab08]

I didn't have to take the MCT as an applicant as I had childhood exercise-induced asthma until I was 12. That met the DoDMERB standard. However, I did have to take one to get qualified to fly. I'm guessing you have taken a spirometry before. It is pretty much a series of spirometries given after increasing concentrations of methacholine, which is a bronchoconstrictor (a drug that makes your airways swell). The degree of broncoconstriction is measured by the decrease in FEV1 from the baseline measurement. FEV1 is Forced Expiratory Volume in 1 second. In layman's terms, it is the amount of air you exhale in one second.

As you alluded to earlier, a positive MCT (indicative of asthma) is a drop of greater than 20% in FEV1. A negative test (suggestive of not having asthma) is where the patient does not experience a drop greater than 20% FEV1 after receiving the highest concentrations. Doses are given in a stepwise manner (You start with no methacholine to get a baseline and then you are given a series of 4-5 doses of increasing concentration. I had 5 if I remember correctly). After the test, you are given albuterol and you take additional spirometries to ensure your airways are back to normal. Everyone will experience some drop in FEV1, but 20% is what is considered hyperresponsive.

My experience: I was pretty tired during in the latter part of the test since you are breathing out as hard as you can over and over. You most likely won't feel any chest tightness. My chest was actually kind of sore for a few days after, but I passed the test so I didn't mind. If you have been unrestricted asthma-wise, you shouldn't have any problems.

Thanks for the detailed response! Good to have an idea of what I'll be doing beforehand.

DD had the MCCT as part of AMI for USNA waiver. She has an LOA contingent on medical so like you she felt a LOT of pressure going in to the test. She passed the MCCT but has yet to get word on being granted a waiver. She was granted one for USAFA without the MCCT.
Best advice- RELAX!!!! they are testing your breathing- you cannot fully breathe if you are uptight and worried. Also there is nothing you can do to prepare for the test. You will inhale methacholine from a nebulizer in increasing doses. after each dose you blow into a spirometer. If at any point you cannot blow at 80% percent of your baseline the test stops and you fail. If you stay above 80% you are considered to have passed. RELAX RELAX RELAX. Air flows much better when you are not stressed. Relax and breathe! Good luck with the test!
DD did not feel a thing in her chest during or after the test at all. We are really hoping to hear soon about a waiver. OH THE WAIT!!!

Thanks for the advice! I'll be sure to do that. I normally get really nervous, had to deal with a bit of White Coat syndrome earlier in my medical tests. Luckily that served as a "calming down" practice.

 

[IrishBrewer]

My daughter got an asthma DQ also and had to take the MCT test as part of the waiver process. How that happened is a bit of a long story but the short story is that she never had asthma to begin with. One thing I wanted to mention is that the technician who administered the test did not do a very good job explaining what the subject should strive for in the spirometry tests. As a result my daughter just tried to breath out as long as possible which is part of what you want to do but not all of it. The measurements being taken don't just measure the total volume of air that is being expelled but also the rate of expulsion. As such, you want to breath out forcefully, quickly and completely. I think that simple description alone would have changed the outcome of her test but as it turned the lack of that understanding resulted in test results that were somewhat inconclusive.

Fortunately, that was not the end of the road for her waiver and she underwent a treadmill stress test where her breathing and heart rate were monitored. When she took that test, they got to the point where they couldn't make the machine go any faster or incline any further yet she just kept running so she passed with flying colors and ultimately her waiver was granted. I'm happy to say that she's now finishing up her junior year and having a very successful college experience as a ROTC cadet so I'm glad she didn't give up on getting past the barriers she had to get over to make that happen.

Best of luck!

 

[usna1992]

My daughter got an asthma DQ also and had to take the MCT test as part of the waiver process. How that happened is a bit of a long story but the short story is that she never had asthma to begin with. One thing I wanted to mention is that the technician who administered the test did not do a very good job explaining what the subject should strive for in the spirometry tests. As a result my daughter just tried to breath out as long as possible which is part of what you want to do but not all of it. The measurements being taken don't just measure the total volume of air that is being expelled but also the rate of expulsion. As such, you want to breath out forcefully, quickly and completely. I think that simple description alone would have changed the outcome of her test but as it turned the lack of that understanding resulted in test results that were somewhat inconclusive.

Fortunately, that was not the end of the road for her waiver and she underwent a treadmill stress test where her breathing and heart rate were monitored. When she took that test, they got to the point where they couldn't make the machine go any faster or incline any further yet she just kept running so she passed with flying colors and ultimately her waiver was granted. I'm happy to say that she's now finishing up her junior year and having a very successful college experience as a ROTC cadet so I'm glad she didn't give up on getting past the barriers she had to get over to make that happen.

Best of luck!

Just curious I was doing some research on these tests...can I ask what made her MCT test inconclusive? Was her decrease in airflow just a little over the 20% ?

 

[IrishBrewer]

Just curious I was doing some research on these tests...can I ask what made her MCT test inconclusive? Was her decrease in airflow just a little over the 20% ?

It had to do with her rate of exhalation. She did not have enough volume fast enough. I'm certain that she could have passed the test if she was better informed on what to do.