What is a B.C?
A bronchial challenge or Methacholine challenge helps to determin if you have asthma, and how severe your asthma is. The test involves blowing into a tube with your nose plugged so that we can measure your airflow. These measurements are taken at a baseline and after inhaling small and slowly increasing doses of a drug called Methacholine.
Methacholine is a drug which mimics a substance let off by our bodies during an allergic reaction called histamine. If your airways react to the Methacholine the results of your airflow will slowly decrease. The test can be stopped at any time and will be stopped if you react to the drug with increased symptoms such as wheezing, coughing and shortness of breath.
The test does involve a lot of effort on the part of the patient. The doctor may order the test only after a full pulmonary function test (PFT) has been completed with in the last year.
Why did my doctor order this test?
The bronchial challenge test is ordered after you have completed a ful pulmonary function test (PFT). It is sometimes possible to diagnose asthma during a PFT and no further testing is necessary. If there is not a significant enough change seen to diagnose asthma, the doctor will sometimes order a bronchial challenge test.
How should I prepare for this test?
There are questions to be completed and a consent form to sign before proceeding with the test.
- Wear loose fitting clothing;
- There is a list of medications/puffers to be avoided between 8-48hrs prior to your test. You will receive a list of these medications from your ordering physician or the therapist in special testing unit after you have completed your PFT. If you have not received instructions about medications to avoid, please call us at 519-749-4235 at least three days before your test;
- Please arrive 15 minutes before your test so that you can register with our receptionist;
- You can eat before the test but avoid a large meal beforehand;
- If you are sick, please call and rebook your appointment; and
- Bring a complete list of your medications, puffers and allergies.
How long with the test last?
The test takes approximately 45 minutes. If you should have a reaction to the Methacholine and your breathing becomes more difficult with wheezing, coughing and shortness of breath, we will give you Salbutamol (Ventolin) and you can rest until your breathing returns to normal. We will redo part of the test to ensure that your breathing has returned to normal and that you are feeling fine before the test is completed.
Why should I have this test done at the hospital?
Grand River Hospital strives for quality testing by qualified therapists. We follow the guidelines set by the American Thoracic Society/European Respiratory Society and use state of the art equipment. We are able to perform a variety of tests that are not offered at other labs. All breathing tests are interpreted by a respirologist, a physician who specializes in breathing problems.
When will I get the results?
A respirologist on staff or your own respirologist will interpret the results. We’ll also send a copy to your family doctor or the reading physician which takes approximately 10 days to two weeks. If you are seeing your respirologist or family doctor within two weeks of the test, please advise the technologist so that we can fax a copy to that doctor.