Methacholine challenge test

The methacholine challenge test (also known as bronchoprovocation testing) is used to confirm a diagnosis of asthma and determine its severity by assessing bronchial hyper-responsiveness, especially when pulmonary and spirometry tests reveal no anomaly.

The respiratory therapist will explain the procedure to you and guide you throughout the appointment.

The therapist will instruct you to empty your lungs, without forcing, then breathe in as far as you can, and then breathe out again, as fast and for as long as you can.

You may need to repeat these steps a few times until the therapist gets satisfactory results.

After that, the therapist will ask you to inhale an initial dose of methacholine, a drug that causes bronchoconstriction, a contraction of the muscles of the bronchi of the lungs that may cause difficulty breathing. The therapist will then measure your exhaled lung volumes (spirometry). These steps are repeated with an increasing dose of methacholine until your exhaled volumes are 20% lower than the first measurement. At that time, you may experience shortness of breath, wheezing and coughing.

The test is carried out in complete safety and when you leave, your level of breathing comfort will be comparable to what it was before the test.

The methacholine challenge test interpreted by a pulmonologist requires a medical prescription. When you make an appointment, our agent will provide important instructions for you to follow in order to satisfy the essential conditions for a successful test.