Bronchoprovocation Challenge Testing for Asthma

Test used to diagnose asthma when others are uncertain

Spirometry Woman undergoing a lung function test using a spirometer that measures the maximum rate at which air is expelled from the lungs, Respiratory diseases department, Limoges hospital, France.
Woman undergoing a spirometry test. BURGER/PHANIE/Getty Images

 Bronchoprovocation is one of the tests doctors use to make an asthma diagnosis. To do this, you would be asked to either inhale a nebulized solution or perform exercise. in this way, the doctor can if you to see if you develop symptoms of asthma or have evidence of airway obstruction (as measured by a device called a spirometer).

If either of these things occur, you are said to be hyperresponsive.

What a Bronchoprovocation Challenge Tells Us

The aim of a bronchoprovocation is, as its name suggests, to provoke a response in the lungs. Spirometry alone will often not be able to make a diagnosis if the airway passages are clear and the only evidence of asthma are the symptoms reported by the patient. In such case, bronchoprovocation is used to trigger a response with the use of:

  • Methacholine, a bronchoconstrictor drug which you inhale
  • Histamine, an organic compound known to trigger allergic response, also inhaled
  • Cold air, a known environmental trigger for asthma
  • Exercise, the trigger for exercise-induced asthma

If you take the test and your lungs fail to demonstrate hyperresponsiveness, it is less likely that you have asthma. If you are hyperresponsive, the degree of that response will determine both the severity of your asthma and the appropriate course of treatment.

When a Bronchoprovocation Test May Be Requested

Bronchoprovocation testing is typically performed when there are asthma symptoms but normal pulmonary functions, and the person has no response to albuterol (a rescue inhaler).

There are other situations where bronchoprovocation may be requested:

  • Persons with ill-defined symptoms such as shortness of breath but no evidence of airway obstruction in whom no other causes can be found
  • Persons who may be seriously harmed by an asthma attack in the course of their occupation (such as a surgeon or military personnel).
  • Persons who are regularly exposed to inhaled irritants in the course of their occupation.

How Results Are Measured

During the course of bronchoprovocation, a spirometry test will be performed to test how much and how fast air goes in and out of your lungs. One of the measures the doctor will look for is how much air you can forcefully expel in one second. This is called forced expiratory volume (FEV) and is measured in increments of one second (FEV1), two seconds (FEV2), and three seconds (FEV3).

The doctor will compare your FEV1 from before bronchoprovocation and after. A decline in FEV1 of 20 percent or more from your baseline reading is considered a positive test.

In addition to positively diagnosing asthma, bronchoprovocation testing has a high negative predictive value. Therefore, if you have a negative result, it is highly unlikely you have asthma.

Bronchoprovocation Is Not For Everyone

Not everyone should have bronchoprovocation testing as it may, in some cases, lead to a potentially severe asthma attack. These include persons with the following conditions:

  • Moderate to severe airway obstruction (as measured by the FEV1)
  • A heart attack within the last three months
  • Uncontrolled hypertension

Source:

Leuppi, J. "Bronchoprovocation tests in asthma: direct versus indirect challenges." Current Opinions in Pulmonary Medicine. 2014; 20(1): 31-36.

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