What Is a Bronchoprovocation Challenge?

A bronchoprovocation challenge, also known as bronchoprovocation testing, is an in-office test used to diagnose asthma. It involves either inhaling aerosolized chemicals or cold air, or performing exercises, to see if it induces asthma symptoms. By measuring your lung function after exposure to these triggers, your doctor may be able to determine if you have asthma.

Woman undergoing a lung function test using a spirometer that measures the maximum rate at which air is expelled from the lungs
Burger / Phanie / Getty Images

Purpose of Test

A bronchoprovocation challenge is commonly ordered if pulmonary function tests (PFTs) fail to provide definitive evidence of asthma.

With PFTs, a breathing device called a spirometer can often diagnose asthma if lung function improves after inhaling a short-acting bronchodilator, a type of drug designed to dilate (open) the airways.

In some cases, however, the response may not be enough to definitively diagnose asthma. If so, the doctor may take a different tack and see if certain asthma triggers have the opposite effect, causing airways to constrict (narrow) rather than open.

This is where the bronchoprovocation challenge comes in. As its name suggests, the aim of the test is to provoke a response in the lungs.

Central to making an asthma diagnosis is a value called forced expiratory volume (FEV) which measures the amount of air you can forcefully expel from the lungs. With bronchoprovocation, asthma can be definitively diagnosed if the FEV value drops by a certain percentage after exposure to an asthma trigger.

Triggers that may be used in a bronchoprovocation challenge include:

  • Methacholine, an inhaled chemical that causes the mild constriction of the airways (similar to asthma)
  • Histamine, an inhaled organic compound that can trigger an allergic response in people with allergic asthma
  • Cold air, an environmental trigger for cold-induced asthma
  • Exercise, a physiological trigger for exercise-induced asthma

Less commonly, an inhaled sugar called mannitol may be used, although it has lower sensitivity compared to methacholine or histamine.

If you take the test and your lungs fail to demonstrate airway hyperresponsiveness (increased sensitivity to stimuli), it is unlikely 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.

Bronchoprovocation is less commonly used to evaluate the effectiveness of an asthma drug or to determine your relative risk of developing asthma (such as might occur in certain high-risk occupations).

Risks and Contraindications

A bronchoprovocation challenge is rarely the first test used when diagnosing asthma due to certain risks associated with the test. Unlike exposure to bronchodilators, which improve breathing, bronchoprovocation triggers the opposite response and makes breathing harder. This is not appropriate for everyone.

One of the major concerns is that exposure to certain triggers may provoke a severe asthma attack requiring emergency intervention. Because of this, doctors will make every effort to avoid bronchoprovocation in those at risk of severe bronchospasms.

In some people, the test is absolutely contradicted, and, in others, there are relative contraindications that may exclude some individuals but not others.

Absolute contraindications for bronchoprovocation testing are:

Relative contraindications for bronchoprovocation testing are:

Before the Test

To ensure that bronchoprovocation testing is safe and effective, your doctor will conduct a pre-test evaluation to identify any contraindications for testing. Central to this is your FEV1 value as measured by a spirometer. Among the limitations:

  • People with severe airflow restriction (defined as an FEV1 of less than 50% of the predicted value) should never undergo bronchoprovocation.
  • Those with moderate restriction (with an FEV1 of less than 60%) may be excluded if there are other contributing risk factors.
  • Because exercise challenges are physically demanding, people with a baseline FEV1 of less than 75% may not be able to cope and may require other means of testing.

Timing

The timing of a bronchoprovocation challenge can vary depending on the type of challenge ordered, but the test usually takes around two hours from start to finish. This is particularly accurate for methacholine or histamine challenges; cold-air and exercise challenges may take less time.

Location

Bronchoprovocation testing can be performed in a pulmonary function lab of a hospital or in the office of a pulmonologist equipped with the appropriate tools. Central to the test is a hand-held spirometer connected to a laptop or digital monitor than can measure FEV1 values before and after bronchoprovocation.

In addition:

  • For inhaled challenges, a pressurized nebulizer will deliver metered doses of methacholine or histamine in powdered form to the lungs.
  • For cold-air challenges, a pressurized inhaler will deliver sub-frigid air to the lungs while simultaneously measuring the rate of respiration.
  • For exercise challenges, there will be a treadmill or stationary bike for you to use.

There will also be the appropriate resuscitation equipment and emergency medications should a severe asthma attack occur.

What to Wear

With the exception of the exercise challenge, you can usually wear comfortable, loose-fitting street clothes.

For the exercise challenge, you can either wear or bring clothes you feeling comfortable exercising in (such as a tracksuit or shorts and a T-shirt) along with athletic shoes with skid-free soles.

Because a heart monitor will be used during the test, bring a light top that you can either lift or remove.

Food and Drink

Your doctor will give you instructions on how to prepare for the test, but, generally speaking, you should not eat or drink a lot prior to the test if only to prevent discomfort and nausea (especially if undergoing an exercise challenge).

Most doctors will advise you to avoid caffeine on the day of the test, including coffee, tea, cola, and chocolate, as it can increase airway hyperresponsiveness and throw off the results.

There is a long list of drugs that can also undermine testing, including antihistamines that blunt the effect of the inhaled histamines. Some drugs, particularly those used to treat breathing problems, need to be stopped anywhere from three to 72 hours prior to the test.

These include:

  • Short-acting beta-agonists (generally stopped eight hours before the test)
  • Medium-acting beta-agonists (stopped 24 hours before the test)
  • Long-acting beta-agonists (stopped 48 hours before the test)
  • Oral bronchodilators (stopped eight to 48 hours before the test)
  • Cromolyn sodium (stopped three hours before the test)
  • Nedocromil (stopped 48 hours before the test)
  • Leukotriene inhibitors (stopped 24 hours before the test)
  • Antihistamines (stopped up to 72 hours before the test)

You will also need to stop smoking on the day of the bronchoprovocation test.

Cost and Health Insurance

The cost of a bronchoprovocation can vary significantly by location and facility, ranging from a few hundred dollars to well over a thousand.

Bronchoprovocation challenges almost invariably require prior authorization from your insurance, if you're covered, which may include a written motivation from your doctor as to why the test is necessary. Pulmonologists are usually well-versed in how to push through approvals with insurers.

Before getting tested, check what your copay or coinsurance costs will be and whether the testing facility is an in-network provider with your insurance company. Having a pulmonologist who is in-network doesn't necessarily mean that the off-site lab you're referred to will be.

If you don't have insurance, ask the facility if they offer reduced rates for upfront payment, or have no-interest payment plans. It usually pays to shop around to find the best rates in your area.

What to Bring

Be sure to bring an official form of identification (such as your driver's license), your insurance card, and an accepted form of payment to cover any copay or coinsurance costs.

It is also important to bring along your rescue inhaler in the event of an asthma attack during or after the test. This is uncommon but can occur.

During the Test

Once you have checked in at the reception, you will be provided forms to detail any medical conditions you have or any treatments you are taking. Although this should have been discussed with your doctor before the test, be detailed when filling these out.

A patient consent form will also be provided.

Pre-Test

Once all of the forms are completed, you will be taken to the testing room by a nurse who will record your pulse, blood pressure, weight, and height.

Either the nurse or lab technologist will then confirm that all food and medication restrictions have been adhered to.

Throughout the Test

The goals of bronchoprovocation challenges are similar but the procedure used can vary based on the type ordered.

Methacholine or Histamine Challenge

For this form of direct testing, the choice of methacholine or histamine may be based on the types of triggers that provoke asthma in everyday life. If asthma attacks increase in tandem with seasonal allergies, for example, histamine may be a reasonable choice.

Generally speaking, methacholine is preferred because histamine is associated with more side effects, including headache and hoarseness. Methacholine also tends to be more effective in inducing airway hyperresponsiveness.

The general steps for a methacholine or histamine challenge are as follows:

  1. A baseline FEV1 reading is taken, which involves inhaling deeply and exhaling forcefully into the spirometer.
  2. A nose clip is placed on your nose so that air is directed in and out of the mouth only.
  3. You will then be given a nebulizer that delivers an accurate dose of methacholine or histamine under pressure.
  4. Place the nebulizer mouthpiece in your mouth.
  5. With the air pressure turned on, inhale and exhale comfortably for two minutes, being sure to keep the nebulizer upright rather than tilted. (If breathing solely through a mouthpiece worries you, ask the technologist in advance if a nebulizer face mask is available.)
  6. After that time, the machine is turned off and the mouthpiece removed.
  7. Between 30 and 90 seconds later, a second FEV1 reading is taken. Additional FEV1 readings may be taken thereafter, the highest of which will be recorded on the lab results.

Multiple doses of the inhalant are often given in gradually decreasing concentrations. This may help support the diagnosis if the hyperresponsiveness is repeatable. Each dose would be separated by a 10-minute waiting period, with FEV1 readings taken between each dose.

Cold-Air Challenge

The procedure for a cold-air challenge is similar. Instead of nebulized powder, you will inhale air chilled to around -4 degrees F.

The cold-air challenge is performed as follows:

  1. A baseline FEV1 reading is taken.
  2. A nose clip is placed on the nose.
  3. The mouthpiece of a sub-thermal inhaler is placed in the mouth.
  4. With the mouthpiece on, you will breathe normally for around a minute to adapt to the cold air.
  5. You will then be asked to hyperventilate (breath rapidly) until the digital meter on the inhaler says that you have reached the target speed.
  6. Continue breathing at this rate for three minutes.
  7. The inhaler is then removed.
  8. Thereafter, FEV1 readings are taken every five minutes for the next 20 minutes.

The test may be repeated to determined whether the hyperresponsiveness is repeatable under the same conditions.

Exercise Challenge

Treadmills are generally preferred to stationary bikes for exercise challenges, in part because running induces hyperventilation quicker. Exercise challenges can be performed on their own but are often used in combination with inhaled methacholine, mannitol, or hypertonic saline to better provoke airway hyperresponsiveness.

The exercise challenge is performed as follows:

  1. A baseline FEV1 is taken.
  2. A heart rate monitor is placed on your chest or arm, and a nose clip is placed on the nose.
  3. If a nebulized or aerosolized substance is used, you will be given instructions on how to inhale it properly.
  4. You will then step onto the treadmill or mount a stationary bike.
  5. The speed of the treadmill will be graded so that you gradually run faster. If you on a stationary bike, you will be asked to peddle faster to raise your heart rate.
  6. Once your heart rate is 85% of your estimated maximum (ideally within two to three minutes), the speed is adjusted so that you maintain that heart rate for no less than four minutes in total.
  7. After completion, you will rest for around five minutes.
  8. The second FEV1 reading is then taken.

If reasonable, the test may be repeated to see if hyperresponsiveness is repeatable under the same conditions.

After the Test

After completion of a bronchoprovocation challenge, you should be able to breathe normally and should not experience any asthma symptoms when you go home.

If you have wheezing, shortness of breath, or coughing after the test, let the technologist know—even if the symptoms are mild.

In such cases, the nurse or technologist will want to monitor you until your breathing normalizes and provide you with a bronchodilator, if needed.

Most people can drive home on their own once the test is completed.

Methacholine may cause side effects, such as headache, dizziness, sore throat, nausea, and vomiting.

Histamine may also cause headaches and dizziness as well as flushing, hoarseness, rapid heartbeat, and jitteriness.

While most of these side effects will resolve on their own within several hours, do not hesitate to call your doctor if they persist or worsen.

Interpreting Results

If the test is performed in your pulmonologist's office, you may be able to review results while you are there. In other cases, the results of a bronchoprovocation challenge will be forwarded to your doctor, usually within a day or so.

The pulmonary lab report will detail your FEV1 value before bronchoprovocation and after. A decline in FEV1 of 20% or more from your baseline is considered a positive diagnosis for asthma.

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 that you have asthma.

Follow-Up

Bronchoprovocation is only one test used to diagnose asthma, and its accuracy can be affected by the quality of the testing protocols. If the test is inconclusive, it may be repeated on a different day.

Furthermore, since some people without asthma may experience bronchoconstriction when exposed to methacholine, borderline results can be even harder to interpret. In cases like these, doctors will sometimes prescribe a trial course of asthma medications; if symptoms improve, a presumptive diagnosis of asthma can be made.

If bronchoprovocation testing is strongly negative and symptoms persist, the doctor will likely order tests to explore other possible causes, including:

A Word From Verywell

A bronchoprovocation challenge is a highly valuable test that can help pinpoint asthma when other tests fail to do so. While not without risks, the test is generally safe if a proper evaluation is conducted beforehand.

If a result is inconclusive, don't take that to mean that you don't have asthma. Asthma can often go into periods of low activity in which the lungs are less sensitive to the triggers. If symptoms develop or persist after a borderline result, let your doctor know.

Was this page helpful?
Article Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Coates AL, Wanger J, Cockcroft DW, et al. ERS technical standard on bronchial challenge testing: general considerations and performance of methacholine challenge tests. Eur Respir J. 2017;49(5):1601526; doi:10.1183/13993003.01526-2016

  2. Lee MK, Yoon HK, Kim SW, Kim TH, Park SJ, Lee YM. Nonspecific bronchoprovocation test. Tuberc Respir Dis (Seoul). 2017;80(4):344-50. doi:10.4046/trd.2017.0051

  3. Diamant Z, Gauvreau GM, Cockcroft DW, et al. Inhaled allergen bronchoprovocation tests. J Allergy Clin Immunol. 2013;132(5):1045-55.e6. doi:10.1016/j.jaci.2013.08.023

  4. Hyrkäs-Palmu H, Ikäheimo TM, Laatikainen T, Jousilahti P, Jaakkola MS, Jaakkola JJK. Cold weather increases respiratory symptoms and functional disability especially among patients with asthma and allergic rhinitis. Sci Rep. 2018;8(1):10131. doi:10.1038/s41598-018-28466-y

  5. Tan JHY, Chew WM, Lapperre TS, Tan GL, Loo CM, Koh MS. Role of bronchoprovocation tests in identifying exercise-induced bronchoconstriction in a non-athletic population: a pilot study. J Thorac Dis. 2017;9(3):537-42. doi:10.21037/jtd.2017.02.70

  6. Leuppi JD. Bronchoprovocation tests in asthma: direct versus indirect challenges. Curr Opin Pulm Med. 2014;20(1):31-6. doi:10.1097/MCP.0000000000000009

  7. Yurach MT, Davis BE, Cockcroft DW. The effect of caffeinated coffee on airway response to methacholine and exhaled nitric oxide. Respir Med. 2011;105(11):1606-10. doi:10.1016/j.rmed.2011.06.006

  8. Sayeedi I, Widrich J. Methacholine challenge test. In: StatPearls [Internet]. Updated November 18, 2019.

  9. Gallucci M, Carbonara P, Pacilli AMG, Di Palmo E, Ricci G, Nava S. Use of symptoms scores, spirometry, and other pulmonary function testing for asthma monitoring. Front Pediatr. 2019;7:54. doi:10.3389/fped.2019.00054

  10. McGrath KW, Fahy JV. Negative methacholine challenge tests in subjects who report physician-diagnosed asthma. Clin Exp Allergy. 2011;41(1):46-51. doi:10.1111/j.1365-2222.2010.03627.x

  11. Ullmann N, Mirra V, Di Marco A, et al. Asthma: Differential diagnosis and comorbidities. Front Pediatr. 2018;6:276. doi:10.3389/fped.2018.00276