Bronchoprovocation Study: Overview and Practice Questions

In respiratory care, accurate diagnosis is the foundation for effective treatment. Many patients present with symptoms such as wheezing, coughing, or shortness of breath, yet their baseline pulmonary function tests may appear normal.

In such cases, a bronchoprovocation study provides essential diagnostic insight. For respiratory therapists, understanding this test is vital, as they are often involved in its administration, interpretation, and patient education.

Free Access

RRT Course and Quiz Bundle (Free)

Get free access to 15+ premium courses and quizzes that cover the most essential topics to help you become a Registered Respiratory Therapist (RRT).

Get Free Access

What is a Bronchoprovocation Study?

A bronchoprovocation study, also known as a bronchial challenge test, is a diagnostic procedure used to identify airway hyperreactivity, most often linked to asthma. During the test, the patient inhales a provoking agent such as methacholine, histamine, cold air, or performs exercise that may trigger airway narrowing.

After each exposure, spirometry is conducted to measure lung function, with a focus on the forced expiratory volume in one second (FEV1). A drop in FEV1 of 20 percent or more is considered a positive result, confirming increased airway sensitivity.

This study is valuable when patients show asthma-like symptoms but normal baseline spirometry, as it assists in diagnosis, distinguishes conditions, and helps guide effective treatment in respiratory care.

Why is it Relevant in Respiratory Care?

Bronchoprovocation testing plays a crucial role in the field of respiratory therapy for several reasons:

1. Diagnosis of Asthma

Many patients have intermittent symptoms or present with normal spirometry results. A bronchoprovocation study can reveal hidden airway hyperresponsiveness, confirming an asthma diagnosis when routine testing falls short.

2. Differentiating Disorders

Not all wheezing or coughing is asthma. By assessing airway reactivity, respiratory therapists help physicians differentiate asthma from other respiratory conditions, such as chronic obstructive pulmonary disease (COPD), vocal cord dysfunction, or bronchiectasis.

3. Occupational and Environmental Health

Workers exposed to dust, chemicals, or fumes may develop occupational asthma. Bronchoprovocation studies are often used in occupational health to establish whether symptoms are linked to workplace exposures.

4. Guiding Therapy and Management

By determining airway sensitivity, providers can tailor treatment plans. Patients with strong hyperreactivity may require preventive therapies, closer monitoring, or lifestyle modifications to control their condition effectively.

5. Educational Opportunities

Respiratory therapists are uniquely positioned to educate patients about the nature of their airway disease, triggers, and the importance of adhering to treatment regimens. The bronchoprovocation test results often serve as a visual and numerical tool to improve patient understanding.

Safety and Precautions

Because the test deliberately induces bronchospasm, safety is a top priority. Laboratories performing bronchoprovocation testing must follow strict protocols, including:

• Ensuring the availability of short-acting bronchodilators and supplemental oxygen.
• Having a crash cart and staff trained in Advanced Cardiac Life Support (ACLS) on site.
• Screening patients to confirm baseline FEV1 values are above a safe threshold (commonly >40% predicted).

Note: Respiratory therapists are responsible for both patient monitoring and immediate intervention if adverse reactions occur.

The Role of Respiratory Therapists

Respiratory therapists are integral to the success of bronchoprovocation studies. Their responsibilities include:

• Preparing and coaching patients through the spirometry maneuvers.
• Administering methacholine or other agents according to established protocols.
• Monitoring patient safety, recognizing early signs of distress, and delivering rescue therapy if needed.
• Documenting and reporting results accurately to assist in physician interpretation.

Note: Their expertise ensures both the validity of the results and the well-being of the patient.

Bronchoprovocation Testing Practice Questions

1. What does a bronchial challenge test assess in a patient?  
Airway hyperresponsiveness and bronchial hyperreactivity

2. Which patients are good candidates for a bronchial challenge test?  
Those with suspected bronchospasm but normal pulmonary function, environmental or occupational exposure, uncertain bronchodilator test results, or for quantifying airway reactivity

3. What is the most commonly used provocative agent in a bronchial challenge test?  
Methacholine, a direct-acting parasympathomimetic drug

4. Which agents used in bronchial challenge testing have received FDA approval?  
Methacholine and Provocholine

5. What is Aridol, and how is it administered during bronchoprovocation?  
Aridol is a mannitol inhalation powder administered via a dry powder inhaler (DPI)

6. When are pulmonary function tests performed during a bronchial challenge study?  
Before and after exposure to the provocative agent

7. Which pulmonary function value is most closely monitored during bronchoprovocation?  
FEV1 (Forced Expiratory Volume in 1 second)

8. How is methacholine administered during a bronchoprovocation test?  
By inhaling increasing concentrations of the drug

9. What indicates a positive methacholine challenge test result?  
A sustained 20% or greater decrease in FEV1 from baseline

10. What is the name for the methacholine dose that causes a positive test?  
Provocative dose or PD20%

11. What are the baseline requirements for a patient undergoing bronchoprovocation?  
Asymptomatic, free from recent respiratory infections, FEV1 ≥ 70% predicted, and able to perform reproducible spirometry

12. How is methacholine typically delivered during the test?  
By a small-volume nebulizer using a dosimeter that nebulizes only during inspiration

13. What safety feature is included in the nebulizer setup for bronchoprovocation?  
The nebulizer delivers aerosol only during inspiration to protect the respiratory therapist

14. What pressure is typically used to operate the nebulizer in methacholine testing?  
20 psi

15. What are the steps in the 5-breath dosimeter method for methacholine delivery?  
Five slow, deep breaths per dose, each dose is 4 times the previous, using nose clips, and holding each breath for 5 seconds.

16. How is the 2-minute tidal breathing method performed during the test?  
Patient breathes normally for 2 minutes with 10 escalating doses using a mouthpiece and an expiratory filter

17. When should spirometry be performed after administering a methacholine dose?  
30–90 seconds after dosing, with 3–4 FEV1 maneuvers, reporting the largest value

18. What two criteria determine a positive bronchial challenge test?  
A ≥ 20% decrease in FEV1 that is sustained

19. How is the percent decrease in FEV1 calculated during the test?  
(Pre-dose FEV1 – Post-dose FEV1) ÷ Pre-dose FEV1 × 100

20. What is the next step if the FEV1 decreases by less than 20% after a methacholine dose?  
Administer the next higher dose of methacholine.

21. What is used as the control FEV1 value in methacholine challenge testing?  
The FEV1 obtained after normal saline inhalation.

22. What is the protocol if the FEV1 drops more than 20% from baseline?  
Stop the test, administer a bronchodilator, and repeat spirometry in 10 minutes.

23. What is the purpose of administering a bronchodilator after a positive test?  
To reverse bronchoconstriction and confirm recovery

24. What is the target value in a methacholine challenge based on normal saline FEV1?  
80% of the normal saline FEV1 value

25. If the FEV1 remains above 80% of baseline, what should be done next?  
Administer a higher methacholine dose and retest.

26. If the FEV1 drops below 80% of the baseline after a methacholine dose, what is the response?
Stop the test, give a bronchodilator, and monitor recovery.

27. What does PD20% represent in bronchoprovocation testing?  
The dose of methacholine that causes a 20% decrease in FEV1

28. Why is a filter used on the expiratory limb during tidal breathing method?  
To prevent aerosolized medication exposure to the respiratory therapist

29. What condition is most commonly diagnosed using a methacholine challenge test?  
Asthma

30. Why must patients avoid respiratory infections before undergoing bronchoprovocation testing?  
Infections can affect baseline lung function and skew test results.

31. What is the primary purpose of bronchoprovocation challenge testing?  
To identify and assess airway hyperresponsiveness, diagnose asthma, and quantify the severity of airway reactivity in symptomatic patients

32. Which symptoms are suggestive of asthma and may prompt a bronchoprovocation study?  
Wheezing, dyspnea, chest tightness, or cough—especially when triggered by cold air, exercise, allergens, or inhalant exposures.

33. Which agents are commonly used in bronchoprovocation testing to assess airway hyperreactivity?  
Methacholine, mannitol, histamine, eucapnic voluntary hyperventilation, and exercise

34. What type of agents are methacholine and histamine considered in bronchoprovocation testing?  
Direct-acting agents that act on airway smooth muscle to cause bronchoconstriction

35. How do indirect agents like mannitol and exercise induce bronchospasm?  
By triggering the release of bronchoconstricting mediators, such as histamine or leukotrienes

36. Which pulmonary function variable is most commonly monitored during bronchoprovocation testing?  
FEV1 (Forced Expiratory Volume in 1 second)

37. What characterizes a positive methacholine challenge test result?  
A sustained 20% or greater decrease in FEV1 from the patient’s baseline value

38. Why is methacholine challenge testing useful in diagnosing asthma?  
Because it identifies airway hyperresponsiveness, which is a hallmark feature of asthma

39. How is methacholine administered during challenge testing?  
In increasing concentrations with spirometry performed after each dose to monitor for FEV1 decline

40. How do patients with hyperresponsive airways respond during methacholine testing?  
They exhibit a significant decline in FEV1 at lower methacholine doses compared to healthy individuals.

41. What are absolute contraindications to performing a bronchoprovocation test?  
Recent heart attack or stroke (within 3 months), uncontrolled hypertension, FEV1 < 50% or < 1 L, or inability to produce acceptable baseline spirometry

42. What are the relative contraindications for bronchial challenge testing?  
Pregnancy, nursing, recent upper respiratory infection, FEV1 < 60%, or current use of cholinesterase inhibitors (e.g., for myasthenia gravis)

43. What is the typical dosing routine for methacholine challenge testing?  
Ten doses prepared in doubling or quadrupling concentrations from a 100 mg dry powder base diluted with saline

44. What is the main use of bronchoprovocation testing in clinical practice?  
To identify airway hyperresponsiveness, assess changes in reactivity, and evaluate individuals at risk of environmental or occupational exposure.

45. Which patients should be considered for bronchial challenge testing?  
Patients with bronchospasm symptoms but normal PFTs or inconclusive bronchodilator response

46. How do the methacholine and mannitol challenges differ in mechanism?  
Methacholine acts directly on airway smooth muscle; mannitol triggers mediator release that indirectly causes bronchospasm.

47. What is the purpose of performing spirometry after each bronchoprovocation dose?  
To evaluate changes in FEV1 and detect airway narrowing in response to the stimulus

48. How does hyperventilation provoke bronchospasm in susceptible patients?  
By causing heat and water loss from the airways, which leads to bronchoconstriction

49. Besides FEV1, which other PFT variables may be assessed during bronchoprovocation?  
Airway resistance (Raw) and specific airway conductance (Sgaw)

50. What are examples of direct-acting bronchial provocation stimuli?  
Methacholine, histamine, prostaglandins, and leukotrienes

51. What are examples of indirect bronchial provocation stimuli?  
Mannitol, adenosine, exercise, eucapnic voluntary hyperventilation, propranolol, and hypertonic saline

52. Why is eucapnic voluntary hyperventilation used in bronchoprovocation testing?  
It simulates the airway response to exercise-induced heat and water loss in a controlled environment.

53. What distinguishes a direct from an indirect bronchial challenge agent?  
Direct agents act directly on airway smooth muscle; indirect agents cause the release of endogenous mediators that lead to bronchoconstriction.

54. Why is it important for the patient to have acceptable baseline spirometry before starting the test?  
Because accurate FEV1 measurements are critical for interpreting changes in airway responsiveness

55. What is the role of environmental or occupational screening with bronchoprovocation testing?  
To evaluate airway reactivity in individuals exposed to inhaled irritants in workplace or environmental settings

56. How is a methacholine challenge test typically performed?  
By having the patient inhale increasing doses of methacholine while monitoring for airway changes through spirometry or specific airway conductance (sGaw)

57. What characterizes a positive response to a methacholine challenge test?  
A 20% or greater decrease in FEV1 from the patient’s baseline value

58. What does the term “PC20” refer to in bronchial challenge testing?  
The methacholine concentration that causes a 20% decrease in FEV1.

59. In asthma patients, what methacholine dose is typically associated with a positive test?  
A dose of 8 mg/mL or less that causes a 20% drop in FEV1

60. Besides asthma, in which other conditions may bronchial hyperresponsiveness be observed?  
COPD, cystic fibrosis, and chronic bronchitis

61. What are the recommended patient conditions before starting a methacholine challenge test?
The patient should be asymptomatic with no coughing or wheezing and have a baseline FEV1 ≥ 60–70% predicted.

62. Why should bronchial challenge testing be deferred after a recent respiratory infection?  
Because upper or lower respiratory tract infections can temporarily alter airway responsiveness

63. What FEV1 value is typically required for safe testing in obstructive or restrictive patients?  
An FEV1 that is close to their previously observed highest value

64. What are absolute contraindications to methacholine challenge testing?  
FEV1 < 50% predicted, recent heart attack or stroke, aortic aneurysm, or uncontrolled hypertension

65. Why must bronchodilators be withheld prior to methacholine challenge testing?  
Because they can artificially reduce airway reactivity and lead to false-negative results

66. When might bronchial challenge testing be indicated in an obstructive patient?  
When the clinical question pertains to the degree of airway responsiveness or hyperreactivity

67. What must be established before beginning a methacholine challenge test?  
That the patient’s baseline FEV1 is at least 60–70% of predicted or of their best historical value

68. Why do most obstructive patients not require bronchial challenge testing?  
Because their reduced FEV1 and other flow measures already confirm airway obstruction

69. In what scenario would an obstructive patient still undergo a methacholine challenge?  
To determine the severity or presence of airway hyperresponsiveness

70. Why might a restrictive patient undergo bronchial challenge testing?  
To evaluate for coexisting airway hyperresponsiveness despite reduced lung volumes

71. What are the challenges in testing a patient who cannot perform spirometry?  
Results may be uninterpretable, so alternative measures like sGaw or oscillatory resistance are preferred.

72. What are the relative contraindications to methacholine challenge testing?  
Pregnancy, nursing, FEV1 < 60% predicted, use of cholinesterase inhibitors, or inability to perform acceptable spirometry

73. What are the two most common methods of methacholine delivery during testing?  
The five-breath dosimeter method and the two-minute tidal breathing method

74. What is the main advantage of the dosimeter method in bronchial challenge testing?  
It provides a consistent, quantitative delivery of methacholine during inspiration.

75. How can a dosimeter be activated during bronchial challenge testing?  
Manually by the technician, automatically by a flow sensor, or during inspiration

76. What are key characteristics of the two-minute tidal breathing method?  
Uses a nebulizer only; patient breathes quietly through the mouthpiece with a nose clip for two minutes

77. How is the dose of methacholine standardized during challenge testing?  
By using either five fixed breaths or a fixed time period of two minutes of tidal breathing

78. What is a defining characteristic of a sensitive asthmatic during methacholine testing?  
A 20% FEV1 decrease occurs at lower methacholine doses.

79. Why is acceptable baseline spirometry critical for methacholine challenge testing?  
To ensure accurate detection of a 20% decline in FEV1, which determines test positivity.

80. What are the two dosing routines used during methacholine challenge testing?  
Doubling dose (2x) and quadrupling dose (4x) concentrations

81. What is the primary purpose of a bronchoprovocation study?  
To assess airway hyperresponsiveness in patients suspected of having asthma or other reactive airway diseases

82. Which pulmonary function test is most commonly measured during a bronchoprovocation study?  
Forced Expiratory Volume in 1 second (FEV1)

83. What is the significance of a 20% drop in FEV1 during a methacholine challenge?  
It indicates a positive test result and suggests airway hyperresponsiveness.

84. What is the minimum baseline FEV1 required to safely begin a bronchoprovocation test?  
At least 60–70% of the predicted or previously observed best value

85. What should be withheld before performing a bronchial challenge test to avoid inaccurate results?  
Bronchodilators and certain respiratory medications

86. Which two types of bronchial challenge tests are categorized as direct-acting?  
Methacholine and histamine challenge tests

87. Which two bronchial challenge tests are categorized as indirect-acting?  
Mannitol challenge and exercise challenge

88. Why is methacholine considered a direct agent in bronchial challenge testing?  
Because it acts directly on airway smooth muscle to induce bronchoconstriction

89. How does an indirect challenge agent provoke bronchospasm?  
By triggering the release of endogenous mediators like histamine and leukotrienes

90. What condition may mimic asthma and result in a positive bronchial challenge test?  
Chronic obstructive pulmonary disease (COPD)

91. Which measurement may be used as an alternative to FEV1 in patients who cannot perform spirometry?  
Specific airway conductance (sGaw) or oscillatory resistance

92. What is the maximum methacholine concentration typically used in challenge testing?  
16 mg/mL

93. What is the PC20 value used to represent in methacholine challenge testing?  
The concentration of methacholine that causes a 20% drop in FEV1

94. Why is a dosimeter sometimes used during bronchial challenge testing?  
To deliver consistent and precise doses of methacholine

95. What environmental factor is replicated during eucapnic voluntary hyperventilation testing?  
Cold air exposure and hyperventilation, which can provoke bronchospasm

96. Why must pregnant patients avoid methacholine challenge testing?  
Due to the unknown effects of methacholine on the fetus and increased test risk

97. What is the recommended interval between methacholine doses during testing?  
Approximately 5 minutes, allowing time for spirometry assessment after each dose

98. What symptoms should a patient NOT exhibit before starting a bronchial challenge test?  
Active coughing, audible wheezing, or any signs of acute respiratory distress

99. What would a negative methacholine challenge test suggest in a symptomatic patient?  
That the patient’s airway hyperresponsiveness is unlikely to be the cause of symptoms

100. What is one of the key safety precautions during bronchoprovocation testing?  
Emergency bronchodilators and resuscitation equipment must be readily available.

Final Thoughts

A bronchoprovocation study provides a practical method for identifying airway hyperreactivity when baseline lung function appears normal. It helps clarify whether symptoms such as wheezing or shortness of breath are related to asthma or another condition.

By measuring how the airways respond to specific triggers, the test supports more accurate diagnoses and treatment decisions. For respiratory therapists, it represents an important part of routine clinical practice and contributes to careful, evidence-based patient care.