Bronchial provocation Tests or Bronchial challenge Test

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Bronchial provocation Testsor Bronchial
challenge Test
Attaran D,Pulmonologist , Associate professor
Mashhad university of medical sciences
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Provocation Test

• To assess bronchial hyperresponsiveness (BHR)
• Most clinically useful when the diagnosis of
  asthma not clear-cut

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cont

• Asthma characterized by airway inflammation, BHR
• and reversible obstruction
• Diagnosis of asthma is most often made with
• symptoms and airway obstruction
• While BHR is a key feature of asthma ,
  provocation
• tests are not necessary to establish the
  diagnosis

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Indications

• Atypical features of asthma
• Asthma symptoms with NL Spirometry
• Failure to asthma therapy
• Persistent cough

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Indications

• Evaluation possibility of occupational asthma
• Excluding a diagnosis of asthma in high risk
  occupations
• Monitoring asthma therapy ( BHR inflammation)

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contraindication

• Absolute
• Severe airflow limitation (FEV1 lt 50)
• Acute coronary syn or stroke
• Severe HTN
• Cerebral or aortic aneurysm

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contraindicution

• Relative
• Moderate obstruction (FEV1 lt60)
• pregnancy
• Cholinesterase inhibitor medication
• Recent upper or lower respiratory infection

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Categories of Tests

• Direct test (Methacholine Histamines)
• Direct effect on smooth muscles
• Indirect test (Exercise- cold air )
• Release of cytokines

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Methacholine test

• Most widely used method to assess BHR
• Cholinergic effect
• Sensitive test for diagnosis of asthma gt90
• False positive (COPD CF smoky recent
  infection)

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cont

• The test consists of performing spirometry at
  baseline
• and after each dose of nebulized
  methacholine
• Povocation concentration that results in 20
• reduction in FEV1 (PC 20 ) is determined.

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• The effect of increasing the inhaled dose of
  histamine or methacholine in a healthy subject
  (red) and an asthmatic patient (blue). The
  provocative concentration is the amount of
  inhaled agonist required to drop the FEV1 by 20
  percent from the baseline (PC20 FEV1), and is
  much less in the asthmatic than in the normal
  subject (0.8 versus 20 mg/mL). An increase in
  responsiveness is characterized by a decrease in
  the PC20.

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• Respiration. 2005 Sep-Oct72(5)523-8.
• Airway hyperresponsiveness to methacholine in
  chemical warfare victims.
• Mirsadraee M, Attaran D, Boskabady MH, Towhidi M.
• Department of Pulmonary Medicine, Islamic Azad
  University of Mashhad, Iran.
• Abstract
• BACKGROUND The lung is one of the most exposable
  organs to chemical warfare agents such as sulfur
  mustard gas. Pulmonary complications as a result
  of this gas range from severe bronchial stenosis
  to mild or no symptoms. Airway hyperresponsiveness
  (AHR) which is usually assessed as response to
  inhaled methacholine is the most characteristic
  feature of asthma. AHR is reported in chronic
  obstructive pulmonary disease patients and
  smokers, and may also show in chemical warfare
  victims. However, there are little reports
  regarding AHR in chemical warfare victims.
• OBJECTIVE Therefore, in this study, airway
  responsiveness to methacholine in victims of
  chemical warfare was examined.
• METHODS The threshold concentrations of inhaled
  methacholine required for a 20 change in forced
  expiratory flow in 1 s (FEV1 PC20) or a 35
  change in specific airway conductance (PC35) were
  measured in 15 chemical war victims and 15 normal
  control subjects.
• RESULTS In 10 out of 15 chemical warfare victims
  (two thirds), PC20 and PC35 methacholine could be
  measured and subjects were called responders. AHR
  to methacholine in responder chemical war victims
  (PC20 0.41 and PC35 0.82 g/l) was
  significantly lower than in normal subjects (PC20
  5.69 and PC35 4.60 g/l, p lt 0.001 for both
  cases). There was a significant correlation
  between FEV1 and PC20 methacholine (r 0.688, p
  lt 0.001). The correlations between PC20 and PC35
  were statistically significant as well (r
  0.856, p lt 0.001).
• CONCLUSION Results showed increased airway
  responsiveness of most chemical warfare victims
  to methacholine which correlated with the FEV1
  value and which may be related to chronic airway
  inflammation or irreversible airway changes.

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