1. Sandra D. Anderson and John D. Brannan Department of Respiratory & Sleep Medicine, Royal Prince Alfred Hospital, New South Wales, Australia Current Opinion in Allergy and Clinical Immunology 2011, 11:46–52

2. Asthma : both under and over-diagnosed ! The need to confirm or exclude a diagnosis of asthma Fire fighters, recruits for defence, police and other occupations, recreational activities (SCUBA diving) → Need for bronchial provocation tests !

3. Direct : methacholine, histamine Methacholine chloride → bronchial smooth muscle receptors → the airways to narrow Indirect : exercise, mannitol, AMP, EVH Indirect stimuli (e.g. exercise) → The release of mediators (PG, LT, histamine) locally in the airways → BSM receptors to cause contraction

4. Inflammatory cell Increased osmolarity Exercise, EHV, NaCl, mannitol Direct stimuli:Indirect stimuli: Histamine, methacholine Histamine, prostaglandins, Leukotriens..

5. Methacholine Under-diagnosis : asthma, exercise-induced broncho-constriction (EIB)  Not as sensitive to identify BHR as generally perceived Over-diagnosis : many technical factors, disease states or transient influences of viruses, smoking, allergen exposure  Positive methacholine test → Without EIB, without symptoms of asthma → Reflect transient airway injury rather than asthma

6. Exercise, adenosine monophosphate(AMP), dry powder mannitol, hyperpnoea of cold or dry air [eucapnic voluntary hyperpnoea (EVH)] More specific for identifying the presence of inflammation than methacholine → To confirm a diagnosis of asthma and to follow response to therapy The increase in use to assess athletes, fire fighters, defence force personnel, smokers, children, to evaluate cough, to confirm asthma → Standardized test kit for mannitol inhalation → The need to identify EIB in order to changes of treatment or to demonstrate the need for treatment

7. EVH in asthmatic patients and in athletes with EIB Increase in urinary excretion of the metabolites of PGD2 and LTC4 (9α11β-PGF 2 and leukotriene E 4 ) % fall in FEV1 after EVH and the increase in 9α11β-PGF 2 The significant relationship (r=0.54, P<0.001) Frequently reported in FeNO ↑, eosinophils ↑ in sputum Marker of inflammation that are sensitive to treatment with ICS BHR to mannitol and exercise Also sensitive to treatment with ICS Occur in the absence of FeNO ↑ or eosinophil ↑ → Early in the onset of asthma, mast cell numbers ↑ in the airway epithelium

8. Mast cells Tissue bound in mucous glands, on BSM, and in the epithelium Not readily appear in sputum as do eosinophils Important in containing potent mediators of bronchoconstriction and cytokines for the development of responsiveness of the BSM BPTs that act via release of mast cell mediators Increasingly used as a surrogate for the presence of mast cells The advantage of the indirect BPTs over the direct tests Provide information on the interaction of the two key features of asthma → BHR + airway inflammation → The presence of a sufficient number of inflammatory cells (mast cells with or without eosinophils) and concentration of mediators to cause bronchoconstriction.

10. Mannitol test high specificity to identify a physician diagnosis of asthma the sensitivity : lower than expected --> benefit of current treatment on BHR

11. Response-dose ratio (RDR) to mannitol % fall/cumulative dose to cause that fall Index of airway reactivity useful for making comparisons before or after a successful intervention To compare responses between mannitol and percentage fall in FEV1 after exercise Increasingly reported both for diagnosis and assessment

14. Methacholine (41.6%) no more sensitive than mannitol (44.8%) to detect BHR Discordant findings between exercise and methacholine Differences in potency of the mediators of bronchoconstriction PGD 2, LTC 4 released with exercise and mannitol : Very much more potent than histamine or methacholine alone

15. Bronchial hyper-responsiveness : mild

16. Methacholine(-) : occurred in 45% of patients with EIB 19.7% (-) →>20% FEV1↓after exercise No longer be relied on as a rule-out test for asthma Sensitivity of mannitol to detect EIB : low Different mechanisms of airway narrowing Site of action of the mannitol Not identified >20% fall in FEV1 after exercise tests Bronchial responsiveness can vary over a short period

18. high FeNO (all) low FeNO (84%) : positive to mannitol No significant difference in the PD15 to mannitol between the low and high FeNO group Low FeNO should not be excluded from treatment with inhaled steroids

19. Methacholine is not as sensitive to identify BHR as previously thought A positive methacholine test result, in the absence of a positive response to an indirect stimulus may be an indicator of airway injury or remodelling rather than currently active asthma Mannitol is more sensitive than exercise to identify BHR Mannitol is not as sensitive to identify EIB as previously reported Bronchial provocation using both a direct test and an indirect test may be required in some patients to confirm or exclude a diagnosis of asthma