Spirometry, assessment of bronchial responsiveness and induced sputum

1. Hôpital du Sacré-Cœur de Montréal Spirometry, assessment of bronchial responsiveness and induced sputum Catherine Lemière MD,MSc Université de Montréal

3. Spirometry

7. Flow-volume loop

8. Airflow limitation Normal

9. Reversible airflow limitation

14. Spirometry Cont’d • Airflow limitation (FEV1/VC <70%) is considered reversible if there is an improvement in FEV1 of at least 12% with an absolute increase of 180ml after bronchodilator. • If there is a history suggestive of asthma with normal spirometry or absence of reversibility a methacholine challenge should be performed.

15. Assessing airway responsiveness

16. Methacholine Challenge • Methacholine induces a bronchoconstriction by acting on the airway smooth muscle. • Methacholine inhalation challenge test measures the level of airway responsiveness.

17. Methacholine Challenge • Administration of increasing doses of methacholine via a Wright nebulizer (or dosimeter) until the occurrence of a 20% fall in FEV1. • Determination of the provocative concentration inducing a 20% fall in FEV1 (PC20).

18. Wright nebulizer

20. 2 minutes of nebulization at tidal voulme • Doubling doses of methacholine • .03, .06, .125, .25, .50, 1, 2, 4, 8,16 ( 32, 64, 128) mg/ml • Measure the FEV1 at about 30 and 90 s after the end of nebulization. Obtain an acceptable-quality FEV1 at each time point. This may require repeated attempts. • At each dose, report the highest FEV 1

22. Determining starting dose of methacholine Outside Hospital No history of asthma –No treatment Si FEV1> 75% predicted andFEV1 fall < 10% post-diluant 2 mg/ml 0.5 mg/ml If FEV1 pred < 75% and FEV1 fall < 10% post-diluant 0.125 mg/ml 0.03 mg/ml FEV1 fall > 10% post-diluant 0.03 mg/ml No History of asthma No treatment If FEV1> 75% predicted andFEV1 fall < 10% post-diluant 0.5 mg/ml 0.03 mg/ml If FEV1 pred < 75% and FEV1 fall < 10% post-diluant 0.125 mg/ml 0.03 mg/ml FEV1 fall > 10% post-diluant 0.03 mg/ml No History of asthma- Treatment for asthma If FEV1> 75% predicted andFEV1 fall < 10% post-diluant 0.125 mg/ml 0.03 mg/ml If FEV1 pred < 75% and FEV1 fall < 10% post-diluant 0.03 mg/ml 0.03 mg/ml If FEV1 fall > 10% post-diluant 0.03 mg/ml No

23. Methacholine Challenge Test PC20 Normal > 16 mg/ml borderline 4-16 Mild 1-4 Moderate to severe<1

24. Contraindications for methacholine challenge testing • Absolute: • Severe airflow limitation (FEV1 <50% predicted or <1.0 L) • Heart attack or stroke in last 3 months • Uncontrolled hypertension, systolic BP >200, or diastolic BP>100 • Known aortic aneurysm • Relative: • Moderate airflow limitation (FEV1< 60% predicted or <1.5 L) • Inability to perform acceptable-quality spirometry • Pregnancy • Nursing mothers • Current use of cholinesterase inhibitor medication (for myasthenia gravis)

25. Factor Minimum Time Interval from Last Dose . Short-acting inhaled bronchodilators, such as isoproterenol, 8 h isoetharine, metaproterenol, albuterol, or terbutaline Medium-acting bronchodilators such as ipratropium 24 h Long-acting inhaled bronchodilators, such as salmeterol, 48 h formoterol, tiotropium (perhaps 1 wk for tiotropium) Oral bronchodilators Liquid theophylline 12 h Intermediate-acting theophyllines 24 h Long-acting theophyllines 48 h Standard b2-agonist tablets 12 h Long-actingb2 agonist tablets 24 h Cromolyn sodium 8 h Nedocromil 48 h Hydroxazine, cetirizine 3 d Leukotriene modifiers 24 h Coffee, tea, cola drinks, chocolate Day of study

26. PC20 measurements in addition to PEF monitoring

27. SIC – false negative- Monitoring of PC20

28. Follow-up

29. Sputum Induction and processing

30. Sputum induction • Induction • Bronchodilation • 3 seven-minute periods of nebulisation with increasing concentrations of hypertonic saline (3, 4 and 5%) using an ultrasonic nebuliser. • Monitoring of FEV1 before each increasing concentration of hypertonic saline

31. Sputum Induction • Sputum collection after each period of nebulization. • Sample processing within 2 hours after sputum collection.

33. Processing • . PBS • . Supernatant … . … . .. Centrifuge Selection DTT • .. • . Total cell count -Viability Differential cell count Cytospin

37. Induced Sputum • Normal Values • Total cell count < 5.5x106/ml • Neutrophils 15- 64% • Eosinophils ≤1% • Macrophages: 30- 80% • Lymphocytes <3% • Viability> 40% • Squamous contamination < 20%

38. Advantages • Reproducible • Sensitive • Non-invasive • Measurement of cell counts as well as soluble inflammatory mediators.

39. Advantages • Eosnophils are increased in the majority of asthmatic subjects. • Increase after inhalation challenge to common allergens and decrease after asthma treatment. • Managing asthma treatment according to sputum eosinophils seems to reduce asthma exacerbations in moderate to severe asthmatics.

40. Green et al. Lancet 2002 360: 1715-21

41. Sensitivity and specificity of different diagnostic strategies compared to SIC 1 0.9 0.8 PEF 0.7 PEF/Sputum (1% cutoff) 0.6 Sensitivity PEF/sputum (2% cutoff) 0.5 0.4 0.3 0.2 0.1 0 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 1- Specificity (Girard et al, ARJCCM 2004)

42. Limitations • Some subjects do not produce enough sputum (Success rate 70 to 80%). • Repeated sputum inductions (within 24h) modify cell counts (increase neutrophils).