By: James Simpson

 Why  What – now featuring definitions  When  Interpretation  CA$H MONEY

 Could be on LMCC  Could be on CFPC exam  99 topics – know how to diagnose asthma from spirometry  Can also be done in family medicine setting!  CA$H MONEY???

 Spirometry is easier  Assist in diagnosing simple conditions – asthma, COPD

 People with exposures  Smokers  Environmental irritants  Prolonged or progressive cough  Weak respiratory muscles  Suspicion of underlying disease  To get a baseline before treatment (i.e. with amiodarone, bleomycin etc)

 Smokers – Canadian Thoracic Society recommends:  Screen current/former smokers over 40 years of age IF:  Do you cough regularly  Do you cough up phlegm regularly  Do simple chores make you short of breath  Do you wheeze when you exert yourself or at night  Do you get frequent colds that persist longer than other people you know?

 ALL RELATIVE NOT ABSOLUTE!!  Any condition where increased pressure is not good  Brain conditions  Facial/ear conditions  Lung conditions  Abdominal conditions  Heart conditions (arrhythmia, hypo/hypertension)  Any condition where direction following is not good  Dementia  Kids  Coughing a lot  Any condition where public health concerns are not good  TB  hemoptysis

FLOW VOLUME (total out)

 FVC – total volume out during max effort  FEV1 – volume out in one second  FEV1/FVC ratio – volume in one second divided by total volume  Peak expiratory flow – maximum speed of expiration

 Test can be difficult – patients may not fully understand instructions, or may not fully cooperate  Valid test parameters:  3 acceptable spirograms  At least 6 seconds in length  Measurement of FVC and FEV1 differ between tests by 0.2L or less

 Obstructive  Asthma, COPD, Bronchiectasis  Restrictive  Intrinsic - Pulmonary fibrosis, sarcoidosis, medication toxicity, pneumoconiosis  Extrinsic – obesity, hernia, kyphosis, pectus excavatum  Good news – don’t need to worry about restrictive lung disease for this!

 Obstruction = flow of air gets blocked so the flow is slower!

Diagnosis: FEV1 less than 0.8 FEV1 / FVC less than 0.7

FEV1 less than 0.8 FEV1 / FVC less than 0.7

FEV1 less than 0.8 FEV1 / FVC less than 0.7

FEV1 less than 0.8 FEV1 / FVC less than 0.7

FEV1 less than 0.8 FEV1 / FVC less than 0.7

 Asthma or COPD?  Key = obstruction from asthma is reversible

FEV1 or FVC increases by at least 12% AND >200mL or peak expiratory flow increase > 20%

FEV1 or FVC increases by at least 12% AND >200mL or peak expiratory flow increase > 20%

FEV1 or FVC increases by at least 12% AND >200mL or peak expiratory flow increase > 20%

FEV1 or FVC increases by at least 12% AND >200mL or peak expiratory flow increase > 20%

Diagnosis???

 Methacholine challenge test OR exercise challenge test  Positive test = fall in FEV1 of 20% - but concentration matters  This response to 4mg/mL is diagnostic of asthma  Concentrations from 4mg/mL to 16mg/mL is borderline  Concentrations greater than 16mg/mL is not asthma

 Another alternative – exercise challenge  10 to 15% decrease in FEV1 post exercise

 What if it’s asthma AND COPD?  Spirometry is limited in this situation

 Lung expansion is restrictive  Restricted lungs are smaller  Therefore forced vital capacity is smaller

FVC decreased FEV1 can be decreased or normal FEV1/FVC should be >0.7

 Cannot diagnose definitively from spirometry  Spirometry can’t measure lung volumes only vital capacity (can’t measure reserve volume)  If you see this pattern, referral for full pulmonary function tests +/- respirology

 FEV1, FVC, PEF, FEV1/FVC  No flow volume loop – requires more expensive spirometer i.e.:

 Why is a flow volume loop better?  Quality of effort  More accurate diagnosis of some conditions (i.e. upper airway obstruction)  Due to change in flow as lung volumes change

 Billing (note, must perform AND interpret in office for full payment):  Simple spirometry only (i.e. using $650 model):  J301 - $17.15  Plus J324 - $7.01 (if repeated after bronchodilator)  With flow volume loop (i.e. $2300 model):  J304 - $29.30  J327 - $7.26 (if repeated after bronchodilator)  May be out of basket depending on practice structure  Out of basket FHN, in basket FHO

 Note with doing flow volume loop studies, extra parameters:

 Would be tough to set up in most office practices, particularly fee for service / solo practices  Group practices – 1 flow volume with nurse who performs it?  $24 for simple spirometry vs $4.50 for injection  Flow volume interpretation likely not worth cost unless you want to set up a full day of doing it

 What are three ways to diagnose asthma from spirometry given an obstructive airway pattern?  A)  B)  C  What measurement on spirometry is consistently decreased in restrictive lung disease  A)  What two criteria on spirometry are diagnostic of obstructive airway disease?  A)  B)