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De-mystifying Outpatient Pulmonary Function Tests (PFTs) Mani S. Kavuru, MD Professor & Division Chief Pulmonary & Critical Care Medicine Thomas Jefferson.

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Presentation on theme: "De-mystifying Outpatient Pulmonary Function Tests (PFTs) Mani S. Kavuru, MD Professor & Division Chief Pulmonary & Critical Care Medicine Thomas Jefferson."— Presentation transcript:

1 De-mystifying Outpatient Pulmonary Function Tests (PFTs) Mani S. Kavuru, MD Professor & Division Chief Pulmonary & Critical Care Medicine Thomas Jefferson University / Hospital (No Disclosures)

2 Key learning Objectives Consider the concept of spirometry in the primary care setting; Review the spirometric maneuver, common patterns, concept of normality; Discuss spirometry in the approach to lung disease; Briefly review utility of other pulmonary function measures

3 Office Spirometry: Outline Why do you need it in PCP offices? Utility in screening, smoking cessation What is spirometry? Basics of technique, interpretation, etc. Office vs. Diagnostic (in labs) Who could / should perform it? Training, quality control issues Challenges, controversies?

4 Morbidity and Mortality of COPD COPD is the 4 th leading cause of death Half the patients die within 10 years of diagnosis 100,000 deaths/year in the U.S. $13 billion/year in direct medical costs

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6 The Lung Health Study Preliminary Results: 10 Participating Centers Patient Demographics –5,887 current smokers enrolled –Age 35-59 (mean 48.5 ± 6.8 years) –FEV 1 /FVC 63% ± 5.5 –63% men, 37% women –96% white Tashkin DP, et al. Am Rev Respir Dis. 1992; 145 (2 pt) 1):301-10.

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8 John Hutchinson (1811 – 1861)

9 References ATS/ERS position statements; Books: Miller, Scacci, Gast: Lab Evaluation of Pulmonary Function; Clausen; others Jefferson interpretation statements; CCF Disease Management document;

10 Pulmonary Function Tests Spirogram, +/- BDs Lung volumes Diffusing capacity ABGs, 6 minute walk Bronchoprovocation testing (i.e. mecolyl) Cardiopulmonary exercise testing

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15 HOW: Standardized Testing Spirometry using ATS & AARC standards –Patient sitting in chair with arms –Use nose-clips! (O2 disconnected) –Reproducible tests, 3 valid efforts min. –No cough in first second –Back extrapolation guidelines (good start) –Good peak flow effort –Exhalation 6 seconds or >1 second plateau

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20 Test Reproducibility

21 Non-Reproducible

22 Poor Start of Test

23 Normal Spirometry : Variable Effort

24 Glottic Closure : Cough

25 Mild Obstruction : Severe Obstruction

26 Restriction : Variable Intrathoracic

27 Variable Extrathoracic : Fixed Upper Airway Obstruction

28 Reference Standards AuthorYearPopulationRaceSpirometerATS Criteria LLN Hankinson NHANES III 19997,249 non- smokers, U.S. population White, Black, Hispanic Dry rolling- seal 1987,1994 Predicted - 1.645XS EE Knudson1983746 nonsmoking Tucson AZ WhitePneumotach1979 Snowbird 95% CI Crapo1981251 nonsmoking 1400m Utah WhiteWater seal metal ball 1979 Snowbird 95% CI Morris1971988 no smoking for 6 months, Oregon WhiteStead wellsACCP Kory 80% Predicte d

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31 Spirometric Reference Values From a Sample of the U.S. Population (NHANES III) Age 8-80 (N=7,429), asympt. non- smokers, ’88 – ’94 ATS criteria met (’87, ’94), QA by NIOSH Caucasians, African-Americans, Mex-Am Age, standing Ht > weight, BMI FVC, FEV 1, FEV 6, PEF, FEF 25 – 75 Hankinson. AJRCCM 1999;159:179-187

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37 Spirometry Two main measurements: –total volume exhaled (FVC) lung/thorax expansion –HPP, IPF - restrictive lung diseases –volume exhaled in 1st second of exhalation (FEV1) airway diameter –obstructive lung diseases »asthma, emphysema, chronic bronchitis, etc.

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40 Classification of Lung Diseases Obstructive Disease : asthma; chronic bronchitis; emphysema; CF; Restriction --Intra-parenchymal disease (lung tissue is abnormal, e.g. HP, pulmonary fibrosis) Restriction --Extra-parenchymal disease (lung tissue is normal); chest wall deformities, kyphosis, scoliosis, obesity, pleural effusions, ascites –Neuromuscular disorders (“bellows”)

41 Criticism of FEF 25-75% and Other Tests of Small Airway Disease FEF 25-75% Does not detect small airway disease. Is volume dependent. Is affected by elastic recoil, small airways dysfunction and large airways dysfunction. Is more variable than FEV 1, but not as sensitive as FEV 1 /FVC%.

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46 Defining Normality in PFTs > a pre-defined % (i.e. > 75% pred) Use of 95% confidence intervals

47 Spirometry Spirometry provides an objective measurement of lung function Measures VOLUME; the amount of air a person can breath in (inhale); and breathe out (exhale) And the SPEED or FLOW RATE that is generated during that maneuver ; Into a device called a Spirometer

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