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:
De-mystifying Outpatient Pulmonary Function Tests (PFTs) Mani S. Kavuru, MD Professor & Division Chief Pulmonary & Critical Care Medicine Thomas Jefferson University / Hospital (No Disclosures)
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
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?
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
The Lung Health Study Preliminary Results: 10 Participating Centers Patient Demographics –5,887 current smokers enrolled –Age (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):
John Hutchinson (1811 – 1861)
References ATS/ERS position statements; Books: Miller, Scacci, Gast: Lab Evaluation of Pulmonary Function; Clausen; others Jefferson interpretation statements; CCF Disease Management document;
Reference Standards AuthorYearPopulationRaceSpirometerATS Criteria LLN Hankinson NHANES III 19997,249 non- smokers, U.S. population White, Black, Hispanic Dry rolling- seal 1987,1994 Predicted XS EE Knudson nonsmoking Tucson AZ WhitePneumotach1979 Snowbird 95% CI Crapo nonsmoking 1400m Utah WhiteWater seal metal ball 1979 Snowbird 95% CI Morris no smoking for 6 months, Oregon WhiteStead wellsACCP Kory 80% Predicte d
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:
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.
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%.
Defining Normality in PFTs > a pre-defined % (i.e. > 75% pred) Use of 95% confidence intervals
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