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 4th 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 35-59 (mean 48.5 ± 6.8 years)
– FEV1/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.
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;
Pulmonary Function Tests
•
•
•
•
•
Spirogram, +/- BDs
Lung volumes
Diffusing capacity
ABGs, 6 minute walk
Bronchoprovocation testing (i.e.
mecolyl)
• Cardiopulmonary exercise testing
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
Test Reproducibility
Non-Reproducible
Poor Start of Test
Normal Spirometry
: Variable Effort
Glottic Closure :
Cough
Mild Obstruction
:
Severe Obstruction
Restriction :
Variable
Intrathoracic
Variable Extrathoracic :
Fixed
Upper Airway Obstruction
Reference Standards
Author
Year
Population
Race
Spirometer
ATS
Criteria
LLN
Hankinson
NHANES
III
1999
7,249 nonsmokers, U.S.
population
White,
Black,
Hispanic
Dry rollingseal
1987,1994
Predicted
1.645XS
EE
Knudson
1983
746
nonsmoking
Tucson AZ
White
Pneumotach
1979
Snowbird
95% CI
Crapo
1981
251
nonsmoking
1400m Utah
White
Water seal
metal ball
1979
Snowbird
95% CI
Morris
1971
988 no
smoking for 6
months,
Oregon
White
Stead wells
ACCP
Kory
80%
Predicte
d
Spirometric Reference Values
From a Sample of the U.S.
Population (NHANES III)
• Age 8-80 (N=7,429), asympt. nonsmokers, ’88 – ’94
• ATS criteria met (’87, ’94), QA by NIOSH
• Caucasians, African-Americans, Mex-Am
• Age, standing Ht > weight , BMI
• FVC, FEV1, FEV6, PEF, FEF25 – 75
Hankinson. AJRCCM 1999;159:179-187
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.
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”)
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 FEV1, but not as
sensitive as FEV1/FVC%.
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