De-mystifying Outpatient Pulmonary Function Tests (PFTs) Mani S. Kavuru, MD Professor & Division...
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Transcript of De-mystifying Outpatient Pulmonary Function Tests (PFTs) Mani S. Kavuru, MD Professor & Division...
De-mystifying Outpatient Pulmonary Function Tests
(PFTs)
Mani S. Kavuru, MDProfessor & Division Chief
Pulmonary & Critical Care MedicineThomas 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 StudyPreliminary 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 non-smokers, U.S. population
White,
Black,
Hispanic
Dry rolling-seal
1987,1994 Predicted-1.645XSEE
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% Predicted
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, 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