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

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