Pulmonary Function Testing: Basics of Physiology and Interpretation -- Printable Tables

TITLE:	PULMONARY FUNCTION TESTING: BASICS OF PHYSIOLOGY AND INTERPRETATION
AUTHORS:	THOMAS R. GILDEA, MD -- Department of Pulmonary and Critical Care Medicine
	MANI S. KAVURU, MD -- Department of Pulmonary and Critical Care Medicine
	KEVIN McCARTHY, RCPT -- Department of Pulmonary and Critical Care Medicine
PUBLISHED:	DECEMBER 5, 2002

Table 1:

Indications for Spirometry

Diagnostic

To evaluate symptoms, signs, or abnormal laboratory tests
- Symptoms: dyspnea, wheezing, orthopnea, cough, phlegm production, chest pain
- Signs: diminished breath sounds, overinflation, expiratory slowing, cyanosis, chest deformitory, unexplained crackles
- Abnormal laboratory tests: hypoxemia, hypercapnia, polycythemia, abnormal chest radiographs
To measure the effect of disease on pulmonary function
To screen individuals at risk of having pulmonary diseases
- Smokers
- Individuals in occupations with exposures to injurious substances
- Some routine physical examinations
To assess preoperative risk
To assess prognosis (lung transplant, etc.)
To assess health status before enrollment in strenuous physical activity programs

Monitoring

To assess therapeutic interventions

Bronchodilator therapy
Steroid treatment for asthma, interstitial lung disease, etc.
Management of congestive heart failure
Other (antibiotics in cystic fibrosis, etc.)

To describe the course of diseases affecting lung function
- Pulmonary diseases
- Cardiac diseases
  - Congestive heart failure
- Neuromuscular diseases
  - Culligan-Barre Syndrome
To monitor persons in occupations with exposure to injurious agents
To monitor for adverse reactions to drugs with known pulmonary toxicity

Disability/Impairment Evaluations

To assess patients as part of a rehabilitation program
- Medical
- Industrial
- Vocational
To assess risks as part of an insurance evaluation
To assess individuals for legal reasons
- Social Security or other government compensation programs
- Personal injury lawsuits
- Others

Public Health

Epidemiologic surveys
- Comparison of health status of populations living in different environments
- Validation of subjective complaints in occupational/environmental settings
Derivation of reference equations

Table 2:
Types of Spirometers
Volume	Flow Sensing (Pneumotach)
Bellows Rolling Seal Water Dry	Fleisch Screen Hot-Wire Turbine
Adapted from reference 2

Table 3:

Acceptability and Reproducibility Criteria: Summary

Acceptability Criteria

Reproducibility Criteria

Individual spirograms are "acceptable" if:

They are free from artifacts

	Cough or glottis closure during the first second of exhalation
	Eary termination or cutoff
	Variable effort
	Leak
	Obstructed mouthpiece

Have good starts

	Extrapolated volume less than 5% of FVC or 0.15 L, whichever is greater; OR
	Time-to-PEF of less than 120 ms (optional until further information is available)

Have a satisfactory exhalation

	6 s of exhalation and/or a plateau in the volume-time curve; OR
	Reasonable duration or a plateau in the volume-time curve; OR
	If the subject cannot or should not continue to exhale

After 3 acceptable spirograms have been obtained, apply the following tests:
	Are the two largest FVC within 0.2 L of each other?
	Are the two largest FEV₁ within 0.2 L of each other?
If both of these criteria are met, the test session may be concluded.
If both of these criteria are not met, continue testing until:
	Both of the criteria are met with analysis of additional acceptable spirograms; OR
	A total of eight tests have been performed; OR
	The patient/subject cannot or should not continue
Save at a minimum the three best manuvers

Adapted from reference 4

Table 4:
Equipment Quality Control Summary
Test	Minimum Interval	Action
Volume	Daily	3-L syringe check
Leak	Daily	3 cm H20 constant pressure for 1 min
Linearity	Quarterly Weekly (flow spirometers)	1-L increments with a calibrating syringe measured over entire volume range (flow spirometers simulate several different flow ranges)
Time	Quarterly	Mechanical recorder check with stopwatch
Software	New versions	Log installation date and perform test using "known" subject
Adapted from reference 4.

Table 5:

Performance Standards for an Office Spirometer

A Volume Spirometer Should:
- Accumulate volume for greater than 30 s
- Accomodate volumes of up to 7 liters
- Be accurate to within 3% or 50 ml of a "test" volume
A Flow-Sensing Spirometer Should:
- Be able to measure flows up to 12L/s
- Be accurate to within 5% or 0.2 L/s
Both Need:
- Regular maintenance
- Routine checks of accuracy of the spirometer and the computer

Adapted from reference 4

Table 6:
Common Restrictive and Obstructive Lung Diseases
Common Obstructive Lung Diseases	Common Restrictive Lung Diseases
Asthma Asthmatic bronchitis Chronic obstructive bronchitis Chronic obstructive pulmonary disease (COPD includes asthmatic bronchitis, chronic bronchitis, emphysema and the overlap between them). Cystic fibrosis Emphysema	Idiopathic pulmonary fibrosis Interstitial pneumonitis Infectious inflammation (eg, histoplasmosis, mycobacterium infection) Sarcoidosis/beryllium disease Thoracic deformities Congestive heart failure Neuromuscular diseases

Table 7:

Example of Criteria for Assessing the Severity of Abnormalities

A. Normal: The test is interpreted as "within normal limits" if both the VC and the FEV₁/VC ratio ar in the normal range.

B. Obstructive abnormality: This is interpreted when the FEV₁/VC ratio is below the normal range. The severity of the abnormality might be graded as follows:

"May be a physiological variant"	% Pred FEV₁ > 100
"Mild"	% Pred FEV₁ < 100 and > 70
"Moderate"	% Pred FEV₁ < 70 and > 60
"Moderately severe"	% Pred FEV₁ < 60 and > 50
"Severe"	% Pred FEV₁ < 50 and > 34

C. Restrictive abnormality: This is most reliably interpreted on the basis of TLC. If this is not available, one may interpret a reduction in the VC without a reduction of the FEV₁/VC ratio as a "restriction of the volume excursion of the lung." The severity of the abnormality might be graded as follows:

Based on the TLC

"Mild"	% Pred TLC < LLN but > 70
"Moderate"	% Pred TLC < 70 and > 60
"Moderately severe"	% Pred TLC < 60

Based on spirometry

"Mild"	% Pred VC < LLN but > 70
"Moderate"	% Pred VC < 70 and > 60
"Moderately severe"	% Pred VC < 60 and > 50
"Severe"	% Pred VC < 50 and > 34
"Very severe"	% Pred VC < 34

Adapted from reference 6

Table 8:

Processes Associated with Alterations in DL_CO

Decreases In DL_CO

Obstructive lung diseases
- Emphysema
- Cystic fibrosis
Parenchymal lung diseases
- Interstitial lung disease
  - Caused by fibrogenic dusts, eg, asbestois
  - Caused by biologic dusts, eg, allergic alveolitis
  - Drug reactions, eg, amiodarone, bleomycin
  - Idiopathic
- Sarcoidosis
Pulmonary involvement in systemic diseases
- Systemic lupus erythematosus
- Progressive systemic sclerosis
- Mixed connective tissue disease
- Rheumatoid arthritis
- Dermatomyositis-polymyositis
- Wegener's granulomatosis
- Inflammatory bowel disease
Cardiovascular diseases
- Acute myocardial infarction
- Mitral stenosis
- Primary pulmonary hypertension
- Pulmonary edema
- Acute and recurrent pulmonary thromboembolism
- Fat embolization
Other
- Diseases associated with anemia
- Chronic renal failure
- Chronic hemodialysis
- Marijuana smoking
- Acute and chronic ethanol ingestion
- Freebasing cocaine
- Ciagarette smoking
- Bronchitis obliterans with organizing pneumonia (BOOP)

Increases In DL_CO

Diseases associated with polycythemia
Pulmonary hemorrhage
Diseases associated with increased pulmonary blood flow such as left-to-right intracardiac shunts
Exercise

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