PULMONARY FUNCTION TESTING
by
Michael R. Carr, BA, RRT, RCP
and
Helen Schaar Corning, RRT, RCP
RC Educational Consulting Services, Inc.
16781 Van Buren Blvd, Suite B, Riverside, CA 92504-5798
(800) 441-LUNG / (877) 367-NURS
www.RCECS.com
PULMONARY FUNCTION TESTING
BEHAVIORAL OBJECTIVES
UPON COMPLETION OF THE READING MATERIAL, THE PRACTITIONER WILL BE
ABLE TO:
1.
List the primary indications for pulmonary function tests (PFT’s).
2.
Explain ATPS/BTPS and ATS standards.
3.
Differentiate between lung volumes and lung capacities.
4.
For each lung capacity, list the volumes contained therein.
5.
List the normal values of each lung capacity.
6.
Identify the normal values of each lung volume.
7.
Explain what spirometry is.
8.
Describe the volumes and flow rates that can be determined by spirometry.
9.
List the lung volumes that cannot be measured by spirometry.
10. Identify the special procedures used in Pulmonary Function Testing.
11. Summarize the DLCO procedure.
12. Explain body plethysmography.
13. List the purpose of performing the helium dilution and nitrogen washout.
14. Describe the pulmonary angiogram or arteriogram.
15. List the main purpose of a V/Q scan.
16. Demonstrate ability to differentiate obstructive and restrictive disorders based on
PFT results.
17. Explain the normal and abnormal range in “percent of predicted” values.
18. Specify the formula for ideal body weight (IBW).
19. List the formula calculating the oxygen index.
20. Describe how to calculate the P/F ratio.
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PULMONARY FUNCTION TESTING
COPYRIGHT © 2006 BY RC EDUCATIONAL CONSULTING SERVICES, INC.
TX 6-289-329
Authored by: Michael R. Carr, BA, RRT, RCP and Helen Schaar Corning, RRT, RCP (2006)
ALL RIGHTS RESERVED
This course is for reference and education only. Every effort is made to ensure that the
clinical principles, procedures and practices are based on current knowledge and state of
the art information from acknowledged authorities, text and journals. This information is
not intended as a substitution for diagnosis or treatment given in consultation with a
qualified health care professional.
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PULMONARY FUNCTION TESTING
TABLE OF CONTENTS
INTRODUCTION .............................................................................................................. 7
PRIMARY INDICATIONS FOR PULMONARY FUNCTION TESTS .......................... 7
PFT MEASUREMENT STANDARDS ............................................................................. 8
ATPS / BTPS ................................................................................................................. 8
ATS STANDARDS ....................................................................................................... 8
DESCRIPTIONS OF LUNG VOLUMES AND LUNG CAPACITIES ............................ 9
LUNG CAPACITIES .................................................................................................. 10
LUNG VOLUMES ...................................................................................................... 10
SPIROMETRY ................................................................................................................. 11
FORCED VITAL CAPACITY MEASUREMENTS ....................................................... 11
FORCED EXPIRATORY VOLUME TIMED (FEVt) ............................................... 12
SPECIAL PROCEDURES IN PULMONARY FUNCTION TESTING......................... 13
DLCO - GAS DIFFUSION TESTING........................................................................ 13
BRONCHIAL PROVOCATION TESTS .................................................................... 13
MEASURING RESIDUAL VOLUME, FUNCTIONAL RESIDUAL
CAPACITY, AND TLC .............................................................................................. 14
BODY PLETHYSMOGRAPH.................................................................................... 14
HELIUM DILUTION TEST (CLOSED CIRCUIT) ................................................... 14
NITROGEN WASHOUT TEST (OPEN CIRCUIT) .................................................. 15
GAS/BLOOD FLOW DISTRIBUTION TESTING:
SINGLE BREATH NITROGEN ELIMINATION (SBN 2 )......................................... 15
DESCRIPTIONS OF MISCELLANEOUS PULMONARY MECHANICS ................... 18
MAXIMUM VOLUNTARY VENTILATION (MVV) OR
MAXIMUM BREATHING CAPACITY (MBC)....................................................... 18
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PULMONARY FUNCTION TESTING
PEAK FLOW (PF) OR PEAK EXPIRATORY FLOW RATE (PEFR) ..................... 19
MAXIMAL EXPIRATORY PRESSURE (MEP) ....................................................... 19
MAXIMAL INSPIRATORY PRESSURE (MIP) AND
NEGATIVE INSPIRATORY FORCE (NIF) .............................................................. 19
INCENTIVE SPIROMETRY (IS)............................................................................... 19
INTERPRETING PFT RESULTS .................................................................................... 20
BASED ON PERCENT OF PREDICTED VALUE ................................................... 20
ASSESSING POST BRONCHODILATOR % IMPROVEMENT............................. 20
CALCULATIONS USED IN PFT MEASUREMENTS .................................................. 21
HEIGHT AND WEIGHT CONVERSIONS ............................................................... 21
IDEAL BODY WEIGHT (IBW) ............................................................................ 21
BODY SURFACE AREA M2 (BSA) ..................................................................... 21
BODY MASS INDEX (BMI)................................................................................. 21
BASAL METABOLIC RATE (BMR) AND
RESTING ENERGY EXPENDITURE (REE)....................................................... 22
OXYGEN INDEX (OI) ............................................................................................... 22
BRIEF REVIEW OF ARTERIAL BLOOD GASES (ABG’S)................................... 23
NORMAL VALUES .............................................................................................. 24
INTERPRETATION............................................................................................... 24
MOST COMMON CAUSES OF ABNORMAL BLOOD GASES ....................... 26
RESPIRATORY ACIDOSIS............................................................................. 26
RESPIRATORY ALKALOSIS ......................................................................... 27
METABOLIC ACIDOSIS................................................................................. 28
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PULMONARY FUNCTION TESTING
METABOLIC ALKALOSIS ............................................................................. 29
CONCLUSION................................................................................................................. 29
CLINICAL PRACTICE EXERCISE ............................................................................... 30
APPENDIX ....................................................................................................................... 31
SUGGSTED READING AND REFERENCES ............................................................... 42
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PULMONARY FUNCTION TESTING
INTRODUCTION
R
espiratory therapists are often asked to perform pulmonary function (PF) testing in
different areas of the hospital and oversee the pulmonary function laboratory. Pulmonary
function testing offers many opportunities for a respiratory therapist because the
indications for testing are many and the tests are currently under-used by most physicians.
The pulmonary function technician (respiratory therapist) is responsible for explaining the
testing procedure to the patient and coaching the patient in order to obtain the best possible
results. The results are then documented and given to the attending physician for interpretation
and follow-up treatment if needed.
Evaluation of pulmonary function benefits many types of patients. Pulmonary disease may
frequently be detected by PF tests years before the onset of signs or symptoms. Early detection
of pulmonary disease helps the physician convince patients to stop smoking, reducing the risk of
both cardiovascular and pulmonary disease. Test comparison helps the physician to determine
whether a specific therapeutic regimen is beneficial. Shortness of breath is a common complaint
for which PF tests can help differentiate between a cardiac and a pulmonary cause. The PF tests
performed before planned surgery help to reduce the incidence of postoperative pulmonary
complications by identifying patients at increased risk. Finally, patients who feel that their
ability to work is limited by shortness of breath can be objectively evaluated by PF tests. The
results often carry considerable legal and economic consequences.
This course describes the tests respiratory therapists should be familiar with even if they do not
work in a pulmonary function laboratory. It is not uncommon for a patient to be admitted to the
hospital who has had previous PFT that is reported in the current chart. A quick review of these
results may be instrumental in decision making about current treatment. In addition to defining
the common pulmonary function tests performed, a brief discussion of what may cause
abnormalities in the results is included.
PRIMARY INDICATIONS FOR PULMONARY FUNCTION TESTS
•
Assessment of the respiratory system
•
Test for the presence of lung disease
•
Identify the type of lung disorder (Obstructive vs. Restrictive)
•
Aid in identifying location of disorder (small vs. large airways)
•
Evaluate the extent of pulmonary dysfunction
•
Assess progression of lung disease
•
Aid in establishing a therapeutic regimen for the dysfunction
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PULMONARY FUNCTION TESTING
P
FT’s are used to assess the respiratory system. PFT’s can also aid in differentiating
between obstructive and restrictive lung diseases. Obstructive pulmonary disease includes
asthma, bronchitis, bronchiectasis, emphysema, cystic fibrosis, and bronchopulmonary
dysplasia. Most other lung disorders are classified as restrictive pulmonary diseases. Some of
the most common restrictive diseases include pneumonia, pneumothorax, pulmonary edema,
pleural effusion, myasthenia gravis, and adult respiratory distress syndrome (ARDS).
PFT MEASUREMENT STANDARDS
ATPS / BTPS
•
Volumes measured by spirometry are at ambient temperature, pressure, and saturated
(ATPS) conditions.
•
These measurements are then adjusted for the temperature difference between the
spirometer and the patient’s body temperature, pressure, and saturated conditions
(BTPS).
ATS Standards
ATS standards are guidelines that safeguard against procedural errors, and help assure accurate
results. An important factor in meeting ATS standards are to perform equipment calibration,
maintenance, and cleaning on a regular schedule.
Equipment can go out of calibration, on its own, whether frequently or rarely used. Also,
particulate matter can buildup inside the machine causing it to go out of calibration. It is
important to calibrate PFT equipment on schedule to assure results are valid. One must follow
the manufacturer’s calibration, maintenance, and cleaning schedules, as well as the employing
institution’s policies.
One example of calibrating spirometers involves injecting a known amount of air into the
spirometer, and testing for a readout result of the same value. A 3-liter super syringe is often
utilized for this calibration.
Another important point involving PFT’s is that many tests are very effort dependent. The
patient must be motivated to put forth the very best effort. The patient must be thoroughly
instructed on the procedure before the test, and given three attempts when appropriate.
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PULMONARY FUNCTION TESTING
PFT GRAPHIC DISPLAY OF LUNG VOLUMES AND CAPACITIES
IRV
IC
VC /
FVC
TLC
VT
ERV
FRC
RV
RV
DESCRIPTIONS OF LUNG VOLUMES AND LUNG CAPACITIES
I
n the field of pulmonary function testing (PFT), the air within the lungs is divided into
segments called capacities and volumes. Each lung capacity contains two or more lung
volumes. The reason for assessing the air this way is to more accurately measure specific
lung functions in different areas of the lungs. There are many different pulmonary diseases, and
a broad range of PFT’s are required to assess and diagnose pulmonary dysfunctions.
The total lung capacity (TLC) is a measurement of the total volume of air contained in the lungs.
The total lung capacity contains two segments: the vital capacity (VC), and the residual volume
(RV). Therefore VC plus RV equals TLC.
The vital capacity (VC) is a measurement of the maximum volume of air that can be exhaled
after a maximal inspiration. Forced vital capacity (FVC) is the same in volume as the VC, but
the patient is asked to exhale as quickly and forcefully as possible. The FVC is performed when
one wants to assess flow rates.
The residual volume (RV) is the volume of air remaining in the lungs after a maximal exhalation.
Measuring the RV requires special testing, as this air cannot be measured by spirometry. Since
residual volume is a part of the total lung capacity, measurement of the TLC also requires special
testing.
The total lung capacity contains the inspiratory capacity (IC) and the functional residual capacity
(FRC). Therefore IC plus FRC equals TLC. The inspiratory capacity is the maximum amount of
air that can be inhaled after a normal tidal volume exhalation. The functional residual capacity is
the amount of air remaining in the lungs after a normal tidal volume exhalation.
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PULMONARY FUNCTION TESTING
The inspiratory capacity is divided into two volumes: the inspiratory reserve volume (IRV) and
the tidal volume (VT). The IRV is the maximum volume of air than can be inhaled after a
normal tidal volume inspiration. The VT is the volume of air that is inhaled and exhaled during
normal quiet breathing.
The functional residual capacity is divided into two volumes called the expiratory reserve
volume (ERV), and the residual volume (RV). The ERV is the amount of air than can be
exhaled after a normal tidal volume exhalation.
PFT ABBREVIATIONS AND DESCRIPTIONS 35
Lung Capacities
Lung Capacity
(contains two or more volumes)
TLC Total Lung Capacity
VC Vital Capacity or
FVC Forced Vital Capacity
IC
Inspiratory Capacity
FRC Functional Residual
Capacity
Description
Total volume of air contained in the lungs.
TLC = IC + FRC. Also TLC = VC + RV.
Also TLC = VT + IRV + ERV + RV.
Maximum volume of air that can be exhaled after a
maximal inhalation. VC = VT + IRV + ERV.
FVC is equal in volume to VC, but the patient must exhale
as quickly and forcefully as possible in order to assess
flow-rates.
Maximum amount of air that can be inspired after a
normal VT exhalation. IC = VT + IRV.
Volume of air remaining in the lungs after a normal VT
exhalation. FRC = ERV + RV.
Includes RV air-trapping, which cannot be measured by
simple spirometry, requires special testing. Increased FRC
or increased RV/TLC ratio
(> 20%) indicates an obstructive disorder.
Decreased FRC and TLC indicates restrictive disorder.
Lung Volumes
Lung Volume
VT or TV Tidal Volume
IRV Inspiratory Reserve Volume
ERV Expiratory Reserve Volume
Description
Volume of air that is inhaled and exhaled during
normal quiet breathing.
Maximum volume of air than can be inhaled after a
normal VT inspiration.
Maximum volume of air than can be exhaled after a
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PULMONARY FUNCTION TESTING
normal VT exhalation.
RV Residual Volume
RV/TLC Ratio
Volume of air remaining in the lungs after a maximal
exhalation. Includes air-trapping, which cannot be
measured by simple spirometry, requires special
testing. Increased FRC or increased RV/TLC ratio
(> 20%) indicates an obstructive disorder.
Decreased FRC and TLC indicates restrictive
disorder.
The following table lists the calculations for normal values for each of the lung capacities and
volumes mentioned above.
NORMAL PFT VALUES AND CALCULATIONS FOR ADULTS* 35
Calculation for
Normal Values
Normal Values for
60 Kg Female
Normal Values for
70 Kg Male
TLC
80 mL/kg
4800 mL
5600 mL
VC or FVC
IC
FRC
65 mL/kg
50 mL/kg
30 mL/kg
3900 mL
3000 mL
1800 mL
4550 mL
3500 mL
2100 mL
7 mL/kg
40 mL/kg
17 mL/kg
16 mL/kg
20% of TLC
420 mL
2400 mL
1020 mL
960 mL
20% of TLC
490 mL
2800 mL
1190 mL
1120 mL
20% of TLC
Volumes and Capacities
VT
IRV
ERV
RV
RV/TLC ratio
SPIROMETRY
•
Spirometry can measure: VC/FVC, IC, IRV, VT, ERV, and flow rates.
•
Spirometry cannot measure: RV, FRC, and TLC. These require special testing, covered
later in this course.
FORCED VITAL CAPACITY MEASUREMENTS
T
he forced vital capacity is a commonly utilized tool for assessing lung function. This
FVC aids in diagnosing both restrictive and obstructive pulmonary diseases. The FVC
can also help pinpoint the location of the dysfunction in the small or large airways. The
FVC also gives flow rate results. Flow rates are calculations of the amount of time it takes to
exhale air. The patient inhales as deeply as possible, then exhales as quickly and forcefully as
possible. Patients are usually given three attempts, and the best of the three results are used to
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PULMONARY FUNCTION TESTING
calculate the flow rates. The flow rates also aid in determining whether a small or large airway
dysfunction is present.
PFT Flow Rates and Time%
FEV 0.5
FEV 0.5/%FVC
FEV 1.0
FEV 1/%FVC
FEV 2.0
FEV 2/%FVC
FEV 3.0
FEV 3/%FVC
Description
Forced Expiratory Volume in first 0.5 seconds of
FVC. 0.5 Time% normally 60% of FVC.
Forced Expiratory Volume in first 1.0 seconds of
FVC. 1.0 Time% normally 80% of FVC.
Forced Expiratory Volume in first 2.0 seconds of
FVC. 2.0 Time% normally 94% of FVC.
Forced Expiratory Volume in first 3.0 seconds of
FVC. 3.0 Time% normally 97% of FVC.
Forced Expiratory Flow after first 200 mL exhaled,
until next 1200 mL exhaled during FVC. Also called
Maximum Expiratory Flow Rate. Measures function
of large airways.
Forced Expiratory Flow rate over middle 50% of
FVC. Also called Maximal Mid-Expiratory Flow
Rate. Measure function of small and medium
airways.
FEF 200-1200 or MEFR
FEF 25-75% or MMFR
The following table lists the calculations for normal values for the flow rates listed above. 36
Flow Rates and Time%
FEV 0.5 seconds
FEV 1.0 seconds
FEV 2.0 seconds
FEV 3.0 seconds
FEF 200-1200
or MEFR
FEF 25-75%
or MMFR
Calculation for
Normal Values
60% of FVC
80% of FVC
94% of FVC
97% of FVC
Normal Values for
60 Kg Female
2340 mL
3120 mL
3670 mL
3780 mL
Normal Values for
70 Kg Male
2730 mL
3640 mL
4280 mL
4410 mL
6 L/sec
360 L/min
360 L/min
4.7 L/sec
280 L/min
280 L/min
Forced Expiratory Volume Timed (FEVt)
The forced expiratory volume timed (FEVt) is the volume of air measured at specific timed
intervals during the FVC test. Measurements are taken at 0.5 seconds (FEV 0.5), at 1.0 seconds
(FEV 1.0), at 2.0 seconds (FEV 2.0), and at 3.0 seconds (FEV 3.0). Another measurement of the
FVC is given in a timed percentage of the vital capacity (FEVt%). This is the percentage of air
exhaled during an FVC. The FEF 25%-75% (also called maximal mid- expiratory flow rate) is a
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PULMONARY FUNCTION TESTING
good spirometry test for detecting small airway disease. To assess the function of the large
airways, the forced expiratory flow-rate is measured between 200 mL and 1200 mL of the total
air exhaled during the FVC. This is called the FEF 200-1200, or the MEFR, which stands for the
Maximum Expiratory Flow Rate.
SPECIAL PROCEDURES IN PULMONARY FUNCTION TESTING 37
DLCO - Gas Diffusion Testing
T
his test measures the factors that affect the diffusion of air across the alveolar-capillary
(A/C) membrane. The test aids in diagnosing reduced surface area for diffusion. The
most common test used is the carbon monoxide diffusion capacity or DLCO (Lung
Diffusion for Carbon Monoxide). The patient inspires as deeply as possible, breathing in a small
concentration of carbon monoxide mixed with helium and air. The patient then must hold the
breath for ten seconds, then exhale into a device that analyzes the gas concentrations and
calculates the diffusion capacity. The normal value for a single breath DLCO is 25
mL/minute/mmHg.
A variation of this test is the steady state DLCO test, in which the patient breathes normally for
three minutes, inhaling a mixture of carbon monoxide, helium, and air. The measurement is
taken during the third minute. The normal DLCO steady state value is 17 mL/minute/mmHg.
The DLCO used in conjunction with the FVC is the most useful PFT for detecting emphysema.
The DLCO value is reduced in emphysema and also in some restrictive diseases, including
pulmonary fibrosis and sarcoidosis.
Bronchial Provocation Tests
Some patients have normal spirograms with all the symptoms of asthma or an undiagnosed
cough. These people often have reactive airways disease (RADS). Bronchial provocation is an
easy and save way to make a differential diagnosis. Challenging the patient with inhaled
histamine or methacholine is most commonly used.
A. Use of bronchial provocation test
1. To assess patients with normal PFT’s and symptoms of bronchospasm.
2. To quantify severity of asthma and assess changes in airway reactivity.
3. Screening of those who may be at risk from or to document the effects of environmental
or occupational exposure to toxins,
B. Patients must be asymptomatic at baseline
C. Bronchodilators and antihistamines must be withheld before the test. Inhaled corticosteroids
should not be withheld
D. Appropriate emergency equipment and monitoring devices should be readily available
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PULMONARY FUNCTION TESTING
E. Baseline spirometry test are measured before the challenge and compared with serial
spirometry measurements taken at specified time intervals after the challenge
F. Methacholine challenge (adapted from the AARC Clinical Practice Guidelines)
1. Baseline FEV1 measurements are made before the administration of the aerosolized drug
and after each successive dose is administered.
2. The first dose of methacholine administered is 0.025 mg/ml. The dose used for each
subsequent administration is determined using a predetermined dosing schedule. Dosing
schedules commonly specify doubling the dose each time, up to a maximum of 25 mg/ml.
3. The methacholine concentration that causes a 20% decrease in the FEV1 from baseline is
referred to as the provocative dose or PD20%.
4. The test is stopped once PD20% is reached.
5. Normal, healthy subjects have a PD20% that is greater than the maximum dose used foe
testing. These individuals do not show a 20% decrease in FEV1 during a methacholine
challenge.
6. A PD20% of < 8 mg/ml is common in patients with hyperreactive airways.
Measuring Residual Volume, Functional Residual Capacity, And TLC
Measuring the residual volume requires special testing as it cannot be measured by spirometry.
Since the RV is a part of the FRC and the TLC, these measurements also require special testing.
The RV measurement includes air that is trapped in the lungs after a maximal exhalation, and
can help differentiate between obstructive and restrictive lung disease. An increased FRC or an
increased RV/TLC ratio (more than 20%) indicates an obstructive disorder. If the TLC and the
FRC are decreased, this indicates a restrictive disorder.
Body Plethysmograph
Also called the body box, this is the most accurate method for measuring the FRC. This test can
measure the total thoracic gas volume (TGV), including air trapped in the smallest airways. The
patient sits inside of the body plethysmograph and pants against a closed shutter, at a rate of
approximately 2 breaths per second, while the pressures and volumes are obtained. The TGV is
increased in obstructive disease, and decreased in restrictive disorder.
Helium Dilution Test (Closed Circuit)
Another method of measuring the FRC is the closed circuit helium dilution method. The patient
breathes a mixture of air with 10% helium. The helium is diluted by the breathing until
equilibrium takes place at approximately five to seven minutes. A percentage of that helium is
diluted by the patient’s FRC, and the change in helium percentage is measured to determine the
FRC. If equilibrium takes longer (up to 20 min), it indicates obstructive disease. The FRC is
increased in obstructive disease, and decreased in restrictive disorder. The helium dilution test is
fairly accurate, but if there is a large amount of air trapped in the patient’s lungs, a small amount
of air may be left undetected.
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PULMONARY FUNCTION TESTING
Nitrogen Washout Test (Open Circuit)
Another method of measuring the FRC, and aid in detecting a pulmonary embolism is the
nitrogen washout. In this test, the patient breathes 100% oxygen for about 7 minutes exhaling
all gas into an analyzer, and a breath-by-breath curve is obtained. Then patient exhales
completely. Fractional concentration of alveolar nitrogen (FAN2 ) is noted, and the FRC is
computed. The FRC is increased in obstructive disease, and decreased in restrictive disorder.
After 7 minutes, the normal amount of nitrogen remaining in the lungs is less than 2.5%. If
greater than 2.5% nitrogen remains at 7 minutes, this indicates poor distribution of ventilation,
obstructive disorder, or possible pulmonary embolism.
Gas/Blood Flow Distribution Testing: Single Breath Nitrogen Elimination (SBN2 )
The single breath nitrogen elimination test measures the evenness of distribution of inspired
gases. This test is very sensitive for detecting early airway closure, small airway obstructions,
and pulmonary embolism. The patient exhales maximally, then inhales 100% oxygen
maximally, followed by slowly exhaling the gas until the lungs feel empty. The exhaled gas
passes through a nitrogen analyzer that measures the change in the concentration of nitrogen.
The first 750 mL of air exhaled is mostly deadspace, and is discarded (phase I and II). The next
500 mL of exhaled air (phase III) is used for measurement of nitrogen distribution. The rise of
nitrogen percentage in phase III should be less than 1.5%. A higher percentage represents
uneven distribution, with a possible pulmonary embolism. This test also includes the closing
volume test (CV) and closing capacity test (CC) as listed in the following table.
The following table lists the special procedures used in PFT testing that are discussed above in a
brief reference format. Additionally, this table includes the Flow-Volume Loop, Volume of
Isoflow, Pulmonary Angiogram or Arteriogram, and the Ventilation/Perfusion (V/Q) scan.
TABLE OF PFT SPECIAL PROCEDURES
39
Test
DLCO
Lung Diffusion for
Carbon Monoxide
or
Gas Diffusion Testing
Normal Value
Single breath DLCO
25 mL/minute/mmHg
Body Plethysmograph
or
Normal predicted values for
TGV, TLC and FRC
Steady state DLCO
17 mL/minute/mmHg
Description
Measures factors that affect diffusion of
air across A-C membrane; detects if
surface area for diffusion is reduced.
Patient inhales small concentration of
carbon monoxide, helium and air.
Patient exhales into device that analyzes
gas concentrations and calculates
DLCO.
DLCO reduced in emphysema,
pulmonary fibrosis, embolism, and
sarcoidosis.
Most accurate method for measuring
FRC, RV, and TLC. Measures total
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PULMONARY FUNCTION TESTING
Body Box
or
TGV Thoracic Gas
Volume
Helium Dilution
(closed circuit)
Equilibrium at
<= 7 minutes.
Normal FRC.
Nitrogen Washout
(open circuit)
Less than 8 minutes to reach
less than 2.5% nitrogen in
lungs.
Normal FRC.
SBN 2
Single Breath
Nitrogen Elimination
Includes:
Closing Volume (CV)
and
Phase III N2 rise should be
less than 1.5%.
TGV, including air trapped in smallest
airways. Patient pants at FRC against
closed shutter, at about 2 breaths per
second, while pressures and volumes are
measured.
TGV increased in obstructive disease,
decreased in restrictive disorder.
Method of measuring the FRC, then
calculating RV and TLC; not as accurate
as plethysmograph for detecting trapped
air. Patient breathes mixture of air with
10% helium, until equilibrium takes
place at 5-7 minutes. If equilibrium
takes longer (up to 20 min), it indicates
obstructive disease.
FRC increased in obstructive disease,
decreased in restrictive disorder.
Method of calculating the FRC, and RV;
not as accurate as plethysmograph for
detecting trapped air. Also measures
evenness of distribution of ventilation,
w/breath-by-breath curve. Patient
breathes 100% O2 for about 7 minutes,
exhaling all gas into an analyzer, until
nitrogen remaining in lungs is less than
2.5%. Then patient exhales completely.
Fractional concentration of alveolar
nitrogen (FAN2 ) is noted, and FRC is
computed.
Greater than 7 minutes to reach 2.5%
nitrogen remaining in lungs indicates
poor distribution of ventilation,
obstructive disorder, or possible
pulmonary embolism.
Calculated FRC increased in
obstructive disease, decreased in
restrictive disorder.
Measures the evenness of distribution of
inspired gases. Patient exhales
maximally, inspires 100% O2
maximally, then slowly exhales the gas
until lungs feel empty. The exhaled gas
passes through N2 analyzer that
measures the change in concentration of
nitrogen. The first 750 mL of air
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PULMONARY FUNCTION TESTING
Closing Capacity (CC)
exhaled is mostly deadspace, and is
discarded (phase I and II). The next 500
mL of exhaled air (phase III) is used to
measure distribution. The rise of N2
percentage in phase III should be less
than 1.5%.
A phase III N2 rise > 1.5% indicates
uneven distribution of ventilation or
uneven flow rates, with possible
pulmonary embolism.
Flow-Volume Loop**
Normal volumes and flow
rates as predicted.
Volume of Isoflow
VisoV
and
Vmax50
10-20% of VC.
Pulmonary
Angiogram
or
............
CV is Phase IV. CV should = 10-20%
of VC.
CC is Phase V. CC should = 30-40% of
TLC.
CV% increased in small airway
obstruction. Very sensitive for
detecting early airway closure.
Measures the volumes and flow rates of
the vital capacity. Expiratory flow
above baseline, inspiratory flow below
baseline. Patient inspires to TLC,
exhales forcefully for FVC, then inhales
maximally to TLC again. Graphic loop
results.
Can detect obstructive and restrictive
patterns, decreased volumes, decreased
flow rates, airway resistance and small
airway disease.
Consists of 2 maximal expiratory flow
curves. First FVC uses air. Second FVC
uses O2 20% + helium 80%. Volume
remaining in lungs after 2nd FVC is the
volume of isoflow, normally 10-20% of
VC.
VisoV increased in small airway
disease.
Vmax50 measures flow at 50% of the
VC, similar to FEF 25-75%.
Vmax50 measures changes in airway
resistance in small and medium
airways.
Measures blood flow distribution.
Radio-graphic study of the arteries after
injecting radiopaque dye. Motion and
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PULMONARY FUNCTION TESTING
Arteriogram
V/Q scan
or
Ventilation/perfusion
scan
............
still pictures are obtained, with
observation of blood flow through blood
vessels.
Can detect unperfused blood vessels,
and pulmonary embolism.
Measures gas and blood flow
distribution (ventilation and perfusion).
Involves inhalation of radiolabeled gas
(xenon), and injection of radioisotope,
followed by study of mismatches
between ventilation and perfusion.
Can detect poorly ventilated areas,
unperfused blood vessels, and
pulmonary embolism.
MEASURING MISCELLANEOUS PULMONARY MECHANICS
The following is a table listing the normal values for pulmonary mechanics that will be discussed
next. 35
Misc. Pulmonary
Mechanics
MVV or MBC
PF Peak Flow or PEFR
MEP
MIP or NIF
IS
Calculation for
Normal Values
150-170 L/min
400 – 600 L/min
>= + 80 cmH 2 O
–80 to –100 cmH 2 O
50 mL/kg
Normal Values for
60 Kg Female
150 L/min
400 L/min
>= + 80 cmH 2 O
–80 to –100 cmH 2 O
3000 mL
Normal Values for
70 Kg Male
170 L/min
600 L/min
>= + 80 cmH 2 O
–80 to –100 cmH 2 O
3500 mL
* Normal values based on normal adults with ideal body weight (IBW). Normal value
calculation factors also include age, height, sex, and race. Normal values decrease with age.
DESCRIPTIONS OF MISCELLANEOUS PULMONARY MECHANICS
Maximum Voluntary Ventilation (MVV) Or Maximum Breathing Capacity (MBC)
T
he maximum voluntary ventilation (MVV), also called the maximum breathing capacity
(MBC), gives information on the status of respiratory muscles, and measures compliance
and resistance. The patient is instructed to breathe as deep and as fast as possible for 1215 seconds into a spirometer with an accumulator recording. The maneuver exaggerates airtrapping. The value is then converted into minutes, with the normal value of 150 to 170 liters per
minute for an average adult. This test is very sensitive and can give an indication of an
obstructive disease in the early stages. Results are decreased in obstructive diseases. Results can
be normal with a mild restrictive disease, but are decreased in a severe restrictive disease.
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PULMONARY FUNCTION TESTING
Peak Flow (PF) Or Peak Expiratory Flow Rate (PEFR)
Peak Flow (PF) or Peak Expiratory Flow Rate (PEFR) is a test in which the patient inhales as
deeply as possible, then blows all the air out of their lungs as fast as possible. (This procedure is
basically the same as the FVC, but the PEFR only calculates one value instead of the many
values calculated during an FVC maneuver.) For an average adult, the normal PEFR is
approximately 400-600 liters per minute. This test can be done with a simple and portable handheld peak flow meter. The test is typically used by asthmatic and other COPD patients to
monitor their respiratory status. The PEFR is also frequently utilized in emergency rooms to
quickly assess the pulmonary status of patients. PFT’s are also used to assess a patient’s
response to bronchodilator therapy. Pre- and post- bronchodilator testing of the FVC flow-rates,
or the PEFR, give a reliable indication of the effectiveness of the bronchodilator.
Maximal Expiratory Pressure (MEP)
The maximal expiratory pressure (MEP) is a test to assess respiratory muscle strength. The
patient inhales deeply, then blows all of their air into the device to measure peak expiratory
pressure. The normal value is greater than or equal to 80 cmH 2 O.
Maximal Inspiratory Pressure (MIP) And Negative Inspiratory Force (NIF)
The maximal inspiratory pressure (MIP) and the negative inspiratory force (NIF) are the same
type of maneuver that can be performed on the MIP or the NIF device. The MIP or NIF is done
to assess respiratory muscle strength. The patient inhales maximally with a short breath hold,
and the peak inspiratory pressure is measured. The normal MIP or NIF is -80 to -100
centimeters of water. A value of -20 cm H2 O or better is the minimal acceptable value at which
ventilator weaning is attempted.
The NIF is also commonly utilized to assess for impending respiratory failure as in myasthenia
gravis and Guillian-Barré patients. These patients have neuromuscular disorders that can cause
extreme weakness or paralysis of the respiratory muscles. Here, the VC and NIF are used in
conjunction at set time intervals to monitor these patients. When values are decreasing below the
normal range, it can indicate impending respiratory failure.
Incentive Spirometry (IS)
Incentive spirometry is used both as a lung exercise device and a tool for measuring inspiratory
respiratory muscle strength. Incentive spirometry has proven to improve lung aeration and
prevent atelectasis. The normal values for IS are the same as for inspiratory capacity (IC) at 50
mL/Kg of ideal body weight. The patients are instructed to inhale on the device as deeply as
possible and perform a five second breath hold approximately ten times every one to two hours
while awake. The normal value for the patient’s are calculated by a clinician, and patients can
then be instructed how to monitor their own values.
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PULMONARY FUNCTION TESTING
INTERPRETING PFT RESULTS
OBSTRUCTIVE VS. RESTRICTIVE DISEASE PATTERNS 36
Volumes and Capacities
TLC
VC or FVC
IC
FRC
VT
IRV
ERV
RV
FEV 0.5 seconds
FEV 1.0 seconds
FEV 2.0 seconds
FEV 3.0 seconds
FEF 200-1200
FEF 25-75%
MVV or MBC
PF Peak Flow
Obstructive Disease
Restrictive Disorder
N or
N or
Varies
N or
N or
N or
N or
N or
N or
N or
N or
N or
N or
N or
N or
N or
N or
N or
* N = Normal
Obstructive disease pattern: Decreased flow rates, increased RV, increased TLC.
Restrictive disease pattern: Decreased volumes, decreased TLC.
Obstructive pulmonary diseases include asthma, bronchitis, bronchiectasis, emphysema, cystic
fibrosis, and bronchopulmonary dysplasia. Most other lung dysfunctions are restrictive
pulmonary disorders.
Interpreting PFT Results Based on Percent of Predicted Value:
Normal:
Mild disorder:
Moderate disorder:
Severe disorder:
80-120% of predicted.
65-79% of predicted.
50-64% of predicted.
Less than 50% of predicted.
Assessing Post Bronchodilator % Improvement:
Non-significant improvement:
Less than 15%
Significant improvement:
15% or greater.
(Very large improvements may be indicative of asthma.)
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PULMONARY FUNCTION TESTING
CALCULATIONS USED IN PFT MEASUREMENTS
36, 37
HEIGHT AND WEIGHT CONVERSIONS
Height Inches (in) To Centimeters (cm) Conversion
Calculation:
Convert Inches to Centimeters: in x 2.54 = cm
Convert Centimeters to Inches: cm ÷ 2.54 = in
Inches
cm
Inches
cm
Inches
cm
30
40
50
54
58
76
102
127
137
147
60
62
64
66
68
152
157
163
168
173
70
72
74
76
178
183
188
193
48 in = 4 feet
60 in = 5 feet
72 in = 6 feet
Ideal Body Weight (IBW)
Female: 105 + (5 x height in inches over 60)
Example: 65 inch tall female has an IBW of 130 lb: 105 + (5 x 5)
Male: 106 + (6 x height in inches over 60)
Example: 70 inch tall male has an IBW of 166 lb: 106 + (6 x 10)
Body Surface Area m2 (BSA)
Calculation:
Square root of: Height (in) x Weight (lb) ÷ 3131
or
Square root of: Height (cm) x Weight (kg) ÷ 3600
Sample: Find the BSA of a 65 inch tall 130 lb female: 1.6 m2
Body Mass Index (BMI)
Calculation: (Weight in lb x 700) ÷ (height in inches2 )
Sample: Find the BMI of a 170 lb male who is 70 inches tall
(170 x 700) ÷ (70 x 70)
(119,000) ÷ (4,900) = 24.2
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PULMONARY FUNCTION TESTING
BMI Values as related to Nutritional Status:
BMI
BMI
BMI
BMI
< 20
20-25
25-30
> 30
Underweight
Normal weight
Overweight
Obese
Basal Metabolic Rate (BMR) And Resting Energy Expenditure (REE)
BMR is a measure of the individual’s energy requirements in calories per hour. REE estimates
the daily caloric requirements. Usually obtained after 10 hours of fasting. This can be obtained
by indirect calorimetry that measures VO2 and VCO2 , or by using formulas. Listed here is one
of the quicker calculations to estimate daily caloric requirements:
BMR = IBW (in pounds) x activity factor x illness factor
Multiply desired weight or IBW (in pounds) by the activity factor as follows:
Activity factors:
12 for sedentary
15 for moderately active
18 for vigorously active
(most patients are in the sedentary range)
(lots of walking, and moderate exercise for ½ hour or more
3-5 times/week)
(lots of daily activity and daily strenuous exercise like
jogging).
Next, multiply the result by the illness factor as follows:
1.0
1.15
1.3
1.5
for healthy person/no current illness
for mild illness
for moderate illness,
for severe illness, pregnancy or lactation.
OXYGEN INDEX (OI)
Determining OI is a good clinical tool that can be used to determine the degree of hypoxemia, to
monitor for improvement, and as a weaning tool.
•
•
•
Good oxygenation
Some degree of hypoxemia
Severe hypoxemia
OI is 5 or less
OI is above 5
OI is 20 or greater.
OI takes into account the mean airway pressure (Mean Paw), FIO 2 , and PaO 2 . Since it is
common knowledge that it is not good to be on a high FIO2 and have low PaO 2 , the oxygen
index formula helps by placing a number on the severity of the hypoxemia.
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PULMONARY FUNCTION TESTING
Formula:
Oxygen Index = (Mean Paw x FIO2 )
PaO2
Sample #1
Given: Mean Paw 15, FIO 2 1.0, PaO 2 = 60 mmHg
Oxygen Index = (15 x 100)
60
25
=
Sample #2
Given: Mean Paw 20, FIO 2 0.4, PaO 2 = 80 mmHg
Oxygen Index = (10 x 40)
80
=
5
PaO2 /FiO2 Ratio (P/F Ratio)
The P/F ratio is another tool used to assess the degree of hypoxemia. It can be used for nonintubated patients, since the airway pressure is not included in the calculation. The only factors
are the PaO 2 and FIO 2 .
•
•
•
Normal oxygenation
Moderate hypoxemia
Severe hypoxemia
P/F ratio is 200 or Higher
P/F ratio is 100 to 200
P/F ratio is Less than 100
Formula: P/F Ratio = PaO2 divided by FIO2
BRIEF REVIEW OF ARTERIAL BLOOD GASES (ABG’S)
ABG’s are generally thought of as a category in itself, while ABG’s are classified both as
laboratory data and as PFT’s. Since ABG interpretation is quite complex, we refer you to the
complete course titled “ABG Interpretation” available at RC Educational Consulting Services,
Inc. (RCECS), rcecs.com, or watch for the soon-to-be-released “Laboratory Values Applicable to
Pulmonary Patient Assessment” also at RCECS. Here, we list a table of normal ABG values for
reference, and a review of how to quickly interpret ABG’s.
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PULMONARY FUNCTION TESTING
Arterial Blood Gases – Normal Values
Parameter
Normal Value
Normal Range
pH
PaCO2
PaO 2
HCO3
BE
Hb
O2 content
SaO 2
COHb
MetHb
7.40
40 mmHg
100 mmHg
24 mEq/L
0
14 g/dL
20 vol%
98%
0
0
7.35 – 7.45
35 – 45 mmHg
80 – 100 mmHg
22 – 26 mEq/L
+ or - 2
12 – 18 g/dL
15-20 vol%
> 95%
< 2%
<2%
Interpretation Of Arterial Blood Gases
Interpretation
Respiratory Acidosis / Ventilatory Failure
Acute
Chronic/Compensated
Acute superimposed or chronic
Respiratory Alkalosis / Hyperventilation
Acute
Chronic/Compensated
Metabolic Acidosis
Acute
Compensated
Metabolic Alkalosis
Acute
Compensated
pH
PaCO2
HCO3
N
N
N
N
N
N
N
N
N = Normal
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PULMONARY FUNCTION TESTING
NORMAL ACID-BASE BALANCE
7.10
7.40
ACIDOSIS
7.70
ALKALOSIS
Lungs
Kidneys
40 mmHg
PaCO2
[H+]
48 Meq/L
HCO3 -
pH
Normal
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PULMONARY FUNCTION TESTING
MOST COMMON CAUSES OF ABNORMAL BLOOD GASES
Respiratory Acidosis:
Insufficient alveolar ventilation. Pulmonary disease, CNS depression, drugs causing respiratory
depression. There is a gain in Hydrogen Ion Concentration (PaCO2 ) without a comparable gain
in base (HCO3 ) resulting in a drop in pH.
RESPIRATORY ACIDOSIS
7.10
7.40
ACIDOSIS
7.70
ALKALOSIS
Kidneys
24 Meq/L
HCO3 -
pH
Lungs
50 mmHg
PaCO2
[H+]
Respiratory Acidosis
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PULMONARY FUNCTION TESTING
Respiratory Alkalosis:
Alveolar hyperventilation. Stress, emotional upset, hypoxia, fever, CNS trauma. There is a loss
in Hydrogen Ion Concentration (PaCO2 ) without a related loss in Base (HCO3 ) which results in a
rise in pH.
RESPIRATORY ALKALOSIS
7.10
7.40
ACIDOSIS
7.70
ALKALOSIS
Lungs
30 mmHg
PaCO2
[H+]
pH
Respiratory Alkalosis
Kidneys
24 Meq/L
HCO3 -
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PULMONARY FUNCTION TESTING
Metabolic Acidosis:
Lactic acidosis, ketoacidosis (diabetes), renal failure, diarrhea. The decrease in Base (HCO3 ) is
not matched with a loss in Hydrogen Ion Concentration (PaCO2 ) and therefore, the pH will
decrease.
METABOLIC ACIDOSIS
7.10
7.40
ACIDOSIS
7.70
ALKALOSIS
Kidneys
15 Meq/L
HCO3 -
pH
Lungs
40 mmHg
PaCO2
[H+]
Metabolic Acidosis
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PULMONARY FUNCTION TESTING
Metabolic Alkalosis:
Hypokalemia (most common cause), high chloride, diuretics, corticosteroids, vomiting,
nasogastric tube. Decreases in cations (positive) and/or increases in anion (negative) will
increase pH without a parallel increase in Hydrogen Ion Concentration (PaCO2 ).
METABOLIC ALKALOSIS
7.10
7.40
ACIDOSIS
7.70
ALKALOSIS
Lungs
40 mmHg
PaCO2
[H+]
pH
Kidneys
Metabolic Alkalosis
48 Meq/L
HCO3 -
CONCLUSION
T
he use of spirometry in pulmonary function testing has a major role in determining the
differential diagnosis of pulmonary and cardiac diseases. It may also be used to rule out a
resistive or obstructive process in patients that experience signs and symptoms of lung
injury. The results from pulmonary function studies are used to (1) evaluate pulmonary causes
of dyspnea, (2) assess severity of the pathophysiologic impairment, (3) follow the course of a
particular disease, (4) evaluate the effectiveness of bronchodilator therapy, and (5) assess the
patient’s preoperative status. Abnormal values require additional testing to assess the lung
impairment. Examples of such test include lung volumes, maximum voluntary ventilation,
airway resistance, lung compliance, the nitrogen washout gas distribution test, and CO2 response
curve. Specialized test regimens, such as cardiopulmonary stress testing and
bronchoprovocation, help assess the severity of lung disorders.
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PULMONARY FUNCTION TESTING
CLINICAL PRACTICE EXERCISE
Case #1.
The patient is a sixty-two-year-old white male with a fifty-five pack-year smoking
history. The patient also worked as a sand blaster for forty years. Recently, he has
been complaining of increased shortness of breath.
Pre-Bronchodilator
Parameter
FVC
FEV1
FEV1 %
FEF25-75
PEFR
SVC
FRC
RV
TLC
Actual
1.83
0.65
35%
0.23
2.22
2.22
5.52
5.08
7.30
Predicted
3.37
2.57
76%
3.41
7.31
3.37
3.48
2.46
5.69
Post-Bronchodilator
% Predicted
54%
25%
46%
7%
30%
66%
159%
207%
128%
Actual
2.27
0.78
34%
0.32
3.10
Predicted
3.37
2.57
76%
3.41
7.31
% Predicted
67%
30%
45%
9%
42%
Interpretation
Case #2.
The patient is a thirty-six-year-old black female with a history of systemic lupus
erythematosus. Currently, she is complaining of dyspnea and a persistent cough. She
has an eighteen pack-year smoking history and no apparent occupational exposure to
dust or other noxious materials. She is presently taking prednisone.
Parameter
FVC
FEV1
FEV1 %
FEF25-75
PEFR
SVC
FRC
RV
Pre-Bronchodilator
Actual
Predicted
1.49
3.53
1.16
2.77
78%
78%
0.97
3.25
4.25
6.20
1.62
3.30
1.92
2.61
1.23
1.55
% Predicted
42%
42%
100%
30%
69%
49%
74%
79%
Actual
1.57
1.32
83%
1.44
5.56
1.79
Post-Bronchodilator
Predicted % Predicted
3.53
44%
2.77
48%
78%
106%
3.25
44%
6.20
90%
3.30
54%
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PULMONARY FUNCTION TESTING
TLC
2.85
4.88
Interpretation
Case # 1
Severe obstructive pattern (all flows decreased, FRC, RV increased), unresponsive to
bronchodilator. No restrictive pattern noted.
Case # 2
Severe restrictive pattern with a mild obstructive component (all volumes decreased, FEF25-75
decreased), FEF25-75 did not respond to bronchodilator, PEFR did respond suggesting possible
reversal of large airway obstruction.
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PULMONARY FUNCTION TESTING
APPENDIX
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PULMONARY FUNCTION TESTING
AARC Clinical Practice Guideline
Spirometry, 1996 Update
(Reprinted from RESPIRATORY CARE (Respir Care 1996; 41(7):629-636))
S 1.0 PROCEDURE:
Spirometry (S): The first American Association for Respiratory Care (AARC) Spirometry
Clinical Practice Guideline,(1) published in 1991, was based largely on the American Thoracic
Society (ATS) 1987 recommendations. (2) Since that time, the ATS has published new
recommendations. (3) This updated AARC Clinical Practice Guideline not only reflects these
new ATS recommendations but also contains additional recommendations on the use of
bronchodilators in conjunction with spirometry.
S 2.0 DESCRIPTION/DEFINITION:
The objective of spirometry is to assess ventilatory function. Spirometry includes but is not
limited to the measurement of forced vital capacity (FVC), the forced expiratory volume in the
first second (FEV1), and other forced expiratory flow measurements such as the FEF25-75%. In
addition, it sometimes includes the measurement of maximum voluntary ventilation (MVV). A
graphic representation (spirogram) of the maneuver should be a part of the results. Either a
volume-time or flow-volume display is acceptable. Other parameters that may be obtained by
spirometry include: FEFmax (PEF), FEF75%, FEF50%, FEF25%, FIF50%, and FIFmax (PIF).
S 3.0 SETTING:
These guidelines should be applied to spirometry performed by trained health-care professionals
3.1 in the pulmonary function or research laboratory;
3.2 at the bedside, in acute, subacute, extended care, and skilled nursing facilities;
3.3 in the clinic, treatment facility, and physician’/s office;
3.4 in the workplace or home;
3.5 for public screening.
S 4.0 INDICATIONS:
The indications for spirometry (4-8) include the need to
4.1 detect the presence or absence of lung dysfunction suggested by history or physical
signs and symptoms (eg, age, smoking history, family history of lung disease, cough,
dyspnea, wheezing) and/or the presence of other abnormal diagnostic tests (eg, chest
radiograph, arterial blood gas analysis);
4.2 quantify the severity of known lung disease;
4.3 assess the change in lung function over time or following administration of or change
in therapy;
4.4 assess the potential effects or response to environmental or occupational exposure;
4.5 assess the risk for surgical procedures known to affect lung function;
4.6 assess impairment and/or disability (eg, for rehabilitation, legal reasons, military).
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PULMONARY FUNCTION TESTING
S 5.0 CONTRAINDICATIONS:
The requesting physician should be made aware that the circumstances listed in this section
could affect the reliability of spirometry measurements. In addition, forced expiratory maneuvers
may aggravate these conditions, which may make test postponement necessary until the medical
condition(s) resolve(s).
Relative contraindications (9,10) to performing spirometry are:
5.1 hemoptysis of unknown origin (forced expiratory maneuver may aggravate the
underlying condition);
5.2 pneumothorax;
5.3 unstable cardiovascular status (forced expiratory maneuver may worsen angina or
cause changes in blood pressure) or recent myocardial infarction or pulmonary embolus;
5.4 thoracic, abdominal, or cerebral aneurysms (danger of rupture due to increased
thoracic pressure);
5.5 recent eye surgery (eg, cataract);
5.6 presence of an acute disease process that might interfere with test performance (eg,
nausea, vomiting);
5.7 recent surgery of thorax or abdomen.
S 6.0 HAZARD/COMPLICATIONS:
Although spirometry is a safe procedure, untoward reactions may occur, and the value of the
information anticipated from spirometry should be weighed against potential hazards. The
following have been reported anecdotally:
6.1 pneumothorax;
6.2 increased intracranial pressure;
6.3 syncope, dizziness, light-headedness;
6.4 chest pain;
6.5 paroxysmal coughing;
6.6 contraction of nosocomial infections;
6.7 oxygen desaturation due to interruption of oxygen therapy;
6.8 bronchospasm.
S 7.0 LIMITATIONS OF METHODOLOGY/ VALIDATION OF RESULTS:
7.1 Spirometry is an effort-dependent test that requires careful instruction and the
cooperation of the test subject. Inability to perform acceptable maneuvers may be due to
poor subject motivation or failure to understand instructions. Physical impairment and
young age (eg, children < 5 years of age) may also limit the subject’s ability to perform
spirometric maneuvers. These limitations do not preclude attempting spirometry but
should be noted and taken into consideration when the results are interpreted.
7.2 The results of spirometry should meet the following criteria for number of trials,
acceptability, and reproducibility. The acceptability criteria should be applied before
reproducibility is checked.
7.2.1 Number of trials: A minimum of 3 acceptable FVC maneuvers should be
performed. (3) If a subject is unable to perform a single acceptable maneuver after 8
attempts, testing may be discontinued. However, after additional instruction and
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PULMONARY FUNCTION TESTING
demonstration, more maneuvers may be performed depending on the subject’s clinical
condition and tolerance.
7.2.2 Acceptability: A good ‘start-of-test’ includes:
7.2.2.1 an extrapolated volume of < or = 5% of the FVC or 150 mL, whichever is greater;
7.2.2.2 no hesitation or false start;
7.2.2.3 a rapid start to rise time.
7.2.3 Acceptability: no cough, especially during the first second of the maneuver.
7.2.4 Acceptability: no early termination of exhalation.
7.2.4.1 A minimum exhalation time of 6 seconds is recommended, unless there is an
obvious plateau of reasonable duration (ie, no volume change for at least 1 second) or the
subject cannot or should not continue to exhale further. (3)
7.2.4.2 No maneuver should be eliminated solely because of early termination. The FEV1
from such maneuvers may be valid, and the volume expired may be an estimate of the
true FVC, although the FEV1/FVC and FEF25-75% may be overestimated.
7.2.5 Reproducibility:
7.2.5.1 The two largest FVCs from acceptable maneuvers should not vary by more than
0.200 L, and the two largest FEV1s from acceptable maneuvers should not vary by more
than 0.200 L.
Note: The ATS has changed its recommendations from those made in the 1987 ATS
guideline (2) (a reproducibility criterion of 5% or 0.100 L, whichever is larger). This
change is based on evidence from Hankinson and Bang suggesting that intrasubject
variability is independent of body size and that individuals of short stature are less likely
to meet the older criterion than are taller subjects. (11) In addition, the 0.200-L criterion
is simple to apply. However, there are two concerns with this change. The first is whether
the 0.200-L criterion is too permissive in shorter individuals (eg, children). Enright and
co-workers (12) reported a failure rate of only 2.1% in 21,432 testing sessions on adults
using the 5% or 100-mL criterion. In addition, they found that only 0.4% of test sessions
failed to meet relaxed criteria of 5% or 200 mL. These failure rates are much lower than
the 5-15% failure rates reported by Hankinson and Bang. (11) Enright and co-workers did
not study children, but there was some height overlap in the two studies. Thus, we are not
convinced that the 5% rule is inappropriate when applied to shorter individuals. Indeed,
Hankinson and Bang stated in their report “...it appears that the technician appropriately
responded to the lack of a reproducible or acceptable test result by obtaining more
maneuvers from these subjects.” The second concern is that the 0.200-L criterion may be
too rigid for very tall individuals (eg, height > 75 inches). Hankinson and Bang did not
study subjects taller than 190 cm (ie, 75 inches). In order to send a consistent message,
we recommend the ATS reproducibility criterion but urge practitioners: (a) to use this
criterion as a goal during data collection and not to reject a spirogram solely on the basis
of its poor reproducibility, (b) to exceed the reproducibility criterion whenever possible
because it will decrease inter- and intralaboratory variability, and (c) to comment in the
written report when reproducibility criteria cannot be met.
7.3 Maximum voluntary ventilation (MVV) is the volume of air exhaled in a specified
period during rapid, forced breathing. (3) This measurement is sometimes referred to as
the maximum breathing capacity (MBC).
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PULMONARY FUNCTION TESTING
7.3.1 The period of time for performing this maneuver should be at least 12 seconds but
no more than 15 seconds, with the data reported as L/min at BTPS.
7.3.2 At least two trials should be obtained, and the two highest should agree within ±
10%.
7.4 The use of a nose clip for all spirometric maneuvers is strongly encouraged.
7.5 Subjects may be studied in either the sitting or standing position. Occasionally, a
subject may experience syncope or dizziness while performing the forced expiratory
maneuver. Thus, the sitting position may be safer. If such a subject is standing, an
appropriate chair (ie, with arms and not on rollers) should be placed behind the subject in
the event that he or she needs to be seated quickly. When the maneuver is performed
from a seated position, the subject should sit erect with both feet on the floor, and be
positioned correctly in relation to the equipment. Test position should be noted on the
report.
7.6 Spirometry is often performed before and after inhalation of a bronchodilator.
7.6.1 The drug, dose, and mode of delivery should be specifically ordered by the
managing physician or determined by the laboratory and should be noted in the report.
7.6.2 The length of the interval between administration of the bronchodilator and
postbronchodilator testing varies among laboratories, (13-17) but there appears to be
more support for a minimum interval of 15 minutes for most short and intermediateacting beta-2 agonists.(14-17) This does not guarantee that peak response will be
determined, and underestimation of peak bronchodilator response can occur.
7.6.3 Subjects who use inhaled short-acting bronchodilators should be tested at least 4 to
6 hours after the last use of their inhaled bronchodilator to allow proper assessment of
acute bronchodilator response. Long-acting inhaled bronchodilators may need to be
withheld for a more extended period. Subjects should understand that if they need to
administer their bronchodilator prior to the test because of breathing problems, they
should do so. Bronchodilators taken on the day of testing should be noted in the report.
Table 1 lists commonly used drugs that may confound assessment of acute bronchodilator
response and the recommended times for withholding.
Table 1. Recommended Times for Withholding Commonly Used Bronchodilators
When Bronchodilator Response Is To Be Assessed*
Drug
Withholding Time (hours)
__________________________________________________________
salmeterol
12
ipratropium
6
terbutaline
4-8
albuterol
4-6
metaproterenol
4
isoetharine
3
__________________________________________________________
*Based on consensus of committee and known duration of action
7.6.4 Interpretation of response to a bronchodilator should take into account both
magnitude and consistency of change in the pulmonary function data. The recommended
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36
PULMONARY FUNCTION TESTING
criterion for response to a bronchodilator in adults for FEV1 and FVC is a 12%
improvement from baseline and an absolute change of 0.200 L. (18) However, because
the peak effect of the drug may not always be determined, the inability to meet this
response criterion does not exclude a response. In addition, dynamic compression of the
airways during the forced expiratory maneuver may mask bronchodilator response in
some subjects, and the additional measurement of airway resistance and calculation of
specific conductance and resistance may provide documentation of airway
responsiveness. (19)
7.7 Reporting of results:
7.7.1 The largest FVC and FEV1 (at BTPS) should be reported even if they do not come
from the same curve.
7.7.2 Other reported measures (eg, FEF25-75% and instantaneous expiratory flowrates,
such as FEFmax and FEF50%) should be obtained from the single acceptable ‘best-test’
curve (ie, largest sum of FVC and FEV1) and reported at BTPS.
7.7.3 All values should be recorded and stored so that comparison for reproducibility and
the ability to detect spirometry-induced bronchospasm (as evidenced by a worsening in
spirometric values with successive attempts-and not related to fatigue) are simplified.
7.7.4 The highest MVV trial should be reported.
7.8 Subject demographics and related information:
7.8.1 Age: The age on day of test should be used.
7.8.2 Height: The subject should stand fully erect with eyes looking straight ahead and be
measured with the feet together without shoes. An accurate measuring device should be
used. For subjects who cannot stand or who have a spinal deformity (eg, kyphoscoliosis),
the arm span from finger tip to finger tip with arms stretched in opposite directions can be
used as an estimate of height. (20)
7.8.3 Weight: An accurate scale should be used to determine the subject’s weight while
wearing indoor clothes but without shoes.
7.8.4 Race: The race or ethnic background of the subject should be determined and
reported to help ensure the use of appropriate reference values and appropriate
interpretation of data.
7.8.5 The time of day, equipment or instrumentation used, and name of the technician
administering the test should be recorded.
7.9 Open- and closed-circuit testing:
7.9.1 Open circuit: The subject takes a maximal inspiration from the room, inserts the
mouthpiece into the mouth, and then blows out either slowly (SVC) or rapidly (FVC)
until the end-of-test criterion is met. Although the open-circuit technique works well for
some subjects, others have difficulty maintaining a maximum inspiration while trying to
position the mouthpiece correctly in the mouth. These subjects may lose some of their
vital capacity due to leakage prior to the expiratory maneuver. (11)
7.9.2 Closed-circuit: The subject inserts the mouthpiece into the mouth and breathes
quietly for no more than 5 tidal breaths, takes a maximal inspiration from the reservoir,
and then blows out either slowly (SVC) or rapidly (FVC) until the end-of-test criterion is
met. This rebreathing technique is preferred if the spirometer system permits because it
(1) allows the subject to obtain a tight seal with the mouthpiece prior to inspiration and
(2) allows evaluation of the volume inspired.
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PULMONARY FUNCTION TESTING
S 8.0 ASSESSMENT OF NEED:
Need is assessed by determining that valid indications are present.
S 9.0 ASSESSMENT OF TEST QUALITY:
Spirometry performed for the listed indications is valid only if the spirometer functions
acceptably and the subject is able to perform the maneuvers in an acceptable and reproducible
fashion. All reports should contain a statement about the technician’s assessment of test quality
and specify which acceptability criteria were not met.
9.1 Quality control:(21)
9.1.1 Volume verification (ie, calibration): at least daily prior to testing, use a calibrated
known-volume syringe with a volume of at least 3 L to ascertain that the spirometer reads
a known volume accurately. The known volume should be injected and/or withdrawn at
least 3 times, at flows that vary between 2 and 12 L/s (3-L injection times of
approximately 1 second, 6 seconds, and somewhere between 1 and 6 seconds). The
tolerance limits for an acceptable calibration are ± 3% of the known volume. Thus, for a
3-L calibration syringe, the acceptable recovered range is 2.91-3.09 L. We encourage the
practitioner to exceed this guideline whenever possible (ie, reduce the tolerance limits to
< ± 3%)
9.1.2 Leak test: Volume-displacement spirometers must be evaluated for leaks daily. One
recommendation is that any volume change of more than 10 mL/min while the spirometer
is under at least 3-cm-H2 O pressure be considered excessive. (22)
9.1.3 A spirometry procedure manual should be maintained.
9.1.4 A log that documents daily instrument calibration, problems encountered, corrective
action required, and system hardware and/or software changes should be maintained.
9.1.5 Computer software for measurement and computer calculations should be checked
against manual calculations if possible. In addition, biologic laboratory standards (ie,
healthy, nonsmoking individuals) can be tested periodically to ensure historic
reproducibility, to verify software upgrades, and to evaluate new or replacement
spirometers.
9.1.6 The known-volume syringe should be checked for accuracy at least quarterly using
a second known-volume syringe, with the spirometer in the patient-test mode. This
validates the calibration and ensures that the patient-test mode operates properly.
9.1.7 For water-seal spirometers, water level and paper tracing speed should be checked
daily. The entire range of volume displacement should be checked quarterly. (21)
9.2 Quality Assurance: Each laboratory or testing site should develop, establish, and
implement quality assurance indicators for equipment calibration and maintenance and
patient preparation. In addition, methods should be devised and implemented to monitor
technician performance (with appropriate feedback) while obtaining, recognizing, and
documenting acceptability criteria.
S 10.0 RESOURCES:
10.1 Equipment: The spirometer must meet or exceed the requirements proposed by the
ATS and must be calibrated appropriately. (3) Spirometers should produce a paper record
of volume-time and/or flow-volume displays. Reference values should be appropriate for
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38
PULMONARY FUNCTION TESTING
the population of subjects tested and should be validated by testing a group of healthy,
nonsmoking subjects with the same mix of age, gender, and height used in the reference
study. (18)
10.2 Personnel: Spirometry should be administered under the direction of a doctor (MD,
DO, or PhD) specifically trained in pulmonary function testing. The value of spirometry
results can be compromised by poor patient instruction secondary to inadequate
technician training. Thus, technicians should have documented training, with continued
competency assessments in spirometry administration and recognition of causes for errors
encountered in the testing process and a sound understanding of physiologic effects
caused by bronchodilators. They should be trained in basic life support and emergency
procedures appropriate to the setting. (23) Spirometry can be administered by persons
who meet criteria for either Level I or Level II.
10.2.1 Level I: Persons trained in and with demonstrated ability to perform spirometry.
Minimum educational requirements for Level-I personnel should be a high school
diploma. One or more years of college or equivalent training and strong mathematical
skills are encouraged. We recommend that Level-I personnel take an approved training
course and have at least 6 months of supervised training. Test quality should be reviewed
by Level-II personnel or a physician, with feedback on an ongoing basis.
10.2.2 Level II: Persons with formal education (2 or more years of college-level studies
in biologic sciences and/or mathematics) and training that includes 2 or more years of
experience administering spirometry. One of the following credentials is recommended:
Certified Respiratory Therapy Technician (CRTT), Registered Respiratory Therapist
(RRT), Certified Pulmonary Function Technologist (CPFT), Registered Pulmonary
Function Technologist (RPFT).
S 11.0 MONITORING:
The following should be evaluated during the performance of spirometric measurements to
ascertain the validity of the results:(3,24)
11.1 acceptability of maneuver and reproducibility of FVC, FEV1.(25)
11.2 level of effort and cooperation by the subject.
11.3 equipment function or malfunction (eg, calibration).
11.4 The final report should contain a statement about test quality.
11.5 Spirometry results should be subject to ongoing review by a supervisor, with
feedback to the technologist.(12) Quality assurance and/or quality improvement programs
should be designed to monitor technician competency, both initially and on an ongoing
basis.
S 12.0 FREQUENCY:
The frequency with which spirometry is repeated should depend on the clinical status of the
subject and the indications for performing the test.
S 13.0 INFECTION CONTROL:
Spirometry is a relatively safe procedure, but the possibility of cross-contamination exists, either
from the patient-patient or the patient-technologist interface. The following guidelines should be
applied whenever spirometry is performed.
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PULMONARY FUNCTION TESTING
13.1 Universal Precautions (26,27) should be applied in all instances in which there is the
potential for exposure to blood and body fluids. The appropriate use of barriers (eg,
gloves) and handwashing are recommended. (28-30)
13.2 Due to the nature of forced expiratory maneuvers and the likelihood of coughing
when spirometry is performed by subjects who may have active infection with M.
tuberculosis or other airborne organisms, the following precautions are recommended:
13.2.1 The room in which spirometry is performed should meet or exceed the
recommendations of U.S. Public Health Service (31) for air changes and ventilation. The
ideal situation is an area in the testing department specially ventilated for isolation
patients and incorporating filtration or ultraviolet decontamination of air. If this is not
possible, the patient should be returned to the isolation room as soon as possible or,
alternatively, tested at the bedside using an acceptable spirometer.
13.2.2 When procedures involve patients with suspected infectious airborne diseases,
barrier protection (eg, mask or personal respirator meeting regulatory agency
requirements) is required. (32)
13.2.3 The use of gloves or other impermeable barriers is encouraged when contaminated
equipment is handled. (3)
13.2.4 The air in a volume-displacement spirometer should be flushed out at least 5 times
between subjects. (3)
13.2.5 Equipment can be reserved for the sole purpose of testing infected patients (eg,
those with M. tuberculosis or methicillin-resistant Staphylococcus aureus).
13.2.6 Infected patients can be tested at the end of the day or week and equipment can
then be disassembled and disinfected.
13.2.7 Special precautions may need to be taken for immunocompromised subjects.
13.3 The mouthpiece, tubing, and any parts of the spirometer that come into direct
contact with the subject should be disposable or be disinfected between patients. It is
unnecessary to routinely clean the interior surface of volume-displacement spirometers.
13.3.1 The open-circuit technique (ie, no rebreathing on mouthpiece or through breathing
tube) reduces the risk of infection to the patient but not to the technician. (31,32) The
mouthpiece should be changed between patients, but it is not necessary to change
breathing tube or hose, unless excessive water condensation occurs.(3)
13.3.2 If the closed-circuit technique (subject rebreathes on mouthpiece and through the
breathing tube and spirometer) is used, the breathing tube and mouthpiece should be
disposed of or disinfected between subjects. (3)
13.3.3 For flow-sensing systems in which no breathing tube is interposed between the
subject and the device, inspiration from the device should be avoided or the flow-sensing
element and interior tubing should be disinfected between subjects.
13.4 Bacteria filters are widely used in pulmonary function laboratories, although the
need for such filters and their effectiveness is not well documented. These filters impose
added resistance and have been reported to have a statistical but not clinically meaningful
effect on pulmonary function test results. (33,34) If in-line filters are used during
spirometry, we recommend that the equipment be calibrated with the filter installed and
that the filter be discarded after use on a single subject. The use of in-line filters does not
eliminate the need for regular cleaning and disinfection and does not guarantee that
transmission of disease(s) cannot occur.
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40
PULMONARY FUNCTION TESTING
Cardiopulmonary Diagnostics Focus Group:
Kevin Shrake MA RRT, Chairman, Springfield IL
Sue Blonshine BS RPFT RRT, Lansing MI
Robert A Brown BS RPFT RRT, Madison WI
Gregg L Ruppel MEd RRT, St Louis MO
Jack Wanger MBA RPFT RRT, Denver CO
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41
PULMONARY FUNCTION TESTING
SUGGESTED READING AND REFERENCES
1.
American Association for Respiratory Care. Clinical practice guideline: spirometry. Respir
Care 1991;136: 1414-1417.
2.
American Thoracic Society. Standardization of spirometry-1987 update. Am Rev Respir
Dis 1987;136:1039-1060. Published concurrently in Respir Care 1987;32(11): 1039-1060.
3.
American Thoracic Society. Standardization of spirometry 1994 update. Am J Respir Crit
Care Med 1995;152 (3):1107-1136.
4.
Ferris BG. Epidemiology standardization project. Am Rev Respir Dis 1979;118(Suppl):713).
5.
American Thoracic Society. Evaluation of impairment/ disability secondary to respiratory
disorders. Am Rev Respir Dis 1986;133(6):1205-1209.
6.
Zibrak JD, O’Donnell CR, Marton K. Indications for pulmonary function testing. Ann
Intern Med 1990; 112:793-794.
7.
Hankinson JL. Pulmonary function testing in the screening of workers: guidelines for
instrumentation, performance, and interpretation. J Occup Med 1986;28: 1081-1082.
8.
Crapo RO. Pulmonary function testing. N Engl J Med 1994;331: 25-30.
9.
Miller WF, Scacci R, Gast LR. Laboratory evaluation of pulmonary function. Philadelphia:
JB Lippincott Co, 1987.
10. Montenegro HD, Chester EH, Jones PK. Cardiac arrhythmias during routine tests of
pulmonary function in patients with chronic obstruction of airways. Chest 1978;73:133139.
11. Hankinson JL, Bang KM. Acceptability and reproducibility criteria of the American
Thoracic Society as observed in a sample of the general population. Am Rev Respir Dis
1991;143(3):516-521.
12. Enright PL, Johnson LR, Connett JE, Voelker H, Buist AS. Spirometry in the lung health
study: 1. Methods and quality control. Am Rev Respir Dis 1991;143(6): 1215-1223.
13. Casaburi R, Adame D, Hong CK. Comparison of albuterol to isoproterenol as a
bronchodilator for use in pulmonary function testing. Chest 1991;100:1597-1600.
14. Light RW, Conrad SA, George RB. Clinical significance of pulmonary function tests-the
one best test for evaluating the effects of bronchodilator therapy. Chest 1977;72:512-516.
15. Dales RE, Spitzer WO, Tousignant P, Schechter M, Suissa S. Clinical interpretation of
airway response to bronchodilator: epidemiologic considerations. Am Rev Respir Dis
1988;138(2):317-320.
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42
PULMONARY FUNCTION TESTING
16. Shim C. Response to bronchodilators. Clin Chest Med 1989;10:155-164.
17. Waalkens HJ, Merkus PJE, can Essen-Zandvliet EEM, et al, Assessment of bronchodilator
response in children with asthma. Eur Respir J 1993;6:645-651.
18. American Thoracic Society Workshop on Lung Function Testing, Becklare M, Crapo RO,
co-chairpersons. Lung function testing: selection of reference values and interpretative
strategies. Am Rev Respir Dis 1991;144 (5):1202-1218.
19. American Association for Respiratory Care. Clinical practice guideline: assessing response
to bronchodilator therapy at point of care. Respir Care 1995;40: 1300-1307.
20. Hepper NGG, Black LF, Fowler WS. Relationship of lung volume to height and arm span
in normal subjects and in patients with spinal deformity. Am Rev Respir Dis 1965;91:356362.
21. McKay RT, Lockey JE. Pulmonary function testing: guidelines for medical surveillance
and epidemiological studies. Occup Med 1991;6:43-57.
22. Morris AH, Kanner RE, Crapo RO, Gardner RM. Clinical pulmonary function testing: a
manual of uniform laboratory procedures, 2nd ed. Intermountain Thoracic Society, 1984,
Salt Lake City.
23. American Association for Respiratory Care. Clinical practice guideline: resuscitation in
acute care hospitals. Respir Care 1993;38(11):1169-1200.
24. Glindmeyer HW, Jones RN, Barkman HW, Weill H. Spirometry: quantitative test criteria
and test acceptability. Am Rev Respir Dis 1987;136(2):449-452.
25. Shigeoka JW. Calibration and quality control of spirometer systems. Respir Care
1983;28(6):747-753.
26. Centers for Disease Control. Update: universal precautions for prevention of transmission
of human immunodeficiency virus, hepatitis B virus, and other blood borne pathogens in
health care settings. MMWR 1988;37: 377-388.
27. Centers for Disease Control. Summary: recommendations for preventing transmission of
infection with human T-lymphotrophic virus type III/lymphadenopathy-associated virus in
the workplace. MMWR 1985; 34:681,686, 691-695.
28. Garner JS, Favero MS. CDC guidelines for the prevention and control of nosocomial
infections: guideline for hand washing and hospital environmental control. Am J Infect
Control 1986;14:110-129.
29. Tablan OC, Williams WW, Martone WJ. Infection control in pulmonary function
laboratories. Infect Control 1985;6:442-444.
30. Rutala DR, Rutala WA, Weber DR, et al. Infection risks associated with spirometry.
Infection Control Hospital Epidemiol 1991;12:89-92.
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43
PULMONARY FUNCTION TESTING
31. Centers for Disease Control and Prevention. Guidelines for preventing the transmission of
Mycobacterium tuberculosis in health care facilities, 1994. MMWR 1994; 43:1-32.
32. Centers for Disease Control and Prevention. Guidelines for preventing the transmission of
Mycobacterium tuberculosis in health-care facilities, 1994. MMWR 1994; 43:1-132.
33. Johns DP, Ingram C, Booth H, Williams TJ, Walters EH. Effect of a microaerosol barrier
filter on the measurement of lung function. Chest 1995;107(4): 1045-1048.
34. Fuso L, Accardo D, Bevignani G, et al. Effects of a filter at the mouth on pulmonary
function tests. Eur Respir J 1995; 8:314-317.
35. Wilkins, Robert L., Scanlan, Craig L., Stoller, James K.: Egan’s Fundamentals of
Respiratory Care. 8th edition. 2003. Elsevier Science.
36 Gold, Warren M., Nadel, Jay A.: Atlas of Procedures in Respiratory Medicine. 2002. WB
Saunders Company.
37 Wyka, Kenneth A., Mathews, Paul, Clark, William F., et al.: Foundations of Respiratory
Care. 2001. Delmar Learning.
38 Czervinske, Banrhart, Sherry: Perinatal and Pediatric Respiratory Care. 2002. WB
Saunders Company.
39 Murray, John F., Nadel, Jay A.: Textbook of Respiratory Medicine. 3rd edition. 2001.
Elsevier Science.
40 U.S. Center for Disease Control And Prevention (CDC). On-Line: www.cdc.gov.
Accessed April 2005.
41 Giddens, Jean Foret, PhD, MSN, RN, CS, Langford, Rae W., EdD, RN: Nursing PDQ.
2004. St Louis, Mosby.
42 Myers, Ehren, Hopkins, Tracey: LPN Notes. 2004. Philadelphia, F.A. Davis.
43 Lewis, Sharon, Dirksen, Shannon Ruff, Heitkemper, Margaret. Medical Surgical Nursing.
2003. Elsevier Science.
44 Oaks, Dana, BA, RRT, NPS, Clinical Practitioner’s Pocket Guide to Respiratory Care, 20th
Anniversary Issue, 6th Edition 2004.
45 WebMD Health, on-line, www.webmd.com, accessed May, 2005.
46. American Association for Respiratory Care: Clinical practice guideline: spirometer Respir
Care 1996; 41(7):629-636)
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PULMONARY FUNCTION TESTING
POST TEST
DIRECTIONS: IF COURSE WAS MAILED TO YOU, CIRCLE THE MOST CORRECT
ANSWERS ON THE ANSWER SHEET PROVIDED AND RETURN TO: RCECS, 16781
VAN BUREN BLVD, SUITE B, RIVERSIDE, CA 92504-5798 OR FAX TO: (951) 789-8861.
IF YOU ELECTED ONLINE DELIVERY, COMPLETE THE TEST ONLINE – PLEASE
DO NOT MAIL OR FAX BACK.
1. What are the primary indications for PFT’s?
a. Test for the presence of lung disease.
b. Identify if the patient has an obstructive or restrictive disorder.
c. Evaluate the extent of lung disease
d. All of the above
2. What are ATS standards?
a.
b.
c.
d.
Governmental regulations assuring conversion of BTPS conditions to ATPS.
Guidelines that safeguard against procedural errors and ensure accurate results.
Standards for predicting % of predicted values.
Standards for assessing post bronchodilator improvement.
3. What is the difference between lung capacities and lung volumes as pertains to PFT
terminology?
a.
b.
c.
d.
Each lung capacity contains 2 or more lung volumes.
Each lung volume contains 2 or more lung capacities.
Each lung volume contains more than 3 lung capacities.
There is no difference between lung volumes and lung capacities.
4. Which volumes are contained in the TLC?
a.
b.
c.
d.
IRV and ERV only.
VT and RV only.
IRV, VT, ERV, and RV.
IRV and RV only.
5. List the calculation for obtaining the normal IC value for adults.
a.
b.
c.
d.
50 mL/Kg of IBW.
80 mL/Kg of IBW.
30 mL/Kg of IBW.
7 mL/Kg of IBW.
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PULMONARY FUNCTION TESTING
6. List the calculation for obtaining the normal RV value for adults.
a.
b.
c.
d.
50 mL/Kg of IBW.
16 mL/Kg of IBW.
50% of TLC.
40% of TLC.
7. Spirometry can be used to measure:
a.
b.
c.
d.
Volumes only, not flow rates.
Flow rates only, not volumes.
Flow rates and volumes (except for the RV)
Residual volume only, no other volumes or flow rates.
8. Which of the following flow rates are best for measuring function of the small and medium
airways?
a.
b.
c.
d.
Inspiratory capacity.
Functional residual capacity.
MEFR.
MMFR.
9. Which lung volumes and capacities cannot be measured by spirometry?
a.
b.
c.
d.
RV, FRC, and TLC.
VC, IC, and VT.
VC, IRV, and ERV
IC, IRV, and VT.
10. Which tests can be used to measure residual volume?
a.
b.
c.
d.
Body box, IS, and V/Q scan.
Body box, DLCO, and arteriogram.
Body box, helium dilution, and nitrogen washout.
TGV, angiogram, and IS.
11. Which of the following can cause the single breath DLCO test result to be less than 25
mL/min/mmHg?
a.
b.
c.
d.
Emphysema.
Pulmonary fibrosis.
Pulmonary embolism
All of the above.
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PULMONARY FUNCTION TESTING
12. The body plethysmogram measures thoracic gas volume. The TGV is increased in:
a.
b.
c.
d.
Restrictive disease.
Obstructive disease.
Pneumonia.
Pneumothorax.
13. The helium dilution (closed circuit) and the nitrogen washout (open circuit) are most useful
for measuring:
a.
b.
c.
d.
FRC.
Peak flow rates.
FEV 2.0 seconds.
MEFR.
14. Which of the following best describes the pulmonary angiogram (arteriogram)?
a. Measures volumes and flow rates of the VC displayed in a graphic loop.
b. The patient inhales a xenon gas while a study is done to detect any areas of poor
perfusion, or poor ventilation.
c. A radiographic study of the arteries useful for detecting pulmonary embolism.
d. All of the above describe the arteriogram.
15. A V/Q scan can detect:
a.
b.
c.
d.
Closing Volume (CV) and Closing Capacity (CC).
Poorly ventilated areas, unperfused blood vessels, and pulmonary embolism.
The total volume of isoflow.
The Vmax50.
16. Which of the following statements are true?
I. The obstructive disease pattern reveals decreased flow rates.
II. The obstructive disease pattern reveals decreased residual volume.
III. The restrictive disease pattern reveals decreased volumes.
IV. The restrictive disease pattern reveals increased TLC.
a.
b.
c.
d.
I and II only.
I and III only.
II and III only.
I, II, III, and IV.
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PULMONARY FUNCTION TESTING
17. A patient’s PFT results on bedside spirometry are 85% of predicted values. These results
show:
a.
b.
c.
d.
Normal lung function.
A mild lung disorder.
A moderate lung disorder.
A severe lung disorder.
18. What is the formula for IBW in pounds for women?
a.
b.
c.
d.
(weight in pounds) / (height in inches2 ).
Height in inches x 2.5.
106 + (6 x height in inches over 60).
105 + (5 x height in inches over 60).
19. An oxygen index of 25 indicates:
a.
b.
c.
d.
Severe hypoxemia.
Mild hypoxemia.
Good oxygenation.
None of the above.
20. What is the formula for the P/F ratio?
a.
b.
c.
d.
PaO 2 / FiO 2 x 5.
PaCO2 / FiO 2 .
PaO 2 / FiO 2 .
PaCO2 / FiO 2 x 5.
HC: Test Version A
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48
PULMONARY FUNCTION TESTING
ANSWER SHEET
NAME____________________________________ STATE LIC #_______________________
ADDRESS_________________________________ AARC# (if applic.)___________________
DIRECTIONS: (REFER TO THE TEXT IF NECESSARY – PASSING SCORE FOR CE
CREDIT IS 70%). IF COURSE WAS MAILED TO YOU, CIRCLE THE MOST CORRECT
ANSWERS AND RETURN TO: RCECS, 16781 VAN BUREN BLVD, SUITE B,
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1. a b c d
16. a b c d
2.
a b c d
17. a b c d
3. a b c d
18. a b c d
4. a b c d
19. a b c d
5. a b c d
20. a b c d
6. a b c d
7. a b c d
8. a b c d
9. a b c d
10. a b c d
11. a b c d
12. a b c d
13. a b c d
14. a b c d
15. a b c d
HC: Test Version A
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49
PULMONARY FUNCTION TESTING
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50