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Pulmonary Function Tests
Wanida Paoin
1
Objectives
Review basic pulmonary anatomy and lung volumevolume.Indication for PFTs.Technique and basic interpretation of spirometryspirometry. Difference between obstructive and restrictive l dilung disease. Clinically application
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y pp
Conducting Airways
Air travels via laminar flow through theflow through the conducting airways:• trachea, • lobar bronchi, • segmental bronchi, • b t l b hi• subsegmental bronchi, • small bronchi, • bronchioles andbronchioles, and • terminal bronchioles.
3
From Netter Atlas of Human Anatomy, 1989
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Gas Exchange
Capillaries are wrapped around alveoliaround alveoli. Approximately 300 million alveolimillion alveoliAlveolar-capillary barrier: 0.3 μm in some places,0.3 μm in some places, surface area of 50-100 square meters! (size of a
M & N d l T b k f R i(
tennis court) Murray & Nadel: Textbook of Respiratory Medicine, 3rd ed., Copyright © 2000 W. B. Saunders Company
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Lung Volumes
4 Volumes
IRV4 Capacities• Sum of 2 or more
l lIC lung volumesICVC
TLCTV
ERVFRC
TLC
RVFRC
RV
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Pulmonary Function Tests
• Pulse oximetry • Blood gasesBlood gases • End tidal CO2• Spirometry
P k i fl• Peak expiratory flow rate • Bronchial challenge testing • Exercise testsExercise tests • Respiratory muscle pressure measurement• Lung volumes by helium dilution or body
plethysmographyplethysmography• Diffusing capacity
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Pulmonary Function Tests
Evaluates 1 or more major aspects of th i t tthe respiratory system• Lung volumes• Airway function• Gas exchangeg
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Indications
Detect disease Evaluate extent and monitor course of diseaseEvaluate treatmentM ff t fMeasure effects of exposuresAssess risk for surgical proceduresg pAssess bronchial hyperreactivity
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Evaluate extent and monitor Evaluate extent and monitor course of disease
Obstructive disease- asthma- asthma- FB- subglottic, tracheal stenosis
t h l i- tracheomalacia- vascular ring- vocal cord paralysis
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Evaluate extent and monitor Evaluate extent and monitor course of disease
Restictive diseaseRestictive disease- external compression: thoracic cage abnormality, pleural
effusion, pneumothorax, obesity, scoliosisunexpanded lung: interstitial fibrosis pulmonary edema- unexpanded lung: interstitial fibrosis, pulmonary edema
- neuromuscular disease: poliomyelitis, myasthenia grevis
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Importance
Patients and physicians have inaccurate ti f it f i flperceptions of severity of airflow
obstruction and/or severity of lung disease by physical examProvides objective evidence inProvides objective evidence in identifying patterns of disease
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Spirometry
Measurement of the pattern of air movementinto and out of the lungsduring controlled ventilatory maneuvers.
Silhouette of Hutchinson Performing Spirometry, From Chest, 2002
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Limitation
They do not act alone.They do not act alone.They act only to supportor exclude a diagnosisor exclude a diagnosis.
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Mechanical Properties
Compliance• Describes the stiffness of the lungs• volume / pressure
Elastic recoil• The tendency of the lung to return to it’sThe tendency of the lung to return to it s
resting state• A lung that is fully stretched has more elasticA lung that is fully stretched has more elastic
recoil and thus larger maximal flows
15
Resistive Properties
Determined by airway caliberAffected by• Lung volumeg• Bronchial smooth muscles• Airway collapsibilityAirway collapsibility
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Factors That Affect Lung Volumes
AgeSexHeightHeightWeightRaceDiseaseDisease
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Special Considerations
Ability to perform spirometry dependent on y p p y pdevelopmental age of child, personality, and interest of the child.Patients need a calm, relaxed environment and good coaching. Patience is key.and good coaching. Patience is key.Even with the best of environments and coaching a child may not be able to performcoaching, a child may not be able to perform spirometry.
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Parameter from spirometer
Spirogram
FVC
PEFR
FVC
FEV1FEF25 75FEF25-75
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Flow-Volume Curve
TechniqueGive instructions and demonstratePatient performs the maneuver
Acceptable criteria< 10 y: > 3 min > 10 y: > 6 minPatient performs the maneuver
• Sit / Stand direct• Puts nose clip on
> 10 y: > 6 minor no more volume > 1 minNot inhaleNo air leak• Inhales maximally
• Puts mouthpiece on mouth and closes lips around mouthpiece
No air leakNo pause
2 maximum FVC different < 10%p• Exhales as hard and fast and long as possible• Repeat minimum of three times (check for
reproducibility )
2 maximum FVC different < 10%
reproducibility.)• Use the best value for interpretation as %predicted of
control (age, height, sex, race)
20(adapted from ATS, 1994)
FVC
Forced vital capacity (FVC):(FVC):• Total volume of air that can
be exhaled forcefully from be e a ed o ce u y oTLC
• The majority of FVC can be exhaled in <3 seconds in normal people, but often is much more prolonged inmuch more prolonged in obstructive diseases
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FEV1
Forced expiratory volume in 1 second:volume in 1 second: (FEV1)• Volume of air forcefully
expired from full inflation (TLC) in the first second
• Normal people can exhaleNormal people can exhale more than 80% of their FVC in the first second (FEV /FVC)(FEV1/FVC)
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FEF25-75
Forced expiratory flow 25-75% (FEF )75% (FEF25-75)• Mean forced expiratory flow
during middle half of FVC du g dd e a o C• May reflect effort independent
expiration and the status of the small airways
• Highly variable• D d h il FVC• Depends heavily on FVC
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PEFR
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PEFR
Peak flow meter deviceTechniqueTechnique • Sit/Stand direct• Inhales maximallyy• Puts mouthpiece on mouth and closes lips around
mouthpiece• Blow out as hard and fast as possibleGreen : > 80%Blow out as hard and fast as possible• Repeat minimum of three times • Use the best value for interpretation as %predicted /
personal best
Yellow : 50-79%Red : < 50% Normal < 20%
Normal < 12%personal best • Clinical application: monitor severity, daily variability,
pre and post bronchodilator
Normal < 12%
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Categories of Disease
ObstructiveRestrictiveMixedMixed
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FVC
Interpretation of % predicted:• 80 % Normal• 70-79% Mild reduction• 50%-69% Moderate reduction• <50% Severe reduction
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FEV1
Interpretation of % predicted:• >80% Normal• 65-79% Mild obstruction• 50-64% Moderate obstruction• <49% Severe obstruction
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Spirometry Interpretation:
% predictedFVC > 80%FEV1 > 80%FEF25-75% > 70%25-75%
PEFR > 80%FEV1/FVC > 80% absolute valueFEV1/FVC > 80% absolute value
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Spirometry in Obstructive Spirometry in Obstructive Disease
Slow rise in upstrokeM t hMay not reach plateau
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Restrictive Disease
Rapid upstroke p pas in normal spirometryp yPlateau volume is lowo
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S i t I t t ti Ob t tiSpirometry Interpretation: Obstructive vs. Restrictive DefectWhat parameter is the most sensitive in airway obstruction?
Parameter Obstructive Disorders
Restrictive Disorders
What parameter is the most sensitive in airway obstruction?
Disorders DisordersFVC N or ↓ ↓
FEV1
FEF
↓ ↓
NFEF25-75%
FEV1/FVC
↓ N to ↓
↓ N or ↑
PEFR
↓ o ↑
↓ N to ↓
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Spirometry Interpretation:Obstructive Disorders• Characterized by a
Restrictive Disorders• Characterized by y
limitation of expiratory airflow
Examples:
yreduced lung volumes/decreased lung compliancea p es
• Asthma• Bronchiectasis • COPD
Examples:• Interstitial Fibrosis• Kyphoscoliosis• COPD
• Cystic FibrosisKyphoscoliosis
• Obesity• Lung Resection• Neuromuscular diseases• Cystic Fibrosis
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Fl V l LFlow-Volume LoopPEFR
Do FVC maneuver and then inhale as
flow
and then inhale as rapidly and as much as ableexpiration as able.The expiratory and inspiratory flow
volumeinspiration
inspiratory flow volume curves put together make a flowtogether make a flow volume loop.RVTLC
34Ruppel GL. Manual of Pulmonary Function Testing, 8th ed., Mosby 2003
Restrictive Lung Disease
Ch t i d bCharacterized by diminished lung volume Decreased TLC FVCDecreased TLC, FVCNormal or increased: FEV1/FVC ratioFEV1/FVC ratio
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Obstructive Lung Disease
Characterized by a limitation of expiratorylimitation of expiratory airflow• Examples: asthma, a p es ast a,
COPD
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Large Airway Obstruction
Characterized by a truncatedtruncated inspiratory or expiratory loopexpiratory loop
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Flow-Volume LoopsL1 R1
L2 R2R2
L3 R3
Variable intrathoracic ob
Incomplete exhalationVariable extrathoracic ob
L4 Variable intrathoracic obFixed central or up aw ob
Inadq effortRestricti e l ng disease
38(Rudolph and Rudolph, 2003)
Restrictive lung disease
Spirometry: Pre and Post Bronchodilator
Obtain spirogram and flow-volume loop.Pre and 15 minutes after administration ofPre and 15 minutes after administration of the bronchodilator Salbutamol MDI 4 puffs via valve spacerSalbutamol MDI 4 puffs via valve spacer • Slow inhale• Breath hold 5-10 secBreath hold 5-10 sec.• 5-10 sec pause between each puff.
Reversibility: FEV1 / PEFR > 12%Reversibility: FEV1 / PEFR > 12% Improve flow-volume loop.
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PEFR
Inhales maximallyyExhales as hard and fast and short as possibleRepeat minimum of three times pUse the best value for interpretation as %predicted of control / personal bestHighly effort dependentDiurnal variation (normal < 20%)Different value in each devices
40
Exercise challenge test
Perform spirometryPerform spirometryExercise 6-8 min (tread mill) till HR
/160-180/minRepeat spirometry at 5, 10, 15, 20, 30Repeat spirometry at 5, 10, 15, 20, 30 minEIB FEV 10 15% h iEIB: FEV1 10-15%, or wheezing
41
Respiratory muscle testing
Measure maximum inspiratory P. (PImax, MIP) or negative inspiratory force (NIF)Maximum inhale via pressure manometerpNormal < -60 cmH2OUseful for evaluation neuromuscular dis:Useful for evaluation neuromuscular dis: myasthenia grevis, Guillian-Barre syndrome, diaphragmatic paralysis pre extubationdiaphragmatic paralysis, pre-extubationOther parameter: FVC, PEFR
42
ClinicalClinical Applicationspp
43
Case #1Case #1
Case #1
Parameter Actual %PredictedFVC (L) 4.11 116
FEV1 (L) 3.28 108
FEV1/FVC (%) 80 93
FEF (L/s) 6 94 88
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FEF25-75% (L/s) 6.94 88
PEFR (L/s) 3.15 107
C #2Case #2
Parameter Actual (best) Predicted %PredictedFVC (L) 4.31 4.44 97
FEV1 (L) 2.15 3.83 56
FEV1/FVC (%) 50 86 58
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FEF25-75% (L/s) 0.93 4.27 22
PEFR (L/s) 5.23 8.01 65
C #3Case #3
Parameter Actual (best) Predicted %PredictedFVC (L) 1.24 3.60 34
1 19 3 09 38FEV1 (L) 1.19 3.09 38
FEV1/FVC (%) 95.65 86.00 111
FEF (L/s) 1 69 3 48 48
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FEF25-75% (L/s) 1.69 3.48 48
PEFR (L/s) 4.37 6.70 65
Case #4
Parameter Actual (best) Predicted %PredictedFVC (L) 3.40 4.93 69
FEV (L) 2 17 4 25 51FEV1 (L) 2.17 4.25 51
FEV1/FVC (%) 63.72 84.68 75
FEF (L/s) 1.09 4.75 23
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FEF25-75% (L/s) 1.09 4.75 23
PEFR (L/s) 6.65 9.00 73
Case #5Case #5
Parameter Pre %Pred Post %Pred %Change
FVC (L) 1.58 84 1.91 102 21.07
FEV1 (L) 1.04 63 1.44 87 38.62
FEV1/FVC 66.05 77 75.63 88 14.50
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FEF25-75% 0.55 27 1.10 55 101.64
PEFR (L/s) 2.39 73 3.42 104 42.85