clinical application of pulmonary function tests.pptm1
TRANSCRIPT
Clinical Application of
Pulmonary Function Tests
Gamal Rabie Agmy, MD, FCCP Professor of Chest Diseases, Assiut University
ERS National Delegate of Egypt
Anatomy
Lungs comprised of
Airways
Alveoli
http://www.aduk.org.uk/gfx/lungs.jpg
Weibel ER: Morphometry of the Human Lung. Berlin and New York: Springer-
Verlag, 1963
The Airways
Conducting zone: no gas exchange occurs
Anatomic dead
space
Transitional zone: alveoli appear, but are
not great in number
Respiratory zone: contain the alveolar
sacs
From Netter Atlas of Human Anatomy, 1989
How does gas exchange occur?
• Numerous capillaries are wrapped around
alveoli.
• Gas diffuses across this alveolar-capillary
barrier.
• This barrier is as thin as 0.3 μm in some
places and has a surface area of 50-100
square meters!
Gas Exchange
From Netter
Atlas of
Human
Anatomy,
1989
The Alveoli
Approximately 300
million alveoli
1/3 mm diameter
Total surface area if
they were complete
spheres 85 sq.
meters (size of a
tennis court)
Murray & Nadel: Textbook of Respiratory
Medicine, 3rd ed., Copyright © 2000 W. B.
Saunders Company
Mechanics of Breathing
Inspiration
Active process
Expiration
Quiet breathing: passive
Can become active
Pulmonary Function Tests
Airway function
Simple spirometry
Forced vital capacity
maneuver
Maximal voluntary
ventilation
Maximal
inspiratory/expiratory
pressures
Airway resistance
Lung volumes and
ventilation
Functional residual
capacity
Total lung capacity,
residual volume
Minute ventilation,
alveolar ventilation,
dead space
Distribution of
ventilation
Pulmonary Function Tests
Diffusing capacity
tests
Blood gases and gas
exchange tests
Blood gas analysis
Pulse oximetry
Capnography
Cardiopulmonary
exercise tests
Metabolic
measurements
Resting energy
expenditure
Substrate utilization
Chemical analysis of
exhaled breath
Terminology
Forced vital capacity
(FVC):
Total volume of air that can
be exhaled forcefully from
TLC
The majority of FVC can be
exhaled in <3 seconds in
normal people, but often is
much more prolonged in
obstructive diseases
Measured in liters (L)
FVC
Interpretation of % predicted:
80-120% Normal
70-79% Mild reduction
50%-69% Moderate reduction
<50% Severe reduction
FVC
Terminology
Forced expiratory volume in 1 second: (FEV1)
Volume of air forcefully expired from full inflation (TLC) in the first second
Measured in liters (L)
Normal people can exhale more than 75-80% of their FVC in the first second; thus the FEV1/FVC can be utilized to characterize lung disease
FEV1
Interpretation of % predicted:
> 80% Mild
50-80% Moderate obstruction
30-50% severe obstruction
<30% Severe obstruction
FEV1 FVC
Terminology
Forced expiratory flow 25-
75% (FEF25-75)
Mean forced expiratory flow
during middle half of FVC
Measured in L/sec
May reflect effort
independent expiration and
the status of the small
airways
Highly variable
Depends heavily on FVC
FEF25-75
Interpretation of % predicted:
>60% Normal
40-60% Mild obstruction
20-40% Moderate obstruction
<20% Severe obstruction
Acceptability Criteria
Good start of test
No coughing
No variable flow
No early termination
Reproducibility
Acceptable and Unacceptable
Spirograms (from ATS, 1994)
Changes in Lung Volumes in
Various Disease States
Ruppel GL. Manual of Pulmonary Function Testing, 8th ed., Mosby 2003
TLC
TLC < 80% of predicted value = restriction.
TLC > 120% of predicted value =
hyperinflation.
1-First Step, Check quality of the test
1- Start:
*Good start: Extrapolated volume (EV) < 5% of FVC or 0.15 L
*Poor start: Extrapolated volume (EV) ≥5% of FVC or ≥ 0.15 L
2- Termination:
*No early termination :Tex ≥ 6 s
*Early termination : Tex < 6 s
2- Look at …………FEV1/FVC
< N(70%)
Obstructive or Mixed
≥ N(70%)
Restrictive or Normal
3- Look at FEV1 To detect degree Mild > 70% Mod 50-69 %
Severe 35-49%
Very severe < 35%
4- Postbronchodilator FEV1/FVC
> 70%
asthma
< 70%
COPD
5- Reversibility test of FEV1
> 12%, 200 ml
Reversible (asthma)
< 12% ,200 ml
Ireversible (COPD)
6- Look at TLC
≥ 100% Pure obstruction < 100% Mixed
2- Look at …………FEV1/FVC
< N(70%)
Obstructive or Mixed
≥ N(70%)
Restrictive or Normal
3- Look at FVC
≥ N(80%) < N(80%) Normal or SAWD
4-Look at FEF25/75
> 50% Normal < 50% SAWD
Restrictive
Patterns of Abnormality
Restriction low FEV1 & FVC, high FEV1%FVC
Recorded Predicted SR %Pred
FEV 1 1.49 2.52 -2.0 59
FVC 1.97 3.32 -2.2 59
FEV 1%FVC 76 74 0.3 103
PEF 8.42 7.19 1.0 117
Obstructive low FEV1 relative to FVC, low PEF, low FEV1%FVC
Recorded Predicted SR %Pred
FEV 1 0.56 3.25 -5.3 17
FVC 1.65 4.04 -3.9 41
FEV 1%FVC 34 78 -6.1 44
PEF 2.5 8.28 -4.8 30
high PEF early ILD
low PEF late ILD
Patterns of Abnormality
Upper Airway Obstruction low PEF relative to FEV1
Recorded Predicted SR %Pred
FEV 1 2.17 2.27 -0.3 96
FVC 2.68 2.70 0.0 99
FEV 1%FVC 81 76 0.7 106
PEF 2.95 5.99 -3.4 49
FEV 1 /PEF 12.3
Discordant PEF and FEV1
High PEF versus FEV1 = early interstitial lung disease (ILD)
Low PEF versus FEV1 = upper airway obstruction
Concordant PEF and FEV1
Both low in airflow obstruction, myopathy, late ILD
Common FVL Shapes
Volume
Flo
w
Normal Young or quitter Poor effort
Hesitation Knee Coughing
Asthma
0 1 2 3 4 5 60
2
4
6
8
10
12
Flo
w in
L/s
Litres
concave FV curve
intrapulmonary airflow obstruction
Restrictive
0 1 2 3 4 5 6
-8
-6
-4
-2
0
2
4
6
8
10
12 F 19 yrs 1.64m
FVC 2.41 L -3.42 SR
FEV 2.41 L -2.62 SR
FEV% 100 +2.23 SR
PEF 5.55L/s -2.00 SR
F/P 7.2 RT 116 ms
Flo
w in
L/s
Litres
COPD
0 1 2 3 4 5
-6
-4
-2
0
2
4
6
8
10
Flo
w in L
/s
Litres
pressure dependent airways collapse
Poorly co-ordinated start
0 1 2 3 4 5 6
-10
-8
-6
-4
-2
0
2
4
6
8
10
12
Flo
w in L
/s
Litres
EV = large
Rise Time = 496 ms
Irregular shape
Poorly repeatable
Upper Airway Obstruction
0 1 2 3 4 5 6
-6
-4
-2
0
2
4
6 Age 40 yrs
FVC 3.52 L 0.84 SR
FEV1 3.0 L 0.74 SR
PEF 4.57 L/s -2.18 SR
FEV/PEF = 10.9
Inspiratory
Expiratory
Flo
w in
L/s
Volume in Litres
FEV1 in mls
PEF in L/min > 8
Upper Airway Obstruction
0 1 2 3 4 5 6
-6
-4
-2
0
2
4
6
8
10
12
Flo
w in
L/s
Volume in Litres
Male aged 62 Height 1.68m
Recorded Predicted Range SR
FEV1 2.23 2.94 2.1 to 3.8 -1.4
FVC 3.40 3.71 2.7 to 4.7 -0.5
FEV1%FVC 66 76 64 to 88 -1.5
PEF 2.85 7.81 5.8 to 9.8 -4.1
FEV1/PEF 13.1
Inspiration
-ve
-ve
Expiration
+ve
+ve
Extra-thoracic UAO
worse on insp. Intra-thoracic UAO
worse on exp.
Variable UAO
Intra-thoracic UAO
0 1 2 3 4 5 6
-8
-6
-4
-2
0
2
4
6
8
10
12F
low
in L
/s
Liters
Age 65 Female
FVC 2.97 L 1.3 SR
FEV1 2.26 L 0.6 SR
FEV1% 76% -0.1 SR
PEF 3.4 L·s-1 -2.5 SR F/P 11.1 RT 455 ms
Variable Extrathoracic Upper Airway Obstruction
Fixed Upper Airway Obstruction
Upper Airway Obstruction
• Variable extrathoracic obstructions 1. vocal cord paralysis,
2. thyromegaly,
3. tracheomalacia, or
4. Neoplasm
• Large airways variable intrathoracic obstructions 1. tracheomalacia or
2. neoplasm
• Fixed obstruction 1. tracheal stenosis,
2. foreign body, or
3. neoplasm.
*If FIVC /FEVC >90, FIF50 <80% predicted and
FEF50/FIF50 <0.8 variable intrathoracic
large and upper airway obstruction.
*If FIVC /FEVC >90, FIF50 <80% predicted and
FEF50/FIF50>1.2 Variable extrathoracic
obstruction.
*If FIVC /FEVC >90, FIF50 <80% predicted and
FEF50/FIF50 = 0.8 – 1.2 Fixed upper
airway obstruction.
Obstruction, Restriction, Mixed
True Restrictive Disorders
Intraparenchymal
Interstitial Infilterative Diffuse alveolar
Chest Wall
Pleural Skeletal
Reduced TLC.FRC,RV,VC and normal to high FEV1/FVC
In 50% DLco/VA>80% The other half had low DLco/VA
Pseudorestrictive Disorders
Normally: IC/ERV=2-3/1
True restrictive: IC/ERV=<2/1
Pseudorestrictive: IC/ERV=6/1
Pseudorestrictive Disorders
Obesity:
*Early airway closure (low ERV & high RV)
*FRC is more reduced than TLC&VC
*Low FEF50% , FEF75%, FEF25-75%,
Pseudorestrictive Disorders
Neuromuscular Disease:
*FRC normal
*IC&ERV decreased
*Decreased TLC
*Increased RV
*A-aO2 gradient normal
*MIP&MEP decreased
Pseudorestrictive Disorders
Asthma:
*FRC &TLC increased
*Improvement of FEV1&FVC with bronchodilators
*Positive bronchoprovacation test
*Increased diffusing capacity and DLco/VA
Pseudopseudorestrictive
Patients with obstructive diseases who do not
complete expiratory effort of FVC. This may
lead to a below normal FEV1 and FVC with
pseudonormalization of ratio.
Where is the pathology ???????
in the areas with increased density meaning there is ground glass
in the areas with decreased density meaning there is air trapping
Pathology in black areas
Airtrapping: Airway Disease Bronchiolitis obliterans (constrictive bronchiolitis)
idiopathic, connective tissue diseases, drug reaction,
after transplantation, after infection
Hypersensitivity pneumonitis granulomatous inflammation of bronchiolar wall
Sarcoidosis granulomatous inflammation of bronchiolar wall
Asthma / Bronchiectasis / Airway diseases
Airway Disease
what you see…… In inspiration
sharply demarcated areas of seemingly increased
density (normal) and decreased density
demarcation by interlobular septa
In expiration ‘black’ areas remain in volume and density
‘white’ areas decrease in volume and increase in
density
INCREASE IN CONTRAST
DIFFERENCES AIRTRAPPING
Bronchiolitis
obliterans
Early Sarcoidosis
Cystic Fibrosis
Chronic EAA
Hypersensitivity pneumonitis
HRCT Morphology
chronic: fibrosis
Intra- / interlobular septal thickening
Irregular interfaces
Traction bronchiectasis
acute - subacute
acinar (centrilobular) unsharp densities
ground glass (patchy - diffuse)
Pathology in white Areas
Alveolitis / Pneumonitis Ground glass
desquamative intertitial pneumoinia (DIP)
nonspecific interstitial pneumonia (NSIP)
organizing pneumonia
In expiration both areas (white and black) decrease in
volume and increase in density
DECREASE IN CONTRAST
DIFFERENCES
DIP
Cellular
NSIP
Mosaic Perfusion
Chronic pulmonary embolism
LOOK FOR
Pulmonary hypertension
idiopathic, cardiac disease, pulmonary
disease
CTEPH =
Chronic thrombembolic
pulmonary hypertension
Mixed Disorder
*Sarcoidosis
*Rhematoid
*Advanced IPF
*Bronchiectasis
*BOOP in smokers
Preoperative Assessment
1- If FVC and FEV1>80% or 2L and DLco75%,
the patient can tolerate pneumonectomy.
2-If FVC,FEV1 and DLco< limits in step 1:
Predicted postoperative values of FEV1 and
DLco
Split Lung Function Studies
• Unilateral ventilation is measured by inhalation Xe133 and perfusion is measured by IV Tc99m albumin macroaggregates.
Split Lung Function Studies
• Postoperative FEV1= preoperative FEV1-preoperative FEV1 x % of function of tumor-containing lung X( no. of segments of resected lobe/ total no. of segments of the lung )
E.g. preoperative FEV1= 2.0L
right lung function=40%
RUL lobectomy will be done.
Postoperative FEV1 = 2.0-2.0x40%x3/10=1.76L
Postoperative FEV1
• If radiospirometry is not done, then
Postoperative FEV1= preoperative FEV1-preoperative FEV1 x 1/19x no. of resected segments
E.g. preoperative FEV1= 2.0L
RUL lobectomy will be done.
Postoperative FEV1 = 2.0-2.0x1/19x3=1.684
Preoperative Assessment
3- Exercise testing:Maximum o2
consumption>75% or 20 mL/kg/min-----
pneumonectomy.
Maximum o2 consumption <40% or 10 mL/kg/min-
----Inoperable