Clinical application of pulmonary function tests.pptm1

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