PULMONARY FUNCTION TESTS

PULMONARY FUNCTION TESTS

1. 03/22/15 Dr. Nilesh Kate ESIC MEDICAL COLLEGE GULBARGA
A Review of
Pulmonary
function
tests
Dr Nilesh N Kate.
Associate Professor,
ESIC MEDICAL
COLLEGE
GULBARGA.

2. Objectives
At the end of the lecture you should know:
Definition & normal values of TV, IRV, ERV, RV, IC, FRC,
VC, TLC, TVC, FEF25-75%, MV, PEFR, MVV, Breathing Reserve
& Dyspnoeic Index.
Clinical significance: obstructive & restrictive lung
diseases.
Factors affecting VC.
Normal functioning of spirometer & normal spirogram.
Measurement of FRC by nitrogen washout and helium
dilution method.
Dead space: definition, normal value, types, measurement
and significance.

3. Introduction
Lung volumes and capacities are
quantitative measurements of
pulmonary ventilation.
Ventilation is the process
whereby the lungs replenish the
gas in the alveoli.
Measures gas volume contained in
the lungs under certain
circumstances and the rate at
which gas can be expelled from
the lungs.

4. History
Borelli –(1679) Earliest physiologist
(Hutchinson)
Humphrey Davy (1800) by mercurial air
holding machine & H
2
dilution technique
measured own RV
Hutchinson-Capacity of lung & respiratory
function
03/22/15 Dr. Nilesh Kate GMC A'BAD

5. Indication
Diagnostic—1
st
grade and 2
nd
grade
Evaluation and control of treatment
In surgery
Occupational hazards--Bysinosis
03/22/15 Dr. Nilesh Kate GMC A'BAD

6. Lung volumes & capacities
It can be of two types:
Static lung volumes & capacities:
Time factor not involved.
Measured in ml or liters.
TV, IRV, ERV, RV, IC, FRC, VC, TLC
Dynamic lung volumes & capacities:
Time dependent.
Measured in ml/min or l/min.
TVC, FEF25-75%, MV, PEFR, MVV
Most of these can be measured by spirometry

7. Tidal Volume (TV)
IRV
TV
ERV
RV
IC
FRC
VC
TLC
RV
Volume of air
inspired or expired
during normal quiet
breathing.
Males = 500 ml
Females = 500 ml

8. Inspiratory Reserve Volume (IRV)
IRV
TV
ERV
The maximum
amount of air
that can be
inhaled after a
normal tidal
inspiration.
Males =3300 ml
Females = 1900 ml
RV
IC
FRC
VC
TLC
RV

9. Expiratory Reserve Volume (ERV)
IRV
TV
ERV
Maximum volume
of air that can be
expired after a
normal tidal
expiration.
Males =1000 ml
Females = 700ml
RV
IC
FRC
VC
TLC
RV

10. Residual Volume (RV)
IRV
TV
ERV
Volume of air
remaining in the
lungs after
maximal
expiration.
Males =1200 ml
Females = 1100 ml
RV
IC
FRC
VC
TLC
RV

11. Inspiratory Capacity (IC)
IRV
TV
ERV
Maximum amount
of air which can
be inspired after
completing tidal
expiration.
IC = IRV + TV
Males =3800 ml
Females = 2400
ml
RV
IC
FRC
VC
TLC
RV

12. Functional Residual Capacity (FRC)
IRV
TV
ERV
Volume of air
remaining in the
lungs at the end of
tidal expiration.
FRC = ERV + RV
Males =2200 ml
Females = 1800 ml
RV
IC
FRC
VC
TLC
RV

13. Vital Capacity (VC)
IRV
TV
ERV
Maximal volume of
air that can be
exhaled from the
lungs after a
maximum inspiration.
VC = IRV + TV +ERV
Males =4800 ml
Females = 3100 ml
RV
IC
FRC
VC
TLC
RV

14. Factors affecting VC
Physiological:
Physical dimensions – size & physical dev. (M>F)
Age – dec. in old age
Strength of respiratory muscles – inc. in swimmers & divers
Posture- standing > sitting > lying
Pregnancy- dec. VC
Pathological:
Diseases of respiratory system- obstructive & restrictive
Diseases of the heart- CHF
Diseases of the pleura- pleural effusion
Diseases of the abdominal cavity- ascitis

15. Total Lung Capacity (TLC)
IRV
TV
ERV
Volume of air in the
lungs after a
maximal inspiration
TLC = IRV + TV +
ERV + RV
Males =6000 ml
Females = 4200ml
RV
IC
FRC
VC
TLC
RV

16. Important

17. Spirometer
Instrument used to measure lung volumes &
capacities.
It records the amount of air and the rate of air that is
breathed in and out over a specified time.

18. SpirometerSpirometer

19. Spirometer
Can not measure RV, FRC &
TLC.
FRC is measured by:
Nitrogen washout method
Helium dilution method
RV = FRC – ERV

20. Nitrogen washout method

21. Helium-Dilution method method

22. DEAD SPACE

23. Introduction
Total 23 generations of
airways b/w trachea &
alveolar sac.
First 16 generations:
Conducting zone
No gaseous exchange
Up to terminal bronchiole
Last 7 generations
Transitional & respiratory zone
Gaseous exchange
Include respiratory bronchiole,
alveolar ducts & alveoli

24. Dead Space
Part of the tidal volume that does not take part
in gaseous exchange with pulmonary capillary
blood.
This can be:
Anatomical dead space
Alveolar dead space
Total (Physiological) dead space

25. Anatomical dead space
Gas in the conducting areas of the
respiratory passage, where no
gaseous exchange occurs.
Volume of air from nose to
terminal bronchiole.
Approximately equal to the body
weight in pounds.
So, in a 68 kg (150 lb) manSo, in a 68 kg (150 lb) man
Anatomical dead space = 150 mlAnatomical dead space = 150 ml
i.e. out of 500 ml inspired air, only 350 ml i.e. out of 500 ml inspired air, only 350 ml
reaches the alveoli for gaseous exchange.reaches the alveoli for gaseous exchange.
rest 150 ml just fills the anatomical dead spacerest 150 ml just fills the anatomical dead space
During expiration,During expiration,
First 150 ml – dead space airFirst 150 ml – dead space air
Last 350 ml – alveolar air Last 350 ml – alveolar air

26. Anatomical dead space
Alveolar ventilation (amount of air
reaching the alveoli per min) is less
than the respiratory minute volume.
If, tidal volume = 500 ml & RR = 12/minIf, tidal volume = 500 ml & RR = 12/min
Dead space volume = 150 mlDead space volume = 150 ml
Then, air reaching the alveoli = 500-150 mlThen, air reaching the alveoli = 500-150 ml
= 350 ml= 350 ml
Minute volume = 500 x 12 = 6 l/minMinute volume = 500 x 12 = 6 l/min
Alveolar ventilation = (500-150) x 12Alveolar ventilation = (500-150) x 12
= 350 x 12= 350 x 12
= 4200 ml= 4200 ml

27. Anatomical dead space
Rapid shallow breathing produces
much less alveolar ventilation than
slow deep breathing at the same
respiratory minute volume.
Respiratory rate Respiratory rate 30/min 30/min 10/min 10/min
Tidal volume Tidal volume 200 mL 200 mL 600 mL 600 mL
Minute volume Minute volume 6 L 6 L 6 L 6 L
Alveolar ventilation (200 – 150) x 30 (600 – 150) x 10Alveolar ventilation (200 – 150) x 30 (600 – 150) x 10
= 1500 mL = 4500 mL= 1500 mL = 4500 mL

28. Alveolar dead space
Gas present in under-
perfused or non-perfused
alveoli and excess gas
present in over-ventilated
alveoli.
Alveolar air that is not
equilibrating with the
pulmonar capillary blood.
If, Tidal volume = 500 mlIf, Tidal volume = 500 ml
Anatomical dead space = 150 mlAnatomical dead space = 150 ml
Alveolar dead space = 100 mlAlveolar dead space = 100 ml
Effective alveolar ventilation = 500 – 150 – 100Effective alveolar ventilation = 500 – 150 – 100
= 250 ml= 250 ml

29. Total (Physiological) dead space
Total volume of inspired air that
does not equilibrate with the
pulmonary capillary blood.
Total DS = Anatomical DS +
Alveolar DS
In a healthy individual, Total DS
and Anatomical DS are equal.

30. Measurement of dead space
Anatomic dead space – Single breath N2 curve
Total dead space – Bohr’s equation
PECO2 x VT = PaCO2 x (VT – VD) + PICO2 x VD
PCO 2 of the expired gas (PECO 2)
Arterial PCO 2 (PaCO 2)
PCO 2 of inspired air (PICO 2)
Tidal volume (VT)
Dead space volume (VD)

31. Single breath N2 curve
Subject is asked to take a
deep breath of Oxygen.
This fills the entire dead
space with pure Oxygen.
Some Oxygen also mixes with
the alveolar air but does not
completely replace their air.
Then the person expires
through a rapidly recording
Nitrogen meter
end exp
VT
VD
VA

32. Results obtained
First portion- from the dead
space regions-Nitrogen
concentration is zero.
After some time- Nitrogen
concentration rises rapidly
because alveolar air containing
Nitrogen + dead space air.
At end- only air from alveoli-
high steady concentration of
nitrogen.

33. CALCULATION :

VE = total volume of
expired air.
VD = dead space air
Suppose gray area = 30 cm ² Suppose gray area = 30 cm ²
Pink area Pink area = 70 cm ² = 70 cm ²
Total volume expired is 500 mlTotal volume expired is 500 ml
Then dead space would be : Then dead space would be : 30 x 50030 x 500
30+7030+70
= 150 ml= 150 ml

34. Timed Vital Capacity (FEV1)
(Forced Expiratory Volume in 1 sec. )
Measures the fraction of FVC
expired in 1 sec.
The majority of FVC can be
exhaled in <3 seconds in normal
people.
FEV
1
= 80%
FEV
2
= 93%
FEV
3
= 98%
Helps to differentiate b/w
obstructive & restrictive patterns
of lung diseases.

If FVC = 5 liter &If FVC = 5 liter &
Volume of air expired in first second = 4 literVolume of air expired in first second = 4 liter
FEVFEV11 = 4/5 x 100 = 4/5 x 100
= 80 %= 80 %

35. Forced Expiratory Flow 25-75% (FEF
25-75%
)
(Maximum Mid-Expiratory Flow Rate, MMEFR)
Mean forced expiratory
flow during middle half
of FVC.
Measured in L/min
Normal = 300 L/min
May reflect effort
independent expiration
and the status of the
small airways.

36. 03/22/15 Dr. Nilesh Kate GMC A'BAD

37. Minute ventilation (MV)
Pulmonary Ventilation (PV)
Volume of air inspired or expired by lungs in
one minute.
MV=TV x RR
= 500 x 12
= 6 liter/min

38. Maximum Breathing Capacity (MBC)
Maximum Voluntary Ventilation (MVV)
Largest volume of air
that can be moved into
and out of lungs in one
minute by maximum
voluntary effort.
Normally 90-170
l/min

39. Pulmonary Reserve (PR)
Breathing Reserve (BR)
Maximum volume of air above the pulmonary
ventilation, which can be breathed in and out of
lungs in one min.
BR = MVV – PV
If, MVV = 100 l/min &
PV = 6 l/min
BR = 100 – 6 l/min
= 94 l/min

40. Dyspnoeic Index (DI)
(Percentage Pulmonary Reserve)
PR expressed as % of MVV
DI = (MVV-PV) x 100
MVV
DI = (100-6) x 100 = 94%
100
Normal DI > 60-70% (~90%)
If <60%, dyspnoea is usually present.

41. Peak Expiratory Flow Rate (PEFR)
Maximum velocity with
which air is forced out of
the lungs in a single
forced expiratory effort.
Normal – 350-400 l/min
Usually indicate large
central airway
obstruction.
Measured by Wright’s
peak flow meter.

42. Obstructive vs Restrictive d/s
Obstructive
Asthma
Chronic obstructive lung
disease (chronic bronchitis,
emphysema)
Bronchiectasis
Cystic fibrosis
Bronchiolitis
Restrictive—
Parenchymal
Sarcoidosis
Idiopathic pulmonary fibrosis
Pneumoconiosis
Drug- or radiation-induced
interstitial lung disease
Restrictive—
Extraparenchymal
Neuromuscular
Diaphragmatic
weakness/paralysis
Myasthenia gravis
Cervical spine injury
Chest wall
Kyphoscoliosis
Obesity
Ankylosing spondylitisa

43. Obstructive vs Restrictive d/s

44. 03/22/15 Dr. Nilesh Kate GMC A'BAD

45. 03/22/15 Dr. Nilesh Kate GMC A'BAD






Flow chart for rapid interpretation of pulmonary function tests.

46. Short & systematic way of
interpretation
See FVC normal / Abnormal
See FEV
1
normal / Abnormal
If both normal-- PFT Normal
If both decreased – Diseased
(Obstructive/restrictive)
 If FEV1% -- 69% or <69%--Obstructive
If FEV1% -- 80-90% or > 80%--Restrictive
03/22/15 Dr. Nilesh Kate GMC A'BAD