Pulmonary function test

1. Pulmonary Function Test
Dr. Sai Sailesh Kumar G
Associate Professor
Department of Physiology
RDGMC

2. Case study
 A holiday in Nepal turned tragic for a group of friends
from Kerala and their families, as eight of them,
including four children, were found dead, presumably
due to asphyxiation after inhaling the gas from the gas
heater used for warming themselves in the room at
night.
 Malfunctioning of gas heater in their hotel room was
noticed.
 All windows were bolted from inside ( No ventilation).

3. Case study
 Carbon monoxide poisoning is caused by inhaling
combustion fumes.
 When too much carbon monoxide is in the air you're
breathing, your body replaces the oxygen in your
red blood cells with carbon monoxide.
 This prevents oxygen from reaching your tissues
and organs.

4. Case study
 Various fuel-burning appliances and engines
produce carbon monoxide.
 The amount of carbon monoxide produced by these
sources usually isn't cause for concern.
 But if they're used in a closed or partially closed
space the carbon monoxide can build to dangerous
levels.
 Leads to permanent brain damage and death.

5. Respiratory Disorders
 Diagnosis and treatment of most respiratory
disorders depend heavily on understanding the basic
physiological principles of respiration and gas
exchange.
 Respiratory diseases result from
 inadequate ventilation
 abnormalities in diffusion
 abnormal transport of gases

6. Pulmonary Function Test
 Includes multiple tests to assess respiratory
functions.
 Provides standardized measurements for assessing
the presence and severity of respiratory dysfunction.

7. Why PFT
 To predict presence of pulmonary dysfunction
 To differentiate obstructive and restrictive pulmonary
disorders
 Prognostic purpose
 To assess severity of the disease
 To identify patients at perioperative risk of pulmonary
complications

8. PFT
 Spirometry
 Bronchial Provocation test
 Static lung volumes
 CO diffusion capacity
 Alveolar arteriolar oxygen gradient
 Cardio pulmonary exercise testing
 Flow volume loop
 Determination of Blood pH, Blood CO2 and Blood O2

9. PFT alone is ok??
 No
 PFT alone is not sufficient
 PFT only support or exclude a diagnosis
 History taking, physical examination, imaging and
laboratory data is essential along with PFT for
diagnosis

10. Spirometry
 Spirometry (spy-ROM-uh-tree) is a common test used to
assess how well your lungs work by measuring how
much air you inhale, how much you exhale and how
quickly you exhale.
 Spirometry is used to diagnose asthma, chronic
obstructive pulmonary disease (COPD) and other
conditions that affect breathing.
 Spirometry may also be used periodically to monitor your
lung condition and check whether a treatment for a
chronic lung condition is helping you breathe better.

11. Why Spirometry??
 Asthma
 COPD
 Chronic bronchitis
 Emphysema
 Pulmonary fibrosis

12. Dis advantages of spirometry??
 Residual Volume,
 Functional Residual Capacity
 Total Lung Capacity
cannot be measured

13. Advantages of spirometry??
 To establish baseline ventilatory function.
 To detect disease.
 To follow course of disease.
 Monitoring treatment.
 Evaluation of impairment.
 Pre-operative evaluation.
 Occupational surveys

14. Recording Spirometer

15. Recording Spirometer

19. Calibration of graph paper
 On Y axis – one (division) box = 100 ml = 0.5 cm
 Two divisions (boxes) = 200 ml = 1 cm
 On X axis time is mentioned – mm/sec

20. Static lung volumes recorded
 Recorded at the speed of 2 mm/sec
 Cannot measure residual volume.
1. Tidal volume
2. Inspiratory reserve volume
3. Expiratory reserve volume
4. Inspiratory capacity
5. Vital capacity

21. Tidal volume
 Volume of the air inspired or expired during normal
breathing
 Normal value 500 ml
 High tidal volumes also decrease venous return and reduce
cardiac output
 lower tidal volume seen in patients with acute lung disease.
Such as, pneumonia, ARDS, fibrotic lung disease, or COPD

23. Tidal volume (TV) calculation
TV = Height of quiet inspiration/ expiration cm X
200ml
Total boxes present is 5 so 5/2= 2.5 cm is height (2
boxes is I cm)
So TV = 2.5 cm X 200 ml = 500 ml

24. Inspiratory reserve volume (IRV)
 Volume of the air inspired forcefully and maximally
after normal inspiration
 Normal value 3000 ml
 Restrictive lung diseases (Pulmonary fibrosis,
pneumothorax): lungs are unable to fully expand, so
they limit the amount of oxygen taken in during inhalation

26. IRV Calculation
Height of inspiration between tidal inspiration to
maximal inspiration X 200 ml
17 boxes (1700 ml)
17/2 = 8.5 cm
8.5 X 200 = 1700 ml

27. Expiratory reserve volume (ERV)
Volume of air expired forcefully and maximally after
normal expiration
Normal value 1100 ml
 Restrictive lung diseases (Pulmonary fibrosis,
pneumothorax): lungs are unable to fully expand, so
they limit the amount of oxygen taken in during inhalation

29. ERV calculation
Height of expiration between tidal expiration to
maximal inspiration cm X 200 ml
6 boxes (600 ml)
6/2 = 3 cm
3 X 200 = 600 ml

30. Inspiratory Capacity (IC)
Volume of air expired forcefully and maximally after
normal expiration
IC = IRV +TV = 3500 ml (normal)
 Restrictive lung diseases (Pulmonary fibrosis,
pneumothorax): lungs are unable to fully expand, so
they limit the amount of oxygen taken in during inhalation

31. IC calculation
IC = IRV +TV
1700 + 500 = 2200 ml

32. Vital Capacity (VC)
 Volume of air that is expired forcefully and maximally and
continuously after a forceful and maximum inspiration
 VC = ERV+ IRV +TV = 4600 ml (normal)
 Restrictive lung diseases (kyphoscoliosis): vital
capacity decreases
 Obstructive lung disease: ( Bronchial asthma) : VC
normal

33. Dynamic lung volumes recorded
 Recorded at the speed of 20 mm/sec
1. Maximum voluntary ventilation
2. Timed vital capacity
3. Minute ventilation
4. Pulmonary reserve

34. Maximum voluntary ventilation
(MVV)
 Largest volume of the air that can be moved into and out
of the lungs in one minute by maximum voluntary effort
 Normal value – 90-170 L/min
 Voluntary ventilation longer than 15 seconds should not
be allowed because prolonged hyperventilation leads to
fainting due to excessive lowering of arterial PCO2 and
H+.

35. MVV calculation
 Number of inspiratory/ expiratory peaks of voluntary
hyperventilation for 15 sec X average height incms X
200ml X 4
 Number of inspiratory/ expiratory peaks of voluntary
hyperventilation for 15 sec = 8
 Average height in cm (35 boxes) = 35/2 = 17.5 cm
 8 X 17.5 X 200 X 4 =11200 ml/min = 112 L/min

37. Timed vital capacity (TVC) or
Forced Vital Capacity (FVC)
 Maximum volume of air, which can be expired out as
forcefully and rapidly as possible following a forceful and
maximal inspiration
 Components of timed vital capacity
1. FEV1 – Forced expiratory volume in 1 sec ( 80% of FRC)
2. FEV2 – Forced expiratory volume in first two sec (95% of FRC)
3. FEV3- Forced expiratory volume in first three sec (98 -100% of
FRC)

38. Timed vital capacity (TVC) – clinical
significance
 Restrictive disorders (Kyphoscoliosis) – chest
expansion is restricted – FEV1 is normal
 Obstructive disorders (Bronchial asthma) –
Inspiration normal but expiration is obstructed –
FEV1 decreases

39. FVC calculation
1. Height of expiration between maximum inspiration
and maximum expiration cm X 200ml
2. 37 boxes (3700ml)
3. 37/2 = 18.5 cm
4. 18.5 X200 = 3700 ml

41. FEV1 calculation
1. Height of rapid forceful expiration in1st second cm
X 200ml
2. 33 boxes (3300ml)
3. 33/2 = 16.5 cm
4. 16.5 X200 / 3700= 89.1 %

42. FEV2 calculation
1. Height of rapid forceful expiration in1st two seconds
cm X 200ml
2. 36 boxes (3600ml)
3. 36/2 = 18 cm
4. 18 X200 / 3700= 97.29 %

43. FEV3 calculation
1. Height of rapid forceful expiration in 1st three
seconds cm X 200ml
2. 37 boxes (3700ml)
3. 37/2 = 18.5 cm
4. 18.5 X200 / 3700= 100 %

44. Minute ventilation (MV)
1. Volume of air inspired or expired in one minute
2. MV = TV X Respiratory rate
3. MV = 500 X 12
4. 6000 ml/minute or 6L/minute

45. Pulmonary reserve (PR)
1. It is maximum volume of air over and above the
minute ventilation which can be breathed in and
out in one minute
2. PR ( breathing reserve/ pulmonary reserve) = MVV-
MV
3. MVV- MV = 112- 6 = 106 l/min
It is expressed as percentage of MVV and called as
dyspneic index (DI)

46. Dyspneic index (DI)
 Breathing reserve/ MVV x 100
 MVV= maximum voluntary ventilation – 110 lit/min
 Breathing reserve for a person breathing 5 lit/ min is
112-6 = 106 l/min
 106/112 x100 = 94.64 %
 When DI becomes 60 or below, then dyspnea starts

47. 40 mmHg test
It will be conducted by asking the subjects to
take in a full breath and blow against the mercury
column to the pressure of 40 mm, maintaining it
as long as possible.
The time for which the subject should maintain
the mercury level at 40 mmHg will be noted.
 The lips will be secured tightly around the
mouthpiece with the help of fingers to ensure that
there is no leak.

48. Maximum expiratory pressure
(MEP):
The participant will be asked to blow against
a mercury column after taking in a full breath
and to maintain the column at the maximum
level for 2 seconds.

49. Breathe holding time expiration
(BHT exp):
It will be determined by noting the maximum
time (in seconds) for which the subject could
hold his breath after breathing out fully.
The participants will be instructed not to make
any abdominal or chest movements during
breathe holding.

50. Breathe Holding time Inspiration
(BHT Insp):
It will be determined after the participant
takes in a full breath.
It will be ensured that there was no
hyperventilation prior to breathe holding.
The participants will be instructed not to
make any abdominal or chest movements
during breathe holding.

51. Bronchial challenge test
 Medical test used to assist in the diagnosis of asthma
 The patient breathes in nebulized methacholine or
histamine.
 Thus the test may also be called a methacholine
challenge test or histamine challenge test
respectively.
 Both drugs provoke bronchoconstriction, or narrowing of
the airways.
 The degree of narrowing can then be quantified by
spirometry.

52. Bronchial challenge test
People with pre-existing airway hyper reactivity,
such as asthmatics, will react to lower doses of
drug.
Sometimes, to assess the reversibility of a
particular condition, a bronchodilator is
administered to counteract the effects of the
broncho constrictor.
The inhaled drug can stimulate the upper
airway sufficiently to cause violent coughing.
This can make spirometry difficult or impossible.

53. Carbon monoxide diffusion capacity
Diffusion Capacity- The rate at which gas enters
the blood divided by driving pressure of the gas
Factors affecting diffusion capacity
Changes in the alveolar capillary membrane.
V/P ratio.
Hemoglobin concentration
Pulmonary circulation

54. Indications for Carbon monoxide
diffusion capacity
Dyspnea
Emphysema
Diagnosis and follow up of patients with
interstitial lung disease
Diagnosis of pulmonary emboli
Bronchospasm (asthma)

55. Diffusion Capacity
Decreased
1. Obstructive lung disease
2. Parenchymal disease
3. Pulmonary vascular
disease
4. Anemia
Increased
1. Asthma
2. Pulmonary hemorrhage
3. Polycythemia

56. Alveolar arterial oxygen gradient
Alveolar oxygen tension is calculated
arterial oxygen tension measured by blood gas
estimation
Difference between the two gives a measurement
of alveolar to arterial oxygen gradient.
In normal →5-15 mm Hg
Increased AAOG is due to 3 mechanisms:-
Ventilation perfusion mismatch.
Increased right to left shunt.
Diffusion block

57. Normal Flow Volume curve
X axis - Volume
Y axis - Flow

58. Normal Flow Volume curve

59. Normal Time Volume curve

60. Normal Time Volume curve
X axis - Time
Y axis – Volume
FEV1/ FVC = 4/5 =0.8 (80%)

61. Obstructive lung disease
 Air remains in lung at expiration
 Reduction in air flow
 Increase in TLC
 TV same
 IRV decreases
 ERV increases
 RV increases
 FVC same or decrease
 FRC increases

62. Normal vs. Obstructive lung
disease

65. Obstructive lung disease
X axis - Time
Y axis – Volume
FEV1/ FVC = 2/5 =0.4 (40%)

66. Restrictive lung disease
 Reduction in lung volume
 Stiffness in the lungs
 TV same
 IRV decreases
 ERV decreases
 RV decreases
 TLC decreases
 FVC decreases
 FRC decreases

70. Obstructive lung disease
X axis - Time
Y axis – Volume
FEV1/ FVC = 3/5 =0.7 (70%)
Not much effected

71. Exercise test
Cardiopulmonary stress test, with the addition
pulmonary factors are also evaluated during
exercise
Evaluate the response of the cardiovascular &
respiratory systems to exercise, allows
measurement of gas exchange
It categorizes disorders that limit exercise
tolerance by documenting their pathophysiology.
Allows for an objective assessment of the
patients symptoms, accurate prescription.

72. Lung Function Test Obstructive Disease Restrictive Disease
Forced Vital
Capacity(FVC)4800ml =
IRV+TV+ERV
Normal Or Lower Than
Predicted Value
Lower Than Predicted
Value
Forced Expiratory Volume Lower
(FEV) 50 – 60 ml/Kg Or
0.75 – 5.5 l
Normal Or Lower
Forced Expiratory Flow
25 – 75 %
Lower Normal Or Lower
Normal Or LowerPeak Expiratory Flow (PEF) Lower
men:400–800 l/min.
Women:200 – 600 l/min.
Maximum Voluntary
Ventilation(MVV)
Lower Normal Or Lower
Male:150 – 170 l/min
Female :80 – 100 l/min

73. Study of blood gases and pH
pH is measured using glass pH electrode
Glass pH electrode can also used to measure
blood CO2
The concentration of O2 in a fluid can be
measured by a technique called Polarography.

74. (1) Oxygen delivery to tissues will be greatly
reduced in a patient with carbon monoxide
poisoning. Answer the following.
1. What is the physiological basis for reduced oxygen
delivery to the tissue?
2. What respiratory changes takes place in this
condition?
3. Describe the functional significance of oxygen –
hemoglobin dissociation curve.
4. Mention the factors which will shift oxygen
dissociation curve to right and left.

75. Case study-1
A. A 58 year old man came to hospital with
complaints of difficulty in breathing especially in
early morning and cough. On examination there
were rhonchi in all lung fields. He is a non – smoker
and there is no history of relevant occupational
exposure. Pulmonary function tests were done and
reports showed.
B. FVC, FEV1 was decreased
C. After bronchodilator therapy FVC increased by
25% and FEV1 increased by 30%

76. Questions
1. What is FVC and FEV1 and give their normal values?
2. What is the probable diagnosis?
3. Explain the increase in FVC and FEV1
4. How do you differentiate obstructive and restrictive
lung diseases?
5. What are the various factors affecting vital capacity?

77. Case study-2
1. 50 yrs. Old male patient was brought to casualty
in semiconscious state by his co- workers from a
boiler factory.
2. Accidentally he was exposed to a toxic gas in his
work place.
3. On examination he was in drowsy and confused
state, his BP was normal, weak pulse and
respiratory rate was 16 /min.
4. Mucous membrane was cherry red in color. His
Hb – 12 gm%.

78. Questions
1. What is your diagnosis? Name the gas involved.
2. Write the various methods of the transport of gas
involved and explain any one method.
3. Write the clinical symptoms for your diagnosis
4. Explain the Physiological basis of hyperbaric O2
treatment in detail

79. Case study-3
1. A 50 years old male come with complaints of
difficulty in breathing. Auscultation revealed the
presence of rhonchi in all the lung fields. Patient’s
pulmonary function tests revealed FVC
decreased.
2. FEV1=60%

80. Questions
1. What is FVC and FEV1?
2. Give the normal values of FEV1 and FEV3
3. Describe the physiological basis for this change of
FEV1
4. What is the probable clinical condition?
5. What is the significance of FEV1

81. Case study-4
1. A 30 years old lady presented with history of
cough and breathlessness that got worse during
the winter months every year.
2. She also complained of occasional whistling
sounds arising from the chest during breathing.
Answer the following

82. Questions
1. What is the most likely clinical diagnosis of her condition
2. What major findings would her pulmonary function tests show
3. What kind of medication would she likely benefit from
4. Depict the different lung volumes and capacities with the help
of a neatly labelled diagram
5. How the functional residual capacity is measured
6. What is significance of RV

83. Case study-5
1. Oxygen delivery to tissues will be greatly reduced
in a patient with carbon monoxide poisoning.
2. Answer the following
 What is the physiological basis for reduced oxygen
delivery to the tissues
 Describe the functional significance of oxygen
hemoglobin dissociation curve
 Mention the factors which will shift oxygen
hemoglobin curve to right and left

84. Case study-6
1. A 40 years old man was admitted to hospital with
complaints of difficulty in breathing and
shortness of breath following a head injury.
Answer the following
 With the help of diagrams describe two types of
periodic breathing
 Explain the physiological basis for the changes in
periodic breathing
 Describe the role of peripheral chemoreceptors in
regulation of normal respiration

85. Case study-7
1. A road traffic accident victim was found to be
unconscious and breathing in an irregular
rhythm. From your knowledge of physiology
 Name the two types of periodic breathing
 Explain the neural regulation of respiration
 What is the mechanism of function of medullary
chemoreceptors

86. Case study-8
25 yrs. old female patient was brought to casualty
in semiconscious state by her Family members
from their bathroom.
For water heating they were using gas geysers. On
examination she was drowsy and in confused
state, her BP was normal, Weak Pulse and
Respiratory rate was 16 /min.
Mucous membrane was cherry red in color.
Her Hb – 12 gm%.

87. Questions
1. What is your probable diagnosis? Name the gas involved
2. Depict its effect on oxyhemoglobin dissociation curve and
discuss.
3. In less severe case what are the symptoms and basis for
them.
4. Explain the Physiological basis of treatment with Oxygen in
detail

88. Give Physiological basis-1
Apex of lung – favorable for growth of tuberculosis
(bacteria)
Ans: Because of high V/P ratio in apices of lungs
predisposes to tuberculosis because of high
alveolar Po2 which provides favorable
environment.

89. Give Physiological basis-2
Compliance increases in old age, emphysemia
Ans: Because of loss of elasticity more pressure is
required to inflate the lungs due to some
modifications in the arrangement of elastic tissue.

90. Give Physiological basis-3
Acclimatized subjects rise in Hb concentration
Ans: Hypoxia powerful stimulant for release of
erythropoietin.

91. Give Physiological basis-4
. Sleep apnoea
Ans: Normaly muscle keeps the tongue forward
when genio glossus fails to contract tongue falls
backwards and obstructs the airways.

92. Qualities of a Doctor
 Punctuality
 Smile
 Greeting and remembering patients
 Appearance
 Confidence and knowledge in the subject
 Updating the subject
 Communication skills
 Patience
 Confidentiality
 Earning patient's confidence
 Empathy
 Easy to reach
 Ethical

93. THANK YOU