Pulmonary function test

1. Chairperson:
Asst. Prof. Dr. Snehangshu Shekhar Samanta
Presenter : Dr. Arijit Biswas

2.  Its a generic term used to indicate a
battery of test or manouvers
performed using standardised
equipment to evaluate function of
lung.

3. 1. Tests for ventilatory functions:
 Evaluate lung volumes and capacities:
- Spirometry
- Body Plethysmography
- Gas dilution method
( FRC & RV detection)
 Evaluate hypersensitivity of airway
- Bronco provocation test

4. 2.Tests for gas exchange:
DLCO , ABG, Oxymetry and Capnography.
3. Other Tests:
 Tests for lung compliance.
 Test for resistance and impedence: Impulse oscillometry.
 Assessment of regional lung functions.
 Assessment of respiratory muscle strength.
 Breath condensate.

5.  Gives the evidence of deranged lung function
 Helps to rule out/ identify resp cause of SOB
 Quantifying lung function in pt undergoing lung resection
 Type of resp failure
 Detects airway hyper responsiveness
 Evaluation of disability
 Course of disease over time

7.  VOLUME
DISPLACEMENT
SPIROMETER:
 FLOW SENSING
SPIROMETER:


8. 500ml
4.5l
1.2+1 L 1.2L
1L
4.5+1.2 L
3L
TV= AMOUNT OF GAS GOING IN AND OUT WITH
EACH RESPIRATION

9. 500ml
4.5l
1.2+1 L 1.2L
1L
4.5+1.2 L
3L
IRV= EXCESS AIR THAT CAN BE BREATHED IN WITH
EXTRA EFFORT AFTER TIDAL INSPIRATION

10. 500ml
4.5l
1.2+1 L 1.2L
1L
4.5+1.2 L
3L
ERV= EXTRA AMOUNT OF GAS THAT CAN BE BREATHED OUT
WITH EXTRA EFFORT AFTER TIDAL EXPIRATION

11. 500ml
4.5l
1.2+1 L 1.2L
1L
4.5+1.2 L
3L
RV= AIR LEFT BEHIND AFTER MAX EXPIRATION

12. 500ml
4.5l
1.2+1 L 1.2L
1L
4.5+1.2 L
3L
FVC= AMOUNT OF AIR THAT CAN BE BREATHED OUT
WITH MAX EFFORT AFTER FORCEFUL INSPIRATION

13. 500ml
4.5l
1.2+1 L 1.2L
1L
4.5+1.2 L
3L
FRC= AMOUNT OF AIR LEFT IN LUNG AFTER NORMAL
TIDAL EXPIRATION

14.  It can measure:
1. Tidal vol (500ML)
2. IRV (3L)
3. ERV (1L)
4. VC (4.5L)
 What it can not
measure:
1. RV
2. FRC = ERV+ RV
3. TLC = FVC+RV

15. 1.Diagnostic:
A.To evaluate symptoms, signs, and
abnormal lab tests
• Symptoms: dyspnea wheezing, orthopnea, cough, phlegm
production, chest pain
• Signs: diminished breath sound, over inflation, expiratory
slowing, cyanosis, chest deformity, unexplained crackles
• Abnormal lab test: hypoxemia, hypercapnia, abnormal chest
radiograph
B. To measure the effect of disease on
pulmonary function

16. C. To screen individuals at risk of having
pulmonary disease
 Smokers
 Occupational exposure
D. To assess preop risk
prognosis( lung transplant)
health ststus before begining of a
strenous physical activity program

17. 2. Monitoring
To assess therapeutic intervention
a) Bronchodilator therapy
b) Steroid therapy (Asthma, ILD)
c) Antibiotics in cystic fibrosis
To describe the course of disease that affect lung
function
 Pulmonary disease (obstructive airway disiese,ILD)
 Cardiac disease (CHF)
 NM disorders (GB syndrome)

18. To monitor people exposed to injurious agent
To monitor adverse reaction to drug with known
pulmonary toxicity
3.To identify Flow Volume Loop patterns
4. Disability/Impairment evaluation
To assess patients as part of rehabilitation
program
To assess risk as a part of an insurance
evaluation
5. Public Health: For clinical research

19. Due to increased
myocardial
demand
1. AMI within1WK
2. Hypo / severe
hypertension
3. Ventr
arrhythmia /
non
compensated
HF
4. PAH / Acute
corpulmonale
Due to increased
intracranial/intraocul
ar/intrathoracic
pressure
1. Cerebral aneurysm
2. Brain surgery 4wk
3. Eye surgery 1 wk
4. Pneumothorax
5. Thoracic/ abd sx
4wk
6. Late term
pregnancy
Infection controle
issue
1. Active /
transmissable
resp inf
(TB/covid)
2. Hemoptysis
3. Oral lesion/ bleed
Should be discontinued if pt feels pain during procedure

20.  In pulm funtion lab, where operator are
experienced enough,
 Emergency care can be given if needed
 Callibration of the device
 Quiet and calm env.
 Temp and barometric pressure is a important
variable in PFT

21.  Smoking within 1 hr
 Consuming intoxicants before 8hr of test
 Vigorous exercise within 1 hr
 Tight clothes that interrupt chest and abd
wall expansion freely

22.  Seated erect
 Shoulder slightly back, Chin slightly up
 Chair without wheel with height adjustment
 Feet should be flat on the floor
 Nose clip or manual occlusion of nose
should be used
 Test in standing position are more or less
similar to sitting

23.  Spirometry can be a major source of infection as
well as place of infection transmission
Directly by : Mouthpiece, noseclip, chair arms
Indirectly by : Aerosol droplet generation
Avoide this risks by : Handwashing/sanitisation
Use of disposable
equipment where possible

25. 1. FEV1 and FVC manouver
2. Expiration only manouver
3. Bronchodialator responsive testing
manouver (Reversibility test)
4. SVC (slow vital capacity) manouver

26.  Equipment must be Calibrated
 Loosen tight fitting clothes
 Denture if they are loose better tobe removed
 Age, Weight, Height is recorded
 Explain the pt about the procedure
 Counsel that the procedure may not be comfortable

27. Maximum
inspiration
•Start at flow zero
•Inspire as deeply as possible
•No pause
•Wait till the inspiration is complete ( eye brow
becomes widened, head starts quivering)
Blast of
expiration
• Don’t just blow, blow as much and as forcefully
possible
Continued
expiration
At least 6 sec is acceptable
3 sec for <10 yrs
Wait for the plateau phase in display
Ask for the next step
Maximum
inspiration
after forced
expiration
•To return to TLC and complete the flow volume
curve
•This will cross check whether the
pt began exp from full
inspiration or not
FEV1/FVC MANEUVER

28. Expiration only manouver
(Done for children only)
Inspire maximum lung vol within 2 s
Insert mouth piece
Innitiate max expiration
Remove mouth piece at end of forced expiration

29. Bronchodialator responsive test
Degree of improvement of air flow in response to bronco
dilator
Can differentiate Asthma from other COPD
But neither asthma nor COPD is diagnosed on
spirometry
bronchodilator Dose FEV1 before and
after
Salbutamol 200-400mcg
via large spacer
15 min
Terbutaline 500 mcg via
turbohaler
15 min
Ipratropium 160 mcg via
spacer
45 min

30. The test can be concluded
when both ACCEPTABILITY and
REPEATABILITY criteria are met
To ensure the REPRODUCIBILITY of
the test
Requires 5 to maximum 8 attempt

31.  Free from artefact ( Cough / Early glottis closure)
 Good start
 Free from leaks
 Extrapolation back from the PEFR gives a
theoretical start time (should be within 5% of FVC
or within 150 ml)
 Acceptable exhalation
 Adults :at least 6 sec of exhalation and plateue
 Children <10yrs : at least 3 sec of exhalation

32.  Three acceptable maneuvers (meeting above
criteria)
 Two largest FVC measurements within 150 ml
of each others
 Two largest FEV1 measurements within
150ml of each others

33. 1. FVC
2. FEV1
3. FEF 25-75
4. Change in FVC and FEV1 after broncho
dialator use
5. Flow volume curve
6. Flow time curve

34. Flow volume Loop
FEV!
Effort
dependent
part
Effort
independent
part
PEFR

36.  Total volume of air that
can be exhaled forcefully
from TLC
 The majority of FVC can
be exhaled in<3 seconds
in normal
 Often prolonged in
Obstructive lung disease
 Measured in liters

37.  80-120% = Normal
 70-79% = Mild
reduction
 50-69% = Moderate
reduction
 <50% = Severe
reduction

38.  Volume of air forcefully
expired from full
inspiration (TLC) in first
second
 Normally 75-80% of
FVC is exhaled in first
second
 Thus FEV1/FVC can be
utilised to characterise
lung disease

39.  Mean forced
expiratory flow
during middle half of
FVC
 May reflect effort
independent
expiration And the
status of the small
air way

41.  >60% normal
 40-60% mild obstruction
 20-40% moderate obstruction
 <20% Severe obstruction

42. INTERPRETETION
FVC alone does not make any sense unless
and until we compare it with the time
dimension i.e. FEV1
Main determinant of PFT is the FEV1/FVC
FEV1/FVC
(>80%)
LOW Normal/high
Always
obstructive
Restrictive

43. Obstructive
1. COPD
(Emphysema/
Bronchiectasis/S
AD)
1. ASTHMA
2. CF
3. BRONCHIOLITIS
4. BRONCHIECTASIS
For expiration driving force >Air pressure
Driving force = IPP + Elastic recoil pressure
Elastic recoil pressure is low in obstructive ds
That is why exp function (FVC) starts falling day by day
Hyperinflation Air trapping
FEV1 low Low
FVC normal Low
RV High High
TLC
(FVC+RV)
High Remain unchanged

44. Obstructive

45. Q. Can obstr lung dis have normal FEV1/FVC ?
Yes, in Small air way disease.
Here we diagnose SAD by FEF 25-75 /MMEFR/MEAN FORCED
EXPIRATORY FLOW RATE
It is the average flow rate of lung in middle 50% of
the FVC manouver
It is the slope of the line

46.  Reversibility test by SABA
 If FEV1 > 12%
and
FVC > 200ml
It indicates
Bronchial
Asthma

47. RVERSIBILITY TEST

49.  Here lung’s inspiratory function is affected
 So IRV is decreased
 FVC= IRV + TV +ERV = FVC
 FEV1 remains normal more or less
 FEV1/FVC remains normal/high

51. Flow volume Loop

52.  Restrictive
Restrictive
Extra
parenchymal
NM disorders
(TLC Low
Chest wall
deformities
Intra
parenchymal
DLCO
normal
DLCO low
KCO
normal

53. Intra
parenchymal
NM disorder Chest wall
deformity
DLCO LOW NORMAL
TLC LOW LOW NORMAL
RV LOW NORMAL
RV/TLC HIGH NORMAL
KCO
(DLCO/VOL)
NORMAL HIGH

54.  It uses a small amount of CO to measure gas
exchange across the alveolar membrane
during a 10 sec breath hold.
 CO in exhaled air is analysed to determine
the quantity of CO crossing the membrane

55. FACTORS INCREASD DLCO DECREASED
DLCO
Thickness of alveolar
membrane
ILD
smoking
Altered
volume/surface area
ratio
Emphysema
Hb available Polycythemia Anaemia
Pregnancy
Blood coming to
capilleris
Pulmonary Hge
Asthma
Left to right shunt
Exercise
Pulmonary vascular
disease

56.  Diffusion limited gas
 Affinity of Hb for CO is >200 times
 Partial pressure of CO in pulmonary
capillaries rises very slowly
KCO (Diffusion coefficient)= DLCO/
Lung Volume
Normal in ILD
Raised in Extra parencymal disease

57. Intra
parenchymal
NM disorder Chest wall
deformity
DLCO LOW NORMAL
TLC LOW LOW NORMAL
RV LOW NORMAL
RV/TLC HIGH NORMAL
KCO
(DLCO/VOL)
NORMAL HIGH

58. Different flow vol loops
NORMAL
Scooped
pattern
Fixed airway
obstruction
Extra thoracic
variable obstruction
Intra thoracic
variable obstr

59. LEVEL OF OBSTRUCTION

60.  Narrowing is maximal
in Expiration
 As lesion is intra
thoracic
 Intra thoracic pressure
is maximum in
expiration and lower
than air
 Thus expiratory limb is
flattened
e.g. Tracheomalacia

61.  Obstruction worsens
in inspiration
 As negative pressure
narrows trachea
 Thus Inspiratory limb
flattens
 E.g extrinsic
compression from
Goiter, LN

62.  Maximum airflow is
limited to a similar
extent in both
inspiration as well as
expiration
 Both limbs are
affected
 E.g. Tracheal
stenosis, FB

63.  Most common cause is poor patient technique
Sub optimal inspiration
Sub maximal expiratory effort
Delay in forced expiration
Shortened expiratory time
Air leak around the mouth piece
Poor posture = leaning forward
Subjects must be observed and encouraged through the
procedure

65. Premature
ending

66.  Highly dependent on patient compliance and
effort
 Thus FEV1 and FVC may be underestimated
 Not useful for <4years/unconcious/sedated
 Can not measure RV,FRC,TLC