This document discusses the goals and techniques of assessing pulmonary function. It aims to predict and characterize pulmonary dysfunction, assess disease severity and progression, evaluate treatment response, and identify surgical risk. Methods described include measuring chest expansion, breathlessness scale, chest x-ray, spirometry, arterial blood gas, echocardiography, and the 6-minute walk test. Spirometry is a key test that measures lung volumes and airflow to detect obstructive or restrictive lung defects.

1. ASSESSMENT OF
PULMONARY FUNCTION
Presented by
Dr. S M Mortaza Ahsan & Dr MD Abdul Quiyum
Phase-B resident,
HBPS,BSMMU.
.
.

2. GOALS
 To predict the presence of pulmonary dysfunction
 To know the functional nature of disease (obstructive
or restrictive)
 To assess the severity of disease
 To assess the progression of disease
 To assess the response to treatment
 To identify patients at increased risk of morbidity
and mortality, undergoing major surgery

3.  To wean patient from ventilator in icu
 Medicolegal- to assess lung impairment as a result of
occupational hazard
 Epidemiological surveys- to assess the hazards to
document incidence of disease
 To identify patients at peri-operative risk of pulmonary
complications

4. INDEX
 Goals
 Chest expansibility
 MRC breathlessness scale
 CXR
 Spirometry
 ABG
 Echocardiography
 6 mins walk test

5. Chest expansibility
 Normal chest movement: symmetrically and equal on
both sides.
 Chest expansion is the difference of deep maximum
inspiration and forced expiration. It is measured at
nipple level or 4th intercostal space in males and below
the breasts in females.
 Normally, it is 2 cm in children and >5 cm (5-8 cm) in
adult person.
 In case of lung and pleural diseases, the expansibility
of lung is reduced.

6. MRC breathlessness scale
Grade Degree of breathlessness related to activities
1 Not troubled by breathlessness except on strenuous exercise
2 Short of breath when hurrying on the level or walking up a slight hill
3 Walks slower than most people on the level, stops after a mile or so,
or stops after 15 minutes walking at own pace
4 Stops for breath after walking about 100 yds or after a few minutes
on level ground
5 Too breathless to leave the house, or breathless when undressing

7. Importance of MRC breathlessness scale
 The MRC breathlessness scale does not quantify breathlessness
itself. Rather, it quantifies the disability associated with
breathlessness by identifying that breathlessness occurs when it
should not (Grades1 and 2) or by quantifying the associated
exercise limitation (Grades 3–5).
 There is up to 98% agreement between observers recording MRC
breathlessness scores.
 The score correlates well with the results of other breathlessness
scales, lung function measurements and with direct measures of
disability such as walking distance.

8. CXR findings

10. SPIROMETRY

11. LUNG VOLUMES
Tidal Volume (TV):
volume of air inhaled or
exhaled with each breath
during quiet breathing (6- 8
ml/kg)
Inspiratory Reserve
Volume (IRV): maximum
volume of air inhaled from
the end-inspiratory tidal
position (3000ml).

12.  Expiratory Reserve Volume
(ERV): maximum volume of air
that can be exhaled from resting
end-expiratory tidal position
(1300ml).
 Residual Volume (RV): Volume
of air remaining in lungs after
maximium exhalation (20-25
ml/kg) (1200ml). It can not be
measured by spirometry

13. Lung capacities
Inspiratory Capacity (IC): It
is the maximum volume of air
that can be inhaled after a
normal expiration. It is the sum
of IRV and TV (2400-3800ml).
Functional residual Capacity
(FRC): It is the amount of air
remaining in the lungs after a
normal expiration. It is the sum
of RV+ ERV (2200-2500 ml).

14. Lung capacities
 Total Lung Capacity (TLC):
Sum of all volume
compartments or volume of
air in lungs after maximum
inspiration ( 4-6 L).
 Vital Capacity (VC):
Maximum volume of air
exhaled after maximal
inspiratory level. Measured
by TLC minus RV (60-70
ml/kg) (3100-4800ml)

15. SPIROMETRY: CORNERSTONE OF ALL PFTs.
 John hutchinson – invented spirometer.
 “Spirometry is a medical test that measures
the volume of air an individual inhales or
exhales as a function of time.”
 Measure- VC, FVC, FEV1, PEFR.
 Can’t measure – FRC, RV, TLC.

16. PREREQUISITIES
 Prior explanation to the patient
 Not to smoke /inhale bronchodilators 6 hrs prior or
oral bronchodilators 12hrs prior.
 Remove any tight clothings/ waist belt/ dentures
 Pt. Seated comfortably If obese
 Child < 12 yrs- standing

17. PREREQUISITIES cont.
 Nose clip to close nostrils.
 Exp. effort should last ≥ 4 secs.
 Should not be interfered by coughing, glottic closure,
mechanical obstruction.
 3 acceptable tracings taken & largest value is used.

18. Measurements obtained from the FVC curve
 Max vol. Of air which can be expired out as forcefully
and rapidly as possible, following a maximal
inspiration to TLC.
 Exhaled volume is recorded with respect to time.
 Indirectly reflects flow resistance property of airways.
 Normal healthy subjects have VC = FVC.
 Exhalation should take at least 4 sec and should not be
interrupted by cough, glottic closure or mechanical
obstruction.

19.  FEV1 ---the volume exhaled during the first second of the FVC
maneuver Expressed as an absolute value or % of FVC.
Normally FEV1 (1 SEC)- 75-85%, FEV2 (2 SEC)- 94% and
FEV3 (3 SEC)- 97% of FVC
 FEF 25-75%---the mean expiratory flow during the middle half
of the FVC maneuver; reflects flow through the small (<2 mm in
diameter) airways. So, it is a good indicator of small distal
airway obstruction.
 FEV1 /FVC---the ratio of FEV1 to FVC X 100 (expressed as a
percent); an important value because a reduction of this ratio
from expected values is specific for obstructive rather than
restrictive diseases

21. Spirometry Interpretation:
Obstructive vs. Restrictive Defect
Obstructive Disorders :
Characterized by a limitation
of expiratory airflow so that
airways cann’t empty as
rapidly compared to normal
(such as through narrowed
airways due to bronchospasm,
inflammation, etc.) Examples:
– Asthma
– Emphysema
Restrictive Disorders –
Characterized by reduced
lung volumes / decreased
lung compliance
Examples:
– Interstitial Fibrosis
– Scoliosis
– Lung Resection
– Neuromuscular diseases
– Cystic Fibrosis

22. Graphical presentation of
Obstructive vs. Restrictive Defect

23. Spirometry Interpretation:
Obstructive vs. Restrictive Defect
 Obstructive Disorders
– FVC normal or↓
– FEV1 ↓
– FEF25-75% ↓
– FEV1/FVC ↓
– TLC normal or ↑
 Restrictive Disorders
– FVC ↓ ↓
– FEV1 ↓
– FEF 25-75% normal to ↓
– FEV1/FVC normal to ↑
– TLC ↓

24. Spirometry Interpretation:
 FVC
Interpretation of % predicted:
80-120% Normal
70-79% Mild reduction
50%-69%Moderate reduction
<50% severe reduction
 FEV1
Interpretation of % predicted:
>75% Normal
60%-75% Mild obstruction
50-59% Moderate obstruction
30-49% Severe obstruction
<30% very severe obstruction

25. Spirometry Interpretation
 FEF 25-75%
Interpretation of % predicted:
>79% Normal
60-79% Mild obstruction
40-59% Moderate obstruction
< 40% Severe obstruction
 FEV1/FVC
Interpretation of absolute
value:
>70% – Normal/ restrictive
<70 % - Obstructive

27. Spirometry
Pre and Post Bronchodilator
 15 minutes after administration of the bronchodilator,
calculate percent change (FEV1 most commonly
used---so % change FEV 1= [(FEV1 Post-FEV1 Pre)
/ FEV1 Pre] X 100).
 Reversibility is with 12-15% or greater change
indicates reversible obstructive disease like B
asthma.
 Irreversibility indicates COPD.

28. TESTS FOR CARDIOPLULMONARY
INTERACTIONS
 Reflects gas exchange, ventilation, tissue O2, CO.
• QUALITATIVE- history, exam, ABG, stair climbing test
• QUANTITATIVE- 6 minute walk test
STAIR CLIMBING TEST:
•If able to climb 3 flights of stairs without stopping/dypnoea
at his/her own pace- ↓ed morbidity & mortality
• If not able to climb 2 flights – high risk
ABG: Exclude respiratory failure,
Type of respiratory failure

29.  6 MINUTE WALK TEST:
 Gold standard
 C.P. reserve is measured by estimating max. O2 uptake during
exercise
 Modified if pt. can’t walk – bicycle/ arm exercises
 If pt. is able to walk for >2000 feet during 6 min pd, - VO2 max >
15 ml/kg/min
 If 1080 feet in 1 min : VO2 of 12ml/kg/min
 Simultaneously oximetry is done & if Spo2 falls >4%- high risk

30.  A low 6 MWD is prognostically useful, but nondiagnostic
(i.e. does not inform about the reason for the low 6 MWD). It
may be due to lung disease, cardiovascular disease, PAD,
fatigue, cognitive issues, neuromuscular disease,
musculoskeletal problems, poor nutrition, and or lack of
motivation

31. In case of MP-3
parameter predic
t
Pre
medi
Post
medi
FVC 2.53 L 1.83 L 1.86 L
FEV1 1.80 L 1.37 L 1.34 L
FEV1/FVC 71.15
%
74.86
%
72.04
%
PEFR 7.09
L/s
1.08
L/s
2.32
L/s

32.  An obstructive defect is indicated when FEV1/FVC ratio less than
70% in aduts and less than 85% in patients five to 18 years of age.
 If an obstructive defect is present, the physician should determine if
the disease is reversible based on the increase in FEV1 or FVC after
bronchodilator treatment (i.e., increase of more than 12% in patients
five to 18 years of age, or more than 12% and more than 200 mL in
adults). Asthma is typically reversible, whereas chronic obstructive
pulmonary disease is not.

33.  A restrictive pattern is indicated by an FVC below the fifth
percentile based on NHANES III data in adults, or less than
80% in patients five to 18 years of age. If a restrictive pattern
is present, full pulmonary function tests with diffusing
capacity of the lung for carbon monoxide testing should be
ordered to confirm restrictive lung disease and form a
differential diagnosis.

34.  If both the FEV1/FVC ratio and the FVC are low, the patient
has a mixed defect. The severity of the abnormality is
determined by the FEV1 (percentage of predicted). If
pulmonary function test results are normal, but the physician
still suspects exercise- or allergen-induced asthma,
bronchoprovocation (e.g., methacholine challenge, mannitol
inhalation challenge, exercise testing) should be considered.