Pulmonary function tests measure lung volumes and capacities including tidal volume, vital capacity, inspiratory reserve volume, and residual volume. Spirometry evaluates parameters such as FEV1, FVC ratio, and peak expiratory flow. Restrictive patterns show reduced lung volumes while obstructive patterns feature reduced flow rates. Tests assess reversibility, diffusion capacity, and respiratory muscle strength. Interpretation requires considering factors like posture, effort, and medications. Bedside tests include match blowing, breath-holding, and peak flow measurement.

1. Pulmonary Function
Tests

3. O Tidal Volume (TV): volume of air inhaled or exhaled
with each breath during quiet breathing (6-8 ml/kg)
O Inspiratory Reserve Volume (IRV): maximum volume
of air inhaled from the end-inspiratory tidal
position.(1900-3300ml)
O Expiratory Reserve Volume (ERV): maximum volume
of air that can be exhaled from resting end-expiratory
tidal position.( 700-1000ml).
O Residual Volume (RV):
O Volume of air remaining in lungs after maximium
exhalation (20-25 ml/kg) (1700-2100ml)
O Indirectly measured (FRC-ERV)
O It can not be measured by spirometry

4. • Total Lung Capacity
(TLC): Sum of all volume
compartments or volume
of air in lungs after
maximum inspiration (4-6
L)
• Vital Capacity (VC): TLC
minus RV or maximum
volume of air exhaled from
maximal inspiratory level.
(60-70 ml/kg) (3100-
4800ml)
• Inspiratory Capacity (IC):
Sum of IRV and TV or the
maximum volume of air
that can be inhaled from
the end-expiratory tidal
position. (2400-3800ml).
• Expiratory Capacity
(EC): TV+ ERV

5. Vital Capacity
O Considered abnormal if <80% of
predicted value.
O Physiological factors influencing VC:
 Height
 Sex
 Age
 Posture
 Strength of respiratory muscle

6. Factors decreasing Vital
Capacity:
① Alteration in muscle power.
② Pulmonary diseases.
③ Space occupying lesions in chest.
④ Abdominal causes.
⑤ Depression of respiration.
① Posture – by altering pulmonary Blood volume.

7. Different postures affecting VC
O POSITION
 TRENDELENBERG
 LITHOTOMY
 PRONE
 RT. LATERAL
 LT. LATERAL
O DECREASE IN VC
 14.5%
 18%
 10%
 12%
 10%

8. Vital Capacity pre and post op.
Before
epidural
1hr after
epidural
24hrs after
epidural
1. Upper
Abdominal
35.2% 69% 83.2%
2. Lower
Abdominal
55.5% 84.8% 94.7%
Vital capacity readings expressed as a % of pre op values.

9. Functional residual capacity
O Functional Residual Capacity (FRC):
O Sum of RV and ERV or the volume of air in the lungs
at end-expiratory tidal position.(30-35 ml/kg)
(2300-3300ml).
O Measured with multiple-breath closed-circuit
helium dilution, multiple-breath open-circuit
nitrogen washout, or body plethysmography.
O It can not be measured by spirometry)

10. Functional Residual Capacity
• FRC INCREASES WITH
• Increased height
• Erect position (30% more than in supine)
• Decreased lung recoil (e.g. emphysema)
• FRC DECREASES WITH
• Obesity
• Muscle paralysis (especially in supine)
• Supine position
• Restrictive lung disease (e.g. fibrosis, Pregnancy)
• Anaesthesia

11. Functions of FRC:
• Oxygen store
• Buffer for maintaining a steady arterial
po2
• Partial inflation helps prevent atelectasis
• Minimise the work of breathing
• Minimise pulmonary vascular resistance
• Minimised v/q mismatch
- only if closing capacity is less than FRC.

12. Maximum Voluntary
Ventilation
O Also known as the Maximum Breathing Capacity
(MBC)
O It is the largest volume of gas that can be moved
into and out of the lungs in 1 minute by voluntary
effort.
O Normal- 125-170L/min
O Subject is asked to breathe as hard and fast as
possible for 10-15secs. The value obtained is
converted to 60secs.
O Reflects the status of respiratory muscle,
compliance of chest wall and airway resistance.
O Effort dependent test.
O It can reveal diminished reserves of weak
respiratory muscles.

13. What are pulmonary function
tests?
O A group of studies or maneuvers that may
be performed using standardized
equipment to measure lung function.

14. Bedside PFT’s
O Sniders match blowing test
O Forced expiratory time
O Saberazes single breath count
O Saberazes breath holding test
O Cough test
O De bono’s whistle test
O Wrights peak flowmeter

15. Saberazes breath holding test
Ask the patient to take a full but not too deep breath &
hold it as long as possible.
>25 SEC.-NORMAL Cardiopulmonary Reserve (CPR)
15-25 SEC- LIMITED CPR
<15 SEC- VERY POOR CPR (Contraindication for
elective surgery)
25- 30 SEC - 3500 ml VC
20 – 25 SEC - 3000 ml VC
15 - 20 SEC - 2500 ml VC
10 - 15 SEC - 2000 ml VC
5 - 10 SEC - 1500 ml VC

16. Saberazes single breath count
After deep breath, hold it and start counting till
the next breath.
 N- 30-40 COUNT
 Indicates vital capacity.

17. Sniders match blowing test
Ask to blow a match stick from a distance of 6”
(15 cms) with-
 Mouth wide open
 Chin rested/supported
 No purse lipping
 No head movement
 No air movement in the room
 Mouth and match at the same level

18. O Can not blow out a match
O MBC < 60 L/min
O FEV1 < 1.6L
O Able to blow out a match
O MBC > 60 L/min
O FEV1 > 1.6L
O MODIFIED MATCH TEST:
DISTANCE MBC
9” >150 L/MIN.
6” >60 L/MIN.
3” > 40 L/MIN.

19. Cough test
Deep breath followed by cough
 ABILITY TO COUGH
 STRENGTH
 EFFECTIVENESS
INADEQUATE COUGH IF:
FVC<20 ML/KG
FEV1 < 15 ML/KG
PEFR < 200 L/MIN.
VC should be 3 TIMES TV FOR EFFECTIVE COUGH.
A wet productive cough / self propagated paraoxysms of
coughing :patient susceptible for pulmonary
complication.

20. Forced expiratory time
After deep breath, exhale maximally and
forcefully & keep stethoscope over trachea &
listen.
Normal FET – 3-5 SECS.
OBS.LUNG DIS. - > 6 SEC
RES. LUNG DIS.- < 3 SEC

21. Wrights Peak FLowmeter
• Measures tidal volume, mv (15 secs times
4)
• Simple and rapid
• Instrument- compact, light and portable.
• Disadvantage: It under- reads at low flow
rates and over- reads at high flow rates.
• Can be connected to endotracheal tube or
face mask
• Prior explanation to patients needed.
• Ideally done in sitting positoin.

22. Wrights peak flowmeter
• MV- instrument record for 1 min. And read
directly
• Accurate measurement in the range of 3.7-
20l/min.(±10%)
• USES: 1)BED SIDE PFT
2) ICU – Weaning patients from
Ventilation.
Measures PEFR (Peak Expiratory Flow Rate)
Normal – MALES- 450-700 L/MIN.
FEMALES- 350-500
L/MIN.
<200 L/ MIN. – INADEQUATE COUGH
EFFICIENCY.

23. De bono’s whistle test
MEASURES PEFR.
Patient blows down a wide bore tube at the
end of which is a whistle, on the side is a hole
with adjustable knob.
As subject blows → whistle blows, leak hole is
gradually increased till the intensity of whistle
disappears.
At the last position at which the whistle can
be blown , the PEFR can be read off the scale.

24. Components of PFT
1.Tests of
mechanical
function:
 Spirometry
 Static lung volumes
 Respiratory
Mechanics
 Respiratory muscle
strength
2.Tests of gas
exchange: ABG,
DLCO.
3.Cardiopulmonary
interaction:
• Qualitative- stair
climbing
• Quantitative- 6min
walking test

25. Indications for spirometry:
O Diagnostic:
• evaluate symptoms and signs
• Effect of disease on PFT
• Screen individuals
• Pre-op risk
O Monitoring- to assess therapeutic
interventions
O Public health

26. Contraindications
• Hemoptysis
• Pneumothorax
• Recent MI, unstable angina pectoris
• Thoracic, abdominal and cerebral
aneurysm
• Recent abdominal or thoracic surgical
procedure.
• H/o Syncope with forced exhalation
• Recent eye surgery

27. Pre-requisites
O Prior explanation to the patient
O Not to smoke /inhale bronchodilators 6 hrs prior or oral
bronchodilators 12hrs prior.
O Remove any tight clothings/ waist belt/ dentures
O Pt. Seated comfortably
O Nose clip to close nostrils.
O Minimum exhalation time of 6 seconds, but up to 15
seconds
O Number of maneuvers: Minimum of 3 and maximum
of 8
O Should not be interfered by coughing, glottic closure,
mechanical obstruction.

29. Requirements of a good PFT.
O Lack of artifact
O Satisfactory start
O Satisfactory exhalation with six seconds of
smooth continuous exhalation.
O ATS Criteria for reproducibility after obtaining
3 acceptable spirograms:
1) Largest FVC within 0.15L of next largest
FVC
2) Largest FEV1 within 0.15L of next largest
FEV1

31. Measurements obtained from
the FVC curve:
O FEV1---the volume exhaled during the first second
of the FVC maneuver
O 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
O 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

34. Causes of restrictive PFT
O Lung parenchymal pathology
O Inter pleural pathology
O Neuromuscular problems

35. Grading of severity of
abnormality
O Based on TLC:
 Mild: predicted TLC is less than lower limit of normal but
>70%
 Moderate: predicted TLC is <70% and >60%
 Moderately severe: predicted TLC <60%
O Based on spirometry:
 Mild: Predicted VC is less than lower limit of normal but
>70%
 Moderate: Predicted VC <70% and >60%
 Moderately severe: Predicted VC <60% and >50%
 Severe: Predicted VC <50% and >34%
 Very Severe: Predicted VC <34%

36. Causes of obstructive PFT
O Narrowing of airways due to bronchial smooth muscle
contraction.
O Narrowing of airways due to inflammation and swelling
of bronchial mucosa.
O Material inside the bronchial passage.
O Destruction of lung tissue with loss of elasticity.

37. Severity of obstructive lung
disease:

38. Obstructive vs Restrictive
diseases on spirometry
Obstructive disorders Restrictive disorders
O FVC N or↓
O FEV1 ↓
O FEF25-75% ↓
O FEV1/FVC ↓
O TLC N or ↑
O FVC ↓
O FEV1 ↓
O FEF 25-75% N to ↓
O FEV1/FVC N to ↑
O TLC ↓

42. Criteria for reversibility of small
airway obstruction on PFT:
O 2 PFTs should be done one before and one
after administration of bronchodilator.
O Drug used is usually beta-2
sympathomimetic.
O If 2 out of 3 measurements improve then
patient has reversible airway obstruction.
1) FVC of 10% or more
2) FEV1 an increase of 200ml or 15% of baseline FEV1
3) FEF25-75% an increase of 25% or more

43. Flow volume loops
O Helpful in evaluation of air flow limitation on
inspiration and expiration
O In addition to obstructive and restrictive
patterns, flow-volume loops can provide
information on upper airway obstruction:
O Fixed obstruction: such as in tumor, tracheal
stenosis
O Variable extrathoracic obstruction: such as in vocal
cord dysfunction
O Variable intrathoracic obstruction:as in malignancy
or tracheomalacia

47. Measurement of other lung
volumes
O Nitrogen washout technique
O Helium dilution technique
O Body plethysmography

48. DLCO (diffusion lung CO)
O The diffusing capacity is a measure of the
ability of the lungs to transfer gas.
O Measure of interaction of alveolar surface
area, alveolar capillary perfusion and
physical properties of the alveolar
capillary interface.
O CO is rapidly taken up by haemoglobin, its
transfer is therefore limited mainly by
diffusion

49. Causes of decreased
DLCO:
Causes of increased
DLCO:
O Anemia
O Emphysema
O ILD
O Pulmonary edema
O Pulmonary vascular
disease
O Obesity
O Asthma
O L to R shunt
O Alveolar
hemorrhage

50. DLCO- capacity of the lungs to transfer CO (ml/min/mmHg)
DLCOc- DLCO corrected for Hb (ml/min/mmHg)
DLVA- DLCO corected for volume (ml/min/mmHg/L)
DLVC- DLCO corrected for both volume and Hb (ml/min/mmHg/L)

51. Respiratory muscle
function
O A number of diseases such as motor neuron disease
can result in respiratory muscle weakness, which can
ultimately lead to respiratory failure
O Inspiratory mouth pressure
A measure of inspiratory muscle function in which
subjects generate as much inspiratory pressure as
possible against a blocked mouth piece .Values of 80
cm of water or more exclude any significant inspiratory
muscle weakness
O Expiratory mouth pressure
A measure of expiratory muscle function in which
subjects generate as much expiratory pressure as
possible against a blocked mouth piece. Values of 80
cm of water or more exclude any significant expiratory
muscle weakness

52. Tests for cardiopulmonary
reserve:
O Number of flights of stairs patient can
climb: inability to climb 2 flights of stairs
indicates increased risk of post-op
cardiopulmonary complications.
O Six minute walking test (6 MWT)

53. Anesthetic Implications

54. COPD classification by GOLD

55. ATS classification of severity of
COPD

56. Evaluation of patient for lung
resection
GOALS:
1) to identify patients at risk of increased post-
op morbidity & mortality
2) to identify patients who need short-term or
long term post-op ventilator support.
Lung resection may be followed by – inadequate
gas exchange, pulm HTN & incapacitating
dyspnoea.

57. EXAMPLE:
Assuming pre op FEV1 to be
70%
ppoFEV1= 70 X (1-29/100)
ppoFEV1= 50%

59. References
O A practice of anesthesia by Wylie 5th edition
O Millers 7th edition
O Clinical Anesthesiology- Morgan 5th edition
O Interpreting pulmonary function tests: Recognize the
pattern, and the diagnosis will follow. CLEVELAND
CLINIC JOURNAL OF MEDICINE VOLUME 70 •
NUMBER 10
O SERIES ‘‘ATS/ERS TASK FORCE: STANDARDISATION
OF LUNG
FUNCTION TESTING’’ 2005

60. Thank You
THE END