This document provides information on pulmonary function tests (PFTs). It discusses the goals of PFTs which include predicting and assessing pulmonary dysfunction. It outlines various lung volumes and capacities that can be measured through PFTs such as tidal volume, vital capacity, and total lung capacity. The document also discusses indications for preoperative PFTs and provides guidelines from different organizations. It summarizes different PFT measurements and their clinical significance. Overall, the document serves as a guide for understanding PFTs and their role in evaluating pulmonary function and perioperative risk.

1. D R Y O G E S H R A T H O D
D E P T O F A N E S T H E S I A
K E M H O S P I T A L
M U M B A I
PULMONARY FUNCTION
TESTS

2. PULMONARY FUNCTION TESTS
 Includes a wide variety of Objective tests to assess
lung function.
 Provides Standardized measurements for assessing
the presence and severity of Respiratory
dysfunction.

3. GOALS
 To predict the presence of pulmonary dysfunction
 To know the functional nature of disease
(Obstructive or Restrictive)
 To assess the severity and progression of disease
 To identify patients at Perioperative risk of
Pulmonary complications

4. INDICATIONS OF PFT IN PAC
TISI GUIDELINES FOR PREOPERATIVE SPIROMETRY
 Age > 70 yrs.
 Morbid obesity
 Thoracic surgery
 Upper abdominal surgery
 Smoking history and cough
 Any pulmonary disease

5. INDICATIONS FOR PREOPERATIVE
SPIROMETRY
 ACP GUIDELINES FOR PREOPERATIVE
SPIROMETRY
 Lung resection
 H/o smoking, dyspnoea
 Cardiac surgery
 Upper abdominal surgery
 Lower abdominal surgery
 Uncharacterized pulmonary disease
(defined as history of pulmonary Disease or symptoms
and no PFT in last 60 days)

6. Lung Volumes and Capacities
 Four Lung volumes:
Tidal volume
Inspiratory reserve volume
Expiratory reserve volume
Residual volume
 Five capacities:
Inspiratory capacity
Expiratory capacity
Vital capacity
Functional residual capacity
Total lung capacity
Addition of 2 or more Volumes comprises a Capacity.

8. TIDAL VOLUME (TV)
 Volume of air inhaled/
exhaled in each breath
during quite respiration.
 N – ~6-8 ml/kg.
 TV FALLS WITH-
1. Decrease in compliance
2. Decreased ventilatory
muscle strength

9. INSPIRATORY RESERVE VOLUME (IRV)
 Maximum volume of air
which can be Inspired
after a Normal Tidal
inspiration i.e. from end
inspiration point.
 N- 1900 ml- 3300 ml.

10. EXPIRATORY RESERVE VOLUME (ERV)
 Maximum Volume of air
which can be expired
after a normal tidal
expiration i.e.
from end expiration
point
 N- 700 ml – 1000 ml

11. RESIDUAL VOLUME (RV)
 Volume of air remaining in
the lungs after a maximum
expiration.
 N- 20-25ml/kg
(1700- 2100 ml)
 Indirectly measured-
FRC-ERV
 Cannot be measured by
Spirometry

12. INSPIRATORY CAPACITY (IC)
 Maximum volume of air
which can be inspired
after a normal tidal
expiration.
 IC = TV + IRV
 N-2400 ml – 3800 ml
 Detects extrathoracic
airway obstruction
 Changes parallel changes in
VC

13. VITAL CAPACITY (VC)
 Maximum volume of air
expired after a maximum
Inspiration
 VC= TV+ERV+IRV
 N- 3100ml-4800ml
(60-70 ml/kg)

14. VITAL CAPACITY- CONTD
 Coined by John Hutchinson
 VC is considered abnormal if ≤ 80% of predicted value
 Factors Influencing VC
 PHYSIOLOGICAL :
 Physical dimensions- directly proportional to height
 SEX – More in males : large chest size, more muscle
power.
 AGE – decreases with increasing age
 STRENGTH OF RESPIRATORY MUSCLES
 POSTURE – decreases in supine position
 PREGNANCY- unchanged or increases by 10%
( increase in AP diameter in pregnancy)

15. FACTORS DECREASING VC
1. Alteration in muscle power- d/t drugs, n-m
diseases.
2. Pulmonary diseases – pneumonia, chronic
bronchitis, asthma, fibrosis, emphysema,
pulmonary edema,.
3. Space occupying lesions in chest- tumours,
pleural/pericardial effusion, kyphoscoliosis
4. Abdominal tumours, ascites.

16. 5. Depression of respiration : Opioids/ Volatile
agents
6. Abdominal Splinting – Abdominal binders,
tight bandages, hip spica.
7.Abdominal pain – decreases by 50% & 75% in
lower & upper abdominal Surgeries respectively.
8. Posture

17. DIFFERENT POSTURES AFFECTING VC
POSITION DECREASE IN VC
TREDELENBERG 14.5%
LITHOTOMY 18%
PRONE 10%
RT LATERAL 12%
LT LATERAL 10%

18. CLINICAL SIGNIFICANCE OF VC
VC correlates with capability for deep
breathing and effective cough.
So in Post Operative period if VC falls below 3
times TV– Artificial Respiration is needed to
maintain airway clear of secretions.

19. FUNCTIONAL RESIDUAL CAPACITY (FRC)
 Volume of air remaining in the lungs after normal
tidal expiration.
 N- 2300ml -3300ml or 30-35 ml/kg
 FRC = RV + ERV
 Decreases under anaesthesia-
-With Spontaneous Respiration – decreases by 20%
-With paralysis – decreases by 16%

20. FACTORS AFFECTING FRC
 FRC increases with-
Increased height
Erect position (30% more than in supine)
Decreased lung recoil (e.G. Emphysema)- Gas Trapping
 FRC decreases with-
Obesity
Muscle paralysis (especially in supine)
Supine position
Pleural Effusion
Restrictive lung disease (e.G. Fibrosis, pregnancy)
Anaesthesia
FRC does NOT change with age.

21. 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
Keep airway resistance low

22. TOTAL LUNG CAPACITY (TLC)
Maximum volume of air attained in lungs after
maximal inspiration.
N- 4000ml-6000ml or 80-100 ml/kg
TLC= VC + RV

23. DEFINITIONS
1. Forced Vital Capacity(FVC)-
Max vol. of air which can be expired out as forcefully and rapidly
as possible, following a maximal inspiration.
 Normal healthy subjects have VC = FVC.
2. FORCED VITAL CAPACITY IN 1 SEC. (FEV1)-
Forced expired volume in 1 sec during FVC maneuver.
 Expressed as an absolute value or % of FVC
 N- FEV1 (1 SEC)- 75-85% OF FVC
 FEV2 (2 SEC)- 94% OF FVC
 FEV3 (3 SEC)- 97% OF FVC

24. CLINICAL RANGE(FEV1) PATIENT GROUP
 3 - 4.5 L
 1.5 – 2.5 L
 <1 L
 0.8 L
 0.5 L
 NORMAL ADULT
 MILD.OBSTRUCTION
 MOD.OBSTRUCTION
 HANDICAPPED
 DISABILITY
 SEVERE EMPHYSEMA

25.  FEV1 – Decreased in both obstructive & restrictive lung
disorders.
 FEV1/FVC – Reduced in obstructive disorders.
 NORMAL VALUE (FEV1/FVC) 75 – 85 %
 < 70% of predicted value – Mild obstruction
 < 60% of predicted value – Moderate obstruction
 < 50% of predicted value – Severe obstruction

26. DISEASE
STATES
FVC FEV1 FEV1/FVC
1) OBSTRUCTIVE NORMAL ↓ ↓
2) STIFF LUNGS ↓ ↓ NORMAL
3 ) RESP.
MUSCLE
WEAKNESS
↓ ↓ NORMAL

27. PEAK EXPIRATORY FLOW RATE (PEFR)
 It is the maximum flow rate during FVC maneuver in
the initial 0.1 sec.
 Normal value in young adults (<40 yrs)= 500l/min
 Clinical significance - values of <200l/min- impaired
coughing & hence likelihood of post-op complication

28. FORCED MID-EXPIRATORY FLOW RATE
(FEF25%-75%):
 Maximum flow rate during the mid-expiratory part of
FVC maneuver.
 value – 4.5-5 l/sec. Or 300 l/min.
 CLINICAL SIGNIFICANCE: SENSITIVE & IST
INDICATOR OF OBSTRUCTION OF SMALL
DISTAL AIRWAYS

29. MAXIMUM BREATHING CAPACITY:
(MBC/MVV)
 Largest volume that can be breathed per minute by
voluntary effort , as hard & as fast as possible.
 N – 150-175 l/min.
 Measured for 12 secs – extrapolated for 1 min.
MVV(max voluntary ventilation) = FEV1 X 35
 Discrepancy b/w FEV1 and MVV means inconsistent /
submaximal inspiratory effort
 MBC/MVV altered by- airway resistance
- Elastic property
-Muscle strength
- Learning
- Coordination
- Motivation

30. BED SIDE PFTS
1) Sabrasez 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 (normal-3100-4800ml)
20 – 25 SEC - 3000 ml VC
15 - 20 SEC - 2500 ml VC
10 - 15 SEC - 2000 ml VC
5 - 10 SEC - 1500 ml VC

31. 2) Single breath count:
After deep breath, hold it and start counting
till the next breath.
Indicates vital capacity
N- 30-40 COUNT
BED SIDE PFTS

32. 3) SCHNEIDER’S MATCH BLOWING TEST:
(MEASURES Maximum Breathing Capacity)
Ask the patient 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
BED SIDE PFTS

33.  Can not blow out a match
 MBC < 60 L/min
 FEV1 < 1.6L
 Able to blow out a match
 MBC > 60 L/min
 FEV1 > 1.6L
 MODIFIED MATCH TEST:
DISTANCE MBC (N-150-175 L/min)
9” >150 L/MIN.
6” >60 L/MIN.
3” > 40 L/MIN.
BED SIDE PFTS

34. 4) COUGH TEST: DEEP BREATH F/BY COUGH
 ABILITY TO COUGH
 STRENGTH
 EFFECTIVENESS
-VC ~ 3 TIMES TV FOR EFFECTIVE COUGH.
A wet productive cough / self propagated paroxysms of coughing –
patient susceptible for pulmonary Complication.
5) WHEEZE TEST :
 Patient asked to take 5 deep breaths, then auscultated between
shoulder blades to check presence or absence of wheeze.
BED SIDE PFTS

35. 6) FORCED EXPIRATORY TIME:
After deep breath, exhale maximally and forcefully & keep
stethoscope over trachea & listen.
N FET – 3-5 SECS.
OBS.LUNG DIS. - > 6 SEC
RES. LUNG DIS.- < 3 SEC
7) DEBONOs WHISTLE BLOWING 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.
BED SIDE PFTS

36. DEBONO’S WHISTLE

37. 8) Wright Respirometer : measures TV, MV
 Simple and rapid
 Can be connected to endotracheal tube
or face mask
 Prior explanation to patients needed.
 Ideally done in sitting position
 MV- instrument records for 1 min and reads directly.
 TV-calculated by dividing MV by counting Respiratory Rate.
9) BED SIDE PULSE OXIMETRY
10) ABG.

38. CATEGORIZATION OF PFTs
1. MECHANICAL VENTILATORY FUNCTIONS OF LUNG /
CHEST WALL:
A) STATIC LUNG VOLUMES & CAPACITIES – VC, IC,
IRV, ERV, RV, FRC.
B) DYNAMIC LUNG VOLUMES –FVC, FEV1, FEF 25-75%, PEFR,
MVV, RESP. MUSCLE STRENGTH
C) VENTILATION TESTS – TV, MV, RR.

39. 2) GAS- EXCHANGE TESTS:
A) Alveolar-arterial pO2 gradient
B) Diffusion capacity
C) Gas distribution tests -Single breath N2 test.
- Multiple Breath N2 test
- Helium dilution method.
D) Ventilation – Perfusion tests
A) ABG
B) single breath CO elimination test
CATEGORIZATION OF PFTs

40. 3) CARDIOPULMONARY INTERACTION:
A) Qualitative tests:
- History , Examination
- ABG
- Stair Climbing Test
B) Quantitative tests
- 6 min Walk test (Gold standard)
CATEGORIZATION OF PFTs

41. 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.”
 MEASURES - VC, FVC, FEV1, PEFR.
 CAN’T MEASURE – FRC, RV, TLC

42. Flow-Volume Curves and Spirograms
 Two ways to record results of FVC maneuver:
 Flow-volume curve--- Flow meter measures flow rate in
L/s upon exhalation; Flow plotted as Function of Volume
 Classic Spirogram---Volume as a Function of Time

44. Measurements Obtained from the FVC Curve
 FEV1---the volume exhaled during the first second of the FVC
maneuver
 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
 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

45. OBSTRUCTIVE DISORDERS RESTRICTIVE DISORDERS
 Limitation of expiratory
airflow as airways cannot
empty as rapidly compared
to normal (e.g. narrowed
airways from bronchospasm,
inflammation, etc.)
Examples:
 Asthma
 Emphysema
 Cystic Fibrosis
 Characterized by reduced
lung volumes/decreased lung
compliance
Examples:
 Interstitial Fibrosis
 Scoliosis
 Obesity
 Lung Resection
 Neuromuscular diseases
 Cystic Fibrosis
Spirometry Interpretation:
Obstructive vs. Restrictive Defect

46.  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 ↓

47. Normal vs. Obstructive vs. Restrictive

48. Spirometry Interpretation:
What do the numbers mean?
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
 <49% Severe obstruction

49. 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:
 80 or Higher
Normal
 79 or Lower
Abnormal
Spirometry Interpretation:
What do the numbers mean?

50. Lung Volumes and Obstructive and Restrictive Disease?

51. MEASUREMENTS OF VOLUMES
 TLC, RV, FRC – MEASURED USING
Nitrogen washout method
Inert gas (helium) dilution method
Total body plethysmography

52. 1) N2 WASH OUT METHOD
 Patient breathes in 100% oxygen and on expiration all nitrogen
is washed out.
 The exhaled volume and nitrogen conc. in it is measured.
 The difference in nitrogen volume at the initial concentration
and at the final exhaled concentration allows a calcul;ation of
the intrathoracic volume, usually the FRC

53. 2) HELIUM DILUTION METHOD:
Patient breathes in and out of a spirometer filled with 10% helium
and 90% O2, till conc. in spirometer and lung becomes same
(equilibirium) as no helium is lost; (as He is insoluble in blood)
C1 X V1 = C2 ( V1 + V2)
V2 = V1 ( C1 – C2)
C2
V1= VOL. OF SPIROMETER
V2= FRC
C1= Conc.of He in the spirometer before equilibrium
C2 = Conc, of He in the spirometer after equilibrium

54. 3) TOTAL BODY PLETHYSMOGRAPHY
Subject sits in an air tight box. At the end of normal exhalation –
shuttle of mouthpiece closed and pt. is asked to make resp.
efforts. As subject inhales – expands gas volume in the lung so
lung vol. increases and box pressure rises and box vol.
decreases.
BOYLE’S LAW:
PV = CONSTANT (at constant temp.)
For Box – p1v1 = p2 (v1- ∆v)
For Subject – p3 x v2 =p4 (v2 - ∆v)
P1- initial box pr. P2- final box pr.
V1- initial box vol. ∆ v- change in box vol.
P3- initial mouth pr., p4- final mouth pr.
V2- FRC

55. MEASUREMENT OF AIRWAY RESISTANCE
1) Body Plethysmography
2) Forced expiratory maneuvers:
 Peak expiratory flow (PEFR)
FEV1
3) Response to bronchodilators (FEV1)

56.  Patients with small airway obstruction tested twice-
before and after administration of bronchodilators to
evaluate responsiveness.
 If 2 out of 3 measurements improve, patient has a
reversible airway obstruction that is responsive to
medication.
1) FVC- increase of 10% or more
2) FEV1- increase of 200ml or 15% of baseline
3) FEF25%-75%- increase of 20% or more
Spirometry Pre and Post Bronchodilator

57. FLOW VOLUME LOOPS
 Do FVC maneuver and then inhale as rapidly and as
much as possible
 This makes an Inspiratory curve.
 The Expiratory and Inspiratory Flow Volume Curves
put together make a Flow Volume Loop.

59. TESTS FOR GAS EXCHANGE FUNCTION
1) ALVEOLAR-ARTERIAL O2 TENSION GRADIENT:
 Sensitive indicator of detecting regional V/Q inequality
 Normal value in young adult at room air = 8-25 mm Hg.
 Abnormal high values at room air is seen in
asymptomatic smokers & chr. Bronchitis.

60. 2)DIFFUSING CAPACITY OF LUNG:
- defined as the rate at which gas enters into blood.
 DL IS MEASURED BY USING CO:
A) High affinity for Hb which is approx. 200 times
that of O2 , so does not rapidly build up in plasma
B) Under N condition it has low blood conc ≈ 0
C) Therefore, pulm conc.≈0

61.  Pt inspires a dilute mixture of CO and hold the
breath for 10 secs.
 CO taken up is determined by infrared analysis:
DLCO = CO ml/min/mmHg
PACO – PaCO
 N range 20- 30 ml/min./mmhg
SINGLE BREATH TEST USING CO

62. DLCO decreases in-
 Emphysema, lung resection, Pul. Embolism, Anaemia
 Pulmonary fibrosis, sarcoidosis- increased thickness
DLCO increases in:
(Cond. Which increase pulmonary blood flow)
 Supine position
 Exercise
 Obesity
 L-R shunt

63. TESTS FOR CARDIOPLULMONARY INTERACTIONS
 Reflect gas exchange, ventilation, tissue O2, CO2.
 QUALITATIVE-
History, examination, ABG, Stair climbing test
 QUANTITATIVE- 6 minute walk test

64.  1) STAIR CLIMBING TEST:
 If able to climb 3 flights of stairs without stopping/dyspnoea - ↓ed
morbidity & mortality
 If not able to climb 2 flights – high risk
 2) 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
- VO2 max > 15 ml/kg/min
- If 1080 feet in 6 mins : VO2 of 12ml/kg/min
- Simultaneously oximetry is done & if Spo2 falls >4%- high risk

65. PREDICTION OF POSTOPERATIVE PULMONARY
COMPLICATIONS
 1) Nunn and Miledge criteria:
a. FEV1<1L, N PaO2, PaCO2- Low risk of POPC
b. FEV1<1L, Low PaO2, N PaCO2- patient will need prolonged
O2 supplementation
c. FEV1<1L, Low PaO2, High PaCO2- patient may need postop
ventilation
 2) Based on Spirometry:
a. Predicted FVC< 50%
b. Predicted FEV1 < 50% or <2 L
c. Predicted MVV <50% or < 50L/min

66. PATIENT WITHOUT CHEST OPTIMIZATION FOR
GENERAL ANESTHESIA IS AN EXTRA BURDON
ON ANESTHETIST…….!

67. Thanks! Any Questions?