important discussion and anaesthesia related stuff

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?