VarSeq 2.6.0: Advancing Pharmacogenomics and Genomic Analysis
Pulmonary Function Tests Guide
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.
7.
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)
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
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
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
43.
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 ↓
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?
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.
58.
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
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…….!