pulmonary function tests ppt

PULMONARY FUNCTION TESTS
Dr. Chavan P. R.
Pharm D

PFT
 Pulmonary function tests is a generic term used to
indicate a battery of studies or maneuvers that may
be performed using standardized equipment to
measure lung function.
Evaluate one or more aspects of the respiratory
system
Respiratory mechanics
Lung parenchymal function/ Gas exchange
Cardiopulmonary interaction

ASPECTS OF PULMONARY FUNCTION:
 Perfusion- Blood flow.
 Diffusion- Movement of O2 & CO2.
 Ventilation- Air exchange btwn alveolar spaces &
the atmosphere.

SIGNIFICANCE
1. Investigation of patients with symptoms/signs/
investigations that suggest pulmonary disease e.g.
• (Cough/Wheeze/Breathlessness/Crackles)
2. Monitoring patients with known pulmonary disease
for progression and response to treatment e.g.
• Interstitial fibrosis
• COPD
• Asthma
• Pulmonary vascular disease

3. Investigation of patients with disease that may
have a respiratory complications e.g.
• Connective tissue disorders
• Neuromuscular diseases
4. Preoperative evaluation prior to e.g.
• Lung resection
• Abdominal surgery
• Cardiothoracic surgery

5. Evaluation patients a risk of lung diseases e.g.
• Exposure to pulmonary toxins such a radiation/
medication/environmental/occupational exposure
6. Surveillance following lung transplantation to
assess for
• Acute rejection
• Infection
• Obliterative bronchiolitis

CONTRAINDICATIONS
Myocardial infarction within the last month
Unstable angina
Recent thoraco-abdominal surgery
Recent ophthalmic surgery
Thoracic or abdominal aneurysm
Current pneumothorax

LUNG VOLUME
 Four Lung volumes:
• Tidal volume (500-750ml)
• Inspiratory reserve volume(2500-3000ml)
• Expiratory reserve volume(1000-1500ml)
• Residual volume( 1300-1500ml)

LUNG CAPACITIES
 Five capacities:
• Inspiratory capacity ( TV + IRV )
• Expiratory capacity ( TV + ERV )
• Vital capacity ( IRV + TV + ERV )
• Functional residual capacity ( RV + ERV )
• Total lung capacity(IRV+TV+ERV+RV)

TESTS
 Bed side pulmonary function tests
 Spirometry
 N2 Washout Technique
 Helium Dilution technique
 Body Plethysmography
 Cardiopulmonary interaction

BED SIDE PULMONARY FUNCTION TESTS
1. SABRASEZ BREATH HOLDING TEST
>25 SEC.-NORMAL Cardiopulmonary Reserve
15-25 SEC- LIMITED CPR
<15 SEC- VERYPOOR 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

2. SCHNEIDER’S MATCH BLOWING
TEST
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
9” >150 L/MIN.
6” >60 L/MIN.
3” > 40 L/MIN

3. COUGH TEST
 Deep breath followed
by cough
 Inadequate cough if:
FVC<20 ml/kg FEV1 <
15 ml/kg PEFR < 200
l/min.
 VC ~ 3 times TV for
effective cough.

4.FORCED EXPIRATORY TIME
Normal FET – 3-5 SECS.
Obstructive Lung Disease. - > 6 SEC
Restrictive Lung Disease.- < 3 SEC

5. SINGLE BREATH COUNT
After deep breath, hold it and start counting till the
next breath.
N- 30-40 COUNT
Indicates vital capacity

6. WRIGHT PEAK FLOW METER:
Measures PEFR (Peak Expiratory Flow Rate)
N – MALES- 450-700 L/MIN.
FEMALES- 350-500 L/MIN.

7. DE-BONO 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.

8. WRIGHT RESPIROMETER :
 measures TV,MV Instrument- compact, light and
portable.
 Can be connected to endotracheal tube or face
mask MV- instrument record for 1 min.
 And read directly TV-calculated and dividing MV by
counting Respiratory Rate.
Disadvantage: It under- reads at low flow rates and
over- reads at high flow rates.

PREREQUESITE
Do not smoke for at least 1 hour before the test.
Do not drink alcohol for at least 4 hours before the
test.
Do not exercise heavily for at least 30 minutes
before the test.
Do not wear tight clothing that makes it difficult for
you to take a deep breath.
Do not eat a large meal within 2 hours before the
test.

DISADVANTAGE
• Only for single use due to CO2 accumulation & O2
cannot be supplied.
• Residual Volume, Functional Residual Capacity and
Total Lung Capacity cannot be measured.

N2 WASHOUT TECHNIQUE
 The patient breathes
100% oxygen, and all the
nitrogen in the lungs is
washed out.
 The exhaled volume and
the nitrogen concentration
in that volume are
measured.
 The difference in nitrogen
volume at the initial
concentration and at the
final exhaled concentration
allows a calculation of
intrathoracic volume,
usually FRC.

HELIUM DILUTION TECHNIQUE
 Pt breathes in and out
from a reservoir with
known volume of gas
containing trace of
helium.
 Helium gets diluted by
gas previously present
in lungs.
 eg: if 50 ml Helium
introduced and the
helium concentration is
1% , then volume of
the lung is 5L.

BODY PLETHYSMOGRAPHY
 Plethysmography (derived
from greek word meaning
enlargement).
 Based on principle of
BOYLE’S LAW(P*V=k) A
patient is placed in a sitting
position in a closed body box
with a known volume The
patient pants with an open
glottis against a closed
shutter to produce changes
in the box pressure
proportionate to the volume
of air in the chest.
 As measurements done at
end of expiration, it yields
FRC

CARDIOPULMONARY INTERACTION
 Stair climbing test
 Shuttle walk test
 6min walk test
 Cardiopulmonary exercise test

SHUTTLE WALK TEST
 Walk test is based on 20m
shuttle walk test
 Measures maximum distance
walked by the patient at a
pace set by audio signals
 Requires patients to walk at
increasing speads up and
down a 10m course
 Speed walking is increased
every minute by 0.17m/s

6MIN WALK TEST
 The tester will measure your blood pressure, pulse and
oxygen level usually with a pulse oximeter before you start
to walk.
 You should be given the following instructions: The object
of the test is to walk as far as possible for six minutes. You
will walk at your normal pace to a chair or cone, and turn
around. And you continue to walk back and forth for six
minutes.
 Let the staff know if you are having chest pain or
breathing difficulty.
 It is acceptable to slow down, rest or stop. After every
minute interval, you will be given an update.

pulmonary function tests ppt

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