pulmonary function test’s

Welcome you all

By : LOKENDRA YADAV

What is pulmonary function test’s?(PFTs)

• Pulmonary function tests are a group of test that measure how well the lungs take in and release air and how well they move oxygen into the blood.(it is a non invasive)

How the test is performed?

SPIROMETRY…

In a spirometry test, you breathe into a mouthpiece that is connected to an instrument called a spirometer. The spirometer records the amount and the rate of air that you breathe in and out over a period of time.

Lung volume measurement can be done in two ways:

•The most accurate way is to sit in a sealed, clear box that looks like a telephone booth (body plethysmograph) while breathing in and out into a mouthpiece. Changes in pressure inside the box help determine the lung volume.

Body plethysmograph

•Lung volume can also be measured when you breathe nitrogen or helium gas through a tube for a certain period of time. The concentration of the gas in a chamber attached to the tube is measured to estimate the lung volume.

•To measure diffusion capacity, you breathe a harmless gas for a very short time, often one breath. The concentration of the gas in the air you breathe out then is measured. The difference in the amount of gas inhaled and exhaled can help estimate how quickly gas can travel from the lungs into the blood.

Why the test is performed?

Pulmonary function tests are done to:

•Diagnose certain types of lung disease (especially asthma, bronchitis, and emphysema)•Find the cause of shortness of breath •Measure whether exposure to contaminants at work affects lung function

It also can be done to:•Assess the effect of medication•Measure progress in disease treatment

Spirometry measures airflow. By measuring how much air you exhale, and how quickly, spirometry can evaluate a broad range of lung diseases.

Lung volume measures the amount of air in the lungs without forcibly blowing out. Some lung diseases (such as emphysema and chronic bronchitis) can make the lungs contain too much air. Other lung diseases (such as fibrosis of the lungs and asbestosis) make the lungs scarred and smaller so that they contain too little air.

Testing the diffusion capacity (also called the DLCO) allows the doctor to estimate how well the lungs move oxygen from the air into the bloodstream.

Normal value of PFTs is depend upon subject height ,age and sex normal results

Are expressed as a percentage .A value is usually considered abnormal if it less than 80% of predicted value.

Abnormal value usually mean that subject may have some chest or lung disease

PULMONARY FUNCTION ANALYZERS(PFA)

Three basic type of measurement made in pulmonary clinicVentilation: simple inhalation and exhalation.

Distribution: This is measurement quantify the degree of lung obstruction and also determine the residual volume(second method by inhaling Nitrogen)

Diffusion: This measurement is performed to determine the rate at at which gas is exchanged with the blood stream.

PFA provide a complete evaluation of lung function or the respiratory process

NITROGEN ANALYZER

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It allows rapid analysis of nitrogen concentration (volume%) in respiratory air.

NITROGEN LINEARIZER: In case of nitrogen washout during human physiological investigation require stable linear input device. for this purpose it was necessary to obtain a precision of 0.02% nitrogen (0.02% of the avg nitrogen usually encountered during a breath near the end of the wash out)

By using low drift op-amp in nitrogen analyzer

AUTOGAIN CIRCUIT

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AUTO GAIN CIRCUIT is nothing but it is a automatic gain control(AGC).

The avg o/p signal level is fed back to adjust the gain to an appropriate level of range of input signal level

PNEUMOTACH FLOW

TRANSDUCER?

A Device that measure a the flow of gases in form of pressure gradient.

And a pressure gradient developed by PHEUMOTACH METER is directly relatedto flow.

PRESSURE TRANSDUCER

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LINEAR AMP?

LINEAR AMP is stand for linear amplifier very familiar term.

A linear amp is an electronic circuit whose o/p is proportional to its i/p but capable of delivering more power into a load if it required

BTPS

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B : BODY

T : TEMPERATURE

P : PRESSURE

S : SATURATION

BTPS : ABBREVATION is used for body temperature ambient pressure saturated water vapors condition of a volume of gas for humans normal respiratory tract temperature is measured at 37 degree Celsius ,ambient pressure and the partial pressure of water vapors at 37 degree Celsius at 47 mm Hg

What is BTPS compensation?

A/D CONVERTOR

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TRANDUCERS

PRESENT TRANSDUCER USED IN SPIROMETER……

TURBINE TRANDUCERS

actually a rotating vane, this spins, the revolutions are counted as they break a light beam

TRANDUCERS

RESTRICTIVE

INS

NORMAL

√

COMBINED

BOTH

OBSTRUCTIV

EXP

120

100

60

40

20

0

20 40 80 100120

FEV

FVC%

FVC/FVCref %

MILLER,S QUADRANT…….

Thank You