mgm’s college of engineering & technology

8/14/2019 Mgms College of Engineering & Technology

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MGMS COLLEGE OF ENGINEERING & TECHNOLOGY [Pick the date]

INSTRUMENT REPORT

ON

VENTILATOR

BY

JUNED SIDDIQUE

REMARK: ______________ SIGN. :

__________________

JASLOK HOSPITAL AND RESERCH CENTRE | [Type the company address]


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SIEMENS SERVO VENTILATOR 900 S

INTRODUCTION

Respiration is the process of supplying oxygen

to & removing carbon dioxide from the tissues. These gases

are carried in the blood; oxygen from the lungs to the tissues

& CO2 from the tissues to the lungs. The gas exchange in

the lungs is called external respiration and that in the tissues

is called internal respiration. There is a very delicate balancebetween the absorption & excretion of O2 & CO2 in the lungs

& tissues & this balance is maintained by the respiratory or

breathing activity.

For reduced respiratory or breathing failure

(insufficiency), mechanical devices or respirators are used in

hospitals. When artificial ventilation needs to be maintainedfor long time, a ventilator is used. Ventilator is also used

during anesthesia & is designed to match human breathing

waveform.



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COMPONENTS

Gas supply section: -

The respiratory gases are connected via a low-pressure inlet or a

high-pressure inlet. The low-pressure inlet (upper) is used for gas that

is supplied via a flow meter. The high-pressure inlet (lower) is used for

compressed air, or for gas from a gas mixture.

Gas Inlets: -

The gas fed to the high-pressure inlet flows via & inlet valve, anon-return valve, & O2 cell & bacteria filter to the bellows. The O2 cell

measures the O2 concentration in the gas mixture.

The gas fed to the low-pressure inlet flows, via a non-return valve, an

O2 cell & a bacteria filter to the bellows.

High & low-pressure gas supplies should normally not be connected at

the same time. (The gas mixture may then get altered)

Controlled inlet valve:-

The working pressure in the bellows is kept at a relatively

constant level. It is set mechanically by means of an adjustment screw

at the pressure between 10 & 120 cm. H2o & normally at 60cm H2O.

The adjustment screw tensions a spring pack, which keeps the gas in

the bellow under constant pressure. When the volume in the bellows

decreases a lever activates the inlet valve, which then allows more gas

to enter, until the filling volume is attained.

When the filling volume has been attained, the inlet valve closes



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Safety valve:-

From the bellows the gas flows past a safety valve, which

prevents high pressure from building up in the system. The valve

opens if the pressure in the bellows should reach 120cm H2O (safety

function).

The pressure in the bellows (preset working pressure) is shown on the

manometer on the front of the pneumatic unit. There is bacteria filter

& a tube connection from the safety valve to the manometer. The

bacteria filter protects the manometer against the contamination.

The preset working pressure is the highest pressure that can arise in

the system. That is the highest pressure available for the distributionof gas to the patient.

If the bellows is blocked mechanically, so that it becomes overfilled,

then the safety valve will open (surplus function).

Inspiration section:-

The gas flows via a flow transducer & an inspiration valve.

The regulation of the flow to the patient is carried out by means of

feedback servo-system. The flow continuously measures the actual

flow to the patient. This information is compared, in the electronic unit;

to the setting on the front panel i.e. the value of the flow should have

at each moment. If there is difference between actual value & preset

values signals are fed to the inspiration valve, which then changes the

actual flow so that it attains the same value as the desired flow. A

pressure transducer is fitted in the inspiration channel after the

inspiration valve. This transducer continuously measures the actual

pressure in the inspiratory section (Airway pressure).



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Flow transducer:-

From the safety valve, the gas flows onwards, via a

silicone rubber tube, to the flow transducer, which measures the gas

flow. The gas flows through the flow transducer in two parallelchannels, one with a large diameter & one with smaller diameter. The

disc is attached to the thin pin, which is fixed at the other end.

Between the disc & the fixed end there is pressure sensitive strain

gauge.

Pressure transducer & inspiration outlet:-

From the inspiration valve, the gas flows onwards to the

inspiration outlet.

The outlet tube has a thin, metal nipple onto which a plastic tube is

threaded. The pressure transducer continuously measures the

pressure in the patient circuit. The filter protects the pressure

transducer against possible contamination. The gas pressure in the

inspiration channel influences silicone rubber membrane in thepressure transducer. A strain gauge is embedded in the membrane.

When the gas pressure influences the membrane, the strain

gauge bends, & an electric signal is generated. This signal is

proportional to the pressure. The electric signal is fed to the electronic

unit & is compared to the preset values for upper pressure limits &

INSP pressure level. The pressure is indicated on the airway pressure

instrument.

Expiration section:-

The expired gas from the patient is fed back to a separate

expiration channel. The expiration inlet is angled downwards, to

prevent water & secretion from entering the expiration channel. In the



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MGMS COLLEGE OF ENGINEERING & TECHNOLOGY [Pick the date]expiration channel are a flow transducer & a pressure transducer.

These continually measure the patients expired minute volume & the

pressure expiratory system (Airway pressure). On the basis of

information received from the pressure transducer, the expiration

valve regulates the pressure so that a constant positive pressure can

be maintained during expiration (PEEP).

The electronic unit controls the expiration valve. The valve opens

when the expiration phase begins. It is closed during inspiration &

phase.

After the expiration valve theyre as an outlet with built-in flap valve,

which prevents a back flow of expired gases.

Expiration inlet:- The expired gas from the patient flows into the inspiration

channel of the ventilator. This channel is entirely separated from the

inspiration channel.The inlet to the expiration channel is angled. Its

purpose is to prevent water & secretion from entering the expiration

channel.

Flow transducer:-

A silicone rubber tube is connected between the expiration

inlet & a flow transducer, which is similar to the one in the inspiration

channel. The difference between the flow transducers is that the

expiratory flow transducer is heated to about 60C by the embedded

resistor. This is done in order to prevent water from condensing in the

transducer, which could result in incorrect flow measuring & minute

volume reading.

This flow transducer generates electric signals. Which, via the electric

unit, give the reading on the expired minute volume instrument.



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Pressure transducer: -

From the flow transducer, the gas flows onwards, via a

silicone rubber tube & a connection piece, to a metal pipe with a

nipple.

From the nipple of the metal pipe a thin, plastic tube with bacteria

filter goes down to the electronic pressure transducer, which

continuously senses the expiratory pressure & regulates the expiration

valve according to preset PEEP (positive end expiratory pressure).

This pressure transducer also senses when the patient makes

breathing effort. When the patient creates a negative pressure

according to a preset value (trig sensitivity) the inspiration valve

opens.



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VENTILATOR TERMS

Tidal volume:- It is the depth of breathing or the volume ofgas inspired or expired during respiratory cycle.

Minute volume:- This refers volume of gas exchanged perminute during quiet breathing.

Respiration rate:-This is number of breaths per second. Itrepresents total respiratory rate of the patient.

PEEP:- Positive end expiratory pressure.

Mean Airway Pressure (MAP): - An integral taken over onecomplete cycle expresses the mean airway pressure.

Inspiratory Pause Time:- When the pressure in thepatient circuit and alveoli is equal, there is a period of no flow; this

period is called inspiratory pause time.

Inspiratory Flow:- Inspiratory flow is represented as apositive flow above the zero line.



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Expiratory Flow: - Expiratory flow is a negative flow belowthe zero line.

Inspiratory/Expiratory Flow.

Fig. a Mean airway pressure.

b Inspiratory pause time



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MGMS COLLEGE OF ENGINEERING & TECHNOLOGY [Pick the date]c Inspiratory/Expiratory Flow.

SPECIFICATIONS: -

O2 concentration

Range: 0 to 100%

Airway pressure

Range: -40 to 160 cmH2O

Supply pressure

Range: 0 to 7 bar

Inspiratory tidal volume

Adult range: 100 to 2000/4000ml

Infant range: 5 to 350ml

Inspiratory minute volume

Adult range: 0.5 to 60 l/min

Infant range: 0.3 to 20 l/min



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Expiratory tidal volume

Adult range: 0 to 2000/4000ml

Infant range: 0 to 350ml

Expiratory minute volume

Adult range: 0 to 60 l/min

Infant range: 0 to 20 l/min


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