updated slides from previous slides too much precise and very help full information for Bio-medical Engineers, Doctors, thanks for slides comment below email.

1. The Anaesthesia Machine
PRESENTED BY-
ENGR: BANGUL KHAN(F16BM05)
DEPARTMENT :
BIOMEDICAL ENGINEERING(MUET)
SUPERVISOR:
PROF: DR SYED AMJAD ALI

2. Anaesthesia Introduction
An anesthesia workstation integrates most of the
components necessary for administration of anesthesia
into one unit
It is a device which delivers a precisely-known but
variable gas mixture, including anaesthetizing and
life-sustaining gases.
Consists of:
The anesthesia machine
Ventilator
Breathing system
Monitors
Added to this may be drug delivery systems,
suction equipment, and a data management system

3. WHY ANESTHESIA MACHINE IS USE IF THERE IS AVAILABILITY
OF OTHER SIMPLE METHODS(CAUSES)

4. History
The original concept of Boyle's machine was invented
by the British anaesthetist H.E.G. Boyle in 1917
1920 – A vapourizing bottle is incorporated
to the machine.
1926 – A 2nd vaporizing bottle and by-pass
controls are incorporated.
1930 – A Plunger device is added to the
vaporizing bottle.
1933 – A dry-bobbin type of flowmeter is
introduced.
1937 – Rotameters displayed dry-bobbin
type of flowmeters

5. Types of Anesthesia Machine
Intermittent-Gas flows only during inspiration
Egs: Entonox apparatus, Mackessons apparatus
Continuous-Gas flows both during inspiration and
expiration. Egs :
Boyle Machine
Forregar
Dragger

6. Standards for Anesthesia Machines and
Workstations
 Standards for anesthesia machines and workstations
provide guidelines to manufacturers regarding their
minimum performance, design characteristics, and
safety requirements. During the past 2 decades, the
progression of anesthesia machine standards has been
as follows:
 1979: American National Standards Institute
 1988: American Society for Testing and Materials,
 1994: ASTM F1161-94 (reapproved in 1994 and
discontinued in 2000)
 2005: International Electrical Commission (IEC)
 2005: ASTM (reapproved)F1850
 European standard is EN740

7. Contd….
To comply with the 2005 ASTM F1850-00 standard, newly
manufactured workstations must have monitors that
measure the following parameters:
 continuous breathing system pressure,
 exhaled tidal volume,
 ventilatory CO2 concentration,
 anesthetic vapor concentration,
 inspired oxygen concentration,
 oxygen supply pressure,
 arterial hemoglobin oxygen saturation
 arterial blood pressure,
 and continuous electrocardiogram.

9. Basic Schematics

10. Systemcomponents
Electrical
1.Master Switch
2.Power Failure Indicator
3.Reserve Power
4.Electrical Outlet
5.Circuit Breakers
6.Data Communication Port
Pneumatic
1.High Pressure System
2.Intermediate System
3.Low Pressure System

11. Electrical Components
Master Switch
Master (main power) switch activates both the pneumatic
and electrical functions . On most machines, when the
master switch is in the OFF position, the only
electrical components that are active are the battery
charger and the electrical outlets
Standby position - allows the
system to be powered up
quickly
Computer-driven machines should be
turned OFF and restarted with a
full checkout at least every 24
hours.
STANDBY mode is not used for an
extended period.

12. Most machines are equipped with a visual
and/or audible indicator to alert the
anesthesia provider to the loss of mains
power .
The machine will usually give an indication
when mains power is lost.
Power Failure Indicator
Reserve Power
Backup source of power for the occasional outage is necessary

13. Electrical Outlets
 Most modern anesthesia machines have electrical
outlets.
 These are intended to power monitors and other
devices.
 As a general rule, these outlets should only be used
for anesthesia monitors.
 Other appliances should be connected directly to mains
power.
Next to each outlet is a circuit breaker.

14. Circuit Breakers
There are circuit breakers for both the anesthesia
machine and the outlets .
When a circuit breaker is activated, the electrical
load should be reduced and the circuit breaker reset
Data Communication Ports
 Most modern anesthesia machines have
data communications ports.
 These are used to communicate between
the anesthesia machine, monitors, and
the data management system

15.  The anaesthesia machine receives medical gases from a
gas supply; controls the flow of desired gases
reducing their pressure, to a safe level.
 So the pressure inside a source ( cylinder or pipeline
) must be brought to a certain level before it can be
used for the purpose of ventilation.
 And it needs to be supplied in a constant pressure,
otherwise the flow meter would need continous
adjustment.
.

16.  This is achieved by bringing down the pressure of a
gas supply in a graded manner with the help of three
pressure reducing zones .
 Thus the pneumatic part of the machine can be
conveniently divided into three parts-
High pressure system
Intermediate pressure system
Low pressure systems

18. • Consists of:
– Hanger Yolk
– Check valve
– Cylinder
Pressure
Indicator
(Gauge)
– Pressure
Reducing
Device
(Regulator)
• Usually not
used, unless
pipeline gas
supply is off

19. Hanger Yoke Assembly
The Hanger yoke assembly
1) Orients and supports the cylinder
2) Provides a gas-tight seal
3) Ensures uni-directional gas flow
The workstation standard recommends that
there be at least one yoke each for
oxygen and nitrous oxide.
If the machine is likely to be used in
locations that do not have piped gases,
it is advisable to have a double yoke,
especially for oxygen.

21. CHECK VALVE:
 It allows gas from a cylinder to enter the machine but
prevents gas from exiting the machine when there is no
cylinder in the yoke.
 It allows an empty cylinder to be replaced with a full
one without having to turn off the `in–use` cylinder.
 Prevents transfer of gas from one cylinder to the
other with a lower pressure in a double yoke.
 It consists of a plunger that slides away from the
side of the greater pressure.

23. A Bourdon tube is a hollow metal tube(copper alloy) bent into a
curve, then sealed on one side and linked to a clock
like mechanism

24. Electronic Cylinder PressureIndicator
Light emitting diodes(LED’S)in electronic
pressure gauge indicate
Cylinder valve is close –Dark color
Cylinder valve is open –
Pressure adequate –Green
Pressure inadequate-Red

25.  The pressure in a cylinder varies. The anesthesia
machine is fitted with devices (reducing valves,
regulators, reducing regulators, reduction valves,
regulator valves) to maintain constant flow with
changing supply pressure.
 These reduce the high and variable pressure found in a
cylinder to a lower (40 to 48 psig, 272 to 336 kPa)
and more constant pressure suitable for use in an
anesthesia machine.
PRESSURE REDUCING DEVICE
(REGULATOR)

26. INTERMEDIATE
PRESSURE
SYSTEM
Begins at the regulated
cylinder supply source
at 45 psig includes the
pipeline sources at 50
to 55 psig and extends
to the flow control
valve.

27. Consists of:
Pipeline inlet
connections
Pipeline pressure
indicators
Piping
Gas power outlet
Master switch
Oxygen pressure failure
devices
Oxygen flush
Additional reducing
devices
Flow control valves
Check valve

28. MASTER SWITCH (PNEUMATIC COMPONENT )
 The pneumatic portion of the master switch is located
in the intermediate pressure system downstream of the
inlets for the cylinder and pipeline supplies
 The oxygen flush is usually independent of this
switch.
 The master switch may be a totally electronic switch
that when activated controls the various pneumatic
components in the anesthesia machine.
 When the master switch is turned off ,the pressure in
the intermediate system will drop to zero

29. PIPELINE INLET CONNECTIONS
 It is the entry point for gases from the pipelines.
 The anesthesia workstation standard requires pipeline
inlet connections for oxygen and nitrous oxide.
 A unidirectional (check) valve prevents reversed gas
flow from the machine into the piping system
 Each pipeline inlet is required to have a filter with
a pore size of 100μm or less. The filter may become
clogged, resulting in a reduction in gas flow.

30. PIPELINE PRESSURE INDICATORS
 Indicators to monitor the pipeline pressure of each
gas are required by the anesthesia workstation
standard.
 They are usually found on a panel on the front of the
machine and may be color coded for the gases that they
monitor
Pipeline pressure indicators should always be checked
before the machine is used. The pressure should be
between 50 and 55 psig (345 and 380 kPa). The
indicators should be scanned repeatedly during use.

31. Piping is used to connect components inside the
machine
It must be able to withstand four times the intended
service pressure
Leaks between the pipeline inlet or cylinder pressure
reducing system and the flow control valve not exceed
25 mL/minute
If the yoke and pressure reducing system are included,
the leakage may not exceed 150 mL/minute.
PIPING

32. Some machines have gas selector
switch that prevents air and
nitrous oxide from being used
together.
GAS SELECTOR SWITCH
GAS POWER OUTLET
One or more gas power (auxiliary
gas) outlets may be present on
an anesthesia machine. It may
serve as the source of driving
gas for the anesthesia
ventilator or to supply gas for
a jet ventilator. Either oxygen
or air may be used.

33.  One of the most serious mishaps that occurred with
early machines was depletion of the oxygen supply
(usually from a cylinder) without the user awareness.
 The result was delivery of 100% anesthetic gas.
 Numerous inventions have been devised to prevent this
Oxygen Failure
Safety Device
Oxygen Supply
Failure Alarm
OXYGEN PRESSURE FAILURE DEVICES

35. OXYGEN FLUSH
 The oxygen flush (oxygen bypass, emergency oxygen
bypass) receives oxygen from the pipeline inlet or
cylinder pressure regulator and directs a high
unmetered flow directly to the common gas outlet.
 It is commonly labeled “02+.”
 On most anesthesia machines, the oxygen flush can be
activated regardless of whether the master switch is
turned ON or OFF.
 A flow between 35 and 75 L/minute must be delivered.
 The button is commonly recessed or placed in a collar
to prevent accidental activation.

36. FLOW ADJUSTMENT CONTROL
Controls flow of gas through it’s
associated indicator by manual adjustment
of a variable orifice
Current standard requires that there be
only one flow control for each gas. It
must be adjusted or identifiable with its
flow indicator

37. CONTROL KNOB
Touch and colour coded
joined to stem
Large enough to be turned easily
•Oxygen knob- Fluted Profile, as large/
larger than any other gas knob
•Knobs turned counter clockwise- increase
flow
•Knobs turned clockwise
decrease flow

38. LOW PRESSURE SYSTEM
The low-pressure system is downstream of the flow
control devices. Pressure in this section is only
slightly above atmospheric and variable.
Consists of:
1. Flowmeters
2. Hypoxia prevention safety devices
3. Unidirectional valve
4. Pressure relief devices
5. The common gas outlet
6. Vaporizers and their mounting devices

39. Flowmeters (flow indicators, flow tubes, rotameters)
indicate the rate of flow of a gas passing through
them.
They may be mechanical or electronic.
Electronic flowmeters usually have a representation of
a mechanical flowmeter on a screen or a number
representing the flow.
FLOWMETER

40. Mechanical Flowmeters
 Measuring gas flow in a mechanical flowmeter is
based on the principle that flow past a
resistance is proportional to pressure.
 Mechanical flowmeters measure the drop in
pressure that occurs when a gas passes through a
resistance.

42. Physical Characteristics of the Gas
At (low flows) flow is laminar and is a function of
the viscosity of the gas (Hagen-Poiseuille equation).
When the constriction is shorter and wider (high
flows), flow is more turbulent and depends on gas
density (Graham's law).
Q is flow; n is viscosity; p/l
is the pressure gradient; r
is the radius of the tube

43. Physical Principle of Gas Flow
 Traditional mechanical flow indicators used in
anesthesia machines have been of the variable orifice
(variable area, Thorpe tube) type.
 A vertical glass tube is internally tapered with its
smallest diameter at the bottom. It contains an
indicator that is free to move up and down inside the
tube.
 When there is no gas flow, the indicator rests at the
bottom of the tube.
 When the flow control valve is opened, gas enters at
the bottom and flows up the tube, elevating the
indicator.
 Gas passes through the annular opening between the
indicator and the tube and on to the outlet at the
top of the tube.

44. PREVENTIONSAFETY DEVICEPREVENTIONSAFETY DEVICE

45. UNIDIRECTIONAL CHECK VALVES
When ventilation is controlled or assisted, positive
pressure from the breathing system can be transmitted
back into the machine.
This pressure can affect flowmeter readings and the
concentration of volatile anesthetic agents delivered
from the vaporizers on the machine.
This valve is located between the vaporizers and the
common gas outlet, upstream of where the oxygen flush
flow joins the fresh gas flow.

51. WORKING OF ANESTHESIA MACHINE

52. HOSPITAL VISIT PICTURE: