SAFETY FEATURES IN SAFETY FEATURES IN ANAESTHETIC MACHINESANAESTHETIC MACHINES

-Dr.Prem kumar,

Department of anesthesiology,

Madras medical college

Why safety features?Why safety features?

To safeguard human life from unknown human errors.

Safety devices are to prevent delivery of hypoxic mixture

Regulation to prevent excessive pressure which is traumatic to patient.

Statistics Statistics

Misuse: 70% direct action primary anesthesia provider

30% contributory actions of ancillary personnel

Classification Classification

ELECTRICAL COMPONENTS

PNEUMATIC COMPONENTS.

ELECTRICAL ELECTRICAL COMPONENTSCOMPONENTS

Master switch Power failure indicator Reserve power Automated check out

PNEUMATIC SYSTEMPNEUMATIC SYSTEM

High pressure system

Intermediate system

Low pressure system

Alternative oxygen control

High pressure systemHigh pressure system

GAS CYLINDER –

Color coding

Pin index

Cylinder labels

Safety relief device

COLOR CODINGCOLOR CODING

Oxygen black body,white shoulders[white

for international] Nitrous oxide blue Air white and black Carbon dioxide gray Helium brown Entonox black with blue/white shoulders

PIN INDEX SAFETY SYSTEMPIN INDEX SAFETY SYSTEM

Air - 1,5Oxygen - 2,5Nitrous oxide - 3,5CO2>7.5% - 1,6CO2<7.5% - 2,6Cyclopropane - 3,6N2O-O2 - 7

The safety relief device is composed of atleast one of      Frangible disc [bursts under

extreme pressure]

- Fusible plug [wood’s metal which has a low melting Point ]

  - Safety relief valve [ opens at extreme pressure ]

WOOD’S METAL

A fusible alloy that contains 50% bismuth, 25% lead, 12.5% tin, and 12.5% cadmium, and melts at 158°F (70-72°C); used for automatic sprinkler plugs.

Cylinder pressure indicator [ bourdon’ s pressure gauge]

Pressure regulator - PRIMARY

Washer [ bodok seal ] – rubber made of neoprene Hanger yoke assembly – has pin index safety system.

one way check valve for unidirectional gas flow

BourdonBourdon’’s pressure gauges pressure gauge

Indication of incoming gas supplyIn O2 cylinder – indicates amount of gasN2O cylinder – pressure is not indicative of

amount b’cos N2O is stored in liquified form.

Curved tube can rupture with high pressure and the gauge has a vent on its back which can release the gas in the event of rupture.

Pressure regulatorPressure regulator

Bodok sealBodok seal

Intermediate systemIntermediate system

Pipeline –

- Gas hoses are named and color coded

- Non interchangeable quick

couplers[shrader’s valve-gas specific]

- NIST

- Diameter index safety system[DISS]

- Pipeline pressure indicators

NISTNIST

- In line filter

- Check valve

- Gas power outlet [auxiliary oxygen

as a source of driving

gas for anesthesia ventilator or jet

ventilation] Oxygen pressure failure device Oxygen supply failure alarm [ richter alarm]

OPFDOPFD

Pressure regulators – second stage

Pressure relief valve

Oxygen flush - O2+

Flow control valve – color coding,fluted[O2], size, distance, placement of knobs,guard

PRESSURE REGULATORPRESSURE REGULATOR

Pressure Relief ValvePressure Relief Valve Pressure relief valves are installed

downstream of all pressure regulators Valves set at no more than 50% above

the pressure regulator setting. Function: Fully relieving the pressure at

the set point in case failure of regulator. All pressure relief valves have piping

connections to allow release of to outside facility.

Low pressure systemLow pressure system

Flowmeters – - Bobbin rotates on flow which prevents it from sticking. - Bobbin is antistatic to prevent sticking to the wall of the flowmeter - Fluorescent coating on the back of flowmeter panel and on the dot of bobbins - Float stop - Arrangement - Auxiliary oxygen flowmeter

An oxygen leak from the flow tube An oxygen leak from the flow tube can produce a hypoxic mixture, can produce a hypoxic mixture,

regardless of the arrangement of regardless of the arrangement of

the flow tubesthe flow tubes

Auxiliary oxygen flowmeterAuxiliary oxygen flowmeter

Hypoxia prevention safety Hypoxia prevention safety devices:devices:

Proportionating devices –

- link 25 in datex

ohmeda[mechanical,pneumatic

and electronic linkage]

- S-ORC in draeger,

- Mandatory minimum oxygen

flow

Vaporizers - Selectatec mechanism,

interlocking,low filling port, indicator

of agent,increased wick capacity,

Fraser sweatman pin safety system Unidirectional [check ] valve Back pressure relief valve [opens when the

pressure exceeds 200 cm H2O] Common gas outlet

Breathing systemBreathing system

APL valve open when pressure exceeds 60 cm H2O

Pressure in reservoir bag shouldn’t exceed 60 cm H2O.

Oxygen analyser Canister – To prevent co2,carbon monoxide.

Dessicated absorbents without KOH or ba(OH)2 and with lesser amounts of NaOH produce less heat and no fires.

VENTILATORS – PRESSURE SENSORS TO DETECT EXCESSIVE AIRWAY PRESSURE DUE TO VENTILATOR MALFUNCTION

Alternative oxygen control

Scavenging system

Wheels in anesthetic workstation is made of antistatic rubber.

Safety features of newer Safety features of newer machinesmachines

Ø      More accurate and/or corrected tidal volume through compliance and fresh gas compensation

  Ø      Potential return of sampled gas[SGR]

to facilitate low-flow

Ø      Fresh gas decoupling prevent hyperinflation of the lung

Electronic PEEP

Electronic selection of ventilation parameters

Reduced external connections

Thank youThank you