Machine overview Flashcards
Anesthesia machine
provides delivery of m medical gases and vapors of anesthetics in a KNOWN concentration to the common. gas outlet
- these gases enter a breathing system
- delivered to pt. by SV or CV
- exhaled gases are removed. from breathing system
American National Standards Institute (ANSI)
-anesthesia machines made BEFORE 2000
American Society for Testing and Materials (ASTM)
-anesthesia machine after 2000
9 Components of machine
- electrical supply
- battery back up (30 min)
- Alarms
- Required monitors
a. inspired 02
b. expired 02
c. oxygen supply failure
d. hypoxic guard system
e. anesthetic vapor concentration
d. vital signs - oxygen supple (pipeline/ tank)
- Flowmeter
- 02 flush
- Calibrated Vaporizers
- Waste gas system
3 pressure systems
High pressure
Intermiediate pressure
Low pressure
6 required monitors
- inspired 02
- expired 02
- low 02 supply
- 02 analyzer (prevent hypoxic mixture)
- anesthetic gas concentration
- Vital signs
High Pressure
pressure from pipeline and 02 tank
- exposed to pressure as high as 2000 psi (02 tank)
- gas goes through a pressure regulator and enters intermediate pressure system
4 components of a high pressure system
- E cylinder (02 tank) behind machine
- Yoke assembly
- Bourdon garage
- High pressure regulator
United States Pharmacopeia/ National Formulary (USP/NF)
sets purity of medical gases
Gas cylinders
-sized A-H
A is the smallest
H is the bank for hospital supply
E is the most common cylinder
made of steel
MRI tanks aluminum (might be longer bc aluminum not as strong)
Us color code for gas
C02 = gray air = yellow n20= black 02 = green nitrogen = black
Yoke assembly
- PISS pin index safety system
1. orients tank
2. gas tight seal
3. unidirectional flow of gas
4. contains filter
5. check valve (prevents leaks in atmosphere, prevents full tank from tx gas to empty tank)
Pin index safety system
-attachment of tanks to back of anesthesia machine
N20 3 and 5
Air 1 and 5
Oxygen 2 and 5
Bourdon gauge
- measures pressure using a coil tube that expands when pressure is applied
- linkage of coil tube with rotating arm displays a pressure reading
gas cylinder safety system
- frangible disk; can burst under extreme pressure
- fusible plug; predetermined melting pt
-made of bismuth, lead, tin and cadmium
BLT & cheese
High pressure regulator
changes high and variable pressure to low and constant
- manufactured with set pressure of 40-45 psi
- purposefully lower than hospital supply of 50-55 psi so hospital supply is preferred over 02 tank
Intermediate Pressure system
gas from the regulator that decreased the pressure of pipeline or 02 tank gas
5 intermediate pressure system components
- Hospital supply
- 02 flush valve
- Pneumatic safety system (machine on switch)
- 02 supply alarm
- 02 failure protection devices - Auxiliary 02 flowmeter
- Second stage regulator
Hospital supply
02 typically stored as liquid at -180 C
- supplied to hospital in gas form at 50 psi
- multiple shutoff between supply and machine
- hospital supply connections use diameter index safety system (DISS)
Diameter index safety system (DISS)
- connections of hospital supply gases
- ensures only the correct gas. can be connected
- sized and threaded differently (body, nipple and nut combination)
- contain filter, check valve and pressure gauge
02 flush valve
- provides 100% 02 to circuit
- enters AFTER vaporizer
- flow rate 35-75 L/min
- protected by rim to prevent accidental pressing
Risk of barotrauma from pressure (older vent, on inspiration pop off valve closed and APL out of play with CV, no way to rid access pressure)
risk of diluting gas
Electrical system
- powered by a SINGLE cord
- emergency generator and back up battery needed
- battery backup must last 30 minutes
- do not plug anything into machine outlets, can trip circuit
Pneumatic safety system
- help prevent delivery of hypoxic mixture to pt
- 02 influences flow of other gases
- delivered 02 concentration shall NEVER decrease below 19% at common gas outlet
Low 02 supply alarm (oxygen supply failure alarm)
- older machines have an oxygen filling whistle when you turn the (machine) pneumatic system on
- whistle activated when 02 pressure drops to 38 psi
- alarm will continue to sound until 02 pressure below 6 psi
- other anesthetic gases are stoped when 02 pressure is at 30 psi
Fail safe device
- newer machine way of preventing hypoxic mixture when low 02 pressure sensed
- fail safe valve either proportionally decreases flow of all gases or shuts of flow of other gases based on the sensed pressure of 02
Auxiliary 02 flowmeter
- not mandated but most machines have it
- can use low flow 02 without using circuit
- works with pneumatic power switch off
- good for emergencies with no machine power
- uses same pipeline/ E-cylinder 02
Second stage pressure regulator
-down from gas supply in intermediate pressure system
- supply a constant pressure to flow control valves and proportioning system
- prevents fluctuations of pipeline pressure
-lowers pressure even more
14-35 psi
02 usually 14 psi
N20 usually 26 psi
-ensures 02 is last gas flowing
Low pressure system
-located between flowmeter and common gas outlet
-pressure slightly above atmospheric pressure
(1 atm = 14.7 psi)
-pressure varies
6 components of Low pressure system
- Flowmeters
- hypoxia prevention safety device
- unidirectional valves
- pressure relief device
- anesthetic vaporizers
- common gas outlet
Flowmeter
- controls flow of gases into breathing circuit
- manually or electronically controlled
- 02 and N20 flows linked to prevent hypoxic mixture
- selected flow directed to vaporizer
Flowmeter parts
- control knob
- needle valve
- valve seat
- valve stop
- float
- float stop
Hypoxia prevention device
- proportioning system to prevent creation and delivery of hypoxic mixture
- prevents operator selected delivery of 02 concentration below 21%
-machine automatically limits amount of N20
(max 75% and 02 25% 3:1)
Common gas outlet
-gets all gases and vapors from the machine and delivers them to breathing circuit
5 pathways of oxygen
- Flow to 02 flowmeter
- 02 flush valve
- Activates fail-safe device
(prevent hypoxic mixture) - Activates low 02 supply alarm
- Compress bellows
Department of transportation
DOT
- regulates everything about gas cylinder
- require specific markings on each cylinder
DOT specific markings
- Cylinder specification; cylinder material, woking pressure (psi)
- Serial #
- Date of manufacture
- Neck ring; name of gas with color
- Retest marking ; facility, month, year,
+ means it was 10% overfilled * retested in 10 years not 5 years
cylinder label
- Diamond shape that states the hazard class
- Name of gas
- Signal work (Caution) if necessary based on hazard class
- safety measures to take to avoid injury
Compressed Gas Association (CGA)
requires labels on cylinders, these labels must not cover DOT specific markings
Cylinder Tags
Tag refers to tanks supply
*not for identification purpose
- 3 tabs full, in service and empty
- rip off full once tank in use
- rip off inservice when empty
Safety handling for cylinders
- Never stand cylinder upright without support
- Never leave empty cylinder on machine
- Never leave plastic tape on port while installing cylinder
- Never rely on the color for identification
- Never oil valves
- Before fitting to PISS all dust particles, metal shavings and foreign matter should be cleared from outlet
slowly and briefly crack the valve - Valve should always be fully open when a cylinder is in use
