Anesthesia Machine Week 2

Front 1

Full O2 or AIR =

Back 1

1900 psi (660 L)

Front 2

Full N2O =

Back 2

745 psi (1590 L)

Front 3

Pipeline Supply

Back 3

(Intermediate Pressure)
Hospital supply enters at approximately 50-55 psig

Front 4

Diameter Index Safety System

Back 4

Supply hoses connect the wall outlets or column supply to the back of the anesthesia machine. Connects to the anesthesia machine

Front 5

3 Standards organizations which govern the handling of gas cylinders include the

Back 5

Compressed Gas Association, the Department of Transportation, and The National Fire Protection Agency.
and cylinder specifications

Front 6

CGA= governs

Back 6

manufacture, filling, shipping, storing, and handling; also dictate the colors, markings, labels, contents, and valve design

Front 7

writes standards regarding the transport

Back 7

DOT= writes standards regarding the transport of compressed gases as well as manufacturing and testing specifications; regulate the amount of gas that may be contained in the cylinder and require the specific markings on the cylinder

Front 8

Cylinder Colors Oxygen

Back 8

kelly green

Front 9

Cylinder Colors Nitrous oxide

Back 9

dark royal blue

Front 10

Cylinder Colors Air

Back 10

bright yellow

Front 11

Cylinder Colors Carbon dioxide

Back 11

gray

Front 12

Cylinder Colors Helium

Back 12

brown

Front 13

__________ will identify the contents, manufacturing information and the hazard class of the gas

Back 13

The label

Front 14

Markings are permanently engraved on the cylinder and registered

Back 14

Bureau of Explosives

Front 15

Hazard Identification Green diamond

Back 15

Non-flammable gas

Front 16

Hazard Identification Yellow diamond

Back 16

Oxidizer

Front 17

Hazard Identification Red diamond

Back 17

Flammable gas

Front 18

Cylinders are attached ________ with ________ via a__________ and secured________

Back 18

Cylinders are attached to the hanger yoke with the valve via a pin index safety system and secured with the T-handle

Front 19

Pin index system

Back 19

was designed to prevent misconnection of medical gas cylinders

Front 20

Cylinder Valve is, contains, and has...

Back 20

Conduit for the cylinder contents to reach the machine
Contains a safety relief valve
Pin index safety system

Front 21

Necessary to prevent rupture of the cylinder under extreme conditions of exposure

Back 21

Safety Relief Valve

Front 22

Safety Relief Valve
This device may be of 3x

Back 22

A fusible plug
A frangible disc
A spring loaded valve

Front 23

Fusible plug is

Back 23

Metal alloy, melt at either a low range of 157-170F &/or a high range 208-220F
Cannot be reset

Front 24

Frangible disc is

Back 24

Copper, burst when a certain high pressure is exceeded; the burst pressure for the cylinder must exceed the service pressure by at least a factor of two
Cannot be reset

Front 25

Spring loaded valve is

Back 25

Increase in pressure in the cylinder will force the spring open, excess pressure released & valve will close

Front 26

Hangar Yoke 5 points (components)

Back 26

Color-coded & labeled for each medical gas
Two pin index posts that correspond to the pin index holes on the cylinder valve
Gasket located between the gas outlet on the cylinder valve & the gas inlet on the anesthesia machine
Secure T-handle into seat above the safety relief valve after pins are correctly engaged
Includes filter for entrapment of particulate matter

Front 27

Prevents reverse flow of gases

Back 27

Check Valves

Front 28

Check Valves 3 points

Back 28

Free floating & respond to pressure
Prevent flow of gas from one cylinder to another when a second cylinder is turned on
Not leak proof

Front 29

ASTM allows leak rate of

Back 29

200 ml/minute

Front 30

Safe Handling of Cylinders
4 points

Back 30

Stored upright in holders in cool, dry, clean, and well-ventilated rooms with protective cap on
Placed in a free standing container when being moved
Secured from blunt trauma when being used for patient transport
Do NOT leave standing alone

Front 31

Prior to Placement of o2 cylinder

Back 31

“Cracked” briefly prior to placement in hanger yoke to clear dust, oil, or debris from gas outlet

Front 32

Full E cylinder of compressed oxygen contains

Back 32

660 L at a pressure of 1900 psig

Front 33

Full E cylinder of compressed nitrous oxide contains

Back 33

1590 L at a pressure of 745 psig

Front 34

Full E cylinder of compressed air contains

Back 34

625 L at a pressure of 1900 psig

Front 35

Volume of N2O in a full cylinder is mostly

Back 35

liquid state (small amount in gaseous state)

Front 36

Nitrous Oxide
As gas changes from liquid to gas, the pressure indicated on the gauge remains

Back 36

remains relatively constant until all of the liquid has been converted to gas

Front 37

Nitrous Oxide
Once gauge drops below 745 psig,

Back 37

, the cylinder contains approximately 300 L N2O

Front 38

The critical temperature

Back 38

temperature at and above which vapor of the substance cannot be liquefied, no matter how much pressure is applied.

Front 39

Bourdon Gauge

Back 39

Cylinder gauge displays the pressure of gas in the cylinder in psig
Indicates volume of gas remaining in the cylinder

Front 40

First Stage Regulator are preset

Back 40

at the factory.

Front 41

First Stage Regulator reduce

Back 41

reduced to 45 psig.
ASTM dictates that each gas supplied under high pressure must have at least one pressure reducing regulator.

Front 42

First Stage Regulator Proper functioning

Back 42

is confirmed when an O2 flow of 2L/M is restored to 2L/M within 2 seconds after each operation of the O2 flush valve.

Front 43

Safety relief valve purpose

Back 43

will vent excessive pressure out of the regulator

Front 44

First Stage Regulator and flow

Back 44

the cylinder flow to a intermediate pressure (45 psig) the anesthesia machine will preferentially seek flow from the pipeline supply because it is entering at a slightly greater pressure (50-55 psig.)

Front 45

First Stage Regulators Also called

Back 45

Cylinder Pressure Regulator

Front 46

Bulk gas supply should conform to

Back 46

should conform to the National Fire Protection Agency Standards (NFPA – 99)

Front 47

Pipeline Supply converted to a vapor

Back 47

Multiple vaporizer coils are used to warm the liquid to start the process
Results in expansion of the liquid and conversion to a gas

Front 48

Pipeline supply enters the hospital at

Back 48

50-55 psig

Front 49

Pipeline Supply 3 Safeguards

Back 49

actuating switches, shut off valves, and high pressure relief valves

Front 50

Pipeline connections to the anesthesia machine contain a

Back 50

diameter indexed safety system

Front 51

diameter indexed safety system
3 points

Back 51

Help prevent incorrect connections
Fitting for each gas has a different diameter
Each fitting is also internally keyed so that the operator cannot make a loose connection with a slightly larger fitting

Front 52

4 Hazards from the pipeline supply

Back 52

Fire
Explosion
Cross connection
Cross contamination

Front 53

Auxiliary Oxygen Flowmeter 2 points

Back 53

1. Used to administer O2 during local, MAC, or regional anesthesia
2. The auxiliary O2 flowmeter is operational as long as there is O2 pressure supplied to the machine, it bypasses the master on-off switch.

Front 54

Oxygen Flush Valve 3 points

Back 54

1. Operational when machine has a source of O2 pressure.
2 Inactivated, the intermediate pressure is retained behind the ball valve spring.
3 Once activated, the pin pushes the ball valve against the spring & O2 flows to the machine outlet.

Front 55

Oxygen Flush Valves ASTM standards 4 points

Back 55

1. Should be permanently marked
2. Type 3 O2 flush valve
manually operated with self-closing construction.
3. Does not pass through the vaporizers.
4 No allowable leak rate
5.Flow rate 35-75 psig
6 Minimal back pressure to vaporizers (max of 100cmH2O)

Front 56

Master ON-OFF Switch sends

Back 56

oxygen to ventilator connector

Front 57

Master ON-OFF Switch
4 alarms switches which
warn against hypoxia are connected to this switch Prevents the anesthetists from delivering a hypoxic mixture without also turning on alarms to warn against hypoxia.

Back 57

Oxygen supply failure alarm
Oxygen analyzer
Breathing pressure
Minute volume

Front 58

2 Components not connected to the ON-OFF switch:

Back 58

Oxygen flush valve
Auxiliary oxygen flowmeter

Front 59

Master ON-OFF Switch 2 Problems

Back 59

May resemble ventilator switches
Fail to engage fully or migrate off

Front 60

4 ventilator alarm ASTM Standards

Back 60

Electronic alarms be high, medium, or low priority
Each alarm has different visual & audible indicators
Alarms automatically reset
Silence a high or medium priority alarm for 120 seconds

Front 61

primary driving gas of the ventilator.

Back 61

The oxygen in intermediate pressure portion of the machine acts

Front 62

Drager Narkomed vent driving device

Back 62

uses oxygen supply to drive a venturi device, which augments the driving gas for the ventilator with entrained air

Front 63

ASTM Standards require the ventilator connector to have a

Back 63

check valve.

Front 64

Ventilator Power Inlet Connector includes

Back 64

DISS for O2 & spring and ball valve mechanism that should be leak tight.

Front 65

Second Stage Regulator
5 points

Back 65

1 Used on Ohmeda machines for O2 & N2O
2 O2 – takes intermediate pressure of 50 psig to lower pressure of 16 psig
3 N2O - reduced to 26 psig
4 Occurs prior to gas entering the flowmeters
5 Offer consistent supply of gas & diminish bobbing of flowmeter floats

Front 66

Drager machines do not use

Back 66

second stage regulators, their machines’ internal components exist at an intermediate pressure.

Front 67

Pressure Sensor Shut Off Valve Linked to

Back 67

master ON-OFF switch

Front 68

Pressure Sensor Shut Off Valve Senses

Back 68

O2 pressure and will shut off N2O or any other gases if there is inadequate O2 pressure.

Front 69

N2O and AIR supply dependent on

Back 69

adequate O2 supply.

Front 70

Pressure Sensor Shut Off Valve senses

Back 70

pressure only

Front 71

the last flowing gas if supply lost

Back 71

Pressure Sensor Shut Off Valve
Leaves O2 as the last flowing gas if oxygen supply lost

Front 72

If O2 supply pressure decreases

Back 72

, an internal alarm is activated.

Front 73

O2 Supply Failure Alarm is Connected to

Back 73

the master ON-OFF switch.

Front 74

ASTM standards require that whenever O2 supply pressure decreases below a manufacturer specified threshold

Back 74

, a medium priority alarm should sound within 5 seconds.
. (Usually a pressure below 25 psig).

Front 75

O2 Supply Failure Alarm
Ohmeda-O2

Back 75

Ohmeda-O2 pressure will fill the canister & close the relief valve by pushing against the diaphragm & closing the thrust pin
. A ball bearing in the inlet check valve rests in equilibrium as the pressure in the canister is equal to the pressure inside the machine.
If the pressure inside the machine decreases due to loss of O2 supply, the higher pressure in the canister pushes the ball bearing to close the inlet check valve, the diaphragm relaxes in the relief valve & the gas from the canister flows up to a metal reed, causing a loud 7sec whistle.

Front 76

Flowmeters oxygen recieve flow rate

Back 76

intermediate pressure (Drager 48 psig) or a low pressure (Ohmeda 16-26 psig)

Front 77

Most delicate component of machine

Back 77

O2 flowmeter

Front 78

Standard for O2 placement

Back 78

Standard for O2 flowmeter to be place to the right of other flowmeters

Front 79

constructed of Pyrex glass

Back 79

Thorpe tubes,

Front 80

Tubes are pin indexed

Back 80

to specific medical gas

Front 81

Ohmeda- The float (3)

Back 81

The float is an aluminum triangular device
Should be read at the top
‘Stops’ provide mechanism for minimum O2 flow when the machine is turned on

Front 82

Drager The float (3)

Back 82

The float is a sapphire coated ball type
Should be read in the middle
Uses a resistor device to provide a minimum O2 flow

Front 83

Annular Space

Back 83

The space that exists between the float & the internal surface of the Thorpe tube
Annular space increases as the float rises higher in the tube, as it would in high flows.

Front 84

o2 Laminar Flow occurs

Back 84

Low flows, less than 3L/M
Gas flows from a region of higher pressure to lower pressure

Front 85

Gas flowing next to the sides of the flowmeter

Back 85

will have a decreased velocity d/t frictional resistance of the tube

Front 86

Gas flowing in the middle of the flow tube will have the greatest

Back 86

velocity b/c it encounters less resistance to flow.

Front 87

Turbulent Flow

Back 87

Increased flows, greater than 4 L/M
Gas molecules begin to swirl and convert to turbulent flow

Front 88

Critical velocity-

Back 88

the point when laminar flow changes to turbulent flow

Front 89

At higher flow the flowtube resembles

Back 89

resembles an orifice

Front 90

At turbulent flow the primary determinant of flow is

Back 90

density of the gas (Graham’s Law)

Front 91

4 Factors Decrease Accuracy of the float

Back 91

Dust or dirt accumulating on the float
Static electricity
Changes in temperature
Changes in atmospheric pressure

Front 92

ASTM Standards Require one, visible flow-control system .......

Back 92

for each medical gas adjacent to the gas flowmeter it controls

Front 93

Flowmeter knob should be marked

Back 93

with the name of the gas and color coded appropriately

Front 94

O2 knob must be

Back 94

fluted, larger & protrude out farther than the round, smaller N2O and AIR knobs

Front 95

Knobs should be designed to prevent

Back 95

dis assembly when they are rotated

Front 96

When supplying gas at 50 psig, flowmeters should be accurate to within

Back 96

+/- 10 ml/M

Front 97

Leakrate should be no more than

Back 97

5 ml/M

Front 98

Electronic Flow Devices

Back 98

electronic flowmeters, electronic flow measurement systems, electronic mass flow sensors

Replaces the Thorpe tube flowmeter, reportedly are more accurate & allow the capture of data to be sent to an automated record keeper

Front 99

Proportioning System

Back 99

Components to prevent the delivery of a hypoxic mixture

Front 100

O2 & N2O are

Back 100

interfaced either mechanically or pneumatically with an electronic alarm so that the minimum O2 concentration at the common gas outlet is not less than 25%

Front 101

The ratio of N2O to O2

Back 101

should be approximately 3.5:1

Front 102

Proportioning System Ohmeda is called ___________.
How does it work

Back 102

Link – 25
Mechanical linkage of the O2 & N2O flow control knobs so that if O2 is decreased, the linkage will also pull the O2 up.
The O2 & N2O flowmeters must be adjacent to enable this system

Front 103

Proportioning System Drager
and how it works

Back 103

Oxygen Ratio Monitor Controller
Resistors in the O2 flowmeter create a back pressure to an O2 chamber depressing a diaphragm connected to the N2O control valve
If inadequate O2 the N2O control valve will close & no N2O will flow to the flowmeter

Front 104

Proportioning System Does not protect completely against

Back 104

against a hypoxic mixture.

Front 105

The proportioning system does not protect completely against a hypoxic mixture.
name 4 poss failures

Back 105

If a gas other than O2 is present in the O2 pipeline
If the mechanical linkage or the resistors and diaphragm are defective, the ratio may not be maintained
A leak downstream of these devices can exist
If a 3rd gas, such as helium, nitrogen, or carbon dioxide is administered, O2 may be diluted.

Front 106

Vaporization – involves

Back 106

the process of changing a liquid into a vapor

Front 107

Vaporizer def

Back 107

a container that holds the liquid agent and the gas flow from the flowmeter will either bubble through it or flow over it

Front 108

Majority of deaths related to

Back 108

to anesthetic overdose

Front 109

Majority of deaths occur by

Back 109

Most related to cardiac arrest

Front 110

Keenan & Boyan study

Back 110

Inadequate ventilation & overdose of agent
Morbidity and Mortality

Front 111

Cooper’s critical incident studies
2 parts

Back 111

Unintentional turning off of vaporizer
Technical error leading to overdose

Front 112

AIMS
Morbidity and Mortality

Back 112

Failed vaporizer

Front 113

Caplan closed claims
3 failures

Back 113

Valve failure
Leak
Wrong dial turned on

Front 114

Anesthetic agents
4 points

Back 114

Stored as liquid but converted to vapor
Higher molecular weight
Higher density
Much more complex than anesthesia gases (N2O)

Front 115

Vapor density- density values obtained by

Back 115

dividing the MW by 22.4

Front 116

Vapor density- is

Back 116

Ratio of the density of a gas to the density of a reference gas at the same pressure and temperature
< 1, vapor will rise
> 1, vapor will sink

Front 117

Vapor specific gravity-

Back 117

if the density is compared to air

Front 118

Chloroform, ethyl chloride, & Trichloroethylene (TCE)
4 points

Back 118

Disappeared because of their toxicity
TCE is toxic to multiple organs
Cardiovascular side effects
Damage to liver & kidney

Front 119

Methoxyflurane
2 points

Back 119

Mediated by cytochrome P450- catalyzed metabolism to toxic metabolites
Nephrotoxicity related to fluoride

Front 120

Enflurane
neg side effect

Back 120

Caused seizures with hyperventilation

Front 121

Desflurane
3 initial problems with des

Back 121

Initially produced using a potentially explosive synthesis that used elemental fluorine
No vaporizer
Decreased potency

Front 122

Sevoflurane
1pos 1neg

Back 122

Potential for nephrotoxicity
Very little airway irritability

Front 123

Volatile liquids-

Back 123

change readily and rapidly into vapor

Front 124

Volatile liquids are defined by their

Back 124

vapor pressure

Front 125

Vapor pressure is a measure of a

Back 125

liquid’s ability to evaporate

Front 126

Higher the vapor pressure, the more

Back 126

the more volatile the liquid, more readily the liquid gives off vapor

Front 127

Vapor pressure- def

Back 127

the amount of pressure the vapor of a volatile liquid agent exerts on the walls of a closed container at 20C and 760mmHg atmospheric pressure

Front 128

Vapor pressure Desflurane

Back 128

664

Front 129

Vapor pressure Ether

Back 129

400

Front 130

Vapor pressure halothane·

Back 130

243

Front 131

Vapor pressure Isoflurane

Back 131

238

Front 132

Vapor pressure Enflurane

Back 132

175

Front 133

Vapor pressure Sevo

Back 133

160

Front 134

Vapor pressure , Water

Back 134

18

Front 135

Volatile liquid inside the vaporizer reacts to changes

Back 135

changes in temperature and pressure

Front 136

When the pressure or temperature changes in vaporizer

Back 136

it will make changes to maintain equilibrium

Front 137

Vapor pressure does not change with

Back 137

atmospheric pressure

Front 138

Boiling point changes with

Back 138

atmospheric pressure

Front 139

Vapor pressure numerical value changes

Back 139

changes with temperature

Front 140

Atmospheric pressure changes how easily the vapor can flow but

Back 140

but does not change the vapor pressure of the agent

Front 141

Vapor pressure at higher altitudes

Back 141

Easier flow

Front 142

Boiling point=

Back 142

the temperature at which the vapor pressure equals atmospheric pressure

Front 143

Lower atmospheric pressure (vapor)

Back 143

less gas molecules put pressure on liquid
Takes less heat to turn the liquid into a vapor

Front 144

Vapor pressure changes with changes

Back 144

in temperature

Front 145

As temperature rises, the vapor pressure rises…due to

Back 145

kinetic energy

Front 146

Latent Heat of Vaporization

Back 146

Heat required to change the liquid into a gas during the period of constant temperature

Front 147

No heat =

Back 147

no vaporization

Front 148

Vaporizer- a device that is designed to

Back 148

accurately enrich the oxygen/nitrous oxide/ air mixture with a precise percentage of anesthetic agent.

Front 149

early Copper Kettles &Vernitrols
Concentration-calibrated

Back 149

Use temperature of kettle and temperature of room to calculate the percentage delivered
Measured flow vaporizer- operator determines how much gas should be bubbled through the anesthetic liquid by means of a formula

Front 150

Contemporary vaporizers have internal device for

Back 150

temperature compensation or supply heat to the vaporizer

Front 151

Vaporizers Keep a portion of the mixed gas in contact with the anesthetic agent until

Back 151

(the gas is saturated)
until the gas has absorbed all of the agent vapor it can hold at the current pressure and temperature

Front 152

Concentration dial sets a value that

Back 152

that splits the gas flow as it enters the vaporizer, a thermostatically controlled valve changes how much of the gas flows through the vaporizer chamber to give the correct output concentration

Front 153

Vaporizers Constructed of materials that

Back 153

transfer heat quickly to keep all of the vaporizer parts at the same temperature

Front 154

Variable bypass-flow over vaporizer
‘concentration calibrated’

Back 154

Vaporizing chamber- reservoir where liquid anesthetic is stored
Area above the liquid will be saturated with vapor molecules
Carrier gas enters chamber, flow over liquid and becomes saturated with vapor
Then carries anesthetic out of vaporizer to the patient

Front 155

Variable bypass-flow over vaporizer
Method for regulating the output

Back 155

is determined by the amount of gas flow that bypasses the vaporizing chamber as compared to the amount of carrier gas that flows over the vaporizing chamber

Front 156

vaporizer Bimetallic strip

Back 156

Metal with one side brass & one side nickel
Temperature increases brass side expands causing strip to bend = allows more carrier gas flow to bypass the vaporizing chamber & less to enter it (less anesthetic vapor out)
Temperature decreases the strip is not bent & the amount of carrier gas that bypasses the vaporizing chamber is diminished = allows more anesthetic vapor to be picked up

Front 157

Bellows expansion element

Back 157

Expands & deflates based on the temperature inside the vaporizer
Temperature increases, the bellows expand & allows more carrier gas flow to bypass the vaporizing chamber (less out)
Temperature decreases, bellows deflate, decrease the carrier gas flow thru the bypass tract & increase flow to vaporizing chamber (more out)

Front 158

Wicks placed in the vaporizer

Back 158

increase efficiency
Increases the surface area for gas to flow around allows more liquid into the vaporizer

Front 159

Vaporizer Typically hold

Back 159

hold 125mL of anesthetic agent

Front 160

Baffles placed in vaporizer
3 points

Back 160

1increase efficiency
2Take carrier gas flow closer to the liquid where it can pick up the agent at the liquid-vapor surface
3Give the gas a path to flow and decrease the incidence of spilling with tipping of vaporizer

Front 161

Physical characteristics of Desflurane
Boiling point and Vapor pressure

Back 161

close to room temperature (23.5C)
(664mmHg)

Front 162

To store Desflurane in a closed container at room temperature

Back 162

temperature requires pressure.

Front 163

Desflurane bottle pressurized up to

Back 163

80 psig

Front 164

Desflurane Vaporizer heats to

Back 164

39C

Front 165

Desflurane Vaporizer Pressurized to __________ to keep in liquid form
More controlled & able to store in a closed container

Back 165

1500mmHg

Front 166

Vaporizer cannot be turned on until heated to

Back 166

39C

Front 167

Bellows expansion element

Back 167

Expands & deflates based on the temperature inside the vaporizer
Temperature increases, the bellows expand & allows more carrier gas flow to bypass the vaporizing chamber (less out)
Temperature decreases, bellows deflate, decrease the carrier gas flow thru the bypass tract & increase flow to vaporizing chamber (more out)

Front 168

Wicks placed in the vaporizer

Back 168

increase efficiency
Increases the surface area for gas to flow around allows more liquid into the vaporizer

Front 169

Vaporizer Typically hold

Back 169

hold 125mL of anesthetic agent

Front 170

Baffles placed in vaporizer
3 points

Back 170

1increase efficiency
2Take carrier gas flow closer to the liquid where it can pick up the agent at the liquid-vapor surface
3Give the gas a path to flow and decrease the incidence of spilling with tipping of vaporizer

Front 171

Physical characteristics of Desflurane
Boiling point and Vapor pressure

Back 171

close to room temperature (23.5C)
(664mmHg)

Front 172

To store Desflurane in a closed container at room temperature

Back 172

temperature requires pressure.

Front 173

Desflurane bottle pressurized up to

Back 173

80 psig

Front 174

Desflurane Vaporizer heats to

Back 174

39C

Front 175

Desflurane Vaporizer Pressurized to __________ to keep in liquid form
More controlled & able to store in a closed container

Back 175

1500mmHg

Front 176

Vaporizer cannot be turned on until heated to

Back 176

39C

Front 177

Desflurane vaporizer (if not warm)

Back 177

Carrier gas flow turned on, flow through the vaporizer & encounters flow restrictor

Front 178

Pressure transducer & pressure monitor that measures the pressure of the carrier gas flow & output from the

Back 178

from Desflurane chamber

Front 179

Pressure regulating valve is controlled by input from the

Back 179

the pressure monitoring system to adjust pressure d/t Desflurane vapor until there is no difference between the Desflurane vapor & the pressure of the carrier gas flow

Front 180

Desflurane vaporizer dial regulates the

Back 180

actual quantity of Desflurane vapor available for mixing with the carrier gas flow

Front 181

Desflurane vaporizer
Increasing concentration dial opens the rotary valve more, permits more

Back 181

more Desflurane to enter the carrier gas flow & increases the percent output concentration
There is a zero pressure differential at the transducer system, the percent concentration is determined by the ratio of flow restrictions that are imposed by the fixed carrier gas flow restrictor & the concentration dial

Front 182

Vaporizer Safety Features 2

Back 182

Prevent possible overdose of anesthetic agents
Baffles to decrease chance agent will overflow

Front 183

Vaporizer If tipped, what should you do

Back 183

vaporizer must be flushed out using high flowrates (5-10 L/M) to dry the liquid from the outflow tract; concentration dial set to 4-5%; & flushed for 20 minutes

Front 184

Vaporizer Interlock System

Back 184

Interlock system to assure that only one vaporizer is turned on to prevent the contents of one vaporizer from contaminating the next
Integrity confirmed during the check out of the machine

Front 185

Vaporizer Safety Features
Ohmeda

Back 185

depends on the extension rods of the vaporizers being in contact with one another; if one turned on, the extension rods move in a manner that prevents any other vaporizer from being turned on

Front 186

Vaporizer Safety Features
Drager system

Back 186

is a set of metal rods that change conformation when one of the vaporizers is turned on
It can fail if any of the screws get loosened

Front 187

Vaporizer cannot be turned on unless

Back 187

unless it is properly locked in, this prevents major leaks from developing at the inlet and outlet of the vaporizer

Front 188

To turn vaporizer ON, must

Back 188

must push the ON button in and turn the dial

Front 189

ASTM standards from 1989 for vaporizers include the following:

Back 189

Location in the fresh gas circuit & concentration calibrated
Accept a total gas flow up to 15 L/M
Incorporate an isolation or interlock system
Fittings to demarcate correct flow through
Liquid level indicator
Agent specific filling device
Anesthetic concentration < .1% when OFF
Operator manual should state variation of ambient temperature, pressure, back pressure, input flowrates effect on vaporizer performance, accuracy of calibration and service intervals

Front 190

Vaporizer Outlet check valve

Back 190

Method to diminish the intermittent back pressure that may increase or decrease the percent concentration output of vaporizers
Maybe included in the vaporizer or as a separate component of the anesthesia delivery system

Front 191

Outlet check valve
Drager-

Back 191

Drager- employs a coil system inside the vaporizer; when intermittent back flow occurs, the gas does flow back into the vaporizer but encounters this coil and cannot reach the vaporizer chamber

Front 192

Ohmeda vaporizers have a check valve

Back 192

valve at the outflow tract or incorporate an outlet check valve distal to the vaporizers, but prior to the common gas outlet

Front 193

Ohmeda-Negative pressure bulb must be utilized to

Back 193

valve and evaluate if leaks exist behind it.

Front 194

Vaporizer Pressure relief valve

Back 194

Prior to the medical gases and anesthetic agents exiting the machine at the common gas outlet, there is a valve designed to open in the event of high pressure

Front 195

Pressure relief valve Drager-

Back 195

Drager- employs this inside the vaporizer and it is designed to crack at 18 psig

Front 196

Ohmeda- Pressure relief valve

Back 196

has a separate component in the piping system designed to open between 2.3-2.9 psig or at 5 psig depending on the particular machine

Front 197

Common gas outlet

Back 197

This must be patent and intact to deliver gas to the patient