Anesthesia Machine

Question 1

What would result from delivering atmospheric air for anesthesia?

Answer 1

Hypoxia- due to hypoventilation and V/Q mismatch caused by anesthetics

Question 2

Minimum O2 requirement for anesthesia

Answer 2

30-35% O2

Atmospheric is 21%

Question 3

Metabolic O2 requirement

Answer 3

5-10mL/kg/min

Represents the minimum O2 flow required

Question 4

Gasses

Answer 4

O2
Nitrous oxide
Medical air

Question 5

Two types of O2 cylinders

Answer 5

E- usually in singles, attached to machine via a yoke

H- stored in banks, central O2 supply

Question 6

Green Cylinders

Answer 6

Oxygen

Question 7

Blue Cylinders

Answer 7

Nitrous oxide

Question 8

Yellow Cylinders

Answer 8

Medical Air

Question 9

Why are cylinders stored on their sides?

Answer 9

To prevent explosion and avoid spontaneous combustion

Question 10

Cylinder pressure units

Answer 10

psi

Question 11

Breathing system pressure units

Answer 11

cmH2O

Question 12

High Pressure systems

Answer 12

100-2200+psi

Gas cylinders, yokes, pressure gauges, regulators

Question 13

Intermediate pressure systems

Answer 13

50psi

Central O2 supply, post-regulatory, flush valve, input to flowmeter, driving gas for ventilator

Question 14

Low pressure systems

Answer 14

pressure in patients lungs

Question 15

E-cylinder capacity

Answer 15

660L (need to memorize)

Question 16

H-cylinder capacity

Answer 16

6600L

Question 17

Internal cylinder pressure

Answer 17

2200psi

Question 18

How do you figure out volume left in tank?

Answer 18

Boyle’s law

P1V1=P2V2

Question 19

How do you figure out time left on remaining volume?

Answer 19

Minutes = Volume/(flow liters/min)

Question 20

Can you calculate remaining volume on N2O tanks?

Answer 20

NO- exists as both a liquid and a gas in the tanks and the pressure will only read the gas portion

Question 21

Components to the safety systems

Answer 21

1. Colour coding
2. Labeling
3. Diameter index safety system
4. Pin index system
5. Quick connectors

Question 22

Diameter index safety system

Answer 22

Non-interchangeable gas-specific threaded connection system

Universal between equipment cylinder manufacturers

Question 23

Pin index safety system

Answer 23

Gas-specific pin patters that only allow connections between appropriate cylinder yokes and E-tanks

Commonly found on yokes and some cylinder-specific regulators/flowmeters

Question 24

Quick connectors

Answer 24

Manufacturer-specific

Facilitate rapid connecting/disconnecting of gas hoses

Question 25

Regulator

Answer 25

Aka pressure reducing valve Decreases tank pressure to approximately 50psi and supplies to the flowmeter Prevents pressure fluctuations as tank empties

Question 26

Flowmeter

Answer 26

Controls rate of gas flow through the vaporizer (L/min) Calibrated for 760mmHg and 20C

Question 27

Flowmeter pressure reduction

Answer 27

50psi to 15psi

Question 28

Where do you read the flowmeter?

Answer 28

Middle of ball or top of bobbin depending on type

Question 29

Where should the O2 flowmeter be positioned if there are multiple gas flowmeters? Why?

Answer 29

Far right, to avoid hypoxic mixtures.

Question 30

Quick flush

Answer 30

Delivers intermediate pressure O2 bypassing the vaporizer

Question 31

Flowrate of the quick flush

Answer 31

35-75L/min

Question 32

Use for the quick flush

Answer 32

Quickly decrease gas percentage in circuit Emergency or recovery

Question 33

Should the patient be hooked up to the circuit when using the quick flush?

Answer 33

NO- results in dangerous pressure in the breathing circuit which could result in pneumothorax

Question 34

Anesthetic vaporizers

Answer 34

Change liquid anesthetic into vapor | Deliver selected % of vapor to the fresh gas outlet

Question 35

Vapor

Answer 35

Gaseous state of a substance that is liquid at ambient temp and pressure Eg- halo, iso, sevo, desflurane

Question 36

Gas

Answer 36

Exists in gaseous state at ambient T/P Eg. N20, Xenon

Question 37

Vapor pressure

Answer 37

Pressure exerted by vapor molecules when liquid and vapor phases are in equilibrium Directly related to temperature Inversely related to boiling point

Question 38

Saturated vapor pressure

Answer 38

Maximum administration percentage of vapor Vaporizers reduce this to clinically useful percentages

Question 39

Modern vaporizer characteristics

Answer 39

- Agent specific - Concentration calibrated - Variable bypass - Flow over - Out of circuit - High resistance - Compensated for temperature, flow, and back-pressure

Question 40

Variable bypass system

Answer 40

Delivers a specific concentration by flowing fresh gas over a reservoir of liquid anesthetic and mixing it from carrier gas

Question 41

VOC- precision vaporizer

Answer 41

Out of circuit vaporizer which delivers a known percentage of anesthetic

Question 42

VIC- non-precision vaporizer

Answer 42

OLD model Glass jar containing wicking material saturated with anesthetic Did not deliver a precise percentage of anesthetic

Question 43

Modern vaporizer compensations

Answer 43

Temp: Between 15-35C Achieved using efficient heat conducting materials Flow rate- 0.5-10 L/min Back pressure- associated with positive pressure ventilation and flush valve

Question 44

Desflurane vaporizer

Answer 44

Boiling point close to room temp Electronically heated Commonly used in Human, not in vet

Question 45

Agent-specific key filler port

Answer 45

Prevents filling of vaporizers with improper anesthetics

Question 46

Do modern vaporizers require external power?

Answer 46

No- except desflurane

Question 47

Vaporizer transportation/orientation

Answer 47

Cannot be tipped, must be emptied prior to transport If tipped run 1L/min O2 with vaporizer off to clear lines

Question 48

What do you do if vaporizers are filled with the wrong anesthetic?

Answer 48

Drain and run 1L/min O2 until dry

Question 49

Common gas outlet

Answer 49

Where gas exits the vaporizer, connected by a hose to the fresh gas inlet Universal for rebreathing and non-rebreating units