Anesthesia Machine Flashcards Preview

Anesthesiology > Anesthesia Machine > Flashcards

Flashcards in Anesthesia Machine Deck (49):
1

What would result from delivering atmospheric air for anesthesia?

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

2

Minimum O2 requirement for anesthesia

30-35% O2

Atmospheric is 21%

3

Metabolic O2 requirement

5-10mL/kg/min

Represents the minimum O2 flow required

4

Gasses

O2
Nitrous oxide
Medical air

5

Two types of O2 cylinders

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

H- stored in banks, central O2 supply

6

Green Cylinders

Oxygen

7

Blue Cylinders

Nitrous oxide

8

Yellow Cylinders

Medical Air

9

Why are cylinders stored on their sides?

To prevent explosion and avoid spontaneous combustion

10

Cylinder pressure units

psi

11

Breathing system pressure units

cmH2O

12

High Pressure systems

100-2200+psi

Gas cylinders, yokes, pressure gauges, regulators

13

Intermediate pressure systems

50psi

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

14

Low pressure systems

pressure in patients lungs

15

E-cylinder capacity

660L (need to memorize)

16

H-cylinder capacity

6600L

17

Internal cylinder pressure

2200psi

18

How do you figure out volume left in tank?

Boyle's law

P1V1=P2V2

19

How do you figure out time left on remaining volume?

Minutes = Volume/(flow liters/min)

20

Can you calculate remaining volume on N2O tanks?

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

21

Components to the safety systems

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

22

Diameter index safety system

Non-interchangeable gas-specific threaded connection system

Universal between equipment cylinder manufacturers

23

Pin index safety system

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

24

Quick connectors

Manufacturer-specific

Facilitate rapid connecting/disconnecting of gas hoses

25

Regulator

Aka pressure reducing valve

Decreases tank pressure to approximately 50psi and supplies to the flowmeter

Prevents pressure fluctuations as tank empties

26

Flowmeter

Controls rate of gas flow through the vaporizer (L/min)

Calibrated for 760mmHg and 20C

27

Flowmeter pressure reduction

50psi to 15psi

28

Where do you read the flowmeter?

Middle of ball or top of bobbin depending on type

29

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

Far right, to avoid hypoxic mixtures.

30

Quick flush

Delivers intermediate pressure O2 bypassing the vaporizer

31

Flowrate of the quick flush

35-75L/min

32

Use for the quick flush

Quickly decrease gas percentage in circuit

Emergency or recovery

33

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

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

34

Anesthetic vaporizers

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

35

Vapor

Gaseous state of a substance that is liquid at ambient temp and pressure

Eg- halo, iso, sevo, desflurane

36

Gas

Exists in gaseous state at ambient T/P

Eg. N20, Xenon

37

Vapor pressure

Pressure exerted by vapor molecules when liquid and vapor phases are in equilibrium

Directly related to temperature
Inversely related to boiling point

38

Saturated vapor pressure

Maximum administration percentage of vapor

Vaporizers reduce this to clinically useful percentages

39

Modern vaporizer characteristics

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

40

Variable bypass system

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

41

VOC- precision vaporizer

Out of circuit vaporizer which delivers a known percentage of anesthetic

42

VIC- non-precision vaporizer

OLD model

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

43

Modern vaporizer compensations

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

44

Desflurane vaporizer

Boiling point close to room temp

Electronically heated

Commonly used in Human, not in vet

45

Agent-specific key filler port

Prevents filling of vaporizers with improper anesthetics

46

Do modern vaporizers require external power?

No- except desflurane

47

Vaporizer transportation/orientation

Cannot be tipped, must be emptied prior to transport

If tipped run 1L/min O2 with vaporizer off to clear lines

48

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

Drain and run 1L/min O2 until dry

49

Common gas outlet

Where gas exits the vaporizer, connected by a hose to the fresh gas inlet

Universal for rebreathing and non-rebreating units