Gas systems and Vaporizers Flashcards Preview

Intro To Anesthesia > Gas systems and Vaporizers > Flashcards

Flashcards in Gas systems and Vaporizers Deck (43):
1

Thermal conductivity

a measure of speed with which heat flow through a substance

*higher thermal conductivity, the better the substance conducts heat

2

PISS for Oxygen

2-5

3

Isoflurane (20°C)

240 mmHg

4

Critical temp of O2

-118.6°C

  • bc ambient/room temp (20C) is above oxygens CT, it CANNOT be stored as liquid, no matter how much pressure we apply. 

 

  • HOWEVER, the main supply of oxygen in a hospital is in liquid oxygen stores. The containers are insulated from the outside and the temp is kept at -160C. 
    • ie:  ambient temp is below O2's CT, so if you apply enough pressure, you can make it a liquid. 

5

Enflurane Vapor pressure (20°C)

172 mmHg

6

Changes in altitude

Increase altitude, decrease barometric pressure

 

decrease altitude, increase barometric pressure

7

Gas/tank color blue

Nitrous oxide

 

8

Latent heat of vaporization

Number of calories required to change one gram of liquid into vapor without a temperature change

- the energy comes from the liquid itself or an outside source

9

Halothane (20°C)

244 mmHg

10

Changes in altitude

Increased altitude, decreased barometric pressure, increased concentration of inhaled gas put out through vaporizer

11

Safe handling of cylinders

  1. never stand cylinder upright without support
  2. never leave empty cylinders on the machine
  3. lever leave the plastic tape on the port while installing the cylinder
  4. never rely only on the cylinder's color for id of contents
  5. never oil valves
  6. "crack" the valve first to remove particles of dust or other crap.
  7. valve should always be fully open when a cylinder is in use

12

gas/tank color yellow

air

13

Vaporization

Conversion of a liquid to a gas

molecules combard the surface of the liquid and the walls of the contaner creating a vapor pressure

Dependent on: 

  • vapor pressure
  • temperature
  • amount of carrier gas used

14

Cylinder tag

15

Gas/tank color brown

Helium

16

Nitrous oxide:

liters

pressure

1590 L

750 psi

17

copper kettle

  • measured flow, bubble through
  • dedicated flowmeter for kettle
  • gas comes up through central tube inside vaporizer to the loving cup
  • flow of gas is then directed down toward the liquid (bubble through)
  • highly concentrated vapor then exits the vaporizer and is diluted into the fresh gas flow

18

Air cylinder:

liters

pressure

625 L

1800 psi

19

Changes in Altitude- Effects on Vaporization

  • vaporizers must be re-calibrated to assure accurate % delivered aneestheic gas
  • the % delivered is relative to the agent's vapor pressure in comparison to the barometric pressure:

Vapor pressure

barometric pressure

20

Gas/tank color grey

CO2

21

Altitude effect on Vaporizers 

(variable bypass vs TEC 6)

Variable Bypass

  • effect is that you are delivering a higher concenration of volatile agent at higher altitudes (lower barometric pressure), but maintaining the same partial pressure
    • automatic

TEC 6

  • Effect is that you would have to deliver higher dialed concentration of Des at higher altitude/lower baro pressure
  • you would alter your concetraiton dial to decrease output in lower altitude to avoid delivering overdose of anesthetic
    • you must change the concentration dial 

22

Vapor pressure

Caused by the gas molecules hitting the surface of the liquid and the walls of the container

23

Oxygen cylinder:

liters

pressure

625 L

2000 psi

24

PISS for CO2

1-6

25

Desflurane (20°C)

669 mmHg

26

variable bypass vaporizer

  • a portion of the gas flow will pass into the vaporizing chamber where it will become saturated with vapor
  • vapor-laden portion then rejoins the gas flow for dilution to deliverable concentrations
  • altitude effect: deliver a higher concentration at higher altitued/lower barometric pressure but mainain same partial pressure

 

27

DOT permanent markings

  1. serial number
  2. service pressure in psig
  3. manufacturer and serial number
  4. "SPUN" indicates the end of cylinder was closed by a spinning process
  5. initial qualifying date
  6. "+" indicates cylinder is authorized for charging up to 10% above marked service pressure.
  7. Star indicates cylinder may be retested every 10 years instead of 5

28

critical temp of N2O

36.4°C

  • bc abient room temp (20C), is below N2O's CT, it can be liquified with enough pressure applied to it
  • that's why we store N2O at room temp as liquid under 745psi (in the cylinder)

29

Sevoflurane (20°C)

160 mmHg

30

PISS for air

1-5

31

potential vaporizer hazards

  1. wrong agent in the vaporizer
  2. contamination- close lid quickly to keep crap out
  3. tipping
  4. overfilling
  5. simultaneous admin of more than one vapor
  6. leaks
  7. pumping effect- sputtering, like when sinks are off and turned back on again. 

32

Specific heat

The number of calories required to increase the temperature of one gram of a substance one degree C

*can be liquid, solid, or gas

 

specific heat of an anesthic agent indicates how much heat must be added in order to maintain a constant rate of vaporization

33

boiling point

when vapor pressure = barometric pressure

34

PISS for Nitrous oxide

3-5

35

Cylinder labels

  1. hazard class
  2. type of gas
  3. statement of hazard and measures to avoid injury

36

gas/tank color green

(international white)

Oxygen

37

Temperature and vaporization

direct relationship

increased Temp, increased vaporization

38

critical temperature

the temp above which a gas cannot be made into a liquid no matter how high the pressure

 

** a gas CANNOT be liquified if the ambient temp is greater than the cricital temp (ex: oxygen: CT -118C)

** A gas CAN be liquified if the ambient temp is below the cricical temp (ex: Niitrous Oxide: CT 36.5C or 39.5C depending on slide)

 

39

TEC 6 

  • special vaporizer for desflurane
  • "atmospheric pressure" within vaporizer increased to 2 atm by using heat (39C)
  • requires a plug, will feel warm compared to other vaporizers
  • altitude effect: you have to deliver higher dialed concentration of Des at higher altitude.

40

Gas/tank color black

Nitrogen

41

DISS

Diameter index safety system

  • provides non-interchangeable connections for the medical gas lines
  • consists of body, nipple, and nut
  • only properly mated parts will fit together and allow the threads to engage
  • required on every anesthesia machine. 

42

PISS for heliox

2-4

43

Regulatory Agencies (3)

  1. FDA- enforces purity of medical gases
  2. United States Pharmacopoeia- specifies purity of medical gases
  3. Department of Transportation- establishes requirements for medical gas cylinders and containers
    1. manufcturing
    2. filling
    3. qualification
    4. transportation
    5. storage
    6. handling
    7. maintenance
    8. re-qualification
    9. disposition
    10. labeling