Vaporizers

Question 1

Vaporization

Answer 1

• changing liquid to gas
• molecules of volatile agent in closed container are in the liquid and gas phase
• gas molecules bombard surface of liquids and walls of container and create vapor pressure

Question 2

Sevoflurane

Answer 2

160mmHg

Question 3

Enflurane

Answer 3

172mmHg

Question 4

Isoflurane

Answer 4

240mmHg

Question 5

Halothane

Answer 5

244mmHg

Question 6

Desflurane

Answer 6

669 mmHg

Question 7

Vapor pressure

Answer 7

vapor pressure is dependent on temperature

liquids with high vapor pressures at room temp are Volatile

Question 8

Latent heat of vaporization

Answer 8

of calories required to change 1 gram of liquid to vapor WITHOUT temp change

*1g=1mL

Question 9

Energy for vaporization

Answer 9

vaporization is the change from liquid to gas

• if the energy to change states comes from the liquid
  1. then liquid loses energy and the temperature of the liquid decreases
  2. decreased temp of the liquid decreases the rate of vaporization
• why we have a system to keep temp of liquid constant so rate of vaporization is not affected

Question 10

Specific heat

Answer 10

of calories needed to increase the temp of 1 gram of substance( liquid, solid, or gas) by 1 degree celsius

**helps us design, operate and construct vaporizers

Question 11

How concept of specific heat is applied to vaporizers

Answer 11

1. tells us how much heat must be applied to liquid (loses energy when changing to gas) during vaporization to maintain a constant temp
2. materials with high specific heat are used to manufacture vaporizers bc they are better at resisting the change in temp during vaporization

Question 12

Thermal conductivity

Answer 12

rate at which heat passes through a specific material

higher the thermal conductivity, better the substance is at absorbing heat

Question 13

Why is Thermal conductivity relative to the manufacturing of vaporizers

Answer 13

vaporizers are made of metals because they have a high thermal conductivity, they are able to absorb heat from environment or from liquid when it evaporated to a gas, maintaining a constant temp

Question 14

Vaporizers

Answer 14

• key index safety system (KISS)
• agent specific
• temp compensated
• variable bypass chamber

Question 15

Variable Bypass

Answer 15

• portion of gas flow passes into variable bypass chamber and be comes saturated with vapor
• then rejoins the gas flow to dilute vapor to a safe deliverable concentration

Question 16

temperature compensating valve

Answer 16

• senses the temp in the system and bends right or left
• a bend to the Right occurs with a higher temp and allows more gas to escape and less to variable bypass chamber
• bend to the Left occurs with. a lower temp and allows more FGF down the variable bypass chamber to get saturated with vapor

Question 17

Tec 6

Answer 17

-vaporizer specific only to desflurane

• *gas -vapor blender
• not a variable bypass chamber

-des is heated to 39 degrees celsius so we can pressurized it to 2 atm
(increased temp increased pressure)

-this is done bc des VP is 669mmHh which is very close to 1atm = 760 mmHg

when VP = atmospheric pressure boiling occurs

Question 18

Copper Kettle

Answer 18

• out of circuit vaporizer
• NOT agent specific
• need to calculate vapor output and % concentration
• measured flow, bubble through
• dedicated flowmeter (measured flow)

Question 19

Vapor output equation

Answer 19

Vapor Output =
CG x VP/ BP – VP

BP= atmospheric pressure
VP= vapor pressure 
CG = carrier gas flow rate (this is what you can manipulate)

Question 20

Anesthetic Concentration equation

Answer 20

% = Vapor output/ Total gas flow

*can manipulate total gas flow

Question 21

How a copper kettle works

Answer 21

• measured flow -bubble through
• dedicated flowmeter just for kettle (measured flow)
  1. gas comes up through central tube inside vaporizer to loving cup
  2. gas flow forced down toward liquid (bubble through)
  3. highly concentrated vapor then exits vaporizer and gets diluted by FGF

Question 22

Altitude on vaporization

Answer 22

increased altitude decreased atmospheric pressure

decreased altitude increased atmospheric pressure

• Variable bypass vaporizers are independent to the atmospheric pressure change, depth of anesthesia given at dial setting remains constant
• this does not apply for Tec 6 (desflurane)

Question 23

Altitude and Tec 6

Answer 23

*not a variable bypass chamber

New % = normal (dial setting) % x 760 / current atmospheric pressure

Question 24

Potential hazards of Vaporizers

Answer 24

1. Wrong agent in calibrated vaporizer
   - high VP agent in lower VP vaporizer = overdose
   - low VP agent in higher VP vaporizer = under dosed
2. Containment when open
   - open and close as quick as possible
   - reduce exposure to self
   - dust/ particles can get in
3. Tipping
4. Overfilling
   - too high concentration
   - fill to black fill line
5. Leaks
   - check during machine low pressure check with negative pressure check using bulb suction
6. Pumping effect
   - fluctuation in pipeline pressure (all Ors start at same time)
7. Administration of more than one vapor at same time
   - Interlock system prevents this (cant open more than one vaporizer at a time)