IHS Vaporization and Vaporizers

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  1. What is the definition of Vapor Pressure?
    a measure of the collisions of the molecules with the container
  2. What is saturated vapor pressure?
    In a closed container, when the number of molecules entering the gas phase equals the number of molecules entering the liquid phase
  3. What is volatility?
    the tendency of a liquid to enter the gas/vapor phase
  4. vapor pressure and temperature are ________ related

    As temp increases, vapor pressure increases. As temp decreases, vapor pressure decreases.
  5. How does a change in atmospheric pressure affect the boiling point of a substance?
    As atmospheric pressure decreases, so does it's boiling point.
  6. What is boiling point?
    The temperature at which vapor pressure = atmospheric pressure.
  7. Why does it take longer to cook things in areas with lower atmospheric pressures?
    Because the boiling point is where vapor pressure = atmospheric pressure. Since atmospheric pressure is lower, liquid boils at a lower temperature, therefore taking longer to cook things.
  8. What 3 things does vaporization of an anesthetic agent depend upon?
    • 1) vapor pressure of the agentĀ 
    • 2) ambient temperature
    • 3) amount of carrier gas flow
  9. If you decrease the temperature of a liquid agent, what will happen to the rate of evaporation?
    it will decrease
  10. What happens to the temperature of the liquid and container as an agent evaporates?
    It cools due to the loss of kinetic energy
  11. What are two characteristics of a vaporizer that help prevent slowing of the evaporative rate?
    • 1) high thermal conductivity (steals heat from environment)
    • 2) high thermal capacity (keeps heat from environment)
  12. What is the saturated vapor pressure and boiling point of halothane at STP?
    • 243 mm Hg
    • 50.2 C
  13. What is the saturated vapor pressure and boiling point of Isoflurane @ STP?
    • 238 mmHg
    • 48.5 C
  14. What is the saturated vapor pressure and boiling point of sevoflurane at STP?
    • 160 mm Hg
    • 58.6 C
  15. What is the saturated vapor pressure and boiling point of Desflurane at STP?
    • 660 mmHg
    • 22.8 C
  16. What 2 things does saturated vapor pressure depend upon?
    • 1) agent
    • 2) ambient temperature
  17. If agent 1 has a saturated vapor pressure of 100 mm Hg and agent 2 has a saturated vapor pressure of 200, which agent is more volatile?
    agent 2 - volatility is directly related to saturated vapor pressure
  18. If agent 1 is very volatile and agent 2 is less volatile, which agent will have a higher boiling point?
    agent 2 - volatility is inversely related to boiling point
  19. How do you calculate the volumes percent of a vapor?
    partial pressure/atmospheric pressure
  20. How do you calculate the partial pressure of a gas?
    multiply the percent x atmospheric pressure
  21. What is the purpose of fresh gas flow through a vaporizer?
    To dilute the vapors to a clinically safe and useful level
  22. What are the 2 categories of vaporizers?
    • 1) variable by-pass
    • 2) dual-circuit
  23. What type of vaporizer does desflurane use?
    dual-circuit Tec 6, the carrier gas is not split. Fresh gas flow does not come into direct contact with vapors until the outlet.
  24. What is the difference in heating between the Tec 6 and the Tec 4/5?
    Tec 6 is electronically heated, Tec 4/5 use automatic temp compensation from the material of the vaporizer/ambient temp
  25. How does a variable bypass vaporizer control the amount of anesthetic the patient receives?
    the % dial increases or decreases resistance to flow which proportionally increases or decreases the amount of fresh gas flow comes into contact with the vapor
  26. What is latent heat of vaporization?
    the amount of heat required to convert 1 ml of liquid into a vapor
  27. What is the latent heat of vaporization of desflurane?
    39 C
  28. How many cc's of gas to ml of liquid agent for Isoflurane?
  29. How many cc's gas to ml of liquid agent for halothane?
Card Set
IHS Vaporization and Vaporizers
IHS Vaporization and Vaporizers
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