Vaporizers

Question 1

Definition of VA agent

Answer 1

liquid at room temperature

Question 2

What is the vaporizer used today?

Answer 2

temperature compensated concentration-calibrated variable bypass vaporizer

Question 3

what is saturated vapor pressure?

Answer 3

in a closed container at normal atmosphere and RT a potent VA is in liquid form -> some molecules escape to enter gas/vapor form -> equilibrium established between liquid and vapor phase

Question 4

What concentration of VA do we aim for?

Answer 4

MAC, typically administered at 1.2-1.3 MAC

Question 5

What is the splitting ratio?

Answer 5

vaporizing chamber flow rate:bypass pathway flow rate

Question 6

What are the issues with simple variable bypass?

Answer 6

• high flows result in inadequate vaporization (wiking)
• temperature issues
• accuracy of concentration with mechanical control knobs

Question 7

Why are vaporizers temperature compensated?

Answer 7

• heat of vaporization- E required to promote vaporization -> cooling of liquid anesthetic -> slow vaporization
• now temperature compensated so no reduction in output

Question 8

What is the Ohmeda Tec 6 vaporizer?

Answer 8

• heats DES to 39 C -> 2 atm
• stable SVP
• fresh/diluent gas separate from vaporing chamber