VNTE Prep

Anesthetic Review

Vapor Pressure

A measure of the tendency of a molecule to escape from the liquid phase to the vapor or gas phase.

Determines how readily the anesthetic liquid evaporates in the anesthetic machine vaporizer.

Agents w/ high vapor pressure are considered to be volatile.

Vapor Pressure

High vapor pressure = Evaporate readily = Must use precision vaporizer

Low vapor pressure = Don’t evaporate as readily = Does not require a precision vaporizer

Solubility Coefficient

A measurement of the distribution of the inhalation agent between the blood and gas phases in the body.

Agents w/ a high solubility coefficients take longer to induce and recover from anesthesia.

Agents w/ a high solubility coefficient are extremely soluble in blood & tissues – they do not build up in high levels in the alveoli.

Solubility Coefficient

Agents w/ a low solubility coefficient have rapid induction & recovery from anesthesia.

Agents w/ a low solubility coefficient are less soluble in blood & tissues - they build up in the alveoli in sufficient levels

Associated w/ the speed of induction, recovery, & change in anesthetic depth

Minimum Alveolar Concentration

A measurement of the potency of an agent

The lowest concentration of an anesthetic agent that produces no response to painful stimuli in 50% of the patients.

The lower the MAC the more potent the agent (It takes less to reach desired effect)

Minimum Alveolar Concentration

It takes a higher concentration of an agent w/ a high MAC to maintain a similar anesthetic depth when compared to an agent w/ a lower MAC.

It is more cost effective to use an anesthetic agent w/ a low MAC.

Vaporizer Out of Circuit

AKA – VOC Vaporizer is not in the breathing circuit

- Circuit includes: unidirectional valves,

hoses, CO2 absorber canister, APL

valve, reservoir bag

• Precision vaporizers• Must be placed out of the breathing circuit due

to high resistance to gas flow

Vaporizer in Circuit

AKA – VICVaporizer is part of the circuitNonprecision vaporizersOffer little resistance to gas flow thru the

breathing circuit