Vaporizers

If desired concentration of Sevo is 2% the splitting ratio is

12:1 (12 to bypass, 1 to vaporizer)

The heating of desflurane produces a pressure of about ____mmHG

1550

Less than ___% of FGF enters chamber

20

Output of gases is relatively constant for temps of

20-35

The Tec 6 heats desflurane to a constant temperature of ____

39 C, all of the agent is therefore in the gas form

If desired concentration of Iso is 1% the splitting ratio is

44:1 (44 to bypass, 1 to vaporizer)

Vapor pressure and boiling point of Desflurane

664 mmhg, 23 degrees C (boils at room temp)

Which vaporizer demonstrates whicks and baffles

Tec 7-variable bypass

Amount of anesthetic agent delivered depends on (4)

agent delivered, temp of vaporizer chamber, pressure of vaporizer chamber, flow of FGF ATPF

Most common vaporizer

aladin cassette

Why is the funnel fill system bad

allowed any agent to be added to any vaporizer

Heat of vaporization defintion

amount of heat required to convert 1 g of liquid agent into a vapor

A high blood: gas means that more agent must be taken up in

blood before it goes to brain

Onset of a vaporizer is determined by

blood:gas, the higher means the more dissolvable in blood the slower the onset

Desflurane coded color

blue

FGF is split in _____ and _____

bypass gas (Fb) and carrier gas (Fc)

Two streams of gas in variable bypass

bypass gas, carrier gas

Vaporizers are constructed of metals with high thermal

capacity, mass, conductivity

What picks up volatile agent gas

carrier gas

Flow over vaporization allows

carrier gas flow over the volatile agent

Two methods of regulating concentration

concentration calibrated (variable bypass), (user) measured flow (copper kettle)`

The amount of vapor is controlled by the

concentration dial

In variable bypass what splits the stream of gas

concentration dial setting

Cooler temps will cause bi-metallic strips to

contract, increasing flow

Vaporizers must be able to ____ the amount of vapor added to FGF

control

What type of vaporizer is this? -user diluted measured flow -bubble through -user must continuously adjust temperature -multiple agent -outside circuit

copper kettle

Lowering the temperature of the vaporizer creates a

decrease in vapor pressure

Vaporization requires

energy

Application of heat to the vaporizer causes

equilibrium to shift causing more molecules in the vapor phase

Warmer temps will cause bi-metallic strips to

expand, decreasing flow

Des is agent specific and safety filling system includes

filler cap . wihich is spring loaded with an O-ring on the top

Original/older vaporizers (2)

flow over, in ciruit

Volumes percent definition

gas amount per 100 units of volume for total mixture

How does Bubble through vaporization work

gas bubbles through the volatile agent

Wicks and baffles increases

gas liquid interface to enhance efficiency of vaporization

What creates the vapor pressure in the vaporizer

gas molecules against the walls

In circuit vaporizers have (2)

gas supply go straight to the patient

Most potant inhaled anesthetic

isoflurane

Copper has a very low specific heat meaning

it does not require a lot of energy to heat up and change the temperature, this is why it is a good vaporizer

How are agent specific vaporizers differentiated

keyed and color coded

Low potency of Des mean

large amounts are needed to be vaporized

Why is tipping of vaporizer bad

liquid agent enters bypass chamber

As vaporization proceeds, what two things drop

liquid temp, vapor pressure

Vaporizer converts ___ to _____

liquid, vapor

Aladin Cassette is ____ coded so the machine knows what agent cassette is inserted

magnetically

Des can be filled while machine is on because

maintains closed system

Three methods of temperature compensation

mechanical (metallic strip), computerized (cassette), supplied heat (user controlled)

When is penthrox inhaler used

military/combat situation

Out of circuit vaporizers allow for the use of

multiple vaporizers

How is a desflurane vaporizer different with gas flows

no fresh gas flows through it

Biological properties of an ideal anesthetic (6)

non irritant, low blood gas solubility, high oil gas solubility, minimal effects on other body systems, no biotransformation, non-toxic NIRTBB

Physical properties of an ideal anesthetic (6)

non-flammable, vaporizable, stable at room temp, stable with metal, environmentally friendly, cheap FSEC

If you lose power not good for ___ vaporizer, ok for ___ vaporizer

not good for des ok for sevo

Almost all modern anesthetic machines have vaporizers placed

out of circuit

Partial pressure definition

part of total pressure from 1 gas in a mix

Vapor pressure definition

partial pressure of agent in vapor phase

Besides decreasing temp, what else causes a shift in equilibrium away from vaporization

passing a carrier gas over the liquid

Pressure of Des being introduced is equal to

pressure of des coming out

_____ is injected out of vaporizer into stream of FGF

pure des vapor

Isoflurane coded color

purple

Blood gas coefficient tells you (you want it to stay as a gas, not dissolved in blood) (2)

rate of uptake and emergence

Halothane coded color

red

Why is there no wick system is Des vaporizers

saturates carrier gas quickly

Vaporizers are calibrated at

sea level

Copper kettle requires a ___ ____ for carrier gas

separate flowmeter

Three valves of Des vaporizer (Tec 6)

shut off, pressure regulating, concentration control

The volume change of the liquid in the chamber will also change the ____ and ____ of the chamber which will affect the amount of agent delivered to the patient

temperature and pressure

A ___ senses the amount of FGF and adjusts the injection of vapor accordinglythrough a _____. This makes the vaporizer

transducer pressure regulating valve extremely accurate

Vaporizers are installed on a pair of

two way port valves on the manifold

Maximum agent concentration formula

vapor pressure/barometric pressure

What ensures that only one vaporizer can be used at a time

vaporizer interlock (gas only enters the one that is on)

Altered barometric pressure changes

vaporizing chamber concentration

Modern ways of use of flow over, in circuit

veterinary, OB, military

The volume of gas we introduce to the vaporizer affects the_____ agent

volume of agent and therefore the volume of the liquid in our chamber

Method of vaporization (4)

whick and baffles, flow over, bubble through, injection

Sevoflurane coded color

yellow

Did all of the breathing gases pass through the kettle?

No

Describe Draw-over vaporizers

(uses negative pressure - dependent on Ve): low resistance and inefficient compared with plenum vaporizers. They are portable and best suited to "field anesthesia".

Plenum vaporizers

(uses positive pressure): high resistance, unidirectional, agent specific, variable bypass vaporizers designed to be used outside the breathing system

Two methods of specificity

-Agent specific- all modern vaporizers -Multiple Agent

Two methods of resistance

-out of circuit-all modern vaporizers -in circuit- positive pressure to pass gas along

What type of vaporizer is this? -variable bypass -flow over -temperature compensated -agent specific -out of circuit

-variable bypass

Specific heat of copper

.1 cal/C g

What was added to the fresh gas flow going to the patient in copper kettler?

Carrier+ agent (like N2O)

Characteristics of which vaporizer? Variable bypass, flow over, computerized thermocompensation, agent specific, out of circuit

Characteristics of Aladin cassette vaporizer (5)

What type of vaporizer is this? Electrically heated, constant temp, pressurized, injection, thermostatically/electromechanically coupled, agent specific, out of circuit

Characteristics of Tec 6 and Tec 6 plus, desflurane vaporizer (7)

Which law relates the vaporizer volume and pressure

Daltons Law

Total gas exiting vaporizer is (Ftot)

Fa+ Fb+Fc

% agent delivered equation

Fa/Ftotal x 100

Vaporization classification (4)

Method of regulation concentration, method of vaporzation, temperature compensation, specificity, resistance CTVSR

Can you turn on multiple vaporizers at the same time?

No

Potency is determined by

Oil:gas, the higher the oil gas the more dissolvable in oil (the brain) the highest potency

How does the user dilute gas in the copper kettle

addition of FGF

Fastest rate of uptake/emergence inhaled anesthetic

desflurane

Specific heat definition

heat required to raise the temp of 1 g by 1 degree C

Copper has a ____ thermal conductivity

high

Thermal conductivity definition

speed that heat flows through a substance

Ratio of bypass gas to carrier gas is called

splitting ratio

Temperature compensated ensures ___ vaporized output over a wide range of ambient temperature

steady

Specific amount of volatile agent(Fa) picked up by carrier gas (Fc) depends on____ and____of the agent

temp and vapor pressure

Boiling point definition

temp at which vapor pressure equals the external pressure surrounding the liquid. Therefore, the boiling point of a liquid depends on atmospheric pressure. The boiling point becomes lower as the external pressure is reduced