anesthesia machines

Question 1

absorber

Answer 1

canister (1-2)-source of leaks, will become dessicated–>won’t work

chemical carbon dioxide absorbent-all or part of exhaled CO2 is absorbed

made of calcium hydroxide, KOH, NaOH, LiOH

CO and compound A

Question 2

flow rates: beginning

Answer 2

higher flows at the beginning of the procedure

“wash in”-two fators: gas flow rate & volume

3 time constants required to reach 95% of inspired conc

lower time constant with high flow and lower volume

Question 3

flow rates: maintenance phase

Answer 3

close: flow rate=metabolic need, most economical, change happens slowly, higher vaporizer settings, close attention to volume in circuit, O₂ delivery to patient, airway gas monitoring helpful

semi-closed: flow rate>metabolic need, flow rate<minute>
</minute>

Question 4

advantages of non-rebreathing system

Answer 4

simple inexpensive, lightweight, easy to use

few moving parts

low resistance

low volume, high flows (time constant decreased)

no CO2 absorbent- no risk of toxic compounds

Question 5

disadvantage to non-rebreathing systems

Answer 5

high fresh gas flow rate-expensive, not eco friendly

loss of heat and humidity

low volume-higher risk of volutrauma

Question 6

5 basic function

Answer 6

source of oxygen

support ventialtion

delivers inhalants

removes exhaled CO₂

removes inhalant anesthetics

Question 7

basic components of anesthesia machine

Answer 7

gas source

pressure regulator

flowmeter

vaporizer

Question 8

high pressure zone

Answer 8

cylinger

hanger yoke

high pressure hoses

pressure gauges

regulators

Question 9

intermediate pressure zones

Answer 9

pipeline inlets

conduits from pipeline or regulators

flow control valve

oxygen flush

Question 10

low pressure zones

Answer 10

conduits to vaporizers

vaporizers

conduits to breathing system

Question 11

Cylinders (tanks)

Answer 11

E or H size

colors: Green-O₂, Blue NO, Black N₂, Yellow air, Gray CO₂

permanent markings

Question 12

general rules for cylinders

Answer 12

safe handling

no oils, grease, lubricants or combustibles

gas specific apparatus

20-130 degrees F

secure tanks upright or horizontally in bins or racks (E) or upright and chained to wal (H)

no dropping, dragging, sliding or rollling

crack the tank before fitting it to a machine

use washer

open cylinder slowly

close when not in use

remove empty tanks

Question 13

how will the pressure drop in a cylinder with oxygen?

Answer 13

pressure decreases linearly as the volume decreases

Question 14

how will the pressure drop in a cylinder with nitric oxide?

Answer 14

pressure will not start dropping until 75 to 80% of contents are used

Question 15

how is the gas source connected to the machine?

Answer 15

tanks: hanger yokes or PISS (pin index safety system)
pipeline: quick connectors, DISS (diameter index safety system)

Question 16

what do pressure regulators do?

Answer 16

reduce the high, variable pressures from the cylinder to lower and constant pressures more suitable for anesthesia machine

Question 17

what does a flowmeter do?

Answer 17

allows for precise control of gases being delivered

Question 18

what is the flowmeter composed of?

Answer 18

flow control valve

glass tube

scale

flow indicator

Question 19

flow indicators

Answer 19

read at the top (in the middle for a ball)

should move freely (watch for rotation)

Question 20

vaporizers

Answer 20

most inhaled anesthetics are liquids that must be converted into vapors before they can be used

vaporizers convert liquid into vapors and add a specific amount to the gas being delivered to the patient

concentration-calibrated, variable-bypass with temperature, flow and back pressure compensation are recommended

Question 21

variable bypass vaporizer

Answer 21

fresh gas flows into the vaporizer

part directed through the vaporizing chamber, part bypassing it

gases mix before exiting the vaporizer giving the desired concentration

Question 22

measured flow

Answer 22

gas is direted through the vaporizer and becomes fully saturated

second source of gas dilutes to desired concentration

calculations needed

not as reliable

Question 23

method of vaporization

Answer 23

flow over

bubble through

injection

Question 24

vaporizer in circuit

Answer 24

increased ventilation–>increased inspired anesthetic concentration

increase oxygen inflow–>decreased inspired anesthetic concentration

Question 25

vaporizer out of circuit

Answer 25

increased ventilation –> decreased anesthetic comcentration

increased oxygen inflow–>increased inspired anesthetic concentration

Question 26

precision vaporizers

Answer 26

recommended and most commonly used

variable bypass

flow-over or injection

out of circuit

flow and temperature compensation

agent specific

high resistance

output is controlled accurately by dial setting

relatively complex and expensive

require occasional maintenance

Question 27

oxygen flush valve

Answer 27

gas derived from intermediate pressure system

bypasses the vaporizer

delivers a high flow rate of oxygen directly to patient’s breathing circuit

used to rapidly decrease the inhalant concentration in the breaking circuit

potential for barotrauma in small patients especially on non-rebreathing circuits