anesthesia machine

Question 1

what is the pipeline pressure

Answer 1

50 psi

Question 2

what is the tank pressure

Answer 2

45 psi

Question 3

how to test low pressure system

Answer 3

attach bulb to CGO- create negative pressure- test fails if bulb reinflates within 10 sec

Question 4

high pressure leak test

Answer 4

close APL, pressurize circuit to 30- observe pressure gauge- pressure should remain constant

Question 5

what is the SPDD model

Answer 5

supply: how gas enters the machine

processing: how the anesthesia machine prepares the gas (up to CGO)

delivery: how prepared gases are brought to the patient

disposal: how gases are removed from the circuit (scavenging)

Question 6

5 tasks of oxygen

Answer 6

o2 pressure alarm
o2 pressure failure device
o2 flowmeter
o2 flush
ventilator drive gas

Question 7

what is the pin index safety system

Answer 7

-prevents inadvertant misconnection of gas cylinders
-pin configuration on each hanger yoke- diff for each gas
-o2 pressure drops to 45 psi when it enters entry into intermediate system

Question 8

how can the PISS be bypassed

Answer 8

the prescence of more than one washer between hanger yoke assembly and tank allows PISS to be bypassed

Question 9

diameter index safety system

Answer 9

prevents inadvertent misconnections of gas hoses. each gas hose and connector are sized and threaded for each gas

Question 10

what is the pipeline pressure

Answer 10

50 psi (same as intermediate)

Question 11

how do you tell cylinder content

Answer 11

by LABEL not color

Question 12

how many L and psi are in oxygen

Answer 12

660 L , 1900 psi

Question 13

how many L and psi are in air

Answer 13

625 L and 1900 psi

Question 14

how many L and psi are in n2o

Answer 14

1590 L and 745 psi

Question 15

what law is used to calculate cylinders content

Answer 15

boyles

Question 16

how does n2o exist in the tank

Answer 16

as a liquid unless it is almost empty

Question 17

what is the pressure of the gas n2o above liquid

Answer 17

remains constant at 745 psi regardless of how much liquid is in the tank

Question 17

what is the critical temp of n2o

Answer 17

36.5 (above room temp 20 degrees c)

Question 17

what is the most sensitive part of the gas cylinder

Answer 17

cylinder valve

Question 18

what to do if you suspect a leak in the cylinder

Answer 18

-tighten the connection
-replace washer between cylinder and hanger yoke
-change cylinder
-if you dont have replacement cylinder: insert yoke plug- if valve fails and there is no cylinder/ yoke plug- gas should be going to pt will exit here

Question 19

what cylinders are MRI safe

Answer 19

aluminum. 2 colors: silver tank and color on top

Question 20

what is the oxygen pressure failure device (failsafe)

Answer 20

-monitors for low o2 pressure in the anesthesia machine
-alarms in the event of depleted o2 tank, drop in pipeline pressure or disconnected o2 hose
-does NOT alarm in the setting of pipeline crossover (measures pressure, not o2 concentration!!!)

is in intermediate pressure system: alarms when pressure is below 28-30 psi

will stop n2o when pressure is below 20

Question 21

hypoxic prevention safety device

Answer 21

-prevents a hypoxic pressure
-fio2 should never drop below 25% (3:1 ratio)

Question 22

when will the hypoxic prevention safety device alarm

Answer 22

-o2 pipeline crossover
-leaks distal to flowmeter valves
-administration of a 3rd gas
-defective mechanic/ pneumatic components

Question 23

what begins the low pressure system

Answer 23

flow meters

Question 24

where should the o2 flowmeter be positioned

Answer 24

CLOSEST to CGO

Question 25

reynolds number

Answer 25

laminar <2000 turbulent >4000 transitional 2-4000

Question 26

when is laminar flow favored

Answer 26

low FGF higher FGF annular space acts like an orfice creating turbulent flow pattern

Question 27

what is fresh gas coupling

Answer 27

coupling of FGF to the tidal volume set on the ventilator may lead to errors in predicted Vt and MV (really only seen with older anesthesia machines)

Question 28

what is the tidal volume given to the patient during fresh gas coupling

Answer 28

tidal volume delivered to patient= Vt set on the ventilator + FGF during inspiatrion- volume lost to circuit compliance in flow coupled anesthesia machines, changes in RR, I:E ratio, FGF and height of the bellows impact total Vt given to pt if machine does not couple FGF to Vt, then what is set on ventilator is what gets delivered to patient

Question 29

what is circuit compliance

Answer 29

a chance in volume for a given change in pressure- measure of distensibility

Question 30

do modern ventilators compensate for fresh gas lost to circuit compliance

Answer 30

yes- when ventilator produces positibe pressure inside breathing circuit some of the gas causes circuit to expand. the quality of gas does not reach the patient and does not contribute to vt pateint recieeves. not an issue now

Question 31

what is variable bypass

Answer 31

when FG enters vaporizer- some encounters liquid anesthetic- the rest bypasses the anesthetic. the concentration set on the dial determines the splitting ratio. before leaving the vaporizer the 2 fractions mix- determines final anesthetic concentration to the patient

Question 32

what is flow over?

Answer 32

as fresh gas enters the vaporizing chamber (liquid anesthetic is here)- it flows over a series of baffles and wicks.

Question 33

what do you do if a vaporizer tipped over

Answer 33

run on high FGF for 20-30 mins before using on pt. some liquid anesthetic may enter bypass chamber

Question 34

temp compensated

Answer 34

the valve adjusts ratio of vaporizing chamber flow to bypass flow and guarantees a constant vaporizer output a wide range of temps

Question 35

what does out of circuit mean

Answer 35

the variable bypass vaporizer is positioned outside the breathing circuit

Question 36

what does agent specific mean

Answer 36

each vaporizer is calibrated to one anesthetic agent

Question 37

how does tec 6 vaporizer work

Answer 37

injects a precise amount of des directly into FGF

Question 38

what temp does des heat up to

Answer 38

39 c and presurizes it to 2 atm

Question 39

what is des vaport pressure

Answer 39

3-4 x higher than those of the other agents

Question 40

why cant you use a normal vaporizer with des

Answer 40

boils just above room temp (22 C)

Question 41

tec 6 and changes in elevation

Answer 41

does NOT compensate- important b/c depth of anesthesia is determined by partial pressure NOT concentration

Question 42

higher altitude with tec 6->

Answer 42

higher setting on dial

Question 43

hyperbarbaric oxygen tank and tec 6->

Answer 43

lower setting on dial

Question 44

what is the oxygen analyzer

Answer 44

-typically resides in the inspiratory limb -final defense against hypoxic mixture!!!!

Question 45

what is the only safety device that measures o2 concentration

Answer 45

oxygen analyzer can detect pipeline crossover and hypoxic mixture due to a leak in flowmeter