Anesthetic Delivery Systems: Prodigy

Question 1

what are two components of the circle system test on an anesthesia machine? Between what two machine components does the circle system test?

Answer 1

the circle system test evaluates the circle breathing system from the common gas outlet to the y-piece and consists of two parts, the leak test and the flow test.

Question 2

what is the most common critical incident in anesthesia?

Answer 2

breathing circuit disconnections which most commonly occur at the y-piece

Question 3

which are considered safer on the anesthesia machine, ascending or descending bellows?

Answer 3

ascending (standing) bellows are considered safer than descending (hanging)
in the event of a circuit disconnect, ascending bellows will fail to rise whereas descending bellows will continue to descend due to gravity and ascend during inspiratory phase

Question 4

how is the leak test performed on an anesthesia machine?

Answer 4

closing the pop-off valve, occluding the y-piece and evaluating for a drop in pressure after pressurizing the circuit to 30 cm H2O using the flush valve

Question 5

what anesthesia machine alarms are based on the circuit pressure?

Answer 5

disconnect and high pressure alarms

Question 6

how is the flow test performed on an anesthesia machine?

Answer 6

flow test checks the integrity of the unidirectional valves by removing the y-piece and breathing through each individual hose to observe the movement of each valve

Question 7

on an anesthesia machine, what components are found in the low pressure system?

Answer 7

flowmeters, CO2 absorber, scavenging system, unidirectional valves, ventilator fresh gas delivery tubing to the breathing circuit and the breathing hoses

Question 8

what components are found in the intermediate pressure system?

Answer 8

pneumatic part of the master switch, pipeline inlet connections and pressure indicators, the gas power outlet, oxygen flush valve, oxygen pressure failure devices and flow control valves

Question 9

where does the oxygen flush receive its gas supply?

Answer 9

O2 flush receives an unmetered O2 supply from the cylinder pressure regulator or the pipeline inlet at a flow rate between 35-75 L/min

Question 10

when is use of the O2 flush control valve contraindicated in a mechanically ventilated patient?

Answer 10

should never be used when there is no outlet for excess gas pressure to escape to avoid barotrauma.
when the patient is in the inspiratory phase of mechanical ventilation when the inspiratory valve is open to the patient but there is no vent for gases to escape

Question 11

three functions of the hanger-yoke assembly on the anesthesia machine?

Answer 11

orients the gas cylinder
provides for unidirectional gas flow
provides an air-tight seal

Question 12

how does a variable-bypass vaporizer work?

Answer 12

splits the fresh gas flow into two parts
one portion enters the vaporizing chamber where it becomes saturated with anesthetic agent
the other enters the bypass chamber and does not come into contact with the anesthetic agent
by controlling the amount of gas that enters the vaporizing chamber, the amount of anesthetic agent delivered to the patient can be controlled

Question 13

is the Tec-6 vaporizer a variable-bypass vaporizer?

Answer 13

No
tec-6 vaporizer is heated to 39C and pressurized to 2 atm
no fresh gas flows through the sump

Question 14

which vaporizer is electrically heated?

Answer 14

desflurane
the vaporizers for other contemporary gases are temperature compensated and have a variable-bypass, flow-over design

Question 15

what is the function of the bimetallic strip in a contemporary vaporizer?

Answer 15

temperature sensitive and expands and contracts in response to ambient temperature changes to alter the total gas flow between the vaporizing and bypass chambers
if the temp of the liquid decreases, it will allow more gas flow into the vaporizing chamber to compensate for the decreased vapor pressure of the cooled liquid

Question 16

what color is the CO2 absorbent pH indicator ethyl violet when it is exhausted?

Answer 16

purple

Question 17

what is the pumping effect and when might it occur?

Answer 17

intermittent back pressure caused by positive pressure ventilation or use of the oxygen flush valve results in elevated vaporizer output
more prominent with low flows, low vaporizer dial settings, low levels of anesthetic in the vaporizer chamber, high respiratory rates and high PIP

Question 18

what should you avoid using a desiccated CO2 absorbent with desflurane?

Answer 18

prolonged exposure of desflurane or isoflurane to desiccated CO2 absorbent can result in the degradation of the anesthetic with the resulting production of carbon monoxide
increased temperature and higher doses of anesthetic agent both increase the amount of carbon monoxide produced
the inhaled anesthetic that produces the greatest amount of carbon monoxide is desflurane

Question 19

which gas flowmeter should be positioned last in the anesthesia manifold?

Answer 19

O2 should always be positioned last to reduce likelihood that a leak in one of the flowmeters would allow O2 to escape and lower the inspired O2 concentration

Question 20

pressing the oxygen flush valve allows oxygen to bypass what components?

Answer 20

opens flow directly from the oxygen pipeline or first stage regulator to the common gas outlet bypassing all switches, valves, flowmeters and vaporizers

Question 21

when an anesthesia machine is connected to a pipeline gas supply should the backup cylinder valves be open or closed?

Answer 21

closed
a pipeline pressure failure would be detected earlier and to prevent pressure variations in the pipeline from draining oxygen from the cylinders

Question 22

how much does an oxygen E-cylinder hold?

Answer 22

660 L, 2200 or 1900 psi

Question 23

how much oxygen does a D cylinder hold?

Answer 23

412 L, 2200 or 1900 psi

Question 24

how much N2O does an E cylinder hold?

Answer 24

1590 L, 750 psi

Question 25

how much N2O does an H tank hold?

Answer 25

16,000 L, 750 psi

Question 26

how much oxygen does an H tank hold?

Answer 26

6900 L, 2200 psi

Question 27

how much CO2 does an E cylinder hold?

Answer 27

1590 L

Question 28

how much medical air does an e-cylinder hold?

Answer 28

625 L

Question 29

what is the definition of boiling point?

Answer 29

the temperature at which the vapor pressure of a liquid is equal to the atmospheric pressure

Question 30

what is the heat of vaporization?

Answer 30

number of calories required at a certain temperature to convert one gram of the liquid into a vapor
amount of energy required for a liquid to convert into a vapor
as a liquid such as a volatile anesthetic or N2O converts into a gas, it loses heat and cools

Question 31

a leak in the anesthesia machine due to the vaporizer is most commonly caused by what?

Answer 31

a loose filler cap

Question 32

what safety mechanisms are built into the pipeline inlet connections on the anesthesia machine?

Answer 32

-pipeline inlet connections on an anesthesia machine are fitted with diameter index safety system fittings to prevent connection of a gas line to the wrong connector on the machine
-unidirectional check valve designed to prevent gas from flowing out of the anesthesia machine through an unoccupied yoke

Question 33

how does the oxygen supply failure alarm work?

Answer 33

-it alarms if the oxygen pressure falls below 30 psig
-it must engage within 5 seconds of the disconnect and cannot be disabled by the anesthetist
-it is designed to help prevent hypoxia from lack of oxygen flow, but does not prevent the flow of anesthesia gases
-could still possibly allow a hypoxic mixture of gases to be delivered

Question 34

in the event your oxygen supply fails, and you must switch indefinitely to your backup oxygen tanks, what are appropriate measures to reduce the amount of oxygen consumed and prolong the duration of your backup oxygen supply?

Answer 34

-most anesthesia machines utilize oxygen as the driving gas to power the ventilator
-by reducing fresh oxygen flow rates and eliminating the use of the ventilator by allowing the patient to breathe spontaneously or ventilating via the reservoir bag, you will prolong the backup oxygen supply

Question 35

What is the function of the nitrous oxide shutoff valve on the anesthesia machine?

Answer 35

The nitrous oxide shutoff device (also known as the failsafe device) triggers an alarm and closes the supply of nitrous oxide and other gases when the oxygen pressure falls below 30 psi.

Question 36

Why is the flowmeter tube (also called a Thorpe tube) tapered?

Answer 36

The diameter of the flowtube is such that it is smaller at the bottom than at the top.
At lower gas glows, it takes less pressure to support the bobbin and the diameter is smaller.
At higher gas flows, the diameter is larger and more gas is allowed to pass around the bobbin.

Question 37

How should a flowmeter indicator be assessed?

Answer 37

if using a bobbin, the flow rate should be read at the top of the indicator.
When using a ball-shaped float, the flow rate should be read at the middle of the ball.

Question 38

How do you calculate the inspired oxygen concentration if you are administering air and oxygen simultaneously?

Answer 38

100 x (1.0 x O2 L/min) + (0.21 x air L/min) / (O2 L/min + air L/min)

Question 39

You are testing your anesthesia machine in the morning before cases begin. You disconnect the pipeline supply and turn on the backup oxygen cylinder to make sure it functions correctly. The oxygen cylinder is full and connected correctly but the anesthesia machine still does not pressurize. What could be the cause?

Answer 39

If you have verified that the backup oxygen cylinder is full, connected properly, and opened and the anesthesia machine still does not pressurize, then there is a problem in the high or intermediate pressure system in the anesthesia machine.

Question 40

What is the only machine safety device that detects problems downstream from the flowmeters?

Answer 40

Oxygen monitor/analyzer
- fail safe valve, proportioning system, O2 supply alarms are upstream from the flowmeters