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Fall 2013 Anesthesia Concepts > Anesthesia Machine > Flashcards

Anesthesia Machine Flashcards

1
Q

Why do we have an anesthesia workstation?

A

because it integrates most of the components necessary to administer anesthesia into one unit, the components work together to deliver known concetrations of inhaled anesthetic to the patient.

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2
Q

The anesthesia workstation consists of what 6 things?

A
  1. anesthesia machine 2. vaporizers 3. ventilator 4.breathing system 5. scavenging system 6. respiratory and physiologic monitors
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3
Q

The anesthesia workstation provides delivery of medical gases and vapors of volatile gases at ___________.

A

Common gas outlet

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4
Q

From the common gas outlet, gases enter the anesthetic breathing system, and are delivered to the patient via ________ or ________ respiration, then exhaled gases are removed or __________ from the breathing system.

A

spontaneous or mechanical; scavenged

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5
Q

A common place for disconnect on the anesthesia machine is the ________________.

A

common gas outlet

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6
Q

Standards for anesthesia machines are maintained by which 2 groups?

A

ASTM -American society for testing materials (for current machines) and ANSI- American national standards institute. (for machines made before 2000)

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7
Q

Label.

A
  1. O2 and N2O flowmeters 2. Common manifold
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8
Q

Label components 3 and 4

A
  1. Calibrated vaporizers 4. Common gas outlet
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9
Q

Label component #5

A
  1. Patient circuit
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10
Q

Label compnonents 6, 7, and 8

A
  1. Oxygen hanger yoke with check valves and cylinder pressure gauge 7. O2 flush valve 8. Cabinet
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11
Q

label components 9 and 10

A
  1. Interface valve for scavenging system 10. Nitrous oxide hanger yoke with check valves & cylinder pressure gauge.
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12
Q

What colors are delineated for air? oxygen? and nitrous?

A

air- yellow oxygen- green nitrous- blue.

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13
Q

What are the 5 pathways of oxygen in the anesthesia machine?

A
  1. flow to the fresh gas flowmeters 2. Powers the oxygen flush valve 3.Activates the fail-safe mechanisms 4. activates the oxygen low pressure alarm 5. compresses the bellows of the ventilator.
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14
Q

The bellows of the vent on the anesthesia workstation will not work without which gas?

A

oxygen

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15
Q

The common gas outlet is within the ______ pressure system.

A

low

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16
Q

Is it OK to use a ventilator on a patient with an LMA?

A

Yes, as long as peak pressures are less than 20 cm H2O (otherwise you could damage the vocal cords) note:ventilation with LMA is not recommended by the manufacturer of LMA and Vicki never does this in practice

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17
Q

Do LMAs protect the airway from aspiration?

A

No. LMAs are not cuffed so gastric contents could enter the airway, especially if the pt. has been bvm’d for while and gastric pressure is elevated.

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18
Q

Anesthesia machines need to be ___________ once every 24hours for updates.

A

computerized anesthesia machines need to be powered down.

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19
Q

What happens if the fail safe mechanism is triggered?

A

The machine will shut down all gases except for oxygen

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20
Q

What are the 3 divisions of the air pressure system of the anesthesia machine?

A

High pressure system, Intermediate pressure system, Low pressure system.

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21
Q

Where are the high pressures in the anesthesia system?

A

In the gas tanks. (the cylinder pressure regulator on the tank will down regulate the pressure as it leaves the tank and enters the machine)

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22
Q

The 3 most important pre-procedure machine checks are?

A
  1. calibration of the oxygen analyzer 2.the low pressure circuit leak test 3. the circle system test
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23
Q

Which part of the anesthesia machine is considered the vulnerable area and is most susceptible to breaks and leaks?

A

The low pressure circuit

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24
Q

Why is important to perform a low pressure circuit test?

A

The low pressure circuit is downstream from all of the safety features of anesthesia machines except for the oxygen analyzer. It is the part of the machine that is missed if an inappropriate leak test is performed.

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25
Q

Which part of the anesthesia machine is the only thing that monitors the integrity of the low pressure circuit on an ongoing basis?

A

the oxygen analyzer

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26
Q

The low pressure leak test tests the anesthesia machine from the _________ to the__________.

A

flow control valves to the common gas outlet

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27
Q

What are the implications for the patient if a leak exists in the low pressure system?

A

This is a serious problem. Leaks in the low pressure system can lead to hypoxia or anesthesia awareness as oxygen and anesthetic gases can escape the system before reaching the patient.

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28
Q

The circle system spans from the _____________ to the _____________.

A

common gas outlet; y-piece

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29
Q

A complete anesthesia workstation check must be completed at least:

A

Once a day, and an abbreviated version must be done before each new case (circuit check).

30
Q

The intermediate pressure system begins at the __________, includes the ____________ and extends to the ______________.

A

regulated cylinder supply sources, pipeline sources and extends to the flow control valves.

31
Q

What is the pressure in the high pressure system?

A

The high pressure system is the tanks. A full O2 tank is about 2000psi, and a full N2O tank is about 750 psi

32
Q

Do all machines have second stage pressure regulators? If so, what do they do?

A

No, not all machines have them. They are in some machines to drop the pipeline pressure down as low as 14 psi.

33
Q

The low pressure circuit extends from the _________ to the_____________.

A

flow control valves, common gas outlet

34
Q

The flow tubes, vaporizer manifold, vaporizers, and one way check valve belong to which pressure system?

A

the low pressure system

35
Q

Both oxygen and nitrous have 2 supply sources. What are they and what are their pressures?

A

Oxygen and nitrous typically come from the hospital pipeline (at a pressure of about 50psi) They can also come from tanks, typically a back up system (at a pressure of about 45 psi)

36
Q

If the oxygen pressure drops to 30 psi in the pipes of the machine, what happens?

A

The fail-safe valve exists downstream from the oxygen and nitrous supply source and it shuts down nitrous if Oxygen supply is reduced. It is a safety mechanism to prevent an overdose of nitrous or hypoxic mixture. There are 2 types of fail safe valves. 1. Threshold type- as soon as you hit a low threshold pressure, the nitrous is shut off completely. 2. Proportioning type- where as O2 pressure drops, the N2O pressure drops as well.

37
Q

The fail safe valve serves as an interface between the ________ and _______ supply sources.

A

oxygen and nitrous

38
Q

What is one of the perks of a second regulator?

A

The second regulator drops the pressure of oxygen to about 14psi. This is good because despite fluctuations of pressure in the pipelines, a constant pressure will be maintained to the patient. As long as the oxygen pressure is greater than 14 psi you are good to go.

39
Q

Why are the flow control valves an important anatomic landmark in the anesthesia machine?

A

The flow control valves separate the intermediate from the low pressure circuits.

40
Q

The ___________ circuit is the part of the machine that lies downstream to the flow control valves.

A

low pressure circuit

41
Q

The pressure in the low pressure circuit is controlled by?

A

The anesthesia provider, who regulates the flow by adjusting the flow control valves. It just a bit higher than atmospheric pressure.

42
Q

The oxygen and nitrous flow control valves are connected by a _____________ to help prevent inadvertent delivery of a hypoxic mixture.

A

proportioning system

43
Q

A fter leaving the flow tubes, the mixture of gases travels through a _______________ and may be directed to a calibrated vaporizer.

A

common manifold

44
Q

After the vaporizer, the mixture of fresh gas and anesthetic travels toward the _______________.

A

common gas outlet

45
Q

Between the vaporizer and the common gas outlet there is typically a ____________. It’s purpose is to:

A

one way valve; it prevents backflow into the vaporizer during positive pressure ventilation

46
Q

Why would intermittent backpressure into the vaporizer be bad for the patient?

A

It will cause fluctuations in the delivery of the anesthetic gas and varying levels of anesthesia.

47
Q

If you are ever concerned that there is something wrong with the oxygen delivery pipeline what 2 things must you do?

A
  1. Turn on your backup O2 tank 2. But most importantly, you must turn off the pipeline source or disconnect it. The pipeline source runs at a pressure of 50psi, and the tank only at 45 psi, so simply turning the tank on does not guarantee oxygen delivery. The system prefers the higher pressure of 50psi, regardless of the type of gas (even hypoxic mixture) coming through it.
48
Q

Gas enters the anesthesia machine through ______________

A

the pipeline inlet connections

49
Q

How do you prevent gas from the machine from backing up into the hospital pipeline?

A

A check valve downstream from the inlets prevents backup of gas.

50
Q

Medical gases supplied in E cylinders are attached to the anesthesia machine via the___________.

A

hanger yoke assembly

51
Q

The hanger yoke system does 3 important things, they are:

A
  1. orients and supports the cylinder 2. provides a gas tight seal 3. ensures unidirectional flow of gases.
52
Q

The cylinder pressure regulator on the O2 tank decreases the oxygen tank pressure from __________ to _________; They cylinder pressure regulator on the N2O tank decreases the tank pressure from _________ to ___________.

A

2000 psi to 45 psi; and 750 psi to 45 psi

53
Q

Should the reserve oxygen and nitrous tanks be left in the ‘on’ position or the ‘off’ position?

A

the tanks should be in the off position. Otherwise, if there are pressure fluctuations in the machine and pressure falls below 45 for brief times, the tanks will slowly get depleted.

54
Q

One of the most important alarms the anesthesia machine is the?

A

Oxygen pressure alarm. If the oxygen pressure drops below 30psi the alarm will sound. If low oxygen pressures go undetected and untreated, the risk of delivering a hypoxic mixture the patient and subsequent hypoxic injury to the patient become a threat.

55
Q

A fail safe valve is present in each of the gas lines supplying each of the flowmeters except for the ___________ line.

A

oxygen

56
Q

How is a fail safe valve contolled, how does it work?

A

The fail safe valve is controlled by oxygen pressure. As the oxygen pressure drops, the valves of the other gases will close proportionally, decreasing the pressure of all other gaes and preventing dilution of the mixture that would make it hypoxic.

57
Q

Does the fail safe valve guarantee that a hypoxic mixture will not be delivered to the patient?

A

No. This will not work in machines without a proportioning system or with the proportioning system shut off.

58
Q

What is a pressure sensor shut off valve?

A

A fail safe valve where that does not close proportionally to the decrease in oxygen pressure but rather, closes all the way, stopping nitrous ( or other gas) flow altogether.

59
Q

There are many types of fail safe valves, in general, how do they differ?

A

Either all or nothing, or proportional. Some fail safe valves will decrease the other gases proportionally when a decrease in oxygen pressure is present. Others will shut off the other gases completely when a decreased oxygen pressure is present. The goal of any fail safe valve is to prevent the administration of a hypoxic mixture of gases to the patient.

60
Q

This picture represents: (an all or nothing fail safe valve or a proportioning fail safe valve)

A

Proportioning.

61
Q

Does this picture represent an all or nothing or proportioning fail safe valve?

A

all or nothing

62
Q

Again, the goal of the fail safe valve and second stage oxygen pressure regulators is to:

A

to ensure that oxygen is the last gas flowing if some sort of oxygen pressure failure should occur.

63
Q

The ____________ assembly precisely controls and measures gas flow to the common gas outlet.

A

flow meter assembly

64
Q

The tapered, transparent flow tube of the flowmeter is called the?

A

Thorpe tube

65
Q

When reading oxygen flow in the flowmeter assembly, O2 level is where on the plumb bob float? skirted float? or ball float?

A

In systems with the plumb bob or skirted float, the flow is read at the top edge of the float. In the ball float, the flow is read at the middle of the ball.

66
Q

Name 3 problems that can occur with the flowmeters?

A
  1. Leaks. (Leaks are the most serious problem because they are downstream to all of the machine safety devices except for the oxygen analyzer) One step that helps counter potential leaks is to place the oxygen flowmeter downstream from all other flowmeters, closest to the patient. If oxgen is leaking or falling backward into the system, it will be washed forward by the other gases as they flow forward. This is not a perfect mechanism, but can help prevent hypoxic mixture. 2. Inaccuracy of the flowmeter (sticking floats, static, etc. hold it at the wrong level). 3. ambiguous scale- less likely now, because scales are etched on the tubes, but deaths have occurred in the past due to practitioner error in reading the flowmeter.
67
Q

What is the purpose of the proportioning system?

A

To prevent hypoxic gas mixture. Nitrous oxide and oxygen are interfaced mechanically or pneumatically to ensure that the minimum oxygen concentration at the common gas outlet is between 23-25%

68
Q

How does the proportioning link system work, basically?

A

The proportioning link system works by connecting the oxgyen and nitrous so that no matter which gas you titrate, the other will follow suit to maintain a 3:1 ratio (nitrous : oxygen) maintaining that 25% O2 at the common gas outlet constantly.

69
Q

The proportioning system is great for preventing a hypoxic concentration but does have some limitations, like?

A
  1. Wrong gas connected. (the flowmeters have no way of telling which gas is present, so if the wrong gas is connected somewhere upstream a hypoxic concentration can be delivered. An oxygen analyzer will help detect this) 2. Second stage regulators must be functioning properly. (Again, the flowmeter cannot tell what gas is present, if a failure of second stage regulators sends the wrong thing, a hypoxic delivery could occur) 3. Downstream leaks. (If a leak occurs beyond the flowmeters, oxygen could escape, causing a hypoxic delivery. The only thing to catch it would be the oxygen analyzer) (a negative pressure test will help detect this). 4. Inert gas administration. (Only oxygen and nitrous are linked, so if a 3rd gas is present you could potentially drown out the other gases with it. In a mulitgas system like this an oxygen analyzer is a mandatory piece of equipment) 5. Dilution of inhaled gases by volatile anesthetics. (anesthetic is added downstream to the flowmeter and proportioning system, especially if you are using a less potent anesthetic agent that requires higher flow to maintain a concentration).
70
Q

Which part of the anesthesia machine allows communication between the high pressure system and the low pressure system?

A

The oxygen flush valve.

71
Q

Activation of the oxygen flush valve delivers:

A

35-75 lpm of 100% O2

72
Q

In lab, Brooke said she got ‘pimped’ and asked what the range of available tank sizes are. What are they?

A

Tanks can be size AA-M. Tanks size A are the small ones, like people on home O2 carry around. In practice we typically see E or H size cylinders.

Fall 2013 Anesthesia Concepts (8 decks)

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