Anesthesia machine and vaporizers

Question 1

A more modern and correct name for an anesthesia machine is an?

Answer 1

Anesthesia delivery system

Question 2

Leaving out the safety features and monitors, the anesthesia machine is divided into three sections:

Answer 2

1) Gas delivery system
2) Breathing system
3) Scavenger system

Question 3

What gases are ordinarily available on all anesthesia machines and what are their sources?

Answer 3

1) O2
2) Nitrous oxide (N2O)
3) Air, Helium, Heliox, CO2, nitrogen

Question 4

What is a regulator?

Answer 4

Oxygen and air in the E-cylinders is pressurized up to approximately 2200 psig, but the anesthesia machine needs to work with gas at an initial pressure of about 50 psig, slightly less than the pressure of the gas from the wall supply. A regulator performs this function.

Question 5

Pressures

1) Wall gas
2) Tank

Answer 5

1) 55 psig
2) 45 psig
The anesthesia machine preferentially chooses the source with the highest pressure.

Question 6

A full green E-cylinder of O2

1) Pressure
2) Volume

Answer 6

1) 2000 psi

2) 625 L

Question 7

Room temperature N2O condenses into a

liquid at ___ psi?

Answer 7

747 psi

Question 8

E-cylinders of N2O contain the equivalent of about ____ L of gas when full, whereas E-cylinders of O2 and air hold only about ____ L

Answer 8

1600 L

600 L

Question 9

The pressure of a filled cylinder of O2 and air is?

Answer 9

2200 psi

Question 10

All WALL-SUPPLY GAS CONNECTORS are keyed so only the O2 supply hose can be plugged into the O2 connector on the wall, the N2O hose into the N2O outlet, and so on. This is known as?

Answer 10

Diameter-Index-Safety-System (DISS)

Question 11

The gas cylinders are keyed using a ______, so

that only the correct TANK can be attached to the corresponding YOLK on the anesthesia machine

Answer 11

Pin-Index-Safety-System

Question 12

STUDY

Answer 12

O2 flow knob is distinctively FLUTED. Knobs for other gases are KNURLED.

Question 13

Gas knob colors (US)
O2
Air
N2O

Answer 13

O2 (green)
Air (yellow)
N2O (blue)

Question 14

There are two flowmeters for each gas on an anesthesia machine.

Answer 14

Two flowmeters are used to increase the range of flows over which an accurate measurement can be obtained. The flow tubes in anesthesia machines are always placed in series so all the gas flows sequentially through both tubes. To measure flows accurately in the ranges used for low flow or even closed-circuit anesthesia (200 to 1000 ml/min), two flow tubes are essential.

Question 15

Flow tubes are also known as?

Answer 15

Thorpe tubes

Question 16

Why are the flowmeters for air, O2, and N2O arranged in a specific order?

In the United States the O2 flowmeter must always be on what position?

Answer 16

In the United States the O2 flowmeter must always be on the RIGHT, closest to the point of egress into the common gas manifold, just PROXIMAL TO THE ANESTHESIA VAPORIZER. With the O2 flowmeter in that position, most leaks will tend to selectively lose gases other than O2.

Question 17

the best way to detect a hypoxic gas mixture is through use of an?

Answer 17

Oxygen analyzer

Question 18

Is designed to cut off the flow of all gases except O2 when the O2 pressure falls below a set value.

Answer 18

Fail-safe valve

Question 19

The fail-safe valve device is designed to cut off the flow of all gases except O2 when the O2 pressure falls below a set value, usually a about ___ psig?

Answer 19

25

Question 20

How long can you continue to deliver O2 when the wall supply fails?

Answer 20

The E-cylinders that supply O2 to most anesthesia machines hold 600 L when full. If the ventilator is not in use, with a flow of O2 of 2 L/min, there is approximately
300 minutes (or 5 hours) of O2 available. If the ventilator is in use, the additional gas required for this purpose is roughly equal to the ventilator minute volume.

Question 21

This vaporizer condition means the vaporizer has mechanisms for adjusting the output to compensate for temperature.

Answer 21

Temperature compensation

Question 22

What is a pumping effect?

Answer 22

Positive pressure can be transmitted back into the vaporizer during ventilation of the patient. The positive pressure can briefly cause gas to reverse flow within the vaporizer, allowing gas to periodically reenter the vaporizing chamber. The result of the pumping effect is increased vaporizer output beyond that indicated on the concentration dial.

Question 23

STUDY

Answer 23

Remember that partial pressure of the vapor, and not the concentration in volume percent, is the important factor in depth of anesthesia.