Anesthesia Machine Flashcards
Where does the high pressure system begin and end?
begins at the cylinder and ends at the cylinder regulators
Where does the intermediate pressure system begin and end?
begins at the pipeline and ends at the flowmeter valves.
Where does the low pressure system begin and end?
begins at the flowmeter tubes and ends at the common gas outlet
When you connect a bulb to the common gas outlet and create negative pressure what type of leak test are you performing?
Low pressure leak test (negative pressure test)
The low pressure leak test is testing from what point in the anesthesia machine to what other point?
from the flowmeter valves to the common gas outlet
(this includes the entire low pressure system and the flowmeter valves which are the end of the intermediate pressure system)
How do you perform a high pressure leak test?
closing the APL valve, pressurizing the circuit, and observing the airway pressure gauge (pressure should remain constant)
During a high pressure leak test if the machine does NOT have a check valve what parts of the machine are being assessed (tested)?
the breathing circuit and the entire low pressure system
During a high pressure leak test if the machine does have a check valve what parts of the machine are being assessed (tested)?
the breathing circuit and the low pressure system up to the check valve (which would only be the common gas outlet part of the low pressure system)
(it does NOT assess for a leak between the check valve and the rest of the low pressure system which would be the the vaporizers and flowmeter tubes)
What are the 4 possible components of the low pressure system?
flowmeter tubes
vaporizers
check valve (if present)
common gas outlet
During the high pressure test if the machine has a check valve then what parts are not being tested that are being tested if the check valve is not present?
with a check valve in place the high pressure test DOES NOT assess the vaporizers and flowmeter tubes because these are upstream from the check valve if it is present.
What does SPDD model stand for?
Supply
Processing
Delivery
Disposal
in the SPDD model the breathing circuit would be which part?
Delivery
in the SPDD model the pipeline to the back of the anesthesia machine or cylinders would be which part?
Supply
in the SPDD model the inside the machine up to the common gas outlet (vaporizers) would be which part?
Processing
in the SPDD model the scavenging system would be which part?
Disposal
Name the five tasks of oxygen?
- 02 pressure failure alarm
- 02 pressure failure device (failsafe)
- 02 flowmeter
- 02 flush valve
- Ventilator drive gas
What type of ventilator does not require a drive gas?
Piston driven
Which safety system is in place to prevent inadvertent misconnections of the gas cylinders?
PISS
Which safety system is in place to prevent inadvertent misconnections of the gas hoses?
DISS
What is the 02 pressure in the cylinder vs upon entry into the intermediate system?
02 cylinder pressure = 1900 psi
02 pressure in the intermediate system = 50 psi
What is one thing that can bypass the PISS system (that you should never do)
two washers between the hanger yoke assembly (there should only be one washer)
PISS configuration for air, oxygen, and Nitrous
air = 1,5 oxygen = 2,5 nitrous = 3,5
What is pipeline pressure vs intermediate system pressure?
They are about the same 45-50psi for the gas hoses and 50 psi in the intermediate system
When are the only times that cylinders should be turned on?
when checking them during the machine check or in the event of pipeline failure. (They should never be left in the on position when not in use)
What is the only way of determining a cylinders contents?
looking at the LABEL not the color
Standard US colors for air, oxygen, and nitrous?
air = yellow oxygen = green Nitrous = blue
WHO colors for air, oxygen and nitrous?
air = white and black oxygen = white Nitrous = blue
Air:
max pressure
max volume
pin configuration
max pressure= 1900 psi
max volume = 625 L
pin configuration = 1,3
Oxygen:
max pressure
max volume
pin configuration
max pressure= 1900 psi
max volume = 660 L
pin configuration = 2,5
Nitrous: max pressure max volume pin configuration Full weight Empty weight
max pressure = 1900 psi max volume = 660 L pin configuration = 3,5 full weight = 20.7 lb empty weight = 14.1 lb
Formula for minutes left before tank expires for oxygen or air?
- Tank capacity / full tank pressure = contents remaining / gauge pressure \
- contents remaining / flow rate = minutes left before tank expires
Oxygen exists as a gas inside the cylinder why and what is its critical temp?
oxygen exists as a gas inside the cylinder because it’s critical temperature is BELOW room temp. at -119 C
Does nitrous exist inside the cylinder as a gas or liquid and why?
N2O exists as a liquid (and a tiny bit as a gas) inside the cylinder because it’s critical temperature is ABOVE room temp at 36.5 C
When will the pressure gauge on nitrous start to decrease? How much nitrous is left?
The bourdon pressure gauge on nitrous will only decrease below 745 psi when ALL of the liquid nitrous is gone and only the gas remains.
This means the the cylinder is 3/4 EMPTY so approximately 400 L of Nitrous remains in the tank, thus change the cylinder anytime the psi falls below 745 psi
What is the most delicate part of the cylinder?
Cylinder valve
If you have an empty cylinder on the machine and you do not have a cylinder to replace what should you do?
insert the hanger yoke plug because if no cylinder is present and no yoke plug is present then in the event of the check valve failing- gas that should be going to the patient will exit the machine
What is the fire triad?
oxidizer
fuel
igniter
In the fire triad what are oxygen and nitrous?
oxidizers
What are the three examples of safety relief devices on cylinders?
fusible plug that melts at elevated temperatures
valve that opens at elevated pressures
frangible disk that ruptures under pressure
What is a fusible plug made of?
Wood’s metal : bismuth, lead, tin, and cadmium
BLT with Cheese
If the yoke retaining screw punctures the safety relief valve what may happen?
cause the cylinder to leak
What issue does oiling the cylinder valve cause?
increases the risk of fire because now you have fuel (oil) and an oxidizer (nitrous or oxygen) and now you only need a heat source to start a fire
How should you open a cylinder when checking it or putting it to use?
Slowly open the cylinder this is known as “CRACKING” and this allows for the flush valve outlet to clean of dust and debris
ASTM, who are they and what is their job?
American Society for Testing Materials (ASTM) sets standards for required components of the anesthesia machine
The standard document is called the STM F1850
DOT, who are they and what is their job?
United States Department of Transportation, sets the standards for compressed gas cylinders.
FDA, who are they and what is their job?
Food and Drug Administration, created in 1993 FDA Anesthesia Machine Pre-use checkout procedures
OSHA, who are they and what is their job?
Occupational Safety and Health Administration, sets the standards for acceptable occupational exposure to volatile anesthetics
How often must a cylinder be tested?
every five years unless it has a special permit which is denoted by a five pointed star and then it is good for ten years. The date of the last test must be clearly noted on the cylinder.
What pressure is a cylinder tested at?
1.66 x it’s service pressure (max psi it can hold)
The US DOT requires some information be on the cylinder label, this would include what kind of things?
Government agency (DOT) type of metal used to construct the cylinder maximum filling pressure serial number manufacturer owner date of last inspection
(it does not state that the gas type has to be listed… idk since you are supposed to check the label to know the gas, maybe that is not required by DOT)
If a leak develops distal to the flowmeters will the oxygen pressure failure device activate?
NO, the leak must be in the intermediate pressure system not the low pressure system
What is the main purpose of the oxygen pressure failure device?
What three specific instances will it alert you about?
monitor for and protect against low oxygen pressure in the anesthesia machine.
- depleted oxygen tank
- drop in pipeline pressure
- disconnected oxygen hose