Mod 1 - Anesthesia Machine 8/15 Flashcards
Quiz 2
An E tank is considered a (low/intermediate/high) pressure zone with a PSI of ?.
high
~2000
How many liters of O2 is in a full tank?
~660 L
In the US, what color is the O2 tank?
Anywhere other than the US, what color is the O2 tank?
US = green
international = white
If you want to use an O2 tank to keep a patient under general anesthesia for MRI imaging, what must you ensure specifically?
The O2 tank must be MRI compatible (tank is made of a non-magnetic alloy)
why does an O2 tank have a pressure relief valve?
safety!
- 1-time use
- will crack to release pressure within tank so it doesn’t explode
how does a Bourdon pressure gauge work? (4)
- high pressure gas fills the small hollow tube within the gauge
- tube deforms, or straightens
- mechanical dial transmits the deformation of the tube
- you read the dial
higher pressure = higher number on dial (& vice versa)
A pressure-reducing valve is also called a ?. What is its purpose?
regulator
it reduces high pressure gases to intermediate pressure (~2000 PSI to ~50 PSI)
T/F - you can use the O2 flush valve while a patient is hooked up to the anesthesia machine.
FALSE - NEVER use O2 flush when a patient is hooked up, esp. if on a non-rebreathing system!
What does the O2 flush valve do?
directs high unmetered flow directly to the common gas outlet
What is the purpose of the O2 flush valve?
to flush the entire system of anesthetic gas
What would happen if you used the O2 flush valve while the patient was still connected to the system?
could cause barotrauma to the patient
what does a flowmeter do?
controls rate of gas delivery to a low pressure zone
where should you read if a flowmeter has a bobbin (ball) to measure gas output?
a float?
bobbin = middle
float = top
why is the O2 flowmeter knob larger and textured?
for safety! - even if you can’t see it (in the event of a power outage) you know it’s O2
T/F - vaporizers are agent specific because different anesthetic agents require different compensations for temperatures, flows, and pressures.
True
what is a vaporizer?
machine that reduces liquid anesthetic to a vapor for use as inhalant
what is the purpose of a wick within a vaporizer?
it absorbs liquid anesthetic, which greatly increases the surface area of the liquid, causing more anesthetic vapor to be picked up by fresh gas (O2)
Unidirectional valves are located in the (low/intermediate/high) pressure zone.
low
what prevents backflow of gases in the inspiratory & expiratory unidirectional valves?
thin discs
the inspiratory valve is (open/closed) during exhalation and (open/closed) during inhalation. The opposite is true for the expiratory valve.
closed
open
If the patient takes a large negative pressure breath and there is not enough gases within the system to provide for the breath, what allows for room air to enter to supplement the breath?
negative pressure valve
what is the purpose of the reservoir bag? (2)
- allows for assisted ventilation
- gas reserve volume
How do you determine the correct size of the reservoir bag?
bag size = patient weight (kg) * 66
(size of bag should be ~6x the tidal volume)
T/F - if a patient is in between reservoir bag sizes, always round down.
FALSE - always round UP!
What are 3 areas of compliance within the anesthesia circuit?
- reservoir bag
- corrugated tubing of F or Y circuit
- patient
What does APL (valve) stand for?
What is its purpose in the anesthesia system?
APL = adjustable pressure-limiting valve
allows excess gas to escape from the patient circuit
What happens if the APL valve is left closed while a patient is using the anesthesia system?
excessive pressure can build up and cause barotrauma
What is the occlusion valve?
AKA cheater valve
can be used to give a breath to the patient by pressing the valve (same as if closing the APL valve)
- faster to use than APL valve
what is the difference between the active scavenging system and the passive scavenging system?
active = waste gases are actively piped to the atmosphere via wall connection
passive = flow rate + patient breathing
- can be connected to F/air canister or just flow out the window
F/air canisters are measured by ? to determine when they need to be switched out.
weight
the small granules within the CO2 absorber canister increase the ?.
surface area
What is the highest resistance area in the anesthesia circuit that a patient has to work against when breathing?
CO2 absorber canister
What volume should the CO2 absorber canisters be?
2x the tidal volume at least
what is the primary byproduct of the CO2 absorber canister?
calcium carbonate
when CO2 is absorbed, what color do the granules change?
ethyl violet
T/F - the ethyl violet color lasts forever, so you always know when to change the CO2 absorber canister.
False - track the time! Each canister can handle 6-8hrs of anesthesia.
sometimes during transport, the CO2 absorber granules settle to the bottom and can cause ? of gases through the center of the canister. This makes the canister appear (fresh/used) when it isn’t.
channeling
fresh
what measures the pressure in the anesthesia circuit?
manometer (do doo do-do do)
what is the max peak inspiratory pressure you should go to in a normal or healthy patient?
20 cmH2O
the circle system is a (non-rebreathing/rebreathing) system.
rebreathing
what is the name of the non-rebreathing systems?
which one is the only one we use at MSU?
Mapleson
Mapleson D, Bain modification, Bain block, Bain system
how does a non-rebreathing system differ from a rebreathing system? (3)
- no CO2 canisters - it causes the most resistance & small patients can’t overcome it when breathing
- no unidirectional valves - gas is inhaled thru center tube and exhaled around center tube
- high fresh gas flow (FGF) rates - this is what pushes the exhaled gases out (more wasteful b/c no rebreathing!)
what are the gas flow rates of:
1. rebreathing system
2. non-rebreathing system
- 4-6 mL/kg/min
- 200-300 mL/kg/min
what is the purpose of a positive end expiratory pressure (PEEP) valve?
allows air pressure within the circuit to not drop BELOW the indicated value on the valve
what is the purpose of an anti-positive end expiratory pressure (anti-PEEP) valve?
prevents air pressure within the circuit from building up BEYOND the indicated value on the valve
T/F - a PEEP must be attached to the inspiratory valve to work, however, an anti-PEEP can be placed anywhere in the circuit to work.
False - a PEEP must be attached to the EXPIRATORY valve
The pressure gauge on your E tank says 500 PSI. How many liters of O2 do you have, and how many hours will it last if your flow rate is 1 L/min?
tank PSI x 0.3 = vol (L)
500 x 0.3 = 150 L
150 L x min/1 L x 1 hr/60 min = 2.5 hr
What volume should your reservoir bag be if your patient weighs 22 kg?
patient weight (kg) x 66 = bag size
22 kg x 66 = 1452 mL
(always round up!)
bag size = 2 L
