Final Exam Review Flashcards
What standard is relevant to the AGM machine?
Standard 6
When should a gas machine check be performed?
Complete every day, without fail
abbreviated check between each anesthetic
Which organization is responsible for minimum performance and safety requirements used in design of AGMs for human use to enhance patient/operator safety?
American Society for Testing & Materials
The critical temperature of oxygen is
-118 degrees Celsius
1 L liquid O2 is equal to _______ L of O2 gas
860
The intermediate pressure system includes:
Pipeline source at 50 psi hospital source to wall outlets connecting supply hoses filters and check valves pressure gauges
The high pressure system includes:
pressure regulator, E cylinder or H cylinder, Hanger yoke, filter and check valves, pressure gauge
Concerns & issues with the pipeline supply include:
+/- pressure (50 psi)
cross-connection of supply pipelines
contamination- particulate, bacterial, water
leaks
Describe the key index safety system.
Connects gas hose to the wall outlet
uniquely key connect for each gas
Describe the diameter index safety system.
Connects host to machine
Each fitting has a different diameter nd internal key unique for each gas
Floating valves work by
opening and closes with pressure
moves in direction gas flow pushes it
“check valve”= interface between pipeline and AGM
unidirectional valves in circle system
The ball and spring valve is
the flush valve, all or none, you supply the energy
The diaphragm valve is the
pressure reducing valve; 1st and 2nd stage regulators
The Bourdon Tube pressure gauge measures
high pressures (cylinder pressures) relative to atmospheric pressure
The hanger yoke is used to
connect the cylinder to the AGM
ensures a gas-tight seal
Describe the PISS.
there are holes in cylinder valve that fit two pins in the yoke pins in numbered positions Air: 1, 5 oxygen: 2, 5 Nitrous oxide: 3, 5
Safety relief devices that prevent rupture of the cylinder include:
frangible copper disc
spring-loaded valve
Fusible plug (Wood’s metal)- Bismuth, lead, tin, and cadmium
Cylinder construction is overseen by
the department of transportation
Cylinders are made of
steel & meet certain chemical/physical requirements
walls are 3/8th inch thick
tested at 1.66 times their service pressure
The United States Pharmacopoeia
sets standards for potency/purity of medical gases
The National Fire protection association is responsible for
location, construction, and installation of bulk systems
Safe handling of cylinders includes:
never stand a cylinder upright without support; lay it on its side
never leave empty cylinders on the machine
never leave the plastic cover on the port while installing the cylinder
never rely on a cylinder’s color for ID of its contents
Never oil valves
Never remove a cylinder from a yoke without filling with space with a yoke plug
The critical temperature of nitrous oxide is
36.5 degrees celsius
745 psig until liquid is depleted
O2 tanks must have
> 1000 psi
cylinder supply is for emergencies only
The diaphragm-type valve is
regulator or pressure reducing device
reduces the high, variable pressure to a lower constant pressure
maintains constant gas flow without changing the supply pressure- tension springs and diaphragm supply constant force
List the specs regarding the oxygen gas cylinder
oxygen, green, 1900 PSI, 660 L, pin position 2,5
List the specs regarding the nitrous oxide gas cylinder
nitrous oxide, blue, 745 PSI, 1590 L, 3 & 5
List the specs regarding the air gas cylinder
yellow, 1900 PSI, 625 L, 1 & 5
What law can be utilized to determine how much time is left in the gas cylinder?
Boyle’s law
P1 x V1= P2 X V2
The low pressure system is
distal to the flowmeter needle valve and includes:
flowmeter tubes, vaporizers, check valves, & common gas outlet
The high pressure system is
exposed to cylinder pressure and includes: hanger yoke; yoke block with check valves; cylinder pressure gauge and cylinder pressure regulators
The intermediate pressure is
exposed to pipeline pressure ~50 PSI
it includes: pipeline, check valves, pressure gauges, ventilator power inlet, oxygen pressure-failure devices, flowmeter valve; oxygen second stage regulator & the flush valve
Describe the “Fail-safe” design system.
Designed to prevent unintentional delivery of a hypoxic mixture to the flow control valves
can still occur if the pipeline is switched
Describe the position of the flowmeters.
O2 is positioned closest to the common gas outlet.
Leak in any other flowmeter tube least likely to affect O2 supply to the patient
Protects against accidental decrease in delivered O2 (hypoxic mixture)
when O2 is mounted downstream, there is less chance of a hypoxic mixture
The minimum O2 flow is
200-300 mL/min.
The flowmeters are
color and touch coded have balls (read in the middle) or bobbins (read at the top) known as thorpe tubes or variable orifice tubes diameter is gas specific and not interchangeable among gases
Describe the proportioning system.
hypoxic guard system
links N2O & O2 in a 3:1 ratio to ensure appropriate mixture
also known as the pneumatic link or link 25
These can result in a hypoxic mixture:
wrong supply of gas in oxygen pipeline or cylinder
defective pneumatics or mechanics
leaks downstream of flow control valves on flowmeters
use of a third inert gas (helium)
Vaporizers are used to
blend fresh gases from flowmeters with sufficient vapor to form clinically useful concentration
The vapor pressure increases with
temperature
The vapor pressure of isoflurane is
239 mmHg
The vapor pressure of halothane is
243 mmHg
The vapor pressure of sevoflurane is
170 mmHg
The vapor pressure of desflurane is
669 mmHg
Modern vaporizers are
temperature compensated- ensures steady vaporizer output over wide range of ambient temperatures
agent specific- only calibrated for a single agent
out of circuit- outside the breathing circuit
Variable bypass vaporizers have
concentration dials that split the stream into bypass gas and carrier gas
Factors that influence output include:
flow rate- rates <250 mL or >15 mL/min result in agent output that is
The bimetallic strip
decreases flow through the vaporizing chamber when temperature increases
Safety with vaporizers:
key index safety system to fill
don’t tip
don’t overfill- causes liquid agent to enter bypass chamber
leaks- loose filler cap, malposition
simultaneous inhaled agent administration- removing center vaporizer can defeat interlock system
The vaporizer interlock system ensures that
only one vaporizer can be turned on at a time
If a higher VP agent is placed in a vaporizer of a lower VP aget,
concentration of agent delivered will be higher than dialed setting and vice versa
The Tec 6 vaporizer is a
gas/vapor blender; not variable bypass
has to be plugged in to be usable- battery ONLY powers alarms, not vaporizer
yellow light- warm up, low agent, alarm battery low
no output- red- vaporizer can’t add agent vapor to gas flow due to lack of agent, tilting, or malfunction
operational (green)- vaporizer functional
Describe the oxygen flush valve.
Ball & spring valve
standard delivery= 25-75 L/min @ 50 psi
proceeds directly from gas supply (pipeline or E-cylinder)
can cause barotrauma or awareness b/c no gas is delivered when this is used
5 tasks (direction) of oxygen:
proceeds through flowmeter supplies O2 flush valve activates fail-safe mechanism activates low oxygen pressure alarm drives the ventilator
Describe the open circuit
No reservoir bag, no rebreathing, example is open drop ether
Describe the semi-open circuit
Reservoir bag, no rebreathing, example is nonrebreathing circuit or circle at high FGF
Describe the semi-closed circuit
Reservoir bag, yes partial rebreathing, circle at low FGF
Describe the closed circuit
Reservoir bag, complete rebreathing, circle with APL valve closed
What is the APL valve?
it is the adjustable pressure limiting valve or pop-off valve
used to regulate the pressure in the circuit during normal ventilation
it is bypassed in mechanical ventilation
The most dead space exists in the
Y piece and the patient
When exhausted soda lime is _____ and baralyme is ______
purple; blue-gray
they are colorless when fresh!
What is the granule size of the carbon dioxide absorber?
4 to 8 mesh
compromise between resistance to airflow and surface area for absorptive capacity
Describe the Mapleson A circuit.
FGF, tubing, exp. valve, patient
Describe the Mapleson B circuit.
bag, tubing, FGF, exp valve, patient
Describe the Mapleson C circuit.
same as B but has shorter expiratory limb
bag, tubing, FGF, exp. valve, patient
Describe the Mapleson D circuit.
opposite of Mapleson A
Exp. valve, tubing, FGF, patient
Describe the Mapleson E circuit.
Valveless and bagless- basically a T-piece
EASY because no exp valve or bag
Tubing, FGF, patient
Describe the Mapleson F circuit.
Adaption of the Mapleson D.
Exp. valve, bag, tubing, FGF, patient
The Bain circuit has
bag w/ overflow valve, FGF, corrugated tubing, and face mask
improved humidification, ease of gas scavenging
disadvantages include increased resistance, rebreathing due to unrecognized disconnect of inner tube
Describe the types of bellows
ascending- go up on expiration
descending- go down on expiration
Disposal systems can be
open- used only with active disposal systems (safer for the patient) or closed (safer for the OR staff)
