Safety Features Flashcards
How long can high priority alarms be silenced?
2 minutes
High-priority pressure alarm
User limits exceeded, sensed continuous high pressure or negative pressure
Disconnect alarms
Low pressure, low exhaled volume or absence of CO2
What is breathing circuit pressure limited to?
125 cm H2O
Pressure for primary pipeline gas
50 psi
Flow meters safety
Single control for each gas, unique shape to oxygen, valve stops so you cannot over-rotate & damage flow meter, oxygen on right side of flow meter so a leak will not dilute oxygen, and an auxiliary oxygen flow meter
Common gas outlet shows what?
If you lose electricity can still see FGF by the float ball
Supply to anesthesia machine
Pipeline (DISS)- wall outlets, connecting valves/hoses, filters, check valves, pressure gauges OR Cylinder (PISS)- hanger yokes with yoke block (where cylinder hangs from), filters & check valves, pressure gauge & pressure regulators
Disposal of gases
Closed or open scavenger systems
Devices not reliant on electrical power
Spontaneous/manual assist ventilation, mechanical flowmeters, scavenging, variable bypass vaporizers (though do not count on this)
Devices which rely on electrical power
Mechanical ventilators, electronic monitors and display flowmeters, gas/vapor blenders (for Des..) or vaporizers with electronic controls (aladin)
Pneumatic high pressure cylinder pressure
1900-2200 psi
Pneumatic high pressure parts
Hanger Yoke - PISS
Gas Cylinders - (E)- Oxygen (1900-2200psi with 660L), Nitrous (745 psi 1600 L), Air (1800-1900 psi, 600L)
Cylinder Pressure Gauge- Electronic or bourdin
Cylinder Pressure Regulators- Decreases gas pressure & maintains constant pressure supply to intermediate, outlet pressure is lower than wall pressure to maintain preferential wall pressure supply if tank is left open)
Check Valves- prevent exit of gas from machine when no cylinder is present, prevents transfilling of gas from one cylinder to another
Pneumatic intermediate pressure cylinder pressure
37-55 psi
Pneumatic intermediate pressure parts
Master Switch- when off, pressure in intermediate system falls to zero
Pipeline Inlet Connections- DISS, check valve at inlet (prevents reverse gas flow from machine to pipeline)
Pipeline Pressure Gauges- Should read 50-55 psi
Oxygen Pressure Failure Device- Loss of oxygen pressure results in cessation of N2O gas flow (ONLY SENSES PRESSURE- not a fail safe to prevent hypoxic mixture if pipeline crossover happens)
Oxygen Supply Failure Alarm
Gas Selector Switch
Second Stage Pressure Regulator (Not on all machines, reduces pressure from pipeline to flowmeters)
Oxygen Flush- 35-37 L/min to common gas outlet
Flow Adjustment Controls
Alternate Oxygen Control- Electronic flowmeter backup in case of electrical failure
Pneumatic low pressure cylinder pressure
Pneumatic low pressure parts
Flowmeters- electronic or thorpe (low flow-laminar, based on viscosity.. Poiseuille’s law, high flow- turbulent, based on density.. Graham’s law)
Hypoxia Prevention Safety Devices- O2-N2O Link
Unidirection Check Valve- Located between vaporizers & common gas outlet upstream of where oxygen flush flow joins FGF, prevents backpressure to vaporizers & flowmeters from positive pressure in breathing circuit, negative pressure leak test checks function of valve
Pressure Relief Device- Near common gas outlet to protect machine from high pressure
Common Gas Outlet- May be internal or external
Auxiliary Oxygen Flowmeter
What should you do if you lose pipeline gas?
Open emergency oxygen cylinder fully, disconnect the wall pipeline connection, ventilate by hand & turn ventilator off
Why is oxygen always closest to the common gas outlet?
To prevent oxygen being diluted by other gases and creating a hypoxic mixture
Parts of the circle system
Y piece/port, corrugated tubing (adults are coaxial, peds have outer and inner), expiratory limb, expiratory valve, bag/vent selector switch- APL valve- Reservoir bag- Ventilator, CO2 absorber, fresh gas inlet, inspiratory valve, inspiratory limb
Advantages of circle system
Stable inspired concentrations, conserve moisture/heat, prevention of OR pollution, low gas flows
Purpose of reservoir bag
Reservoir, manual ventilation, visual/tactile monitor, protects from excess pressure
Sources of pollution from anesthetic
Failure to turn off agent at end of case, mask fit, flushing circuit, filling vaporizers, uncuffed ETT, leaks, poorly functioning scavenging system
CO2 absorber
Eliminates CO2, is required for closed & semi-cosed circuits
Interactions with absorbents
Trichloroethylene causes cerebral neurotoxin, Sevoflurane causes Compound A with baralyme, Carbon Monoxide from Des with dryness and/or baralyme
Chemical equation of CO2 absorbent
CO2 + H2O H2CO3 –> H2CO3 + 2NAOH (or KOH) Na2CO3 (or K2CO3) + 2 H2O + Heat –> Na2CO3 (or K2CO3) + Ca(OH)2 ,–> CaCO3 + 2NaOH (or KOH)
Normal working pressure of most anesthesia machines
50 psi
Oxygen supply & regulation pressure
2000 psi, regulated to 45-50 psi after entry
Oxygen flush valve l/min
35-75
Which float meters read at top and which read at middle?
Top: non-rotating, plumb-bob, skirted, “H”. Middle: ball
