Anesthesia machine Flashcards
pressure regulators
reduce cylinder gas to 45-47 psi before enters the flow valves
– gas from both the cylinder and the wall supply encounters a check valve that selects the gas source with the highest pressure for use by the machine, under normal circumstances the wall supply is used preferentially.
oxygen supply failure protection device
oxygen supply can pass directly to its flow control valve
‘fail safe valve’
designed to cut off the flow of all gases except 02 when the 02 pressure falls below a set value (usually 25 psig)
flow valves
each gas passes through flow control valves and is measured by flowmeters
gas lines proximal to flow valves are higher pressure circuit where as lines distal are low pressure circuit
positioning of oxygen flow meter
always furthest to the right and downstream
prevents hypoxia if leakage from flow meter upstream
oxygen analyzer
measures oxygen partial pressure in gas (located in isp or exp limb, not in fresh gas line)
3 main parts of anesthesia machine
- gas delivery system that supplies defined mixture of gases
- the patient breathing system (breathing circuit, absorber, ventilator, gas pressure, and flow monitors)
- scavange system
wall gas pressures are typically?
55 psig
tank gas pressures are typically?
45 psig
A full green E cyclinder has a pressure of? and how many L of gas?
oxygen. 2200 psig. 660L
why does pressure fall proportionally to volume with oxygen and air cylinders?
they are compressed gases and cannot be compressed liquids in room temp. Their critical temperature (temp at which a gas can be compressed to a liquid) is exceeded.
how many L are in a full cylinder of N20?
1600L (@ 747 psig)
describe the DISS system
diameter index safety system - all wall supply gas connectors are keyed so only the o2 supply hose can be plugged into the o2 connector on the wall
describe the PISS system
pin index safety system - the gas cylinders are key so only the correct tank can be attached to the corresponding yolk on the anesthesia machine.
