Breathing Circuits
Anesthesia Workstation Mechanics
Other stuff
Bellows and Piston ventilators and stuff
Trouble shooting & Safety
100
This classic circuit uses a reservoir bag and unidirectional valves and is standard in modern anesthesia machines.
What is a circle system?
100
This safety feature ensures oxygen is the last gas to fail if pipeline pressure drops.
Oxygen pressure‑sensor shutoff (fail‑safe) valve.
The fail‑safe valve reduces or stops flow of other gases when O₂ pressure falls, preventing delivery of a hypoxic mixture.
100
What does APL valve mean?
adjustable pressure‑limiting valve
100
In a traditional bellows ventilator, this driving gas compartment surrounds the bellows and compresses it during inspiration.
What is the driving gas chamber? 
100
A sudden drop in bellows height or piston movement most commonly indicates this problem.
What is a circuit disconnection?
200
This Mapleson circuit is most efficient for controlled ventilation.
What is Mapleson D?
Mapleson D minimizes rebreathing during controlled ventilation because fresh gas is delivered near the patient and exhaled gas is efficiently vented.
200
In the U.S., this color identifies nitrous oxide cylinders.
Blue
200
What is the positive‑pressure relief valve?
It opens to vent excess pressure, often producing a noticeable hiss.
internal, automatic pressure‑relief valves inside the ventilator and breathing system.
Are not user‑adjustable.
Function during mechanical ventilation, when the APL valve is bypassed.
200
This is the first maneuver you should perform when the ventilator alarms for ‘low pressure’ immediately after turning the patient lateral.
What is checking for a disconnected circuit?
200
In a circle system, this component must be functional to prevent rebreathing of CO₂.
What is the CO₂ absorber?
300
This Mapleson circuit is most efficient for spontaneous ventilation.
What is Mapleson A?
300
This pressure (in psi) indicates a full oxygen E‑cylinder.
What is 1900–2200 psi?
300
Increasing circuit compliance has this effect on delivered tidal volume during volume‑controlled ventilation.
Decreases delivered tidal volume to the patient.
More volume is lost to circuit expansion before reaching the patient.
300
This is the most likely cause when FiO₂ drops despite increasing the oxygen flowmeter.
What is a pipeline crossover or supply failure?
300
Even when the anesthesia machine is powered off, this valve still functions because it depends on pipeline pressure, not electricity
What is the oxygen flush valve?
400
A stuck closed expiratory valve in a circle system most likely leads to this dangerous physiologic consequence.
What is breath stacking or barotrauma?
If the expiratory valve fails to open, the patient cannot exhale properly, causing rising airway pressures and potential lung injury.
400
Where does oxygen enter the system when the flush valve is pressed?
It enters the low‑pressure circuit downstream of the vaporizers
400
This malfunction is likely when the breathing bag distends even with the APL valve open.
What is a scavenging obstruction?
If waste gas cannot exit, pressure backs up into the breathing circuit.
400
This bellows type continues to move even when a large circuit leak is present, making it less reliable for detecting disconnections.
What is a descending (hanging) bellows?
400
A stuck open APL valve during manual ventilation causes this dangerous issue.
What is inability to generate positive pressure?
500
In pediatric circuits, this factor increases more rapidly with added tubing length, making circuit design especially important.
What is dead space?
Added dead space disproportionately affects small patients because their tidal volumes are small; even small increases can cause CO₂ retention.
500
This is the only mandatory high‑priority alarm required on all anesthesia workstations by international standards.
Low oxygen concentration (hypoxic mixture) alarm.
The MAN requires continuous oxygen analyzer with a high‑priority alarm for low O₂ concentration because it is the most critical patient safety parameter.
500
Modern anesthesia ventilators use this mechanism to deliver tidal volume accurately despite fresh gas flow changes.
Fresh gas decoupling (or fresh gas compensation, depending on model).
Decoupling diverts FGF away from the breathing circuit during inspiration, preventing
500
DOUBLE JEOPARTYYYYYY
What do the Greek words an- and aisthesis mean together?
Without sensation
500
“=This is the most common cause of excessive pressure buildup in a scavenging system.
What is an obstruction in the scavenging tubing or interface?
Blocked outflow prevents waste gas from escaping, causing pressure to rise in the breathing circuit.