Ventilation & Respiratory Engineering
ISO 80601-2-12, the blower/exhalation-valve/O2-sensor trio, circuit-to-patient matching, and alarm-priority logic specific to ventilators.
Critical care ventilators are governed by ISO 80601-2-12, the particular standard layered on top of general IEC 60601-1 requirements for basic safety and essential performance. Ventilators sit at the top of almost every facility's equipment risk hierarchy because the consequence of an undetected failure is immediate and severe - there is no tolerance-for-drift window the way there might be for, say, a diagnostic display.
The three subsystems behind most real service calls
The blower/turbine - bearing wear produces an audible whine well before outright failure, which makes it one of the few faults you can catch by ear during a routine walk-through, before it ever generates a formal complaint. The exhalation valve assembly - diaphragm fatigue after high cycle counts shows up as erratic expiratory volume readings and auto-PEEP alarms, and it's the single most-replaced component on most ventilator platforms. The O2 sensor - almost always a galvanic cell with a genuinely finite chemical life (roughly 12 months in air), not a fault to keep chasing electrically; a drifting FiO2 reading on an otherwise-healthy machine is very often just the sensor reaching end of life on schedule.
Verification with a gas flow analyzer
A gas flow analyzer with a test lung is the standard tool for verifying delivered tidal volume, pressure, and flow accuracy against the ventilator's own displayed values - self-test alone doesn't confirm clinical accuracy, only internal consistency. Test across the clinically-relevant range (not just one operating point), since a ventilator can be accurate at one tidal volume/rate combination and drift at another.
Circuit-to-patient matching
Circuit matching matters more here than almost anywhere else on this site. Adult, pediatric, and neonatal circuits have meaningfully different compliance and resistance characteristics, and using the wrong one doesn't just look wrong - it invalidates the volumes and pressures the ventilator believes it's delivering, since the machine calculates delivered volume in part from circuit compliance assumptions built into its own compensation algorithm.
Alarm priority
Ventilator alarms carry a formal priority hierarchy - high, medium, and low - and a disconnect or apnea alarm sits at the highest priority for good reason: it represents loss of ventilation, the single fastest path to patient harm on this equipment class. When testing alarm function during PM, confirm the alarm actually escalates in urgency (visual and audible intensity) appropriately by priority level, not just that it fires at all.