Anesthesia Equipment Engineering

The daily pre-anesthesia machine check - a leak test plus O2 sensor calibration, per facility protocol, typically following a checklist derived from ASA guidance - is the single most important routine on this equipment. A machine that fails it does not get used, full stop, regardless of case-schedule pressure, because the failure modes this check catches (a circuit leak, a miscalibrated O2 sensor) are exactly the ones that can silently under-deliver oxygen or anesthetic agent during a case.

Vaporizers: agent-specific by design

Vaporizers are agent-specific by design - a Selectatec-type manifold physically keying to one agent exists specifically to prevent an incompatible agent from being loaded onto a vaporizer calibrated for a different one, and that interlock should never be defeated for convenience. Vaporizer output calibration drifts slowly with bellows and O-ring wear; a machine reporting the correct set concentration but an unexpected clinical effect is a vaporizer-calibration suspicion, not just an operator question, and it's verified with a dedicated agent analyzer/refractometer against the dial setting across multiple concentration points.

CO2 absorbent

CO2 absorbent exhaustion is a common, easily-overlooked cause of symptoms that look unrelated at first - rising inspired CO2 and patient tachycardia can both stem from a spent absorbent canister rather than a ventilation-delivery problem. Check absorbent color-change indication and canister age before deeper troubleshooting; most modern absorbents (low-VOC formulations replacing older soda-lime variants in many facilities) still rely on a visible color-change mechanism as the practical field indicator of remaining capacity.

Scavenging (WAGD)

Scavenging connections should be verified at every PM; a disconnected or occluded scavenging line is both a safety and an occupational-exposure issue, since waste anesthetic gas that isn't properly evacuated accumulates in the OR air rather than being routed out of the building. This ties directly back to the medical-gas infrastructure covered in Chapter 12 - WAGD is one of the piped gas systems governed by NFPA 99 alongside O2, medical air, and vacuum.

Breathing circuit inspection

Reusable breathing hoses and the bag/bellows assembly should be inspected for cracking, perforation, and connector wear at every service - a small leak in a breathing hose produces the same clinical symptom set as a leak-test failure elsewhere in the machine, so a hose-level visual inspection belongs early in the troubleshooting sequence, not as an afterthought.