Essentia / Devices / Anaesthesia Machine

Device Lab 11

Anaesthesia Machine

Flow is set through sensors and valves and shown on a screen. The hypoxic guard is a limit inside a controller, the ventilator is part of the same machine, and almost nothing about the gas path is visible from the front.

Also called: Anesthesia Machine, Anaesthetic Machine, Anesthesia Workstation. Arabic: جهاز التخدير. Device Lab 11 of 69 in BMEssentia Medical City, 2 configurations.

Overview: the configurations

How it works: the main parts

What each part does, from the Anaesthesia Machine lessons in the 3D Device Lab.

Pipeline inlets and cylinder yokes

Two ways in for every gas, at the back of the machine. A hose to a pipeline that comes from somewhere else in the building, and a yoke for a cylinder that hangs on the machine itself.

Regulators and pressure gauges

A row of round faces below the controls, and behind them the parts that turn a cylinder at a pressure that would destroy the machine into a supply it can use. The gauges are the only place on the machine that tells you anything about the world upstream of it.

Vaporisers and manifold

One or two upright blocks on a shelf at the top right of the machine, each holding a litre or so of a volatile liquid. Turn a dial and the machine adds a measured concentration of that agent’s vapour to the gas leaving it.

Oxygen flush

A single recessed button, usually green, that delivers oxygen straight to the common gas outlet at a flow nothing else on the machine can produce. It bypasses the flowmeters and it bypasses the vaporisers entirely.

Common gas outlet

One fitting, usually behind or beside the breathing system, where everything the machine has done arrives. Every gas, every flow setting and every turn of a vaporiser dial ends up here as a single stream, and from here it is the breathing system’s problem.

Absorber head and ports

A machined metal block on the left of the machine with everything screwed into it: the two ports the patient’s hoses leave from, the bag, the valve that sets pressure, and the canister hanging underneath. It is the junction where the circle becomes a circle.

Carbon dioxide absorbent canister

A clear jar of pale granules under the absorber head. It is a chemical reactor with no power, no controls and no output signal, and it is the only thing standing between a patient and the carbon dioxide they breathed out a minute ago.

Inspiratory and expiratory valves

Two ports on the front of the absorber head with a light disc sitting on a seat under a transparent dome. They are the only things in the whole breathing system that make it a circle rather than a corridor, and they do it with no power and almost no moving mass.

Common faults and what to check

Most reported device problems (FDA MAUDE)

Raw counts of adverse event reports for this device type (FDA product code BSZ), all years. Not adjusted for the number of units in use, so they show what gets reported, not failure rates. Report text is never copied.

Standards engineers test against

Recent FDA recalls

From the FDA recall database (openFDA), newest first, imported 2026-10-22. 177 recalls on record for this device type. Recall text is the FDA's public text; each recall links to the official record.

Learn it, see it in 3D, ask about it

• Ask Essentia about the Anaesthesia Machine: answers from named sources, with the device open in its 3D Device Lab beside the answer.
• The Anaesthesia Machine on the BMEssentia Platform: the Device Library course, 13 sections from physics to maintenance.
• BMEssentia Medical City: Device Lab 11, the Anaesthesia Machine fully assembled in 3D, with lab tasks and the simulations.

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