Anesthesia Machine

Overview

An anesthesia machine, or anesthesia workstation, delivers a precisely metered mixture of medical gases and volatile anesthetic agent to a patient under general anesthesia and ventilates the lungs through a closed rebreathing circuit. It draws oxygen, nitrous oxide, and medical air from the hospital pipeline (with backup cylinders), blends them to a chosen flow and oxygen fraction, adds anesthetic vapor, and recirculates exhaled gas after stripping carbon dioxide.

Fresh gas enters through the Gas Supply Module, where pipeline and cylinder inlets are pressure-regulated and protected by a hypoxic guard that mechanically links nitrous oxide to oxygen so the delivered mixture can never fall below roughly 25% oxygen. The Gas Mixer & Flowmeters meters each gas through flow-control valves and rotameter tubes into a common manifold, and the Agent Vaporizer saturates a controlled fraction of the carrier flow with liquid agent. The blended gas passes to the Breathing Circuit (Circle System), a circle system, where the Anesthesia Ventilator drives the patient's breaths.

How it works

Exhaled gas returns through the circle system and crosses a CO2 absorber filled with soda lime before being rebreathed, allowing low fresh-gas flows that conserve agent and warm and humidify the circuit. Unidirectional dome valves enforce one-way flow, and an adjustable pressure-limiting valve vents excess. Waste anesthetic gas is captured by the Scavenging System (AGSS) interface and routed to hospital vacuum rather than into room air.

The Control Electronics regulate ventilator timing, drive the displays, and run the alarm logic that monitors airway pressure, volumes, and apnea. A sidestream Gas Analyzer Module continuously measures inspired and expired oxygen, carbon dioxide, nitrous oxide, and agent concentration, reporting end-tidal values and minimum alveolar concentration. The whole assembly rides on the Cart & Chassis, a braked-caster frame with a work surface, supply drawers, and monitor mounts, and an integrated battery sustains delivery through a mains interruption.