Breathing system for anesthesia machine

An anesthesia machine comprising:

• a gas mixer that receives gas from at least two gas sources and provides an anesthetic gas for delivery to a ventilated patient;
• a breathing system comprising:
• a reusable ventilation portion including a mechanical ventilation section, a manual ventilation section, a ventilation port, and a switch configured to switch between connection of the mechanical ventilation section to drive patient ventilation through the ventilation port and connection of the manual ventilation section to drive the patient ventilation through the ventilation port;
• a disposable circle portion removably connected to the reusable ventilation portion, the disposable circle portion including:
• a vent connector that connects to the ventilation port;
• an inspiratory channel configured to conduct inspiratory gasses and terminating at an inspiratory port that connects to a patient connector and delivers the inspiratory gases thereto;
• a gas intake port providing anesthetic gas from the gas mixer to the inspiratory channel;
• an expiratory channel configured to conduct expiratory gasses and terminating at an expiratory port that connects to the patient connector and receives the expiratory gases therefrom;
• a CO2 absorber connecting between the expiratory channel and the inspiratory channel;
• and
• a filter positioned between the expiratory port and the vent connector and between the CO2 absorber and the vent connector, wherein the filter prevents moisture and bacteria from entering the reusable ventilation portion of the breathing system.