Development of an adsorption/membrane based system for carbon dioxide, nitrogen and spur gases removal from a nitrous oxide and xenon anaesthetic closed loop

This paper presents a new technological solution for a long standing problem: how to recycle nitrous oxide or xenon in a closed low-flow anaesthetic circuit. For a nitrous oxide anaesthetic circuit, a CMS hollow fiber membrane module, where the permeate side is filled with a diamine, is proposed to remove carbon dioxide and simple CMS hollow fiber membrane module is proposed to remove nitrogen, methane and acetone. Some oxygen ends up also being lost. In a xenon anesthetic circuit, carbon dioxide can be removed using a CMS hollow fiber membrane module and nitrogen with a Pressure Swing Adsorption (PSA) unit packed with a special CMS adsorbent. Some of the acetone is also removed. In both cases (nitrous oxide and xenon recycling), the halogenated anesthetics remain in the closed circuit. Both the adsorbents and the membranes are sterilizable in-situ by rising the temperature up to 121 degrees C.