ISO 80601-2-55:2011 specifies particular requirements for the basic safety and essential performance of a respiratory gas monitor (RGM) intended for continuous operation for use with a patient. ISO 80601-2-55:2011 specifies requirements for: - anaesthetic gas monitoring, - carbon dioxide monitoring, and - oxygen monitoring. ISO 80601-2-55:2011 is not applicable to an RGM intended for use with flammable anaesthetic agents.