An additive gas delivery apparatus for delivery of additive gas to inspirational gas can be set to deliver the additive gas according to a dosing setting in normal therapy, and can be set to deliver according to a backup dosing setting in response disruption of signals representing data for controlling the delivery of additive gas according to the dosing setting in normal therapy. An additive gas delivery apparatus has an inlet for the additive gas and an integrated inlet for gas for oxygenating the patient that are connected to a backup line to mix the additive gas and gas for oxygenating the patient to a set concentration of additive gas in the gas mixture at an integrated backup outlet of the additive gas delivery apparatus.
