Anaesthetic gas monitoring comparison between two side-stream monitors.

End-tidal gas monitoring has become standard of care during inhaled general anaesthesia. We studied the performance of a new side stream gas monitor the ISA multi-gas monitor. The performance was studied at constant low flow of calibration gas and end-tidal anaesthetic measure was studied during routine day case anaesthesia. Pair wise readings of end-tidal halogenated anaesthetic concentration were recorded during low flow anaesthesia. Performance was found to be high; all calibration gas measures were within 0.1 vol% deviation. During routine anaesthesia mean bias was -0.036 vol% and 93 out of 97 pair-wise readings were within the agreement limits as compared to the reference Datex instrument.