Respiratory mass spectrometry during general anaesthesia.

The performance of a respiratory mass spectrometer, modified commercially for use during general anaesthesia, has been evaluated. Stability and linearity proved satisfactory for monitoring respiratory gases and accurate measurement was possible when the inspired concentration of all gases was less than 80%. The system has been installed centrally in a three-room operating theatre suite and the selection of long sampling probes which permit an adequate response time for all gases is discussed.