An anaesthetic circuit to improve patient monitoring by gas analysis

This circuit is designed to maximise the range of respiratory variables that can be monitored by a mass spectrometer either alone, or preferably in association with blood gas analysis. In particular, it permits monitoring of respiratory dead space, lung shunt, ventilation, and gas exchange, as well as inspired and end-expired gas concentrations. Laboratory and clinical data indicate satisfactory performance of the circuit both clinically and analytically. The circuit is most suitable for controlled ventilation where, by operating as a "minute volume divider", it confers stability of minute volume on the manual ventilation technique.