An end-tidal sampler for use with slow response analysers during anaesthesia

An end-tidal sampler is described which can be used during anaesthesia with spontaneous respiration at rates of at least 60 b.p.m. It can be used with slow response analysers such as refractometers and fuel cells to indicate end-tidal concentrations. It can also be used to extend the scope of those breath-to-breath analysers which have a response time which is too slow for the respiratory rates which may occur during anaesthesia with spontaneous breathing. Using the device, mean PCO2 of the samples was 0.13 kPa less than the corresponding values for the end-expiratory PCO2 measured by conventional breath-by-breath analysis. Full response was achieved in 12 breaths.