An evaluation of five carbon dioxide analysers for use in the operating theatre and intensive care unit

Five commercially available carbon dioxide analysers were assessed with respect to accuracy, response time, stability, the effect of water vapour and the effect of rebreathing. Two side-stream sampling analysers (Datex Normocap and Engstrom Eliza) and one main-stream sampling analyser (Hewlett-Packard Capnoshot) were found to be satisfactory for use both in the operating theatre and intensive care unit. The Instrumentation Laboratory (IL) 200, a side-stream monitor, performed satisfactorily but neither it nor the Siemens Sirecust 404, a main-stream monitor, has the facility to compensate for the presence of nitrous oxide. The Siemens analyser, in the form tested, could not be recommended for clinical use, as it was less accurate than the other monitors, could not detect rebreathing, and was subject to fluctuations when used with gas mixtures saturated with water vapour.