Accuracy, alarm limits and rise times of 12 oxygen analysers

The Comité Européen de Normalisation recently proposed a new standard for 'the particular requirements of oxygen monitors for medical use'. The feasibility of this proposed standard was tested in respect of (1) accuracy of alarm activation (2) accuracy of oxygen display value during both continuous and cyclical gas flows (3) rise time during rapid changes in oxygen concentration in the following 12 analysers: Datex Capnomac II and Servomex 570A (paramagnetic); Brüel & Kjaer 1304 (magnetoacoustic); Criticare Poet II, Multinex, Dräger Oxydig, Dräger PM 8030, Megamed 046A (part of the Megamed 700 ventilator), Ohmeda 5120, Spacelabs Multigas, Teledyne TED 200 (galvanic); Kontron OM 810 (polarographic). All the analysers tested displayed an oxygen reading which was within +/- 3 vol% of the actual oxygen concentrations of the test gases (15, 21, 40, 60 and 100 vol%). A cyclical pressure of between -1.5 to +8 kPa did not affect the measured oxygen concentration as displayed by the Brüel & Kjaer 1304, Datex Capnomac II and Servomex 570A analysers. The remainder, however, showed, depending on their measuring principle, a display error of between -1 and +6 vol%. After exposure to high pressure all the oximeters functioned normally. Some of the tested devices showed more than 2% of deviation between their alarm activation and the preset alarm limits. Only the Kontron OM 810, the Megamed 046A and the Spacelabs Multigas monitors satisfied the requirements at all the tested oxygen concentrations. The time required by the oxygen analyser to display the rise from 29 to 92 vol % after a sudden change of concentration from 21 to 100 vol % O2 is defined as "rise time" and must not, according to the Comité Européen de Normalisation standard proposal, exceed the manufacturers' specification by more than a factor of 1.15.(ABSTRACT TRUNCATED AT 250 WORDS)