Abstract
Six mainstream and twelve sidestream infrared carbon dioxide (CO2) analysers were tested for accuracy of the CO2 display value, alarm activation and the effects of nitrous oxide (N2O), oxygen (O2) and water vapour according to the ISO Draft International Standard (DIS) #9918. Mainstream analysers (M-type): Novametrix Capnogard 1265; Hewlett Packard HP M1166A (CO2module HP M1016A); Datascope Passport; Marquette Tramscope 12; Nellcor Ultra Cap N-6000; Heilige Vicom-sm SMU 611/612 ETC. Sidestream analysers: Brüel & Kjaer Type 1304; Datex Capnomac II; Marquette MGA-AS; Datascope Multinex; Ohmeda 4700 OxiCap (all type S1: respiratory cycles not demanded); Biochem BCI 9000; Bruker BCI 9100; Dräger Capnodig and PM 8020; Criticare Poet II; Heilige Vicom-sm SMU 611/612 A-GAS (all type S2: respiratory cycles demanded). The investigations were performed with premixed test gases (2.5, 5, 10 vol%, error ⪯1% rel.). Humidification (37° C) of gases were generated by a Dräger Aquapor. Respiratory cycles were simulated by manually activated valves. All monitors complied with the tolerated accuracy bias in CO2 reading (≤ 12% or 4 mmHg of actual test gas value) for wet and dry test gases at all concentrations, except that the Marquette MGA-AS exceeded this accuracy limit with wet gases at 5 and 10 vol% CO2. Water condensed in the metal airway adapter of the HP M1166A at 37° C gas temperature but not at 3(P C. The Servomex 2500 (nonclinical reference monitor), Passport (M-type), Multinex (S1-type) and Poet II (S2-type) showed the least bias for dry and wet gases. Nitrous oxide and O2 had practically no effect on the Capnodig and the errors in the others were max. 3.4 mmHg, still within the tolerated bias in the DIS (same as above). The difference between the display reading at alarm activation and the set point was in all monitors (except in the Capnodig: bias 1.75 mmHg at 5 vol% CO2) below the tolerated limit of the DIS (difference ≤ 0.2 vol%). The authors conclude that the tested monitors are safe for clinical use (except those failing the DIS limits). The accuracy of the CO2-reading (average of mean absolute bias) is better in the M-type than in the S1- or S2- type analysers although no statistical (nor clinical) significant differences could be detected. Most manufacturers work with stricter limits than those proposed by the DIS.
Résumé
Des analyseurs de gaz carbonique (CO2 à infrarouge dont six à soutirage latéral et 12 de courant central sont évalués au regard de la précision, de l’activation des alarmes et des effets du protoxyde d’azote (N2O), de l’oxygène (O2 et de la vapeur d’eau conformément à la norme internationale ISO (DIS) 9918. Les analyseurs de courant central sont les suivants: (Type-M): Novametrix Capnogard 1265; Hewlett Packard HP M1166A (CO2module HP M1016A); Datascope Passport; Marquette Tramscope 12; Nellcor Ultra Cap N-6000; Hellige Vicom-sm SMU 611/612 ETC. Les analyseurs à soutirage latéral: Brüel & Kjaer Type 1304; Datex Capnomac II; Marquette MGA-AS; Datascope Multinex; Ohmeda 4700 OxiCap (tous de type S1: sans demande de cycle respiratoire); Biochem BCI 9000; Bruker BCI 9100; Dräger Capnodig et PM 8020; Criticare Poet II; Hellige Vicom-sm SMU 611/612 A-Gas (tous de type S2: avec demande de cycle respiratoire). Les études sont réalisées avec des gaz étalons prémélangés (2,5, 5, 10 vol.%, erreur relative ≤ 1%). Les gaz sont humidifiés (37% C)grâce à un Dräger Aquapor. Les cycles respiratoires sont simulés par des valves actionnées manuellement. Par rapport au biais de tolérance, tous les capnographes sont précis pour la lecture du CO2 (≤ 12% ou 4 mmHg de la valeur du gaz étalon) pour les gaz secs et humidifiés entre 5 et 10% en vol. de CO2. L’eau se condense sur le raccord métallique du HP M1166A à 37° C mais non à 30°C. Le Servomex 2500 (moniteur de référence non clinique), Passport (Type M) Multinex (Type S1) et Poet II (Type S2) sont ceux qui offrent le moins de biais pour les gaz sees et humides. Le protoxyde d’azote et l’O2 n’ont pratiquement pas d’influence sur le Capnodig et les erreurs pour les autres capnographes sont au maximum de 3,4 mmHg, ce qui est toujours en deçà du biais toléré par le DIS. La difference entre l’affichage et l’activation de l’alarme pour un niveau donné est la même pour tous les moniteurs (à l’exception du Capnodig: biais 1,75 mmHg pour un vol. CO2 5%) sous la limite tolérée du DIS (difference ≤0,2 vol%). Les auteurs concluent que les moniteurs mis à l’épreuve sont satisfaisantspour l’usage clinique (excepté ceux qui sont en deçà des limites déterminées par le DIS). La précision de la lecture du CO2 (la moyenne du biais absolu) est supSrieure pour les appareils de type M aux analyseurs de type SI et S2 bien qu’aucune difference statistique (ou clinique) n’ait été décelée. La plupart des manufacturers utilisent des limites plus strides que celle que recommande le DIS.
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Lauber, R., Seeberger, B. & Zbinden, A.M. Carbon dioxide analysers: accuracy, alarm limits and effects of interfering gases. Can J Anaesth 42, 643–656 (1995). https://doi.org/10.1007/BF03011887
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DOI: https://doi.org/10.1007/BF03011887