Evaluation of a transportable capnometer for monitoring end-tidal carbon dioxide

We compared a small and transportable Capnometer (EMMA?) with a reference capnometer, the Siesta i TS Anaesthesia. During air‐breathing through a facemask, both the EMMA (nine modules) and reference capnometer sampled expired gas simultaneously. A wide range of end‐tidal carbon dioxide values were obtained during inhalation of carbon dioxide and voluntary hyperventilation. The median IQR [range] difference between all sets of carbon dioxide values (EMMA – reference) was ?0.3 (?0.6 to 0.0 [?1.7 to 1.6] kPa; n = 297) using new batteries, which was statistically significant (p = 0.04) and located to two of the nine EMMAs tested. Using batteries with reduced voltage did not influence the measurements. The 95% CI of the medians of the differences were ?0.4 to ?0.2. We conclude that the EMMA can slightly under‐read the end‐tidal carbon dioxide but is generally comparable with a free‐standing monitor. The precision of the EMMAs was similar whether new batteries or batteries with reduced voltage were used.