In vitro performance of a new non-invasive extracorporeal saturation monitor

A simulated cardiopulmonary bypass circuit was constructed in the laboratory to compare the accuracy and precision of a new non-invasive extracorporeal oxygen saturation monitor-- the M3 monitor (Spectrum Medical LLP, Gloucester, UK) against the Siemens RAPIDLab(®) blood gas analyser (Siemens AG, Munich, Germany). Comparisons were made across a range of oxygen saturations and at different temperatures and different haemoglobin concentrations. Results showed that under all conditions, when recording oxygen saturation, the M3 monitor achieved a mean (SD) bias of -0.9 (1.7)% with limits of clinical agreement of -4.2 to 2.5. However, the difference between the two monitors was larger at lower saturation levels (p < 0.001), lower haemoglobin levels (p = .002) and lower temperatures (p = 0.013). The mean (SD) haemoglobin concentration was 15.4 (0.6) when recorded by the M3 monitor, compared to 15.4 (0.5) g.dl(-1) measured by the blood gas analyser The M3 monitor compares favourably with the gold standard of the blood gas analyser and has the advantage of giving a continuous reading. You can respond to this article at http://www.anaesthesiacorrespondence.com.