The trend interchangeability method M.O. Fischer, E. Lorne  British Journal of Anaesthesia  Volume 117, Issue 6, Pages 826-828 (December 2016) DOI: 10.1093/bja/aew367 Copyright © 2016 The Author(s) Terms and Conditions

Fig 1 Four different changes in cardiac output (CO) between the reference method and an experimental method are identified by coloured points in this example. The repeatability of measurement of the reference method was set at 20%. The four changes in CO are depicted on a 4-quadrant plot (Fig 1A), a polar plot (Fig 1B), a clinical concordance plot (Fig 1C), and trend interchangeability plot (Fig 1D). All points were in the concordance zone in the 4-quadrant plot (Fig 1A), polar plot (Fig 1B), and clinical concordance plot (Fig 1C). However, the TIM showed each point at each time (before and after change) with their value (with their repeatability of 20%) and their interchangeability line (solid line) and limits of interchangeability lines (dotted lines) (Fig 1D). The TIM identified one not interpretable change (blue colour: overlapping of confidences intervals), and among the interpretable changes: one not interchangeable point (red colour: neither the second point nor its repeatability was not in the interchangeability zone defined by using interchangeability lines), one in the grey zone (orange colour: only the repeatability of the second point was in the interchangeability zone), and one interchangeable change (green colour: the second point was in the interchangeability zone). CO, cardiac output; COexp, CO measured with experimental method; COref, CO measured with reference method; TIM, trend interchangeability method; ΔCOexp, change in CO measured with experimental method; ΔCOref, change in CO measured with reference method. British Journal of Anaesthesia 2016 117, 826-828DOI: (10.1093/bja/aew367) Copyright © 2016 The Author(s) Terms and Conditions