Background and Aims: The performance of non-invasive techniques remains inconsistent in cardiac surgical patients. This study assessed the level of agreement and trending abilities of cardiac index (CI) values obtained using Noninvasive Cardiac System (NICaS TM ) and FloTrac TM (version 4.0) in adult patients undergoing cardiac surgery. Methods: This retrospective observational study was conducted over 6 months at a tertiary care centre and included 16 patients undergoing elective cardiac surgery with cardiopulmonary bypass. CI was measured simultaneously using FloTrac TM from the radial (FCIrad) and femoral (FCIfem) arteries and using NICaS TM at corresponding time points (NCIrad and NCIfem). CI measurements were recorded at six time points: baseline (T1), post-induction (T2), post-sternotomy (T3), post-CPB weaning (T4), post-protamine (T5), and post-sternal closure (T6). Agreement between methods was assessed using Bland–Altman analysis, while trending ability was evaluated using four-quadrant and polar plot analyses. A ±30% change in CI relative to FloTrac™ values was considered the acceptable limit of agreement. Results: A total of 90 paired measurements were available for FCIrad–NCIrad and 73 for FCIfem–NCIfem. Bland–Altman analysis showed a bias of 0.33 L/min/m² (limits of agreement: -1.81 to 2.48 L/min/m²) for FCIrad–NCIrad and 0.52 L/min/m² (-2.03 to 3.07 L/min/m²) for FCIfem–NCIfem. Four-quadrant plots demonstrated concordance rates of 69% (radial) and 63.4% (femoral). Polar plot analysis showed angular concordance rates of 46% (radial) and 31% (femoral). Conclusion: NICaS TM showed limited agreement and trending ability compared with FloTrac TM at radial and femoral sites, indicating limited interchangeability between the two methods during cardiac surgery.
Patro et al. (Sun,) studied this question.