Clearsight™ use for haemodynamic monitoring during the third trimester of pregnancy – a validation study

•Clearsight™ is a non-invasive cardiac output monitor.•We present a Clearsight™ validation study against transthoracic echocardiography.•Clearsight™ shows a systematic error of overestimation.•Clearsight™ is not interchangeable with transthoracic echocardiography. We assessed the validity of Clearsight™ as a non-invasive cardiac output and stroke volume monitoring device, comparing it with transthoracic echocardiography measurements during the third trimester of pregnancy. Measurements obtained from Clearsight™ were compared with those from echocardiography as the gold standard. The precision and accuracy of the Clearsight™ was measured using the Bland and Altman method. Clinical agreement with echocardiography was assessed using the agreement tolerability index. Measurements were recorded from 44 pregnant women with a median [IQR range] gestational age of 33 [30–37] weeks. We found that Clearsight™ measurements presented a systematic overestimation of cardiac output, with mean bias [CI 95%] of 2.7 [2.3–3.0] L/min, with limits of agreement of −0.1 to 5.4 L/min. It overestimated stroke volume, with a bias of 29.5 [25.0–33.4] mL and a limit of agreement of −1.6 to 60.1 mL. In addition, the analysis of cardiac output showed a percentage of error of 41% and intra-class correlation [CI 95%] of 0.37 [0.17 to 0.53, P