Agreement between manual and automatic ultrasound measurement of the velocity–time integral in the left ventricular outflow tract in intensive care patients: evaluation of the AUTO-VTI® tool

Transthoracic echocardiography is widely used in intensive care unit (ICU) to manage patients with acute circulatory failure. Recently, automated ultrasound (US) measurement applications have been developed but their clinical performance has not been evaluated yet. The aim of this study was to assess the agreement between automated and manual measurements of the velocity–time integral in the left ventricular outflow tract (VTI-LVOT) using the auto-VTI® tool. This prospective, single-center, interventional study included ICU patients with acute circulatory failure. The examination involved two successive manual measurements of VTI-LVOT (mean of 3 consecutive heartbeats in regular sinus rhythm, and 5 heartbeats in irregular rhythm), followed by a measurement using auto-VTI® software. In patients receiving a fluid challenge, trending ability in detecting fluid responsiveness was also evaluated. Seventy patients were included between January 19, 2020, and September 24, 2020, at the Nîmes University Hospital. The feasibility of the auto-VTI® was 94%. The mean difference between the two methods was 11% with limits of agreement from − 19% to 42%. The proportion of agreement at the 15% difference threshold was 68% [58%; 80%]. The precision and least significant change measured for the manual measurement of VTI were 7.4 and 10.5%, respectively, and by inference for the automated method 28% and 40%. The new auto-VTI® tool, despite interesting feasibility, demonstrated an insufficient agreement with a systematic bias and an insufficient precision limiting its implementation in critically ill patients.

Clinical trial registration: ClinicalTrials.gov identifier: NCT04360304.