Transthoracic Echocardiography as the Reference for Validating Non-invasive Hemodynamic Monitoring During Passive Leg Raising in Term Pregnancy

Background Pregnancy is characterized by profound hemodynamic changes, which complicate perioperative monitoring and fluid therapy. Non-invasive cardiac output monitoring device, ClearSight™ system, provides continuous stroke volume estimates, but their reliability in pregnant women remains uncertain. Passive leg raising (PLR) is a reversible preload test that can elucidate fluid responsiveness without fluid administration. To date, no study has simultaneously validated ClearSight™ against echocardiographic reference standards during PLR in term pregnant women.

Methods This is a prospective, single-centre, method-comparison and diagnostic accuracy study in term pregnant women (≥37 weeks). Simultaneous ClearSight™ and transthoracic echocardiography (TTE) measurements will be obtained at baseline, during PLR, and during recovery. The primary outcome is agreement between ClearSight™-derived stroke volume index (SVI) changes and TTE-derived Left Ventricular Outflow Tract - Velocity Time Integral (LVOT-VTI) changes during PLR. Secondary outcomes include trending ability and diagnostic accuracy of ClearSight™ Δ%SVI for detecting PLR responders. Four-quadrant and polar plot analyses are the parameters for advanced hemodynamic monitoring methods used in echocardiography to assess fluid responsiveness and cardiac output (CO) trending Sample size: 60 participants, providing at least 180 paired observations.

Conclusions This study will establish whether ClearSight™ can reliably detect preload responsiveness in term pregnant women. Findings could support safer, real-time, non-invasive hemodynamic management during obstetric anaesthesia and maternal critical care.