Passive Leg Raising in Term Pregnancy on Hemodynamic Monitoring - Validating With Transthoracic ECHO (LG-ECHO)

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

This prospective observational validation study aims to evaluate the agreement and diagnostic accuracy of ClearSight™ compared with transthoracic echocardiography (TTE) during PLR in term pregnant women.

The ultimate goal is to determine whether ClearSight™ can reliably identify preload responsiveness in term pregnant women compared with the echocardiographic gold standard. The clinical implication is that, if validated, ClearSight™ may reduce unnecessary or harmful fluid administration by accurately detecting preload reserve, and improve maternal safety in peripartum care by providing obstetric anesthesiologists with reliable bedside monitoring tools.

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.

Inclusion Criteria:

• Term pregnant patients
• Singleton pregnancy at ≥37+0 weeks of gestation.
• Maternal age between 18 and 45 years.
• Hemodynamically stable and in sinus rhythm.
• Ability to provide verbal and written informed consent.

Exclusion Criteria:

• Hypertensive disorders of pregnancy, significant valvular or congenital heart disease, cardiomyopathy, or persistent arrhythmias.
• Multiple gestation (i.e., Twin pregnancy and above)
• Endocrine or hematologic conditions likely to affect hemodynamics, including diabetes with or without autonomic neuropathy, thyroid storm, or severe anemia (hemoglobin <8 g/dL).
• Active labor with pain or current infusion of uterotonic or vasoactive agents.
• Ruptured membranes with frequent contractions or indications for emergent delivery.
• Inadequate transthoracic echocardiographic imaging windows at screening.
• Emergency or STAT (statim) Cesarean Deliveries