Serial transthoracic echocardiography for hemodynamic monitoring and early warning of hypotension during elective cesarean delivery: a prospective observational study

Abstract

Abstract BACKGROUND : Spinal anesthesia during cesarean delivery frequently causes maternal hypotension. Early detection of hemodynamic compromise before blood pressure decline could enable timely intervention. This study evaluates the use of serial transthoracic echocardiography (TTE) as a monitoring tool for early detection of hemodynamic fluctuation. OBJECTIVE : To characterize the temporal sequence of hemodynamic changes using serial TTE, with emphasis on the relationship between stroke volume (SV) reduction and subsequent hypotension, and to assess the potential of TTE‑derived parameters as early warning indicators. DESIGN : Prospective observational study. SETTING : Single-center trial. PATIENTS : Thirty healthy term pregnant women (ASA I‑II) undergoing elective cesarean delivery under spinal anesthesia. INTERVENTION : Serial TTE examinations were performed at 13 predefined time points. Left ventricular diameters (LVIDd, LVIDs) were measured and volumes (EDV, ESV) were derived using the Teichholz method, from which stroke volume, cardiac output, cardiac index, and ejection fraction were calculated. MAIN OUTCOME MEASURES : Temporal relationship between SV decline and hypotension onset. RESULTS : After spinal anesthesia, left ventricular end-diastolic volume (EDV) decreased by 34.6%, stroke volume (SV) by 36.2%, cardiac output (CO) by 38.7% (all P<0.001). Hypotension (SBP drop >20%) occurred in 76.7%. Crucially, SV reduction preceded blood pressure fall: at the first post‑spinal measurement, SV had already decreased by 30.6%, while systolic BP had fallen by only 12.2%. Left ventricular ejection fraction (LVEF) remained stable throughout. After fetal delivery, all parameters partially recovered. CONCLUSION : Serial TTE monitoring detects a significant reduction in SV consistently before hypotension becomes clinically apparent, demonstrating the potential of TTE‑derived parameters as early warning indicators of preload reduction. These findings establish a monitoring‑based physiological baseline for future hypothesis‑testing in obstetric anesthesia. TRIAL REGISTRATION : Chinese Clinical Trial Registry (ChiCTR2500111576)