Agreement Between Echocardiography and Ultrasonic Cardiac Output Monitoring (USCOM) for Hemodynamic Assessment in Pediatric Patients: A Bland–Altman Analysis

Background Echocardiography is widely used for non‐invasive measurements of stroke volume and cardiac output, while Ultrasonic Cardiac Output Monitor (USCOM) offers an alternative Doppler‐based approach. Whether these two modalities can be used interchangeably in clinical practice remains unclear. This study aims to evaluate the correlation and agreement between echocardiography and USCOM for hemodynamic assessment. Methods A total of 44 pediatric patients underwent hemodynamic assessment using echocardiography and sequential USCOM measurement during the same evaluation. Spearman's rank correlation was used to assess the relationship between methods. Agreement was evaluated using Bland‐Altman analysis. Results Strong correlations were found for stroke volume (SV; r = 0.97), cardiac output (CO; r = 0.95), cardiac index (CI; r = 0.91), stroke volume index (SVI; r = 0.90), and aortic valve (AV) diameter ( r = 0.91; p < 0.001), with a moderate correlation for left ventricular outflow tract (LVOT) velocity ( r = 0.64, p < 0.001). Bland‐Altman analysis revealed echocardiography produced lower values of all parameters compared to USCOM. Significant proportional bias was identified for SV, SVI, CO, and CI (all p ≤ 0.006), indicating that two methods increased disagreement with higher measured values. AV diameter and LVOT velocity showed no significant proportional bias and narrower limits of agreement. Conclusions Although echocardiography and USCOM correlate strongly for hemodynamic parameters, clinically meaningful systematic bias and proportional error limit their interchangeability for volumetric flow measurements. These devices should not be used interchangeably for quantitative hemodynamic monitoring, particularly in high‐output states.