Precision hemodynamics in the NICU: A phenotype-based functional echocardiography framework.

Functional echocardiography (fECHO) has become a key bedside tool for real-time assessment of neonatal hemodynamics. Unlike conventional monitoring, which relies on indirect surrogates such as blood pressure, fECHO enables direct evaluation of preload, afterload, ventricular performance, cardiac output, and shunt physiology, providing a comprehensive physiologic profile of circulatory status. Neonatal hemodynamic instability is inherently heterogeneous, with similar clinical presentations arising from distinct underlying mechanisms, including preload limitation, myocardial dysfunction, altered vascular resistance, and flow redistribution. Consequently, interpretation requires a structured, physiology-based approach rather than reliance on isolated parameters or diagnostic labels. This review presents a phenotype-based framework for fECHO interpretation in the neonatal intensive care unit, integrating ventricular function, vascular loading conditions, and systemic perfusion. The approach incorporates multimodal monitoring to link central hemodynamics with organ-level oxygen delivery. By enabling identification of dominant hemodynamic phenotypes and their evolution over time, this framework supports precision, physiology-driven bedside assessment and provides a foundation for standardized, phenotype-based neonatal hemodynamic care.