Objectives: Noninvasive assessment of cardiac index (CI) in pediatric critical ill patient is crucial. Aortic Velocity Time Integral (VTI) valuable in adults, faces age and heart rate variability challenges in pediatrics, complicating CI interpretation in shocked patients. Measurement errors can complicate CI evaluation, particularly in shocked patients. Considering the proportional relationship between aortic annulus and Body Surface Area (BSA) in children, along with the relatively constant mean aortic velocity, we studied if Left Ventricular Outflow Tract mean-velocity (LVOTmv) reliably estimates bedside CI.

Design : retrospective, observational, single-center study.

Setting : Pediatric Intensive Care Unit (PICU) in a tertiary care hospital.

Patients : one hundred forty-four children in PICU (age 0-17 years, BSA 0.11-1.69 m2) requiring hemodynamic evaluation.

Intervention : Bedside ultrasound by expert cardiologists

Measurements and Main Results : We explored the correlation between LVOTmv (measured in pulse wave doppler from the apical five-chamber view) and standard CI estimation (multiplying aortic VTI, heart rate, and aortic valve area). We excluded arrhythmia and anomalies of the left ventricular outflow tract.

Inclusion Criteria:

• infants, children, and adolescents hospitalized in our Pediatric Intensive Care Unit (PICU) in a non-surgical cardiology unit requiring hemodynamic assessment

Exclusion Criteria:

• documented irregular heart rates (HR) or with congenital heart malformations that could affect aortic measurements or LVOT velocity (such as aortic valve anomalies)

infants, children, and adolescents hospitalized in our Pediatric Intensive Care Unit (PICU) in a non-surgical cardiology unit