Systemic hypotension and patterns of cerebral blood perfusion in newborns

The relationship between systemic hemodynamics and cerebral perfusion in neonates, particularly those with systemic hypotension, is complex and not clearly elucidated. Targeted neonatal echocardiography (TNE) provides valuable insights into cerebral hemodynamics by quantifying middle cerebral artery (MCA) flow in the context of systemic hemodynamics.

To investigate the correlation between blood pressure (BP), cardiac output (CO), and MCA Doppler indices in neonates, hypothesizing that BP alone is not a reliable measure of cerebral perfusion.

A retrospective cohort study of neonates who underwent their first TNE in the Neonatal Intensive Care Unit. The analysis focused on the relationship between BP components and MCA Doppler measures (i.e., resistive index and pulsatility index).

The study included 194 neonates born at a mean gestational age and weight of 30.7 ± 6 weeks and 1744 ± 1246 g, respectively, classified into normotensive, hypotensive, and normotensive-treated groups. Weak correlations were observed between MCA Doppler measures and BP components across the entire cohort. Group comparisons found that neonates in the hypotensive group exhibited higher MCA-RI compared to both normotensive and normotensive-treated groups. Exploratory analyses revealed significant variation in MCA-RI that was explained by cardiac output after accounting for BP and gestational age.

These findings suggest that BP alone is not a sufficient indicator of cerebral perfusion status. While the correlations were expected to be weak given the dynamic nature of cardiac output, the results highlight the need for comprehensive hemodynamic assessments in neonates with cardiovascular compromise to avoid reliance on oversimplified metrics such as BP versus Dopplers.