Neonatal reference values and nomograms of systemic vascular resistances estimated with electrical cardiometry

Scanty data are available about neonatal systemic vascular resistances (SVR). We aim to provide reference values and nomograms for neonatal SVR.

Multicenter, cross-sectional,descriptive study performed in France and Italy. Neonates with complete hemodynamic stability were enrolled. Non-invasive measurements of SVR by electrical cardiometry performed once, after the first 72 h and before the 7th day of postnatal age.

We studied 1094 neonates: SVR was correlated with gestational age (ρ = −0.55, adj-r = −0.46, p < 0.001) and birth weight (ρ = −0.59, adj-r = −0.45, p < 0.001) irrespective of newborn sex. The relationships between SVR, gestational age and birth weight were represented by power equations and SVR was decreasing with increasing age and weight. Age- and weight-based SVR nomograms had optimal goodness-of-fit (non-linear R² ≥0.74). Similar results were obtained for body surface indexed-SVR.

In hemodynamically stable neonates, SVR decrease with increasing gestational age and birth weight. Specific gestational age and birth weight-based nomograms are provided for the clinical interpretation.