The relationship between central venous pressure and inferior vena cava diameter and distensibility in neonates under mechanical ventilation.

backgroundCentral venous pressure (CVP) is a fundamental hemodynamic parameter in critically ill neonates, yet its invasive measurement poses technical challenges and risks, particularly in those receiving mechanical ventilation. The inferior vena cava (IVC) diameter and distensibility index (DI), as assessed by bedside ultrasound, have emerged as potential non‑invasive surrogates, but their quantitative relationship with CVP remains inadequately characterized in mechanically ventilated neonates across different ventilator modes.

methodsIn this single-center prospective observational study, 62 neonates receiving mechanical ventilation who had an internal jugular central venous catheter inserted, admitted to the NICU in Maternal and Child Health Hospital of Hubei Province from January 2023 to December 2024, were enrolled. CVP, IVC-Dmax, IVC-Dmin, and IVC-DI were recorded in addition to the ventilator modes and settings for each measurement.

resultsCVP was significantly positively correlated with IVC-Dmax (Pearson's r = 0.823, 95% confidence interval [CI]: 0.722-0.890, P < 0.001) and IVC-Dmin (Pearson's r = 0.879, 95% CI: 0.812-0.924, P < 0.001), while a moderate negative correlation was observed between CVP and IVC-DI (Pearson's r = -0.428, 95% CI: -0.614 to -0.207, P < 0.001). A comparison of different ventilatory modes showed that neonates receiving high-frequency oscillatory ventilation (HFOV) had significantly higher CVP and IVC diameters, but a significantly lower IVC-DI. In contrast, neonates receiving pressure-controlled assist/control (PC-AC) ventilation had significantly lower CVP and IVC diameters, but a significantly higher IVC-DI.

conclusionUltrasonographic measurements of the IVC correlate with invasively measured CVP in mechanically ventilated neonates and may serve as a non-invasive alternative for CVP monitoring when invasive catheterization is contraindicated or unavailable. IMPACT: In ventilated neonates, IVC diameter demonstrates a strong positive correlation with CVP (r ≈ 0.8-0.9), whereas the distensibility index exhibits a moderate negative correlation (r ≈ -0.4). This first prospective study quantifies the CVP-IVC relationship specifically in newborns, reveals that HFOV independently elevates both CVP and IVC diameter while suppressing distensibility, and provides regression models (R² = 0.69 for diameter, 0.41 for distensibility index) that estimate CVP within ±1.2 mmHg. Bedside IVC ultrasound serves as a non‑invasive alternative for CVP monitoring when invasive catheterization is contraindicated or unavailable.