PhD defence T. (Tanja) van Essen

Below is a brief summary of the dissertation:

This thesis focuses on developments in non-invasive monitoring of oxygenation, carbon dioxide exchange and hemodynamics in neonates admitted to the Neonatal Intensive Care Unit. Preterm and critically ill newborns are particularly vulnerable to disturbances in oxygen and carbon dioxide levels, which may contribute to complications such as hypoxemia, hypercapnia, hypocapnia, retinopathy of prematurity, bronchopulmonary dysplasia and neurological injury. Reliable monitoring is therefore essential in neonatal intensive care.
The first part of this thesis explores transcutaneous monitoring of oxygen and carbon dioxide. It focuses on the OxiVenT™ sensor, a combined sensor for tcPO₂, tcPCO₂ and SpO₂. The studies show that this sensor can provide accurate measurements, while also demonstrating that its reliability depends on clinical factors such as sepsis, sensor temperature, postnatal age, gestational age, blood pressure and body temperature. During therapeutic hypothermia, tcPCO₂ monitoring appeared adequate, whereas tcPO₂ did not reliably reflect arterial oxygen values.
The second part addresses hemodynamic monitoring. High-frequency cardiorespiratory data were used to evaluate the effect of red blood cell transfusions on desaturations. In addition, the thesis discusses the possibilities and limitations of near-infrared spectroscopy, as well as the development of dynamic light scattering as a novel technique for heart rate and potentially microvascular monitoring. Future applications include automated control systems and predictive monitoring, for which accuracy, reliability and careful clinical implementation remain essential.