Exploration of cardiovascular and cerebral physiology in preterm infants during the transitional period with continuous haemodynamic monitoring.

The transition from intrauterine to extrauterine life represents a critical phase of physiological adaptation after preterm birth. The aim of this research was to explore cardiovascular and cerebrovascular physiology in preterm infants during postnatal transition using a continuous, non-invasive comprehensive monitoring system. Transitional haemodynamics were explored in preterm infants <32 weeks’ gestation or with a birth weight <1500g using a non-invasive integrated multiparametric monitoring, which included electrical velocimetry, near-infrared spectroscopy, pulse oximetry and serial echocardiographic assessments. Sixty-four preterm infants with a mean gestational age of 29.6 weeks were included. A progressive improvement in overall cardiovascular function and cerebrovascular reactivity occurred during the transitional period. The presence of an haemodynamically significant patent ductus arteriosus was associated with significantly different patterns of cardiac output (CO), stroke volume (SV), heart rate (HR), cardiac contractility and with a greater impairment of cerebral autoregulation. Furthermore, characteristic transitional haemodynamic profiles were outlined in relation to gestational age, antenatal Doppler status and ductal status. The investigation of the relationship between CO and its direct determinants revealed that the correlation between CO and HR was not perfectly linear and was significantly influenced by HR ranges, ductal status and ongoing cardiovascular drugs. A strong association between SV and CO was also observed, supporting the role for SV in CO determination even in preterm infants. The haemodynamic response to brief cardio-respiratory events during the transitional period was finally evaluated, showing that the impact of these events on both cardiovascular and cerebral sides was modulated not only by the event characteristics, but also by gestational age, antenatal Doppler features and ductal status. This research demonstrates how multifaceted the transitional haemodynamic status is in such a heterogenic population as preterm infants and provide valuable hints in support of the development of an individualized haemodynamic management during this delicate early phase.