Assessing haemorrhage-critical values of cerebral blood flow by modelling biomechanical stresses on capillaries in the immature brain

Abstract

The development of intraventricular haemorrhages ( IVH ) in preterm newborns is triggered by a disruption of the vessels responsible for cerebral microcirculation. Analysis of the stresses exerted on vessel walls enables the identification of the critical values of cerebral blood flow ( CBF ) associated with the development of IVH in preterm infants. The purpose of the present study is the estimation of these critical CBF values using the biomechanical stresses obtained by the finite element modelling of immature brain capillaries. The properties of the endothelial cells and basement membranes employed were selected on the basis of published nanoindentation measurements using atomic force microscopes. The forces acting on individual capillaries were derived with a mathematical model that accounts for the peculiarities of microvascularity in the immature brain. Calculations were based on clinical measurements obtained from 254 preterm infants with the gestational age ranging from 23 to 30 weeks, with and without diagnosis of IVH . No distinction between the affected and control groups with the gestational age of 23 to 26 weeks was possible. For infants with the gestational age of 27 to 30 weeks, the CBF value of 17.03 ml/100 g/min was determined as the critical upper value, above which the likelihood of IVH increases.

Accounting for arterial and capillary blood gases for calculation of cerebral blood flow in preterm infants

“…Infants born before 30 weeks of gestation (WG) or those with a birth weight below 1500 g are at risk with an overall incidence of 20 to 25% [1,2]. In the preterm brain, IVH typically originates from the highly vascularized area of the germinal matrix [3,4], which is present until 32 WG [5]. This crucial region for physiological fetal brain development contains numerous glial and neuronal precursor cells migrating to the cortex [3,6].…”