(570) An In Silico Model of Circle of Willis Blood Flow in Pediatric Patients With Sepsis

Introduction: Ensuring adequate end-organ perfusion remains a key element of sepsis management. Sepsis encephalopathy is a significant source of morbidity in pediatric patients, and may be related to inadequate cerebral blood flow. Our aim in this study was to create an in silico model of cerebral artery blood flow to determine the effects on cerebral perfusion in pediatric patients with sepsis.

Methods: We created a novel one-dimensional Navier-Stokes model of the primary branches of the Circle of Willis and scaled the model for patients from birth to 18 years of age using published data. Systemic vascular compliance (SVC) and systemic vascular resistance (SVR) were calculated using age-specific values for blood pressure, stroke volume, and heart rate described in the literature. We then simulated cerebral blood flow velocity (CBFv) in the middle cerebral artery in two states: the healthy state (in which the SVC and SVR correspond to a blood pressure at the fiftieth percentile for age) and the septic state (in which the SVC and SVR correspond to a blood pressure at the fifth percentile for age). The simulation was performed for four age groups: a neonate, a five-year-old, a ten-year-old, and an adult.

Results: Peak aortic blood flow decreased between 13.9% and 39% in the septic state relative to the healthy state across the four age groups. CBFv through the middle cerebral artery for the neonate, the five-year-old, the ten-year-old, and the adult were estimated as 0.29, 0.33, 0.40, and 0.54 m/s, respectively, which approximate values reported in the literature (0.28-1.29 m/s for children ranging from birth to 18 years of age). In the septic state, these values decrease to 0.27, 0.26, 0.35, and 0.40 m/s, or 93, 79, 88, and 74% of the CBFv for the healthy neonate, five-year-old, ten-year-old, and adult, respectively.

Conclusions: Our novel in silico model of cerebral artery blood flow for pediatric patients, approximated for four age groups, shows that CBFv decreases in sepsis and to a proportionally greater degree at higher ages. Future work will attempt to incorporate unique hemodynamic states in sepsis, such as early sepsis and septic shock, as well as the effects of cerebral autoregulation into the model.