A novel method for assessing cerebral autoregulation in preterm infants using transfer function analysis

Background:Autoregulatory dysfunction is an important contributor to brain injury in premature infants, particularly intraventricular hemorrhage (IVH). The autoregulatory system acts as a filter that dampens the systemic blood flow to follow a normal cerebral perfusion profile.Methods:Simultaneous arterial blood pressure and cerebral near-infrared spectroscopy (NIRS) data were collected from infants born before 28?wk estimated gestational age. The resulting data were preprocessed and then divided into nonoverlapping 20-min epochs. The transfer function estimate was calculated to determine dampening ability.Results:Sixty-two infants were prospectively recruited with a mean estimated gestational age of 25.4?±?1.3?wk and birth weight of 832?±?199?g. 67% were male, 24/62 had IVH, 17/62 received dopamine, 47/62 had antenatal steroid exposure, and 22/62 received fentanyl.Advancing estimated gestational age and birth weight z-score predicted stronger dampening while African-American race and IVH of any grade predicted weaker dampening.Conclusion:This preliminary report suggests an impairment in dampening ability associated with immaturity, decreased birth weight z-score, and African-American race. Decreased dampening is also associated with IVH, although these results cannot distinguish between decreased dampening as an antecedent or sequela of IVH. These observations should be studied in a larger sample.