Impaired cerebral autoregulation and brain injury in newborns with hypoxic-ischemic encephalopathy treated with hypothermia

Abstract

Impaired cerebral autoregulation may contribute to secondary injury in newborns with hypoxic-ischemic encephalopathy (HIE). Continuous, noninvasive assessment of cerebral pressure autoregulation can be achieved with bedside near-infrared spectroscopy (NIRS) and systemic mean arterial blood pressure (MAP) monitoring. This study aimed to evaluate whether impaired cerebral autoregulation measured by NIRS-MAP monitoring during therapeutic hypothermia and rewarming relates to outcome in 36 newborns with HIE. Spectral coherence analysis between NIRS and MAP was used to quantify changes in the duration [pressure passivity index (PPI)] and magnitude (gain) of cerebral autoregulatory impairment. Higher PPI in both cerebral hemispheres and gain in the right hemisphere were associated with neonatal adverse outcomes [death or detectable brain injury by magnetic resonance imaging (MRI), P < 0.001]. NIRS-MAP monitoring of cerebral autoregulation can provide an ongoing physiological biomarker that may help direct care in perinatal brain injury.

Keywords: cerebral blood flow; hypoxic-ischemic encephalopathy; magnetic resonance imaging; newborn.

Fig. 1.

Median systemic mean arterial blood pressure (MAP) over time in infants with hypoxic-ischemic encephalopathy (HIE) who died or had moderate to severe MRI injury (solid line) compared with survivors with no or mild MRI injury (dashed line). Bars represent interquartile range.

Fig. 2.

Median pressure passivity index (PPI) over time in HIE infants with adverse (death or moderate to severe MRI injury, solid line) vs. favorable (survivors with no or mild MRI injury, dashed line) outcome. Bars represent interquartile range. Measurements from the left (LH; A) and right (RH; B) hemispheres are shown.