NIRS Monitoring in Premature Infants

Introduction and specific aims:

Germinal matrix-intraventricular hemorrhage (GM-IVH) occurs in 45% of extremely low birth weight (ELBW) premature infants, often leading to long-term neurodevelopmental impairments (NDI). Post-hemorrhagic hydrocephalus (PHH) is a common complication of GM-IVH and increases the risk of major NDI to 75-90%. Currently, the only bedside tool to assess for hemorrhage and monitor for secondary hydrocephalus is ultrasound. Although increasing ventricular size is currently used to determine need for intervention, measures based on cerebral physiology are needed to better determine the impact of the expanding ventricles on individual cerebral metabolism.

Our group has developed advanced FDNIRS-DCS technology for monitoring cerebral oxygen metabolism (CMRO2) in newborns at the bedside. We hypothesize that baseline and evoked cerebral metabolic dysfunctions are better biomarkers for GM-IVH and PHH severity and response to PHH treatment. To test our hypotheses, we will address the following specific aims:

Aim 1: Determine post-natal cerebral hemodynamics and oxygen metabolism trajectories in GM-IVH and PHH neonates with respect to normal controls and differences between PHH infants and infants affected by hydrocephalus due to other pathologies.

We hypothesize that:

• Infants with GM-IVH have lower CBF and CMRO2 than healthy controls and the decrease is in proportion to the severity of GM-IVH. (GM-IVH vs HC)
• Infants with PHH have lower CBF and CMRO2 than healthy controls. (PHH vs HC)
• For infants who developed PHH, the decrease of CBF and CMRO2 is affected by both hemorrhages and the severity of hydrocephalus. (PHH vs VC)

Aim 2: Test the efficacy of cerebral hemodynamics and metabolism in detecting hydrocephalus treatment response in both PHH and VC groups.

We hypothesize that CBF and CMRO2 increase in response to treatment-associated improvements in hydrocephalus but remain depressed when response to treatment is inadequate.

Aim 3: Test the sensitivity of FDNIRS-DCS measured cerebral hemodynamics and oxygen metabolism in predicting developmental outcomes in infants with GM-IVH and PHH. We will assess neurodevelopmental outcomes in all enrolled infants at 5-7, 10-12, and 22-24 months corrected age and correlate with FDNIRS-DCS measurements of CBF and CMRO2, and related quantities with neurodevelopmental outcomes at approximately 5-7, 10-12, and 22-24 months corrected age.

• GM-IVH group:

Inclusion criteria

for GM-IVH group: born at gestational age (GA) 24-32 weeks; < 3 months old corrected-GA (cGA) at first measure or eligible for measurement within 12 weeks after the infant reaches 40 weeks post-menstrual age (PMA). Grade I-III IVH diagnosed by clinical cranial ultrasound or magnetic resonance imaging (MRI).

Exclusion criteria

for GM-IVH group: chromosomal abnormalities known at the time of enrollment; known or suspected metabolic disorder or neoplasm; critical congenital heart disease; congenital hydrocephalus; brain lesions that affect cerebral brain metabolism, other than GMH-IVH; central nervous system (CNS) infection.

• PHH group:

Inclusion criteria

for PHH group: born at gestational age (GA) 24-37 weeks < 3 months old cGA at first measure or eligible for measurement within 12 weeks after the infant reaches 40 weeks age (PMA). PHH diagnosed by clinical cranial ultrasound or MRI.

Exclusion criteria

for PHH group: chromosomal abnormalities known at the time of enrollment; known or suspected metabolic disorder or neoplasm; critical congenital heart disease; congenital hydrocephalus; brain lesions that affect cerebral brain metabolism, other than IVH-PHH; CNS infection. Implanted devices or other devices that preclude the use of MRI.

• HC group:

Inclusion criteria

for HC group: born at gestational age (GA) 24-32 weeks; < 3 months old cGA at first measure or eligible for measurement within 12 weeks after the infant reaches 40 weeks age (PMA); Apgar >7 at 5 min.

Exclusion criteria

for HC group: any clinical indication of brain injury or congenital brain malformation; chromosomal abnormality known at the time of enrollment; known or suspected metabolic disorder or neoplasm; critical congenital heart disease; CNS infection.

• VC group:

Inclusion criteria

for VC group: < 12 months old cGA at first measure or eligible for measurement within 1 year after the infant reaches 40 weeks age (PMA). Symptomatic hydrocephalus of any etiology or at high risk of developing hydrocephalus of any etiology, except post-hemorrhagic etiology; characterized by abnormal rate of head growth and full anterior fontanelle. Ventricular enlargement diagnosed by ultrasonography or MRI; no signs of IVH.

Exclusion criteria

for VC group: known or suspected metabolic disorder or neoplasm; critical congenital heart disease; CNS infection. Implanted devices or other devices that preclude the use of MRI.