Abstract
Low-grade germinal matrix-intraventricular hemorrhage (GM-IVH) is the most common complication in extremely premature neonates. The occurrence of GM-IVH is highly associated with hemodynamic instability in the premature brain, yet the long-term impact of low-grade GM-IVH on cerebral blood flow and neuronal health have not been fully investigated. We used an innovative combination of frequency-domain near infrared spectroscopy and diffuse correlation spectroscopy (FDNIRS-DCS) to measure cerebral oxygen saturation (SO2) and an index of cerebral blood flow (CBFi) at the infant’s bedside and compute an index of cerebral oxygen metabolism (CMRO2i). We enrolled twenty extremely low gestational age (ELGA) neonates (seven with low-grade GM-IVH) and monitored them weekly until they reached full-term equivalent age. During their hospital stay, we observed consistently lower CBFi and CMRO2i in ELGA neonates with low-grade GM-IVH compared to neonates without hemorrhages. Furthermore, lower CBFi and CMRO2i in the former group persists even after the resolution of the hemorrhage. In contrast, SO2 does not differ between groups. Thus, CBFi and CMRO2i may have better sensitivity than SO2 in detecting GM-IVH-related effects on infant brain development. FDNIRS-DCS methods may have clinical benefit for monitoring the evolution of GM-IVH, evaluating treatment response, and potentially predicting neurodevelopmental outcome.
Highlights
Variables N Male Gestational age♭ postmenstrual age (PMA) at measurement session(wk)§ Birth weight (g)♭ Apgar at 5 min§ Multiple birth PDA RDS AOP #of measurements
This study demonstrated that the extremely low gestational age (ELGA) infants with low-grade Germinal matrix-intraventricular hemorrhage (GM-IVH) had lower cerebral blood flow (CBF) and CMRO2 than PMA-matched controls, and this difference persists even after the hemorrhages appeared resolved on HUS images
Our study is the first to demonstrate that mild hemorrhage reduces cerebral metabolism in ELGA infants, and this lowered cerebral metabolism is consistent with the hypothesis that germinal matrix (GM)-IVH decreases neuronal migration to the cortex[20]
Summary
Premature infants in the GM-IVH group had younger gestational ages at birth than the control group; the postmenstrual age (PMA), which is more closely correlated with changes in CBF and CMRO2 during early development[31], was the same for both groups for each measurement session. The CBFi and CMRO2i in both groups increased with time but were statistically lower in the GM-IVH group than in the control group (P = 0.04 and 0.03, respectively). Unlike CBFi and CMRO2i, SO2 did not show a significant correlation with PMA or a significant difference between groups (P = 0.16)
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