Early Glycemic Profile Is Associated with Brain Injury Patterns on Magnetic Resonance Imaging in Hypoxic Ischemic Encephalopathy.

OBJECTIVE: To investigate whether the early glycemic profile in infants with hypoxic ischemic encephalopathy is associated with distinct patterns of brain injury on magnetic resonance imaging (MRI). STUDY DESIGN: We performed a secondary analysis of 178 prospectively enrolled infants who received therapeutic hypothermia for hypoxic ischemic encephalopathy. Glycemic profiles were identified by glucose concentrations within 24 hours after birth: normoglycemia (all glucose concentrations of >47 to ≤150 mg/dL; n = 62); hypoglycemia (≥1 concentration ≤47 mg/dL; n = 17); hyperglycemia (≥1 concentration >150 mg/dL; n = 76); and labile glucose (both hypoglycemia and hyperglycemia; n = 23). Patterns of brain injury were identified for 151 infants based on Barkovich scores from the postrewarming brain MRIs at a median age of 9 days. RESULTS: A normal brain MRI was reported in 37 of 62 infants (60%) with normal blood glucose values compared with 37 of 116 infants (32%) with an abnormal glucose profile (adjusted for Sarnat stage of encephalopathy and Apgar score at 5 minutes; P = .02). The distribution of MRI patterns of brain injury differed among the glycemic groups (P = .03). The odds of predominant watershed or focal-multifocal injury was higher in infants with hypoglycemia (aOR, 6; 95% CI, 1.5-24.2) and labile glucose (6.6; 95% CI, 1.6-27) compared with infants with normoglycemia. Infants with labile glucose had higher odds (5.6; 95% CI, 1.1-29.3) of predominant basal ganglia or global injury compared with infants with normal blood glucose values. CONCLUSIONS: The early glycemic profile in infants with hypoxic ischemic encephalopathy is associated with specific patterns of brain injury on MRI. Further investigation is needed to explore its prognostic significance and role as a phenotype biomarker.

The Impact of Surgical Patent Ductus Arteriosus Closure on Autonomic Function in Premature Infants.

Background Patent ductus arteriosus (PDA) is a common complication of prematurity and a risk factor for poor outcome. Infants undergoing surgical PDA ligation are at highest risk for neurodevelopmental injury. Autonomic dysfunction has been described in premature infants with PDA. Aim To interrogate the autonomic nervous system by analysis of advanced heart rate variability (HRV) metrics before and after surgical closure of the PDA. Study Design Prospective, observational study. Subjects Twenty-seven infants born before 28 weeks' gestation were included in this study. Methods Continuous electrocardiogram data were sampled at a rate of 125 Hz for a total of 6 hours before and 6 hours after 30 hours of surgical closure. HRV was determined by detrended fluctuation analysis to calculate the short and long root mean square (RMSL and RMSS) and α components at two time scales (long and short). Results Gestational age (GA) was positively associated with RMSL, RMSS, and αS and was negatively associated with αL. There was no difference between RMSs, RMSL, αS, or αL before and after surgery; however, median heart rate was lower after surgery (p < 0.01). Conclusion Advancing GA is highly associated with increasing HRV; however, surgical ligation does not affect HRV in the postoperative period.

Positive fluid balance is associated with death and severity of brain injury in neonates with hypoxic-ischemic encephalopathy.

OBJECTIVE: To investigate the association between fluid balance during therapeutic hypothermia (TH) and severity of brain injury on magnetic resonance imaging (MRI) in neonates with hypoxic-ischemic encephalopathy (HIE). STUDY DESIGN: This is a secondary analysis of data from a prospective observational study in neonates with HIE. Daily net positive fluid balance during TH was investigated for association with the adverse primary outcome of death or moderate-to-severe brain injury on MRI using multivariable logistic regression. RESULTS: Of the 150 neonates included, 50 suffered adverse outcome and had significantly higher net positive fluid balance (53 vs. 19 ml/kg/day, p < 0.01) during first 24 hours of TH. Neonates with a net positive fluid balance (>25 ml/kg/day) at 24 hours of TH had 3.4 (95% CI 1.3-9) times higher odds of adverse outcome. CONCLUSIONS: Positive fluid balance during TH in neonates with HIE is independently associated with death or moderate-to-severe brain injury on MRI.

Cerebral venous volume changes and pressure autoregulation in critically ill infants.

OBJECTIVE: To determine whether ventilator-related fluctuations in cerebral blood volume (CBV) are associated with cerebral pressure passivity. STUDY DESIGN: In a prospective study of newborns undergoing positive-pressure ventilation, we calculated coherence between continuous mean arterial pressure (MAP) and cerebral near-infrared spectroscopy hemoglobin difference (HbD). Significant HbD-MAP coherence indicated cerebral pressure passivity. CBV changes were measured as the spectral power of total hemoglobin (SHbT) at the ventilator frequency. A regression model tested whether SHbT predicts cerebral pressure passivity and/or death/brain injury, controlling for birth gestational age and other factors. RESULTS: We studied 68 subjects with prematurity (n = 19), congenital heart disease (n = 11), and hypoxic-ischemic encephalopathy (n = 38). SHbT, sedative use, and pCO2 were positively associated, and circulating hemoglobin negatively associated, with cerebral pressure passivity (p < 0.001), which was positively associated with brain injury (p < 0.001). CONCLUSION: In sick newborns, ventilator-related CBV fluctuations may predispose to cerebral pressure passivity, which may predispose to an adverse neonatal outcome.