An Insidious Threat for Cerebral Oxygenation: Neonatal Hypoglycemia

Abstract

Purpose: Neonatal hypoglycemia (NH) is frequent in neonatology practice. This study aimed to evaluate the regional cerebral tissue oxygenation and cerebral blood flow in neonates who developed NH immediately after birth. Methods: This prospective study included infants who developed NH (n=50) and the control healthy term neonates (n=50). Infants with NH are monitored in terms of continuous regional cerebral tissue oxygenation (rcSO2 ) via near-infrared spectroscopy (NIRS) during the first 24 hours of life. Middle cerebral artery (MCA) blood flow was evaluated by doppler ultrasound at the first and 24 hours of life. The pulsatility index (PI) was measured to assess cerebral vascular resistance. Results: The mean gestational age, birth weights and hemoglobin levels of infants were similar. The mean rcSO2 was continuously higher and fractional tissue oxygen extraction (FTOE) was lower in infants with NH. The mean MCA PI values at the first and 24th hours of life were significantly higher in NH. Conclusions: This study shows that cerebral perfusion was impaired in infants with NH. They had higher rcSO2 , lower FTOE values and increased PI compared to healthy term infants. We suggest that increased PI may reflect increased vascular resistance and higher rcSO2 values associated with increased cerebral perfusion as a compensatory auto-regulatory response mechanism. Significantly lower FTOE values may dedicate decreased cerebral tissue oxygen extraction resulting from impaired cerebral perfusion even in the presence of auto-regulatory mechanisms. Therefore, even if they are asymptomatic, long term neurological outcomes should be followed in infants with NH due to impaired cerebral perfusion.

Keywords

• neonate
• hypoglycemia
• nirs
• cerebral oxygenation
• cerebral perfusion