Objective We studied the effect of glycaemia on the cerebral tissue oxygenation index (TOI) and cerebral fractional tissue oxygen extraction (FTOE), as measured by near-infrared spectroscopy (NIRS).

Methods We continuously measured TOI (NIRO 300, Hamamatsu), glycaemia (Medtronic MiniMed CGMS System Gold), mean arterial blood pressure (MABP), saturation (SaO₂) and when possible also tPCO₂ for at least 4 h during the first week of life in neonates with gestational age <32 weeks and weight <1500 g. FTOE was calculated as (SaO₂−TOI)/SaO₂. The Spearman correlation was used to assess the correlations between glycaemia and TOI and FTOE. With partial correlation we corrected for saturation, MABP and tPCO₂.

Results 61 measurements in 22 infants were analysed. In a subgroup of 24 measurements in 11 neonates tPCO₂ was also continuously monitored. None of the patients suffered from severe hypo or hyperglycaemia. In the whole group we found a significant negative correlation (p = 0.0002) between glycaemia and TOI, also after correction for MABP, saturation and tPCO₂ (p = 0.0046). In addition, we found a significant positive correlation between glycaemia and FTOE (p = 0.0055), which remained significant after additional correction for MABP and tPCO₂ (p = 0.01).

Conclusion Our results indicate that in neonates during the first days of life glycaemia influences the cerebral oxygenation—even within the normal ranges and after correction for MABP, SaO₂ and tPCO₂, via changes in the cerebral blood flow.