Introduction Beneath the brain, regional tissue oxygenation of peripheral muscle, abdomen, and kidneys is used in adult and paediatric intensive care patients. The aim of the present study was to measure by means of NIRS cerebral and peripheral tissue oxygenation index (c-TOI, p-TOI) in healthy neonates, in order to establish normal values.

Methods The NIRO 300 (Hamamatsu) was used, the optodes were attached to the frontoparietal region and to the left calf. p-TOI and c-TOI were measured simultaneously. To increase the precision of measurements optodes were re-applied five times. Measurements were performed during undisturbed daytime sleep after a feeding. Heart rate and SaO₂ were measured by pulse oximetry. Central and peripheral temperatures, and mean blood pressure were measured before and after NIRS measurements. Diameter of calf and subcutaneous adipose tissue was measured with ultrasound. p-TOI and c-TOI were determined as mean values of the repeated measurements in each neonate. For comparison a paired t test was performed. Data are represented as mean (± SD).

Results 20 healthy newborn infants were included (gestational age 35 weeks (± 3.8), birth weight 2209 g (± 684)). Out of the 500 measurements 365 were included for further analysis. p-TOI (62.1 ± 5.7%) was significantly lower compared with c-TOI (70.4 ± 6.7%) (p<0.001). The index c-TOI/p-TOI was 1.14 (± 0.14).

Conclusion Comparison of p-TOI and c-TOI in healthy neonates showed a significant difference between the two values. Comparisons of peripheral and cerebral TOI might become helpful in future to detect early disturbances in circulation and oxygenation, especially in states of shock.