Cerebral hypoxia immediately following delivery of very low birth weight infants To the Editor Reference ranges for regional cerebral tissue oxygen saturation (crSO2) reported by Pichler et al are an important step towards implementation of crSO2 monitoring during resuscitations.1 At the Erasmus Medical Centre, Rotterdam, we found a surprising crSO2 observation in the first 10 infants (264/7 weeks [263/7-271/4], birth weight 910 g [705-960g]) that we evaluated. They had very low initial crSO2 (15% [15-15%] [median {IQR}]). Because there is so little variation at the start of the resuscitation there is no variance in the IQR, as can be seen in the Figure. The Figure shows the observed values in relation to the percentiles published by Pichler et al.1 Infants were resuscitated according to local guidelines, based upon European Resuscitation Council guidelines.2 Arterial oxygen saturation was measured with a Nellcor N600-x pulseoximeter, and crSO2 was measured with an Invos 5100C (Covidien, Dublin, Ireland). During resuscitation, SpO2 and Apgar scores were similar to prior observations at our institution.2 Infants left the resuscitation area with crSO2 of 59% (47%-64%). The only other published observation of the crSO2 in very preterm infants is by Fuchs et al in infants