Measurement of Cerebral Oxygenation With Near Infrared Spectroscopy During Blood Sampling From a Peripheral Artery Catheter in Preterm Infants With Gestational Age <37+0

Preterm infants often need peripheral artery catheters for invasive blood pressure recording and to facilitate blood sampling. Near infrared spectroscopy is a method to evaluate cerebral oxygenation and as well as cerebral blood flow. Sampling procedures with identical sampling volumes are performed at a short (40 seconds) and a long (70 seconds) time intervall while changes of cerebral oxygenation are measured. The investigators hypothesise that slower sampling decrease changes in cerebral blood flow.