Pharmacokinetics and Pharmacodynamics of Levobupivacaine During Continuous Caudal Epidural Analgesia in Newborns

The goal of this clinical trial is to learn about the pharmacokinetics of levobupivacaine in newborns during the continus caudal epidural analgesia. This type of analgesia is used for severly ill newborns. There is a need to lower the opioid doses for this population who is undergoing the surgery due to the life threading indication. In some cases it is considered to use the epidural analgesia for the sake of the patient. The main question is: Is the commonly used dosing of 0,25% levobupivacaine in dose 0,2-0,3mg/kg/h the ideal dosing for these patients? Is this type of dosing of epidural analgesia safe and effective for newborns?