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

Inclusion Criteria: * Obtained informed consent of parent(s)/legal representative(s) * Age younger than 45thweek of PMA * Age older than 25thweek of PMA * body weight (BW) more than 500g * Previous or planned operation with great demand on POPM * Other diseases demanding great POPM (even without any need of surgery) * Vital functions of the patient will be stable and there will be no suspicion, that patient current condition might be worsen by insertion of c-CELA (every patient will be discussed with attending physician ) Exclusion Criteria: * Decline of informed consent by parent(s) legal representative * Age older than 45thweek of PMA * Age younger than 25th week of PMA * body weight (BW) lower than 500g * Congenital malformation of caudal part of spine ( spina bifida occulta , meningocele, meningomyelocele) * Disease or congenital malformation significantly restricting liver functions (Elevation of liver enzymes more than twice above the physiological range of the corresponding PMA) * Disease or congenital malformation significantly restricting kidney functions (Elevation of urea and creatinine enzymes more than twice above the physiological range of the corresponding PMA) * Clinical condition, which doesn't long-term POPM * Meningism * Patients with proven withdrawal syndrome caused by opiate administration * High risk of bleeding during insertion (coagulopathy) or known administrated anticoagulants which might be still active in the time of insertion of c-CELA * Substantial anemia (under 90g/l), which could lead to blood transfusion due to blood drawing * frequent blood tests associated with the treatment of the patient(with blood samples necessary for the purposes of the study together), which would exceed maximum * any hemodynamically unstable condition (for example septic shock)