Perioperative Change of Regional Ventilation During Spontaneous Breathing

Inclusion Criteria: * Adult * Inpatient * Surgery under general anesthesia with and without additional regional anesthesia * increased risk for postoperative pulmonary complications according to the ARISCAT-Score (except pilot arm for osteosynthesis of flail chest) Exclusion Criteria: * Missing informed consent * Outpatient * Emergency procedure * Revision surgery of hospitalized patients * Operation under local or regional anesthesia alone * Expected postoperative ventilation * Expected hospital stay of less than three days * Pregnancy * Allergy against material of the electrode belt (silicone rubber, stainless steel, gold-plated brass) * Injured, inflamed or otherwise affected skin within the target region of the electrode belt * Unstable spine injury * Body mass index of more than 50 kg/m2 * Incapacity to lie quietly for the examination * Pacemaker, defibrillator or other active implant * Reoperation before the examination at the third postoperative day