EIT During FCV in the Intensive Care Unit

The goal of this clinical trial is to study the effects of Flow Controlled Ventilation (FCV) following conventional mechanical ventilation (Pressure or Volume Controlled Ventilation) in postcardiac surgery ICU-patients to allow for future power calculations and to obtain experience with FCV.The main questions it aims to answer are:What is the effect of FCV on the lung volume measured by Electrical Impedance Tomography (EIT)?What is the effect of FCV on the minute volume?What is the effect of FCV on the mechanical power and dissipated energy?Participants will be ventilated with PCV at baseline and then switched to FCV for 90 minutes while the lung volume, minute volume and mechanical power and dissipated energy levels are measured.

Inclusion Criteria:18 years or older;Informed consent form signed by the subject or a legal representative;Controlled mechanical ventilation via an endotracheal tube -FiO2 ≤50% and PEEP 10 cmH2O or lowerExclusion Criteria:Severe sputum stasis or production requiring frequent bronchial suctioning (more than 5 times per nurse shift)Severe respiratory insufficiency defined as a PaO2 to FiO2 ratio of <100mmHg or moderate to severe ARDS according to the Berlin definition of ARDSUntreated pneumothorax (i.e. no pleural drainage)Hemodynamic instability defined as a mean arterial pressure below 60mmHg not responding to fluids and/or vasopressors or a noradrenalin dose >0.4mg/kg/minExcessive subcutaneous emphysema (prevents proper functioning of the EIT device)Thoracic wounds, bandages or other obstruction which prevent proper functioning of the EIT deviceHigh (>15 mmHg) or instable (an increase in sedation or osmotherapy is required) intracranial pressureAn inner tube diameter of 6mm or less