Influence of Personalized Lung Volume Optimization Maneuver on Lung Function and Cardiac Performance in Children

This trial is studying whether a special breathing (lung volume) technique used during mechanical ventilation improves heart function and lung flexibility in two groups: children with congenital heart disease undergoing heart surgery, and children with severe respiratory failure who are on or at risk of needing ECMO (a life support machine that does the work of the heart and lungs). **You may be eligible if...** - For the heart surgery group: your child has congenital heart disease and is having surgery requiring a heart-lung bypass machine - For the ECMO group: your child has severe respiratory failure and is on ECMO or at serious risk of needing it, and is on mechanical ventilation **You may NOT be eligible if...** - Your child has a single-ventricle heart defect (for the heart surgery group) - Your child is already on ECMO or a ventricular assist device (VAD) (for the heart surgery group) - Your child was born premature (before 36 weeks) - Your child has chronic lung disease or severe lung underdevelopment - A parent or guardian has not provided informed consent Talk to your doctor to see if this trial is right for you.