Here is the design of a clinical trial:

Official Title: Expiratory Flow Limitation and Mechanical Ventilation During Cardiopulmonary Bypass in Cardiac Surgery

Included conditions:
- Mitral Regurgitation
- Aortic Regurgitation

Study Armgroups:
- {'label': 'PEEP and CPAP', 'type': 'EXPERIMENTAL', 'description': 'Patients will be ventilated with positive end-expiratory pressure(PEEP) before and after cardiopulmonary bypass(CPB); during CPB continous positive airway pressure(CPAP) will be adopted.', 'interventionNames': ['Procedure: Use of PEEP before and after CPB', 'Procedure: Ventilation with CPAP during CPB']}
- {'label': 'ZEEP and CPAP', 'type': 'EXPERIMENTAL', 'description': 'Patients will be ventilated without PEEP(ZEEP) before and after cardiopulmonary bypass(CPB); during CPB continous positive airway pressure(CPAP) will be adopted.', 'interventionNames': ['Procedure: No use of PEEP before and after CPB(ZEEP)', 'Procedure: Ventilation with CPAP during CPB']}
- {'label': 'PEEP and NO VM', 'type': 'EXPERIMENTAL', 'description': 'Patients will be ventilated with positive end-expiratory pressure(PEEP) before and after cardiopulmonary bypass(CPB); during CPB no mechanical ventilation will be adopted(no VM)', 'interventionNames': ['Procedure: Use of PEEP before and after CPB', 'Procedure: No ventilation during CPB']}
- {'label': 'ZEEP and NO VM', 'type': 'PLACEBO_COMPARATOR', 'description': 'Patients will be ventilated without PEEP(ZEEP) before and after cardiopulmonary bypass(CPB); during CPB no mechanical ventilation will be adopted(no VM)', 'interventionNames': ['Procedure: No use of PEEP before and after CPB(ZEEP)', 'Procedure: No ventilation during CPB']}

Interventions:
- {'type': 'PROCEDURE', 'name': 'Use of PEEP before and after CPB', 'description': 'PEEP will be set in order to reach an airway pressure of 5 cmH2O', 'armGroupLabels': ['PEEP and CPAP', 'PEEP and NO VM']}
- {'type': 'PROCEDURE', 'name': 'No use of PEEP before and after CPB(ZEEP)', 'description': 'No PEEP will be used', 'armGroupLabels': ['ZEEP and CPAP', 'ZEEP and NO VM']}
- {'type': 'PROCEDURE', 'name': 'Ventilation with CPAP during CPB', 'description': 'A continuous Positive Airway Pressure (CPAP) will be applied during CPB', 'armGroupLabels': ['PEEP and CPAP', 'ZEEP and CPAP']}
- {'type': 'PROCEDURE', 'name': 'No ventilation during CPB', 'description': 'No ventilation will be provided during CPB. Patients will be deconnected from ventilator. Lungs will completely collapse.', 'armGroupLabels': ['PEEP and NO VM', 'ZEEP and NO VM']}

Primary Outcomes:
- {'measure': 'Incidence of expiratory flow limitation in cardiac surgery', 'timeFrame': 'Immediately after weaning from cardiopulmonary bypass'}
- {'measure': 'Incidence of Postoperative pulmonary complications in cardiac surgery', 'timeFrame': 'From immediately after cardiac surgery until discharge from the hospital'}

Please estimate the sample size based on the assumption: 
Two-sided α error of 0.05, 80% power (β), and a drop-out rate of 10%.
Sample size
          Sample size calculation was based on a two-sided Î± error of 0.05 and a 80% power (Î²). On the basis of our experience, we anticipate that the 50% of patients with ventilation cessation during CPB and no PEEP before and after CPB will reach the composite endpoint of EFL after CPB and respiratory complications at 5âdays, while only the 30% of the patients treated with an optimal ventilatory strategy will develop this composite endpoint. Including a drop-out fraction of 10%, we will enroll 51 patients per group, 204 in total.