Here is the design of a clinical trial:

Official Title: Comparison of Two Methods to Airway Clearance in Patients Admitted to Intensive Care Unit for COVID-19: A Pilot Corssover Randomized Controlled Trial

Included conditions:
- COVID-19
- Physiotherapy

Study Armgroups:
- {'label': 'NIOD first', 'type': 'OTHER', 'description': 'In this arm, we will apply for NIOD first which will be performed by non-physiotherapists such as respiratory therapists and bedside nurses. This arm of patients will receive standard CPT at least 3 hours after the NIOD intervention.', 'interventionNames': ['Procedure: Chest physiotherapy using a non-invasive oscillating device']}
- {'label': 'CPT first', 'type': 'OTHER', 'description': 'In this arm, we will apply for CPT first which will be performed by physiotherapists. This arm of patients will receive NIOD procedures which will be performed by non-physiotherapists such as respiratory therapists and bedside nurses at least 3 hours after the CPT intervention.', 'interventionNames': ['Procedure: Chest physiotherapy using a non-invasive oscillating device']}

Interventions:
- {'type': 'PROCEDURE', 'name': 'Chest physiotherapy using a non-invasive oscillating device', 'description': 'NIOD will be implemented on four different parts of the chest walls, 3 minutes for each part and 12 minutes in total per each session. Left and right front and posterior chest walls will be stimulated, particularly, on the anterior chest, intercostal spaces 1-2 above nipple line and lateral side of the mid-clavicular line 1-2 below intercostal spaces. The intensity of the NIOD can be selected between 80-100%, which is pre-specified on the machine.', 'armGroupLabels': ['CPT first', 'NIOD first']}

Primary Outcomes:
- {'measure': 'SpO2/FIO2 Ratio', 'description': 'Difference before the procedure and 10 minutes from the end of the procedure', 'timeFrame': '10 minutes and 30 minutes from the end of the procedure'}

Please estimate the sample size based on the assumption: 
Power of 0.90, significance level (alpha) of 0.05
Numbers to be randomized (sample size)
          We estimate the necessary sample size as 25 for each arm (total 50 cases), with a power of 0.90 and an alpha of 0.05, with a non-inferiority design.