Here is the design of a clinical trial:

Official Title: Comparing the Effectiveness of Side-lying Sleep Positioning to Back-lying at Reducing Oxygen Desaturation Resulting From Obstructive Sleep Apnoea in Infants With Cleft Palate

Included conditions:
- Obstructive Sleep Apnea
- Cleft Palate

Study Armgroups:
- {'label': 'Back lying sleep position', 'type': 'EXPERIMENTAL', 'description': 'sleep on the back', 'interventionNames': ['Other: back sleep positioning']}
- {'label': 'Side lying sleep position', 'type': 'EXPERIMENTAL', 'description': 'sleep on the side', 'interventionNames': ['Other: side sleep positioning']}

Interventions:
- {'type': 'OTHER', 'name': 'back sleep positioning', 'description': 'sleeping on the back.', 'armGroupLabels': ['Back lying sleep position']}
- {'type': 'OTHER', 'name': 'side sleep positioning', 'description': 'sleeping on the side', 'armGroupLabels': ['Side lying sleep position']}

Primary Outcomes:
- {'measure': 'Oxygen saturation during sleep at 1 month of age', 'description': 'Oxygen saturation during sleep at 1 month of age (expressed as 4% oxygen desaturation index, ODI-4). Oximetry is considered the mainstay of assessment of oxygenation in infants and will be the primary outcome measurement instrument. The ODI-4 represents the average number of times that oxygen saturation falls by at least 4% from baseline every hour.', 'timeFrame': '1 month of age'}

Please estimate the sample size based on the assumption: 
To detect a difference of 0.5 SDS with 80% power and alpha equal to 0.05, and to account for potential unequal variances with a variance ratio of 2. The sample size is inflated to allow for a potential attrition rate of 21%.
Sample size
        Data from the feasibility study21 and published studies22 have reported estimates of the SD of the primary outcome ODI-4 in the side-lying infants at 4 weeks to range from 8 to 11 units, with a higher SD observed in the back-lying group. The observed difference in mean ODI-4 between the side-lying and back-lying infant cohorts was 15 units (a standardised effect size of 0.91).21 It was considered a smaller but more realistic difference in means of five units to be a clinically important difference (SD 10), a standardised effect size of 0.5. The sample size calculation comparing two means with unequal variances for the primary outcome was, therefore, based on a standardised effect size of 0.5. To account for potential unequal variances in each group a variance ratio of 2 was used in the calculations. To detect a difference of 0.5 SDS with 80% power and alpha equal to 0.05 would require 96 infants to be monitored in each arm of the trial (a total of 192 participants). Informed by the multicentre feasibility and oximetry studies the sample size will be inflated to 244 participants in the RCT, to allow for potential attrition of 21%.