Here is the design of a clinical trial:

Official Title: Comparison of Dexmedetomidine and Meperidine for the Prevention of Shivering Following Coronary Artery Bypass Graft: Study Protocol of a Randomized Controlled Trial

Included conditions:
- Coronary Artery Disease
- Postoperative Shivering

Study Armgroups:
- {'label': 'Dexmedetomidine group', 'type': 'EXPERIMENTAL', 'interventionNames': ['Drug: Dexmedetomidine']}
- {'label': 'Meperidine group', 'type': 'ACTIVE_COMPARATOR', 'interventionNames': ['Drug: Meperidine']}
- {'label': 'Control group', 'type': 'PLACEBO_COMPARATOR', 'interventionNames': ['Drug: Placeb']}

Interventions:
- {'type': 'DRUG', 'name': 'Dexmedetomidine', 'description': 'Dexmedetomidine would be intravenously infused at a dose of 1μg/kg over 15 minutes 30 min before the end of surgery', 'armGroupLabels': ['Dexmedetomidine group']}
- {'type': 'DRUG', 'name': 'Meperidine', 'description': 'Meperidine would be intravenously injected at a dose of 0.5mg/kg 30 min before the end of surgery', 'armGroupLabels': ['Meperidine group']}
- {'type': 'DRUG', 'name': 'Placeb', 'description': 'Equal volume of normal saline to dexmedetomidine and meperidine group.', 'armGroupLabels': ['Control group']}

Primary Outcomes:
- {'measure': 'The incidence of postoperative shivering', 'description': 'The incidence and severity of postoperative shivering and the rescue treatment', 'timeFrame': 'Within postoperative 24 hours'}

Please estimate the sample size based on the assumption: 
Statistical power is set to 0.80 with a one-sided type I error of 0.05. An attrition rate of 5% is assumed.
Sample size
        Regarding the sample size, we calculated statistical power prior to the study. We set the statistical power to 0.80 with a one-sided type I error of 0.05. Patients will be randomly assigned into group Dex, group M and group P in 1:1:1 ratio. According to previous studies, we assumed that the incidence of shivering in group Dex and group M was 23% and 46.48%, respectively.20 21 Based on these parameters, we calculated the sample size of 55 patients per group. To compensate for potential drop-outs or inadequate procedures, we assumed an attrition rate of 5% and determined that 60 patients will be required in each group, to make a total of 180 patients.