Here is the design of a clinical trial:

Official Title: High-exchange ULTrafiltration to Enhance Recovery After Pediatric Cardiac Surgery (ULTRA): A Canadian Randomized Controlled Trial

Included conditions:
- Congenital Heart Disease

Study Armgroups:
- {'label': 'High-Exchange Ultrafiltration', 'type': 'EXPERIMENTAL', 'description': 'Subzero-Balance Simple Modified Ultrafiltration (60ml/kg/hour)', 'interventionNames': ['Procedure: Ultrafiltration']}
- {'label': 'Low-Exchange Ultrafiltration', 'type': 'ACTIVE_COMPARATOR', 'description': 'Subzero-Balance Simple Modified Ultrafiltration (6ml/kg/hour)', 'interventionNames': ['Procedure: Ultrafiltration']}

Interventions:
- {'type': 'PROCEDURE', 'name': 'Ultrafiltration', 'description': "Ultrafiltration is used during cardiac surgery with cardiopulmonary bypass to remove both fluid and small molecules such as inflammatory cytokines from the patient's circulation.", 'armGroupLabels': ['High-Exchange Ultrafiltration', 'Low-Exchange Ultrafiltration']}

Primary Outcomes:
- {'measure': 'Peak Vasoactive-Ventilation Renal Score', 'timeFrame': 'Up to 5 days'}

Please estimate the sample size based on the assumption: 
Two-way ANOVA with stratification by STAT score (STAT 1 and STAT 2-5), alpha=0.05, beta=0.2.
Sample size
        The primary outcome of ULTRA is the peak postoperative VVR score. The sample size calculation was based on a minimal clinically important relative reduction in the primary outcome of 25%. This threshold was identified by consultation with clinical experts and represents a significant improvement in cardiopulmonary and vasomotor function. A two-way analysis of variance (ANOVA)which considered the stratification by STAT score (STAT 1 and STAT 2â5) with alpha=0.05 and beta=0.2. The decision to stratify by surgical risk STAT score was crucial to ensure this variable is balanced for comparison between treatment groups, as STAT score is strongly correlated with morbidity and mortality after paediatric cardiac surgery.21 The sample size calculation used peak VVR data from the pilot study for patients that matched ULTRAâs inclusion criteria. According to these parameters, 48 patients in each group are required, yielding a total of 96 patients.