Here is the design of a clinical trial:

Official Title: Early Versus Differed Arterial Catheterization in Critically Ill Patients With Acute Circulatory Failure: A Multicentre, Open-label, Pragmatic, Randomised, Non-inferiority Controlled Trial (EVERDAC Trial)

Included conditions:
- Acute Circulatory Failure

Study Armgroups:
- {'label': 'Non-invasive strategy', 'type': 'EXPERIMENTAL', 'description': 'Non-invasive strategy consisting of blood pressure monitoring by non-invasive automated cuff measurements', 'interventionNames': ['Procedure: Non-invasive strategy']}
- {'label': 'Control strategy', 'type': 'OTHER', 'description': 'Usual strategy of systematic indwelling arterial catheter insertion in the early hours of acute circulatory failure', 'interventionNames': ['Procedure: Control strategy']}

Interventions:
- {'type': 'PROCEDURE', 'name': 'Non-invasive strategy', 'description': 'No indwelling arterial catheter insertion will be allowed during the first 28 days, excepted if predefined safety criteria (indicating absolute need of indwelling arterial catheter insertion) are reached.\n\nIn the "non-invasive" group, automated oscillometric monitor will be used to monitor BP (blood pressure).', 'armGroupLabels': ['Non-invasive strategy']}
- {'type': 'PROCEDURE', 'name': 'Control strategy', 'description': 'An indwelling arterial catheter will be inserted as soon as possible (within the first four hours after randomization) and will be maintained except in case of indwelling arterial catheter futility, suspected or proven indwelling arterial catheter related infection or thrombosis (at discretion of attending physician) until day 28 or ICU (Intensive Care Unit) discharge (whichever comes first). After day 28, clinicians may choose to maintain or to remove indwelling arterial catheter.', 'armGroupLabels': ['Control strategy']}

Primary Outcomes:
- {'measure': 'All-cause mortality by 28 days after randomisation', 'timeFrame': 'Patients will be followed from randomization to day 28'}

Please estimate the sample size based on the assumption: 
Non-inferiority margin set at 5%, power at 80%, and alpha risk at 5%.
Sample size calculation
        The hospital mortality of patients with septic shock, the most prevalent cause of shock in the ICU, is around 30%â35% depending on initial lactate level.52 We speculated that the day 28 mortality would be lower, around 25% in the study cohort for several reasons: (1) Patients with shock other than septic shock can be included, and the mortality rates of haemorrhagic, hypovolaemic non-haemorrhagic and cardiogenic shock are highly variable depending on the cause; (2) The use of vasopressor is not mandatory for inclusion, so patients with short-lived hypotension (but with at least one sign of hypoperfusion) can be included; (3) Patients with very high vasopressor dosages are excluded and (4) Patients with severe traumatic brain injury are excluded, an exclusion policy which should lower the mortality rate of the haemorrhagic shocks of traumatic origin.
        We assume that the mortality rate at day 28 will be 22.5% in the ânon-invasiveâ group and 25% in the control (invasive, usual care) group. With the non-inferiority margin set at 5%, power at 80% and alpha risk at 5%, the inclusion of 1010 patients is needed.
        The 5% non-inferiority margin has been obtained through a consensus between the investigators and the methodologists of the study, considering that a 5% difference is the smallest value that would be clinically relevant between arms.