Here is the design of a clinical trial:

Official Title: Sodium Bicarbonate for the Treatment of Severe Metabolic Acidosis With Moderate or Severe Acute Kidney Injury in the Critically Ill: a Randomized Clinical Trial

Included conditions:
- Metabolic Acidosis
- Acute Kidney Injury

Study Armgroups:
- {'label': 'control group', 'type': 'NO_INTERVENTION', 'description': 'The physicians will resuscitate the patients according to the current critical care medicine guidelines.'}
- {'label': 'Sodium bicarbonate group', 'type': 'EXPERIMENTAL', 'description': "Patients randomly assigned to bicarbonate group will receive intravenous 4.2% sodium bicarbonate titrated from 125ml to 250ml in 30min at physician's discretion to target a pH equal or above 7.30. Bicarbonate infusion will be repeated up to 1000ml per 24h. Arterial blood gases will be repeated from 3 to 6 times during the first 24h at physician's discretion", 'interventionNames': ['Drug: Sodium bicarbonate infusion']}

Interventions:
- {'type': 'DRUG', 'name': 'Sodium bicarbonate infusion', 'description': "Patients randomly assigned to bicarbonate group will receive intravenous 4.2% sodium bicarbonate titrated from 125ml to 250ml in 30min at physician's discretion to target a pH equal or above 7.30. Bicarbonate infusion will be repeated up to 1000ml per 24h. Arterial blood gases will be repeated from 3 to 6 times during the first 24h at physician's discretion.\n\nBicarbonate infusion recommendations will be as follow: a central line is recommended, infusion will be slow (125-250ml in 30 min, no intravenous push), careful surveillance of metabolic alkalosis, cardiogenic pulmonary edema, kalemia, natremia and calcemia. Repeated arterial blood gases will be suggested to monitor these critically ill patients and physicians will be reinformed of the potential side effects of sodium bicarbonate infusion.", 'armGroupLabels': ['Sodium bicarbonate group']}

Primary Outcomes:
- {'measure': 'Day 90 all-cause mortality', 'description': 'Day 90 all cause mortality', 'timeFrame': 'Day 90'}

Please estimate the sample size based on the assumption: 
The trial is designed for 80% power with a two-sided alpha level of 0.05. It assumes less than 8% non-analyzable patients and includes two interim analyses with a p value threshold of 0.001 for interim analyses and 0.05 for the final analysis (Haybittle-Peto boundary).
Sample size
        Based on the BICARICU-1 trial where day 90 mortality was 81% in the control group and 64% in the bicarbonate group (post hoc analysis of BICARICU-1 trial,17) in the population of interest for the BICARICU-2 trial (severe metabolic acidosis and severe acute kidney injury in the critically ill patients), we calculated that a total of 588 patients would be needed for 80% power to show an absolute between-groups difference of 10% in the primary outcome (day 90 all-cause mortality) at a two-sided alpha level of 0.05 (overall p value for the trial), assuming that the administration of bicarbonate would be associated with a day 90 mortality of 70% vs 80% in the control group. Assuming less than 8% non-analyzable patients (lost to follow-up or consent withdrawal; the same rate as in the BICARICU-1 trial), we plan to enrol 640 patients. Two interim analyses are planned. Assuming the overall p value for the trial is 0.05, p value threshold is 0.001 for the two interim analyses and 0.05 for the final analysis (Haybittle-Peto boundary).