Here is the design of a clinical trial:

Official Title: Thiamine As Adjunctive Therapy for Diabetic Ketoacidosis

Included conditions:
- Diabetic Ketoacidosis

Study Armgroups:
- {'label': 'Thiamine', 'type': 'EXPERIMENTAL', 'description': '200mg IV thiamine in 50mL 0.9% saline twice daily for 2 days', 'interventionNames': ['Drug: 200mg IV thiamine in 50mL 0.9% saline']}
- {'label': 'Placebo', 'type': 'PLACEBO_COMPARATOR', 'description': '100mL 0.9% saline twice daily for two days', 'interventionNames': ['Drug: Placebo']}

Interventions:
- {'type': 'DRUG', 'name': '200mg IV thiamine in 50mL 0.9% saline', 'description': 'Thiamine 200mg IV every 12 hours for 2 days', 'armGroupLabels': ['Thiamine'], 'otherNames': ['Vitamin B1']}
- {'type': 'DRUG', 'name': 'Placebo', 'description': '50mL 0.9% saline', 'armGroupLabels': ['Placebo']}

Primary Outcomes:
- {'measure': 'plasma bicarbonate levels', 'description': 'Our primary outcome is change in bicarbonate over the 24 hours following enrollment with measurements at 0, 6, 12, 18, 24 hours using a linear-effects model', 'timeFrame': '24 hours'}

Please estimate the sample size based on the assumption: 
The study assumes a type-I error of 0.05, a power of 99%, and a small dropout rate of less than 20%. The variance-covariance structure of the bicarbonate data follows a compound-symmetry structure with a between-subject variance of 3.8.
Sample size
        The analysis method for the primary endpoint will be linear mixed-effects modelling (LMM). This type of modelling is used in longitudinal or repeated measures studies to take into account the correlation of within-subject measurements. In this study, each subject is expected to have five bicarbonate measurements, one at 0, 6, 12, 18 and 24 hours, which are correlated. Based on preliminary data from a pilot study, which had three consistent time points, we observed that patients with DKA had a mean of 8.9 mEq/L at time 0, 18 mEq/L at 12 hours and 20 mEq/L at 24 hours. We took a conservative position to assume that the potential effect size (the mean difference of bicarbonate between the two groups) will be 20%. That is, we assumed that the mean bicarbonate level at the three different time points was 8.9 mEq/L, 21.6 mEq/L and 22.5 mEq/L. We then simulated the longitudinal data with the assumption that the varianceâcovariance structure of the bicarbonate data followed a compound-symmetry structure with between-subject variance of 3.8. The linear-mixed effects model was used on the simulated data to obtain the estimated F statistic, numerator and denominator df. From these estimates, the non-centrality parameter was computed and used to obtain the power. With 80 subjects with type-I error of 0.05, we have a power of 99% to detect the stated difference over 0, 12 hours and 24 hours. The addition of two more time points with similar between-subject variance will increase our power. We plan to enrol 100 subjects (50 thiamine and 50 placebo) to allow for a small drop-out rate (less than 20%; due to reasons such as subject withdrawal, hospital discharge or death prior to outcomes of interest, potentially missing data due to patient clinical care (eg, having testing done, having access issues for blood draws, etc) and to ensure adequate power for the preplanned key analysis of thiamine-deficient patients.