Here is the design of a clinical trial:

Official Title: Hyperbaric Oxygen for Treatment of Long COVID Syndrome; A Randomized, Placebo-Controlled, Double-Blind, Phase II Clinical Trial

Included conditions:
- COVID-19
- Post COVID-19 Condition
- Post COVID-19 Condition, Unspecified
- Post COVID Condition
- Post-COVID Syndrome
- Post-Acute COVID-19 Syndrome

Study Armgroups:
- {'label': 'Hyperbaric oxygen treatment', 'type': 'EXPERIMENTAL', 'description': 'HBO2 240 kPa, 90 min, maximum 10 treatments', 'interventionNames': ['Drug: Hyperbaric oxygen']}
- {'label': 'Sham treatment', 'type': 'PLACEBO_COMPARATOR', 'description': 'Air 134-120 kPa, 90 min, maximum 10 treatments', 'interventionNames': ['Procedure: Sham treatment']}

Interventions:
- {'type': 'DRUG', 'name': 'Hyperbaric oxygen', 'description': 'Hyperbaric oxygen 240 kPa for 90 minutes (with 10 min compression time, 2 air bakes and 10 minutes decompression time).', 'armGroupLabels': ['Hyperbaric oxygen treatment'], 'otherNames': ['HBO', 'HBO2', 'HBOT']}
- {'type': 'PROCEDURE', 'name': 'Sham treatment', 'description': 'Sham treatment 134-120 kPa Air (with 5 min compression time, and 5 min decompression to 120 kPa, two air brakes will be reported to the subjects)', 'armGroupLabels': ['Sham treatment'], 'otherNames': ['Placebo']}

Primary Outcomes:
- {'measure': 'RAND 36 change', 'description': 'Mean change from baseline to 13 weeks in RAND 36 domains role limitations due to physical health (RP) and physical functioning (PF).\n\nRAND 36 is a self-reporting questionnaire that contains 36 items that measure eight concepts of health in general terms, at present and past four weeks. Numeric values from the survey are coded so that all items are scored from 0 (lowest score) to 100 (highest possible score). Scores then represent the percentage of total possible score achieved. Items in the same scale are averaged together to create the eight scale scores. Items that are left blank (missing data) are not taken into account when calculating the scale scores. Hence, scale scores represent the average for all items in the scale that the respondent answered.', 'timeFrame': 'Baseline and 13 weeks'}

Please estimate the sample size based on the assumption: 
80% power, 0.05 significance level, common SD of 15, t-test for independent groups.
Sample size calculation
        The primary endpoint is mean change from baseline to week 13 in the RAND-36 score. A 10-point higher mean change in the HBOT group compared with the placebo group is considered as a clinically relevant difference. Sample size calculation was performed using t-test for independent groups, with an 80% power), and a type I error rate of 0.05 (5%), assuming a common SD of 15 from prior studies, to detect a 10-unit difference between groups. Power calculations indicate that at least 37 subjects per group are needed. Subsequently, we aim to recruit 80 subjects. nQuery V.7 was used for sample size calculation.