Hyperbaric Oxygen for Ulcerative Colitis

Inclusion Criteria: * known or newly diagnosed moderate to severe ulcerative colitis with a Mayo score of greater than 6 * Mayo endoscopic sub-score of greater than or equal to 2 * Risk score of greater than or equal to 4 points Exclusion Criteria: * Complication requiring urgent surgical intervention (in the opinion of the investigators) Clinically significant cardiac, renal, neurological, endocrine, respiratory or hepatic impairment in the opinion of the investigator, including but not limited to: * Pulmonary i. COPD with CO2 retention; Previous/current imaging showing hyperinflation/air trapping/bullous disease/blebs (opinion of investigators) ii. Current pneumothorax or previous spontaneous pneumothorax iii. Bronchogenic cyst(s) * Cardiac i. Uncontrolled HTN (systolic \>160 or diastolic \>100) ii. Unstable angina or myocardial infarction within the previous 3 months iii. Ejection fraction \< 35% iv. Current or previous amiodarone use v. ICD in place vi. Pacemaker in place not approved for chamber use * Hematological/Oncological i. Current chemotherapeutic drug use, and past history of bleomycin use. ii. Hereditary Spherocytosis iii. Sickle cell anemia * Gastrointestinal and Infectious Disease i. Known or suspected Crohn's disease ii. Previous infection with mycobacterium, fungus, HIV, Hepatitis B or C iii. Gastrointestinal or systemic infection including, but not limited to, --Clostridium difficile iv. Current capsule endoscopy or previously non-retrieved capsule Endocrinology i. Uncontrolled hyperthyroidism Neurological and Psychological i. Vagal or other nerve stimulators ii. Uncontrolled seizure disorder iii. Medications or medical conditions that lower seizure threshold (in the opinion of the investigator) iv. Drug or alcohol abuse/dependence v. Current treatment for alcohol cessation with disulfiram vi. Current or recent (within past week) use of baclofen Head and Neck i. Previous middle ear damage, surgery or infection(s) which may increase the risk for needing ear tubes (in the opinion of the investigator) ii. Current or previous retinal detachment or optic neuritis iii. Retinal or vitreous surgery within the past 3 months Miscellaneous i. Implanted devices not on the approved list for use with HBOT Women who are pregnant or nursing. Women with childbearing potential were required to use effective birth control if not surgically sterile or postmenopausal for \>2 years.