During the last 5 years it has become clear that hyperbaric oxygen for treatment of  medical illness is beneficial at pressures as low as 1.3-1.5 ATA, which decreases the risks of oxygen toxicity to a minimum.

But, though extremely safe when used properly, a mild hyperbaric chamber doesn't increase the concentration of oxygen diffused in body water enough to achieve the best results. Oxygen by mask at more than five liters per minute is also necessary (See The Physiology of Hyperbaric Oxygen). 

• ISCHEMIC STROKE: A minimum of ten 90 min sessions. Serial neurological exams done by a trained professional and bio-feedback may be additional help. Keep in mind that there are a number of neurological scores and the rehabilitation expert must be familiar with them.
• BRAIN INJURY:  As above. Up to 50 treatments may be necessary.
• SPINE INJURY: Early treatment decreases swelling and inflammation. Severance of nervous channels cannot be reversed by hyperbaric oxygen.
• MULTIPLE SCLEROSIS: Studies done in England suggest that early treatment of MS with hyperbaric oxygen is beneficial in slowing down the progression of the disease. Patients who underwent 50 sessions with weekly "maintenance" therapy had a better neurological function for many years that patients who did not receive hyperbaric oxygen.
• NON-HEALING WOUNDS, ENHANCEMENT OF WOUND HEALING: Post-operative wounds and chronic wounds heal well, and after about 10 sessions there is new, permanent capillary growth.
• STATUS POST PLASTIC SURGERY: We recommend 2 preoperative sessions of 90 min and 5 postoperative daily sessions. Used by many plastic facial surgeons.
• OSTEORADIONECROSIS: 10-20 daily treatments at 1.3 ATA are as good as 3 ATA and there are no risks of oxygen toxicity.
• DIABETIC ULCERS: New capillary growth to the lower extremities starts at 10 treatments. Chronic ulcers heal. Improvement of diabetic neuropathy. Must follow scrupolous visual monitoring of lower extremities. 
• AUTOIMMUNE DISEASES SCLERODERMA, RHEUMATOID ARTHRITIS, CROHNS' DISEASE,ULCERATIVE COLITIS: Hyperbaric oxygen STOPS autoimmunity. Recently also used for eczema with weeping wounds and open sores. For CUC, pain and bleeding improved after 15 sessions, and frequency of bowel movements returned to 1-2 a day at 30 sessions. Liver enzymes were cut by 1/3, stool leukocytes drastically decreased.  
• FIBROMYALGIA: Stiffness, swelling of the lowere extremities improve after 10 sessions, but it requires 20 or more to begin feeling normal.
• CHRONIC FATIGUE: Depression improves after as little as 3 sessions. This condition is chronic and requires daily sessions for months.
• AUTISM:  We have treated three autistic children and confirm our colleagues reports. Treatments require over sixty daily sessions, but results are encouraging.