ubtough uses hbot to help heal fistulas. but she was in Canada. there is not much evidence it heals ulcerations that are constantly being renewed by the body attacking its own tissues.
if there was any unwanted consequence of HBOT, and it was being used off-label, the docs could be vulnerable to a malpractice suite, and would almost certainly risk losing their malpractice insurance.
BUT, you might get somewhere if you asked the HBOT doc or the GI their opinion on this recent study that provided some support for HBOT.
/www.ncbi.nlm.nih.gov/pmc/articles/PMC3328239/the discussion should be is or is not you husband similar to the population studied in the article? are there circumstances in your husband's case that might encourage or discourage this idea.
an insurance company can still refuse to cover experimental treatments, so you should also ask yourself if you think the chances are good enough that you will find the money for private pay.
good luck
good luck