I think this is sometimes used to help RSD, but it's old research and very contentious as to whether its a con. Just posting this for information because of my view that some RSD is associated with incorrect healing of damaged collagen and subsequent incorrect nerve growth.
Increasing oxygen concentration in the body also stimulates the growth of cells of connective tissue, the fibroblasts, and the manufacture of collagen. ...The proliferation of fibroblasts to establish a collagen matrix is an essential first step in wound repair and the reconstruction of a blood supply to damaged tissue.
Breathing new life into oxygen therapy: Hyperbaric oxygen may improve the treatment of wounds and infections. But proof is lacking and no one wants to pay for the research. 23 November 1991 by LESLEY NEWSON New Scientist Magazine issue 1796 page 50