Emily, Thank you for your question. Delayed (also known as 'late' or 'chronic') effects of radiation are a complication of modern radiotherapy, which can be treated with HBO. Note that these chronic effects are to normal tissues that are juxtaposed to tumor tissue. Some examples of delayed radiation effects include soft tissue radionecrosis, radiation cystitis, radiation proctitis, and laryngeal chondroradionecrosis. The basic pathophysiology of delayed radiation tissue damage is endarteritis with resultant tissue hypoxia and secondary fibrosis.
Delayed radiation complications often manifest as non-healing wounds in previously irradiated areas. the wounds can be precipitated by an external insult such as surgery or trauma, even minor trauma. Some of these wounds are visible and some are not (e.g., radiation cystitis, vaginitis, proctitis, and urethritis)
It is important to differentiate delayed radiation injuries from acute radiation injuries, which usually resolve within a few weeks to a few months from radiation exposure and are treated symptomatically.
Hyperbaric criteria:
1. Non-healing wound in an irradiated area with onset at least six months since last radiation exposure
2. History of radiation treatment (usually in excess of 40 Gray or 4,000 cGy) to the region of the documented injury
3. A wound that is non-responsive to conservative standard treatment
For radiation cystitis/proctitis, the referring physician must examine the area under direct visualization, (endoscopy, colonoscopy). Please let me know if you have any additional thoughts or questions, Jeff