What is Hyperbaric Oxygen Therapy?
The Undersea and Hyperbaric Medical Society defines hyperbaric oxygen therapy as an intervention in which an individual breathes 100% oxygen intermittently while inside a hyperbaric chamber that is pressurized to greater than sea level pressure (1 atmosphere absolute, or ATA). For clinical purposes, the pressure must equal or exceed 1.4 ATA while breathing near 100% oxygen.
How the Intervention Works
The air we breathe has approximately 21% oxygen at 14.7 pounds of pressure per square inch (psi) when measured at sea level. In the hyperbaric chamber, the atmospheric pressure can be increased to as much as 3 times normal (about 44.1 psi), with the patient breathing 100% oxygen. This increases the amount of oxygen in the blood plasma to many times its normal levels. Higher oxygen levels are delivered to end organ tissues throughout the body.
Rationale for Treatment
Delayed effects of radiation are a complication of modern radiotherapy that can be treated with hyperbaric oxygen therapy. Some examples of delayed radiation effects include soft tissue radionecrosis, osteoradionecrosis, 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 located in previously irradiated areas and are precipitated by an additional insult such as surgery or trauma within the field of radiation.
Goals of HBOT
- To reduce tissue fibrosis and breakdown by inducing neovascularization in the radiated tissue and improving tissue oxygenation
- To prevent wound dehiscence following soft tissue reconstructive surgery in previously irradiated areas
Hyperbaric Criteria for Treatment
- Non-healing wound on irradiated area with onset at least six months since last radiation exposure
- History of radiation treatment (usually in excess of 40 Gray or 4,000 cGy) to the region of the documented injury
- Wound that is non-responsive to conservative standard treatment
Treatment Course
- 2.0-2.5 ATA oxygen for 90 minutes of oxygen breathing (Table 1 or 3)
- Daily basis for 40 treatments
- Referring physician examines the area under direct visualization after 40 treatments and together with the HBO physician decides whether to continue to 60 treatments. There are rarely benefits for therapy beyond 60 treatments.
