Note: last updated before 2015

RATIONALE AND BACKGROUND

1. Predisposing Factors
   1. Relative tissue ischemia leads to wound breakdown by several mechanisms. Healing tissue requires angiogenesis, cell proliferation, and collagen synthesis. A partial pressure of oxygen of greater than 20 mm Hg in the wound is required for the healing process to occur. Ischemia also leads to poor wound healing by decreasing the oxygen gradient needed to trigger the cellular processes of wound healing. Several factors affect the delivery of oxygen and lead to nonhealing soft tissue:
      1. Surgical-induced ischemia secondary to disruption of normal blood flow.
      2. Radiation-therapy-induced obliterative arteritis and loss of tissue cellularity.
      3. Infection increases oxygen consumption in the healing wound leading to a local relative hypoxia.
2. Hyperbaric Oxygen (HBO) Mechanism of Action
   1. Intermittent HBO creates a much steeper gradient in the ischemia tissue. Increasing the initial oxygen gradient allows further diffusion to the areas of relative ischemia. A second and even more important mechanism of action is related to this steep oxygen gradient. It is postulated that this gradient also initiates the healing cascade in areas of relative ischemia. Normal tissue senses an oxygen gradient created by an injury and initiates a cascade of healing. Many studies have shown that HBO creates an oxygen gradient in areas of relative ischemia that are similar to the gradient in normal tissue, therefore, triggering the angiogenesis and fibroplasia cascade in areas that otherwise would not support healing.
3. Protocols
   1. Standard protocols shown to be effective to increase healing after significant radiation exposure include:
      1. Pretherapy assessment: examination and history to evaluate eustachian tube function and check for air-containing cavities (ie, pneumothorax)
      2. Twenty HBO sessions prior to surgical wounding: studies have shown that most angiogenesis, cell proliferation, and collagen production processes are initiated within the first 20 dives.
      3. Ten sessions after surgical wounding: this therapy increases oxygen delivery to the area of surgically induced ischemia.
      4. Each session includes 120 minutes of exposure to 2.4 atmospheres absolute (ATA) and breathing 100% oxygen for interrupted intervals equaling 90 total minutes of oxygen exposure.
4. Indications
   1. Osteoradionecrosis and chondroradionecrosis: several studies have shown improved healing with HBO therapy
   2. Prior to dental extraction or placement of osseointegrated implants in the irradiated patient
   3. Nonhealing surgical wound
   4. Osteomyelitis
   5. Laryngeal radionecrosis
5. Complications
   1. Seizure risk 1.3/10,000 dives at 2.4 ATA (45 fps)
   2. Corneal shape change with greater than standard 30 dives: this change reverses after terminating HBO
   3. Tympanic membrane perforation
   4. Air embolism

REFERENCES

Aitasalo K, Niinikoski J, Grenman R, Virolainen E. A modified protocol for early treatment of osteomyelitis and osteoradionecrosis of the mandible. Head Neck. 1998;20:411-417.

Davis JC, Dunn JM, Gates GA, Heimbach RD. Hyperbaric oxygen. Arch Otolaryngol. 1979;105:58-61.

Marx R. Hyperbaric medical. In: Radiation Injury to Tissue.

Mounsey RA, Brown DH, O'Dwyer TP, Gullane MB, Koch GH. Role of hyperbaric oxygen therapy in the management of mandibular osteoradionecrosis. Laryngoscope. 1993;103:605-608.

Hampson NB and Corman JM: Rate of delivery of hyperbaric oxygen treatments does not affect response in soft tissue radionecrosis. UHM 2007, Vol.34,No.5