Supplementing Diabetic Wound Care With Hyperbaric Medicine
As the diabetes mellitus epidemic continues to grow, so does the number of diabetic wounds in the lower extremity. Researchers have estimated that the number of individuals with diabetes mellitus who eventually develop a lower extremity ulceration may be as high as 25 percent.1
Heel ulcers are notoriously difficult to treat because of their late clinical presentation, which often involves large skin and soft tissue defects, extension to bone and insufficient local tissue for closure. Frequently, simpler treatment options have failed. In this presentation, the wounds have not responded to a trial of offloading or have healed with unstable scars and are now subject to recurrent ulceration due to being on a pressure bearing location.
Our goal as foot and ankle surgeons is to guide therapy to heal these ulcerations and prevent major lower extremity amputations. The backbone to healing these ulcerations starts with good wound care that includes: offloading of the wound site; regular debridement of devitalized and hyperkeratotic tissue; and ensuring an adequate vascular stasis to healing. One also needs to ensure regular follow up by the patient with his or her primary care physician for glycemic control and medical management.
However, even with dedicated care, researchers have estimated that the risk of an individual with diabetes mellitus having an outcome that leads to a major lower extremity amputation is nearly 10 percent.2 When wound healing is not progressing, the use of hyperbaric oxygen therapy (HBOT) could provide the key to healing.
Henshaw first devised the concept of treating diseases with an increased ambient pressure in 1662. He created a sealed chamber called the “domicilium” to treat various ailments. However, his chamber was not based on scientific data but rather that it “seemed like a good idea.”3 Modern use of hyperbaric medicine began in 1955 through the work of Churchill-Davidson, who utilized high oxygen environments to enhance the effects of radiation therapy in cancer patients.4 In 1956, Boerema demonstrated that hyperbaric oxygen could be useful in patients undergoing cardiac surgery.5 Subsequently, other researchers reported success with HBOT, noting an inhibitory effect on anaerobic infections and benefits with the treatment of carbon monoxide poisoning.6,7
Understanding The Physiological Effects Of Hyberbaric Oxygen
When oxygen is in an environment of increased pressure, it behaves like a drug, having specific indications and side effects. Placing a patient in a hyperbaric chamber at 2.8 ATA O2 raises the oxygen tension 10 to 13 times above the normal levels, saturating the plasma and causing hemoglobin to remain fully oxygenated on the venous side. Even though high levels of oxygen cause vasoconstriction, the increased blood oxygen levels more than compensate for this. Furthermore, hypoxic tissue does not respond with vasoconstriction due to local mechanisms that lead to a redistribution effect, which further oxygenates this tissue.8
Collagen synthesis by fibroblasts is triggered by the lactate produced by macrophages in the wound environment. Fibroblasts are unable to synthesize collagen in a hypoxic state as it is required in the steps that produce cross-linking.9 When oxygen levels are low, the collagen framework is unable to be produced, vessel growth into the wound is diminished and subsequent healing stalls. This leads to the formation of a chronic, non-healing wound.