Enhancement of Healing in Selected Problem Wounds
Normal wound healing proceeds through stages of hemostasis, removal of infectious agents, resolution of the inflammatory response, reestablishment of a connective tissue matrix, angiogenesis, and resurfacing.
Problem (or chronic) wounds are those which do not proceed completely through this process because of any number of local and systemic host factors. For this reason, chronic wounds are often categorized as diabetic wounds, venous stasis ulcers, arterial ulcers, or pressure ulcers.
Wounds that fail to heal are typically hypoxic. Multiple components of the wound healing process are affected by oxygen concentration or gradients, which explains why hyperbaric oxygen therapy (HBOT) may be an effective therapy to treat chronic wounds. Angiogenesis occurs in response to high oxygen concentration. This is likely a multifactorial effect of HBOT. First, fibroblast proliferation and collagen synthesis are oxygen dependent, and collagen is the foundational matrix for angiogenesis. In addition, HBOT likely stimulates growth factors involving angiogenesis and other mediators of the wound healing process. Hyperbaric oxygen also has been shown to have direct and indirect antimicrobial activity. In particular, it increases intracellular leukocyte killing.
Diabetic lower extremity ulcers have been the focus of most wound research in hyperbaric medicine, since the etiology of these wounds is multifactorial, and HBOT can address many of these factors. Several randomized controlled clinical trials have studied HBOT for the treatment of diabetic lower extremity wounds. Additionally, many more prospective, noncontrolled clinical trials and retrospective trials have been completed. Based on the body of evidence, major insurance carriers around the world now endorse the use of HBOT for the treatment of diabetic lower extremity wounds that show evidence of deep soft tissue infection, osteomyelitis, or gangrene. HBOT has been shown to reduce the amputation rate in patients with diabetic ulcers as well.
In an effort to select patients appropriately for HBOT, various objective vascular evaluation methods have been used, including transcutaneous oximetry, capillary perfusion pressure, laser Doppler, and other types of vascular studies. Debate is ongoing regarding which method provides the most reliable data and whether these methods are more useful than other clinical markers of wound failure.
Note that HBOT should be used in conjunction with a complete wound healing care plan. As with all chronic wounds, other underlying host factors (eg, large vessel disease, glycemic control, nutrition, infection, presence of necrotic tissue, offloading) must be simultaneously addressed in order to have the highest chance of successful healing and functional capacity.
Because the goals of HBOT for wound healing include cellular proliferation and angiogenesis, HBOT is generally performed daily for a minimum of 30 treatments. Treatment is generally at 2 to 2.4 ATA for a total of 90 minutes of 100% oxygen breathing time. Based on the response to therapy, extended courses of therapy may be indicated.