Hyperbaric Oxygen Therapy
"Treating the 14 conditions covered by OHIP"
What are Compromised Grafts & Flaps?
Tissue grafts and flaps are used to reconstruct wounds from trauma, chronic disease, tumor extirpation, burns, and infection. Despite careful surgical planning and execution, reconstructive failure can occur due to poor wound beds, radiation, random flap necrosis, vascular insufficiency, or ischemia–reperfusion (IR). Traumatic avulsions and amputated composite tissues—compromised tissue—may fail from crush injury and excessively large sizes. While never intended, these complications result in tissue loss, additional surgery, accrued costs, and negative psychosocial patient effects.
Why Hyperbaric Oxygen Therapy?
Hyperbaric oxygen (HBO) has demonstrated utility in the salvage of compromised grafts/flaps. It can increase the likelihood and effective size of composite graft survival, improve skin graft outcomes, and enhance flap survival. Mechanisms underlying these beneficial effects include increased oxygenation, improved fibroblast function, neovascularization, and amelioration of IR injury.
Hyperbaric oxygen (HBO) therapy is a versatile modality that has applications across several medical fields. HBO therapy has become a valuable asset in the management of compromised tissue grafts and flaps. Although classified together, grafts and flaps are distinctly different, in that grafts depend on the wound bed for revascularization, whereas flaps have an inherent blood supply. Evidence has shown that in a compromised graft suffering from hypoxia, HBO can maximize viability and reduce the need for repeat grafting. By comparison, compromised flaps can suffer from both ischemic and reperfusion injury, which can also be attenuated by HBOT to maximize viability.
The beneficial effects of HBO occur by several mechanisms, including hyper-oxygenation, fibroblast proliferation, collagen deposition, angiogenesis, and vasculogenesis. Animal studies have demonstrated several of these mechanisms, including an increase in the number, size, and growth distance of blood vessels after HBO. Likewise, clinical studies have found positive responses in multiple types of tissue grafts and flaps, with some cases involving irradiated fields. Altogether, the data emphasizes that early identification of flap or graft compromise is absolutely critical, with maximized chance for viability when HBO is initiated as soon as possible.
Grafts & HBOT
Grafts contain single or multiple tissue types (referred to as composite grafts) of varying size and depth that lack their own blood supply. The latter property makes these entities reliant upon their recipient bed for initial nutrient diffusion, revascularization, and ultimately, survival. This process of graft “take” follows a characteristic clinical progression, more noticeable in composite grafts. The graft is initially pale and avascular, then adopts a bluish hue due to early congestion (as mature vascular connections have not developed as yet), and finally develops a progressive pink blush.
As a consequence, factors that threaten the recipient bed also threaten graft viability. These factors are ideally identified and treated preoperatively. However, situations may arise in which a questionable wound bed or a graft with metabolic demand greater than the vascularization capacity of the recipient bed (i.e., composite grafts) is encountered. Both of these situations are characterized by hypoxia.
Graft compromise may be evident in the first 24–48 h, characterized by a dusky appearance, epidermolysis, and later, desiccation and necrosis. HBO in these circumstances can improve the wound oxygen tension, local circulation, and angiogenesis and, thus, salvage the failing graft, obviating the necessity for debridement and regrafting.
Flaps & HBOT
Flaps, on the other hand, are units of tissue that carry their own inherent blood supply from the donor to the recipient site. They are susceptible to their own unique sources of compromise. Random-pattern flaps can undergo ischemia usually occurring distally—the area furthest from the source of vascular perfusion—if the flap length exceeds its vascular capabilities. Pedicled flaps can experience mechanical obstruction to blood flow, including pedicle kinking or twisting. Free tissue transfer, in which a flap is divided and transferred to a distant recipient bed with microsurgical reanastomosis, is susceptible to IR injury.
All flaps may be threatened by arterial insufficiency, venous congestion, and complete arterial or venous occlusion. Any surgically correctable etiology for flap compromise should be reversed as soon as it is discovered. HBO, however, can enhance flap survival when tissue damage persists despite no correctable etiology being found during surgical re-exploration.
How do I Qualify for OHIP Coverage?
In order to qualify for OHIP covered hyperbaric oxygen therapy for a Chronic Non-Healing Wound, the individual must be in a wound-care program and/or regularly attending the office of a wound care specialist to monitor the wound and associative healing progress. A referral from a physician or specialist is preferred, however it is not absolutely necessary. Our medical director will look over all supporting documentation, and make the ultimate decision for qualification.