A Guide To Hyperbaric Oxygen Therapy For Diabetic Foot Wounds
Hyperbaric oxygen (HBO) chambers are currently located in over 750 facilities in the United States. New wound care centers are opening monthly across the country and most incorporate HBO chambers. Which foot and ankle conditions benefit from HBO treatment? Does clinical evidence support HBO treatments?
Patients undergoing HBO therapy enter a chamber filled with 100 percent oxygen atmosphere pressurized to 2.0 to 2.5 ATA (atmospheric pressure absolute), which is equivalent to the pressure 33 to 48 feet below sea level. Hyperbaric oxygen therapy treatment “force feeds” oxygen through the lungs to the rest of the body. A 90-minute treatment in this hyperbaric environment induces “hyperoxygenation” with oxygen levels over 10 times the normal amount in the bloodstream.1
Driven by a systemic effect, HBO therapy requires high pressure, sturdy chambers made of metal and acrylic materials. “Portable” or “collapsible” or chambers made of plastic and vinyl materials (often sold as non-medical, over-the-counter devices) are not built to withstand such high pressures over 2.0 ATA. These devices are no more therapeutic than administering oxygen via nasal canula or face mask. “Topical” oxygen therapy that encloses a body part (e.g. a lower extremity with wounds) lacks strong clinical evidence at this time. Medicare does not reimburse either “portable” or “topical” HBO therapy
Oxygen is a metabolite in respiration and an essential component of human physiology. Of the same token, wound repair mechanisms require oxygen to build skin, granulation tissues and new blood vessels. Interestingly, oxygen under hyperbaric conditions “behaves as drugs” and hyper-oxygenation causes:
• a decrease in leg edema and excessive inflammation;
• an increase in the growth factors and receptors (VEGF and PDGF);
• doubled flexibility of red blood cells;
• increase in bacteriocidal capacity; and
• mobilization of the stem cell within the bone marrow to increase the circulating progenitor cells within the blood stream eightfold.2-5
These effects triggered by HBO treatments specifically counteract the factors known to impair wound healing, especially in patients with diabetes
What Are The Guidelines For HBO In Diabetic Foot Wounds?
Four years ago, the Center for Medicare and Medicaid Services (CMS) approved reimbursement of HBO treatments for diabetic foot wounds. Following this decision, virtually every private payor now reimburses HBO treatment of diabetic foot wounds. Medicare’s HBO reimbursement guidelines require patients to meet the following three criteria.
• Presence of diabetes and lower extremity wounds
• Thirty days of standard wound care have shown no improvement
• Wounds must be Wagner Grade III (deep wound with abscess, osteomyelitis or tendonitis extending to those structures), Wagner Grade IV (gangrenous toes and forefoot) or V (gangrenous foot).
Hyperbaric oxygen therapy is not a “cure-all” treatment. It is an adjunctive therapy for proper wound care and is certainly not a substitute for vascular workup and revascularization efforts.
In our wound care center, we assess the vascular status of lower extremity wounds with a skin perfusion pressure (SPP) monitor (Sensilase, Vasamed). If the foot/ankle SPP is below 30 mmHg, it is diagnostic of critical limb ischemia (CLI) and this warrants an immediate referral to a vascular specialist.6
Although it is more time consuming, one may substitute a transcutaneous oximetry monitor (TCOM) as another microcirculatory test predictive of wound healing in the initial vascular assessment stage. The ankle brachial index (ABI) and toe brachial index (TBI) are useful screening tools of ischemia if the patients do not have calcified leg vessels due to diabetes or end-stage renal disease (ESRD).