What is Hyperbaric Oxygen Therapy?
The Undersea and Hyperbaric Medical Society defines hyperbaric oxygen therapy as an intervention in which an individual breathes 100% oxygen intermittently while inside a hyperbaric chamber that is pressurized to greater than sea level pressure (1 atmosphere absolute, or ATA). For clinical purposes, the pressure must equal or exceed 1.4 ATA while breathing near 100% oxygen.
How the Intervention Works
The air we breathe has approximately 21% oxygen at 14.7 pounds of pressure per square inch (psi) when measured at sea level. In the hyperbaric chamber, the atmospheric pressure can be increased to as much as 3 times normal (about 44.1 psi), with the patient breathing 100% oxygen. This increases the amount of oxygen in the blood plasma to many times its normal levels. Higher oxygen levels are delivered to end organ tissues throughout the body.
Rationale for Treatment
Patients with diabetes are at high risk for developing foot ulcers due to neuropathy and peripheral arterial occlusive disease. The pathophysiology of diabetic foot ulcers include progressive development of a sensory, motor, and autonomic neuropathy leading to loss of protective sensation, deformity causing increased plantar foot pressure, and alterations in autoregulation of dermal blood flow. Diabetes causes advanced peripheral vascular disease generally at the trifurcation level just below the knee.
Despite standard wound care, these foot ulcerations can progress and are associated with cellulitis, deep tissue necrosis, abscess formation, and the development of osteomyelitis. This type of ulcer is a Wagner grade III ulcer, an equivalent of the University of Texas IIB, IID, IIIB, or IIID ulcers. Progression to frank distal foot gangrene (Wagner grade IV) or gangrene involving the whole foot (Wagner grade V) can occur.
HBOT Benefits
- Reducing inflammatory and enhancing repair functions of neutrophils, fibroblasts, macrophages and osteoclasts
- Encouraging collagen formation and deposition
- Angiogenesis
- Resistance to infection
- Intracellular leukocyte bacterial killing
Hyperbaric Criteria for Treatment
- The patient has type 1 or 2 diabetes and a lower extremity ulcer due to diabetes
- The ulcer is a Wagner grade III plantar diabetic foot ulcer or higher
- The patient has failed a 30-day standard wound therapy regimen that included assessment and attempts to correct vascular abnormalities, optimizing diabetes control, nutrition, debridement, moist wound dressing, off-loading, and treatment of underlying infection.
Treatment Course
- Hyperbaric oxygen therapy at 2.0 to 2.4 ATA for 90 minutes of oxygen breathing (Table 1 or Table 3). Initiate "air breaks" if treating at pressures >2.0 ATA
- HBOT sessions may be provided on a daily basis 5-7 times per week or twice daily in patients with serious infections requiring hospitalization for intravenous antibiotics, aggressive surgical intervention, and better diabetes control.
- 20-40 HBO sessions will be required to achieve sustained therapeutic benefit.
