Osteomyelitis (Refractory) And Hyperbaric Oxygen Therapy

Osteomyelitis is an inflammatory bone disease caused by bacterial infection or by other types of microorganisms such as Staph. Aureus, Strep. Pyogenes, H. influenza, Gram-negative organisms or Salmonella which can affect those with sickle-cell anaemia.

In some acute cases both the bone and the bone marrow may be infected.

Acute osteomyelitis can occur in children. With acute osteomyelitis the spread of infection into epiphysis can result in joints infection.

If the infection is poorly controlled, chronic osteomyelitis can develop further raising the risk of the bone death.

Symptoms of osteomyelitis include pain, fever, swelling, localized redness, an open wound with drainage. In acute forms affected bone is often exquisitely tender with reduced joint movement. Osteomyelitis can be asymptomatic for quite a long period of time.

Refractory osteomyelitis is a chronic osteomyelitis which often does not responded to the treatment administrated. Some cases of osteomyelitis may represent a complication of surgery or injury, although infection can reach bone tissue through the bloodstream.

Hyperbaric oxygen increases the oxygen concentration in infected tissues, including bone. Hyperbaric oxygen directly kills or inhibits the growth of organisms which prefer low oxygen concentrations (strict anaerobes). These effects occur through the oxygen-induced production of toxic radicals or through an indirect effect medicated through the white blood cells (polymorphonuclear leukocytes).

Conversely, hyperbaric oxygen has no direct effect on organisms which prefer high oxygen concentrations (aerobes). In fact, hyperoxic conditions may induce aerobic organisms to produce increased concentrations enzymes protective against oxygen radicals (e.g. superoxide dismutase). When hyperbaric oxygen increases the oxygen tension in infected tissue, however, the oxygen-dependent killing mechanisms of the polymorphonuclear leukocyte are provided sufficient oxygen to function. Thus, hyperbaric oxygen treatment provides the necessary substrate (oxygen) for the killing of aerobic organisms by the polymorphonuclear leukocyte.

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Refractory Osteomyelitis

By Brett B. Hart, M.D.

Refractory osteomyelitis is chronic osteomyelitis that persists or recurs after appropriate interventions have been performed or where an acute osteomyelitis does not respond to accepted management techniques²⁵⁹. Patients with refractory osteomyelitis frequently suffer from coexisting local and systemic factors that compromise their responsiveness to infection.

Hyperbaric oxygen (HBO₂), when combined with appropriate antibiotics, nutritional support, surgical debridement and reconstruction, provides a useful clinical adjunct in the management of refractory bone infections. Overall, the addition of HBO₂ therapy to the clinical management of previously refractory osteomyelitis produces infection arrest rates in approximately 80% of cases.

Initial evidence for this therapeutic benefit stemmed from reports collected during the 1960s, in which difficult cases of osteomyelitis were successfully treated by the addition of HBO₂ therapy. A series of controlled animal studies subsequently confirmed the perceived clinical benefit of HBO₂. More recently, in vitro and in vivo studies have revealed specific mechanisms of action that explain the benefits seen with HBO₂ treatment of refractory osteomyelitis.

Common to each mechanism is the generation of normal to elevated tissue oxygen tensions in infected bone. Mader and Niinikoski demonstrated that the decreased oxygen tensions typically associated with infected bone can be elevated to normal or above normal while breathing 100% oxygen in a hyperbaric chamber. Such elevations have important consequences for the hypoxic milieu of osteomyelitic tissues.¹²¹

Hyperbaric oxygen also augments the efficacy of bacterial killing by certain antibiotics (aminoglycosides, vancomycin, quinolones and certain sulfonamides). Hyperbaric oxygen therapy provides adequate oxygen for fibroblast activity, cells which promote healing in hypoxic tissues. Finally hyperbaric oxygen prevents polymorphonuclear leukocytes from adhering to damaged blood vessel linings. This decreases the degree of inflammation which may accompany the surgical treatment of refractory osteomyelitis.