Hyperbaric oxygen (HBO) therapy involves the use of oxygen at greater than atmospheric pressure for short intervals to treat a variety of disease states (see the accompanying table)
. The two basic physiologic effects of HBO are: (1) the reduction of bubble size, which is important in the treatment of patients with iatrogenic air embolism or nitrogen saturation illness and (2) increased partial pressure of oxygen in body tissues. For each increased atmosphere of pressure, an additional 2.3 volume percent (vol%) of oxygen is dissolved in plasma. At 3 standard atmospheres of pressure (ATA), which is the most common pressure used, more than 6 vol% of oxygen is carried by plasma. If 100 percent oxygen is inspired at 3 ATA, peripheral tissue oxygen tensions measured through the skin rise from 40 mm Hg to more than 2,200 mm Hg. This increased oxygenation leads to: (1) increased killing and/or inhibition of bacteria by leukocytes, (2) direct killing of anaerobic bacteria and (3) stimulation of fibroblast formation that encourages collagen formation and neovascularization. Other beneficial effects that have been observed include inhibition of neutrophil adherence to ischemic vessel walls and reversal of postischemic vasoconstriction and reduced lipid peroxidation—all components of ischemic tissue injury. The most common adverse effects of HBO are barotrauma of the middle ear, sinuses or teeth. Pulmonary barotrauma may also occur and is especially dangerous in patients with chronic obstructive lung disease, asthma or lung cysts. Rarely, oxygen toxicity can occur, with central nervous system symptoms ranging from agitation to generalized seizures.
Caplan describes the use of HBO in the pediatric population for treatment of infectious diseases. In patients with skin and soft tissue infections, HBO can halt clostridial growth with concordant halt of alpha toxin release. Because blood and muscle tissue contain catalase, an enzyme that inhibits the bacteriostatic effects of HBO, infected wounds require debridement before HBO is administered to achieve optimal results. Patients with necrotizing fasciitis, a rapidly progressing infection of skin, underlying subcutaneous tissue and fascia without muscle involvement, are treated with surgical debridement and antibiotics. HBO can serve as an adjunct therapy, providing reversal of tissue hypoxia, enhanced neutrophil function, a toxic effect on some bacteria and enhanced activity of certain antimicrobial agents. Use of HBO in patients with refractory osteomyelitis is an area that is currently under investigation. Data suggest a benefit when HBO is used as an adjunct to surgical debridement and antimicrobial therapy.
The author concludes that the use of HBO in pediatric patients with infections is expanding. New areas of research include HBO in the treatment of patients with mucormycosis and human immunodeficiency virus–related fatigue. Further study is needed to determine the full potential of HBO.