Hyperbaric oxygen is a mode of therapy in which the patient breathes 100% oxygen at pressures greater than normal atmospheric (sea level) pressure. In contrast with attempts to force oxygen into tissues by topical applications at levels only slightly higher than atmospheric pressure, hyperbaric oxygen therapy involves the systemic delivery of oxygen at levels two to three times greater than atmospheric pressure.
Several beneficial mechanisms are associated with intermittent exposure to hyperbaric doses of oxygen. Either alone, or more commonly in combination with other medical and surgical procedures, these mechanisms serve to enhance the healing process of treatable conditions.
* Undersea and Hyperbaric Medical Society, 2014
Oxygen, when breathed under increased atmospheric pressure, is a potent drug. Besides the beneficial effects discussed above, hyperbaric oxygen can produce noticeable toxic effects if administered indiscriminately. Safe time-dose limits have been established for hyperbaric oxygen exposure, and these profiles form the basis for today's treatment protocols. It is only quite recently that disease-specific hyperoxic dosing has been introduced.
Emergency cases, such as carbon monoxide poisoning or cerebral arterial gas embolism may only require one or two treatments. In those cases for which angiogenesis is the primary goal, as many as 20 to 40 treatments may be necessary. The precise number of treatments often depend upon the clinical response of each patient. Transcutaneous oximetry can provide more exacting dose schedules for wound healing referrals, thereby improving clinical outcomes and cost effectiveness.
Periods of exposure usually last approximately two hours. Decompression sickness and cerebral arterial gas embolism may require five or more hours. Treatments may be given once, twice or occasionally three times daily, and can be provided in both inpatient or outpatient settings.
Hyperbaric oxygen therapy is administered in a pressurized chamber. Two distinct types of chambers are available.
Multiplace Chambers - These units can accommodate between 2-18 or more patients, depending upon configuration and size. They commonly incorporate a minimum pressure capability of 6.0 atmospheres absolute. Patients are accompanied by hyperbaric staff members, who may enter and exit the chamber during therapy via an adjacent access lock or compartment. The multiplace chamber is compressed on air. Patients are provided with oxygen via and individualized delivery system. Dedicated air compressors and high pressure volume receivers provide the chamber air supply. A specialized fire suppression system is necessary.
Space Requirements - Depending upon the size of the complex, a multiplace facility will require between 4,000 and 10,000 square feet of space. Weight constraints dictate that the chamber be ideally located on the ground/basement level.
Advantages include constant patient attendance and evaluation (particularly useful in treating evolving neurological diseases such as decompression sickness and cerebral arterial gas embolism), and multiple patients treated per session.
Disadvantages include high capitalization and staffing costs, large space requirements and risk of decompression sickness in the attending staff.
Monoplace Chambers - These units, first introduced in the 1960's are designed for single occupancy. They are usually constructed of acrylic, have a pressure capability of 3.0 atmospheres absolute, and are compressed with 100% oxygen. Technical innovations have allowed critically-ill and ventilatory-dependent patients to undergo therapy in the monoplace chamber. The high flow oxygen requirement is ideally supplied via a hospital's existing liquid oxygen system.
Space Requirements - A single unit could operate effectively within approximately 400-500 square feet of space. A two-chamber program will operate most effectively in approximately 800-1,200 square feet of space.
Advantages include most cost efficient delivery of hyperbaric oxygen (capitalization and operating costs), and no risk of decompression sickness.
Disadvantages include relative patient isolation and increased fire hazard.