HISTORY OF HYPERBARIC OXYGEN THERAPY

History of Hyperbaric Oxygen Therapy
How is Hyperbaric Oxygen Therapy Delivered?
How Hyperbaric Oxygen Therapy Works
Benefits of HBOT
Contraindications
Side Effects

     HISTORY OF HYPERBARIC OXYGEN THERAPY

    Hyperbaric oxygen treatment (HBOT) is not as new as we might think— but why haven’t we heard much about it?

    Early records of decompression sickness date back to over 150 years ago. In 1845, it was noted that coal miners coming out of deep mines suffered the bends, and the first clinical HBOT applications are recorded about this time. Also named caisson disease for the compressed-air chambers used to enable workers to excavate and build bridge foundations underwater, the disease killed many nineteenth century builders of the Brooklyn Bridge, as well as crippling chief engineer John Roebling. Use of hyperbaric oxygen reduced deaths dramatically.

    Although HBOT was first used in the 1890s to control infection and the U.S. military further tested and developed HBOT after World War I, the basis for modern HBOT was not developed until the 1930s. Decompression sickness, anaerobic bacterial infections, and carbon monoxide poisoning responded favorably enough that the National Academy of Sciences supported the therapy. Improved techologies were developed for the delivery of oxygen. But the technical difficulties of administering oxygen under pressure, as well as the dangers of handling the highly-explosive element, restricted its use until the 1960s.

    Ten years later, HBOT fell into disfavor with the introduction of cardiac surgeries, failure when used for inappropriate conditions, and promotion by medical charlatans.

    Today, there are over 23,000 articles on HBOT in the medical literature promoting its use in the healing and control of infection. In the treatment of diabetes—the control of infection and reduction of the incidence of amputation—HBOT provides value, not only to the patient, but to those who would be responsible for care of the amputee.

    During the past decade, the availability of Hyperbaric Oxygen Therapy facilities has expanded to most metropolitan areas in the United States. The use of HBOT is also increasing in Canada and Mexico.

    Even though HBOT is usually not a primary therapy, it can be a valuable adjunct to improve healing, reduce infection, and favorably alter the symptoms of some chronic diseases. Clinical applications of this innovative and highly effective therapy are increasing rapidly. Recognition of the benefit of HBOT for difficult cases has moved the use of HBOT as a treatment of last resort to an important part of primary treatment—in some cases there is no equivalent treatment which provides results as quickly with such minimal side effects.

    Experts recognize that, although pure oxygen is a drug, properly administered, it is one of the safest drugs a patient can use.

     HOW IS HYPERBARIC OXYGEN THERAPY DELIVERED?

    Hyperbaric Oxygen Therapy (HBOT) provides 100 percent oxygen under increased pressure to treat a wide range of medical conditions. Because pure oxygen can be toxic if taken for too long a period of time, the treatments are professionally administered and typically limited to 1-1/2 to 2 hours five times a week. To reinforce the positive effects, the treatments are given over a period of time, usually one or two months. The prescribing doctor will work with the patient to determine the best course of treatment.

    The increased pressure of HBOT is administered in a monoplace (one person) chamber with 100 percent oxygen, or a multiplace chamber (two to twelve patients) with compressed air. In the multiplace chamber, each patient breathes 100 percent oxygen through a mask or hood. It is the saturation of body fluids with oxygen during HBOT that delivers the majority of oxygen to areas of the body with restricted blood supply.

    The monoplace chamber has the advantage that non-healed incisions, wounds, and ulcers are directly exposed to a hyper-oxygenated environment in addition to receiving the oxygen pushed into the circulatory system through breathing.

     HOW HYPERBARIC OXYGEN THERAPY WORKS

    Human blood is made up of many parts. At sea level, 98 percent of the oxygen in the blood is carried in the hemoglobin and red blood cells with the remaining 2 percent dissolved in the plasma (liquid portion of the blood). The body requires a certain oxygen level to maintain normal cell functions. Too far below that, the cells may survive, but they cannot perform any healing functions.

    When the oxygen is increased from the normal 19 to 21 percent we breathe to a 100 percent saturation, and the atmospheric pressure raised, oxygen is pushed from the circulatory system into the fluids and tissues of the body. Levels of oxygen can rise from 30 mm Hg to 1,100 or even 1,900 mm Hg. In non-technical terms, that means the body tissues can have 63 times the normal levels of oxygen—and perhaps as significantly, the oxygen diffuses farther from the capillaries than normal.

    Tissues of the body, which may have been starved for healing oxygen, are finally receiving what they need. Because HBOT minimizes restriction or blockage of blood vessels, it reduces edema (swelling) while increasing oxygenation. It is the only known methods to accomplish both of these healing functions simultaneously.

    (An interesting note: At 3 times sea level atmospheric pressure and 100 percent oxygen, experimental animals have been shown to function normally without blood cells.)

     BENEFITS OF HBOT

    Several benefits are associated with intermittent exposure to hyperbaric doses of oxygen, either alone or in combination with other medical and surgical procedures.

1. HYPEROXYGENATION: The high oxygen level and elevated pressure within the hyperbaric chamber produces a 10-15-fold increase in plasma oxygen concentration. What this means is that arterial oxygen values increase from 30 mm Hg to 1,500 or even 2,000 mm Hg. Oxygen diffuses four times as far from the capillaries. Although the effect is only temporary, this form of hyper-oxygenation provides immediate support to poorly served tissue in areas where blood flow has been compromised, maintaining tissue viability until corrective measures can be implemented or a new blood supply established.
2. NEOVASCULARIZATION: The development of a new blood supply system is an indirect and delayed response to hyperbaric oxygen exposure. Major injuries, surgery, radiation, refractory osteomyelitis, ulcerations, and diseases can damage or destroy portions of the circulatory system and the tissue supported by that blood supply. To rebuild healthy new capillaries requires the building blocks—new fibroblast cells and collagen—once a blood supploy is re-established, the body can regenerate damaged tissue. HBOT accelerates the processes, both of growing new capillaries (angiogenesis) and repairing tissues.
3. HYPEROXIA: Increased oxygen levels help kill harmful bacteria and inhibit the development and activity of toxins (particularly in Clostridial perfringens infections—gas gangrene). The extra oxygen also makes the body’s immune system function more effectively, increasing efficency in destroying foreign organisms. Recent research has demonstrated a prolonged post-antibiotic effect when hyperbaric oxygen is combined with tobramycin against Pseudomonas aeroginosa—HBOT boosts and prolongs the effectiveness of the medication.
4. DIRECT PRESSURE: Boyle’s Law, where pressure and volume are inversely proportional, is used to reduce the volume of intravascular or other free gas (within the body). This has been used for more than a century to reduce the blood and tissue gases released when a diver or patient undergoes a pressure reduction too quickly. Re-pressurization, with a more gradual return to normal pressures is an effective treament for decompression sickness and cerebral arterial gas embolisms. Untreated decompression sickness results in significant illness and remains grossly underdiagnosed.
5. Hyperoxia-induced VASOCONSTRICTION: With or without causing oxygen deprivation, a swollen circulatory system is less efficient in facilitating tissue healing. HBOT reduces blood vessel swelling, enabling blood to flow more freely through damaged tissues, bringing healing oxygen and nutrients and carrying away cellular debris. In intermediate compartment syndrome (caused by tissue swelling in a limited space), in injured extremites, and in the fluid accumulation associated with grafts, blood vessel swelling restricts blood flow. Studies have shown a significant decrease in fluid resuscitation requirements when hyperbaric oxygen therapy is added to standard burn wound management treatment—limiting the tremendous fluid loss associated with these injuries makes healing a lot faster.
6. ATTENUATION OF REPERFUSION INJURY: A traumatic incident causes immediate, recognizable, and often irreversible damage. Often, when blood flow is restored (reperfusion) after the initial damage, the body responds by sending out protective leukocytes (white blood cells). Recent theory is that these leukocytes react inappropriatedly, causing further damage to marginal tissues. mechanism to be discovered. Hyperbaric oxygen appears to reduce this secondary, indirect injury by preventing such activation. The net effect is the preservation of marginal tissues that may otherwise be lost to ischemia-reperfusion injury.

     CONTRAINDICATIONS

    Contraindicadictions to HBOT are not extensive and often temporary. Communication with your HBOT physician about concerns is essential. Contraindications include: Pneumothorax unless treated with a Heimlich valve.

• Claustrophobia (fear of enclosed spaces, which is usually controllable.
• Acute upper respiratory infection or sinusitis.
• Emphysema, which can usually be treated at lower atmospheric pressure.
• Uncontrolled high fever.
• History of ear complications.
• Thoracic surgery or spontaneous pneumothorax.

    Patients with seizure disorders may have recurrence of seizures while at pressure.

    In China, HBOT is being used to treat seizures in children.

     SIDE EFFECTS

    The predominant side effect of hyperbaric oxygen treatment is barotraumas (pressure damage) to the eardrums. Ear tubes may be required by some patients. Although ruptured eardrums have not occurred in my facilities, this complication has been reported.

    Pure oxygen can produce toxicity, but the treatment parameters used in clinical HBOT are well within the safe limits. In about one in 10,000 compressions, a patient may have an epileptic type seizure due to oxygen sensitivity or low blood sugar—these seizures have produced no long-term effects.

    During a prolonged course of treatment, some patients will note a change in vision caused by the molding of the cornea by the increased pressure—this reverses when HBOT is completed.

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