Welcome to the hyperbaric unit of the centre for musculoskeletal medicine. The unit provides consultation as well as comprehensive management and evaluation services for patients with complex injuries. The Centre for musculoskeletal medicine utilises the benefits of Hyperbaric Medicine as part of a multi disciplinary treatment program.
What is Hyperbaric Oxygen Therapy?
Oxygen is the essential ingredient in life. Biologically, if respirations were to cease, cellular death would result within 4-6 minutes. Thus oxygen is vital. It becomes increasingly important to the sick and injured whose capacity for oxygen is impaired. During HBOT, patients breathe 100% oxygen in a hyperbaric chamber, in which the atmospheric (outside) pressure is increased up to three times. The combination of increased pressure and high concentrations of oxygen causes large amounts of oxygen to be dissolved into the blood and tissues (typically 10 to 15 times the usual amount). This dissolved oxygen can penetrate areas of the body that oxygen-carrying red blood cells cannot reach, revitalizing tissues that receive poor blood flow. The increased oxygen levels in the tissues stimulate healing processes including the growth of new blood vessels, the migration of white blood cells to fight infection and the boost of fibroblasts, which manufacture new tissue.
What are the beneficial mechanisms of HBOT?
At normal atmospheric pressures, most of the oxygen in blood is carried by red blood cells. By giving high concentrations of oxygen under increased pressure (2.0 –2.4 ATA), the dissolved oxygen in the blood can be significantly increased. These levels of dissolved oxygen have been shown to maintain life in the absence of red blood cells. Such doses of oxygen have a number of beneficial biochemical, cellular, and physiological effects.
The pressure component of HBO therapy is used in conjunction with 100% oxygen. Increased oxygen in the blood (hyperoxygenation) is the primary effect of HBO therapy. Increasing the atmospheric pressure in the chamber allows absorption of oxygen in large amounts in the blood. At this pressure, enough oxygen can be dissolved in the plasma to sustain life temporarily without any red blood cells. This marked rise in PO2 is seen at the tissue and cellular level. HBO therapy is the only way that this hyperoxygenation can be provided.
Pain Reduction Recent experimental evidence implies that pain may be decreased with intermittent to long-term exposure to HBO.
Enhanced Rate of Wound Healing
Inflammatory response following injury greatly increases oxygen demand at the wound site. In traumatic injury, physical damage impairs oxygen delivery to circulatory systems and/or cause disruption of the local microcirculation. Hyperbaric oxygen decreases the inflammatory response while significantly improving the microvasculature. Collagen development, necessary for tissue repair and growth, requires oxygen. Exposure to hyperbaric oxygenation substantially increases the oxygen in the blood, causing significant increases in oxygen within wounds, in previously hypoxic (lack of oxygen) wounds. This therefore increase the rate of healing in wounds.
Hyperbaric oxygenation has been used on many occasions to heal certain types of bone fractures. The rationale seems to be that healing is retarded or does not occur in lower oxygen environments. Hyperbaric oxygen exposure appears to accelerate the rate of bone healing.
In controlled human studies, adjunctive HBO therapy has had definite clinical benefits in wound healing and fractures.
Collagen production and fibroblast proliferation are closely related to oxygen availability and cannot proceed without the presence of oxygen.
An animal study using a rat model of surgically lacerated medical collateral ligaments was recently completed. The research group compared ligament strength and stiffness in injured and uninjured ligaments over an 8-week period. The treatment protocol involved exposing the rats to 5 daily exposures for 90 minutes at 2.8 ATA. They concluded that hyperbaric oxygen appears to have promoted the return to normal stiffness of the ligament at 4 weeks. A strong trend also existed towards enhanced recovery of ligament strength in hyperbaric oxygen-treated versus untreated rats, also at 4 weeks.
A clinical study (unpublished observation) examined the short term recovery of a grade 2l ligament tear of the knee in a randomised, controlled, double-blind study. Patients who presented within 72 hours of injury and had no previous knee problems were included in the study. Prior to acceptance into the experiment, patients were examined by a physician and had a magnetic resonance imaging test to ensure that no other structures were involved e.g. the menisci and the cruciate ligaments. Once these parameters were met, the patients received either the sham or hyperbaric oxygen treatment over 2 weeks. Preliminary data analyses suggest positive effects on pain and functional outcomes after 6 weeks.
In addition, preliminary data show that HBO may be beneficial in the treatment of muscle-tendon and ligament injury.
Edema, an important component of acute ankle injury, increases tissue pressure, decreases local perfusion, and causes hypoxia in injured tissues, which have an increased oxygen requirement during the healing process. Thus, reducing edema should facilitate healing by improving oxygenation of the injured tissues. Hyperbaric oxygen is effective in reducing edema while enhancing oxygen delivery. Elevated oxygen pressure causes vasoconstriction while at the same time increasing oxygen partial pressure in the injured tissue. Reduced intravascular pressure resulting from vasoconstriction reverses the transcapillary fluid flow and extravascular fluid is reabsorbed into the circulation.
Antibacterial or Antimicrobial
HBO can double or triple the bacteria-killing ability of the immune system. It is particularly useful in patients where resistance factors are compromised. HBO acts synergistically to most antibiotics.
It has been clinically demonstrated that HBO has a specific role in fighting certain infections.
When oxygen levels in tissues fall bellow a certain point, the bodies responses to infection and poor blood supply are compromised. Studies have shown that the local tissue resistance to infection is directly related to the level of oxygen found in the tissue. High oxygen concentrations may prevent the production of certain bacterial toxins and may kill certain anaerobic organisms.