What is Hyperbaric Oxygen Therapy?
Hyperbaric Oxygen Therapy (HBO) is a method of administering pure oxygen at greater than atmospheric pressure to a patient in order to improve or correct certain conditions. The air we normally breathe is 21% oxygen and at the atmospheric pressure in which we live (1 ATA) this oxygen is almost exclusively carried by the red blood cells. During HBO, when 100% oxygen is breathed at greater than atmospheric pressure, there is a substantial increase in the amount of oxygen carried in all body fluids including plasma, cerebrospinal fluid surrounding the brain and spinal cord, lymph and intracellular fluids. This allows increased oxygen levels even in areas with poor or compromised blood supply as well as in areas of tissue damage.
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Indications for HBO
Accepted indications for Hyperbaric oxygen therapy
encompass a wide range of clinical conditions including:
- Air or Gas Embolism
- Selected refractory
- Anaerobic Infections
- Carbon Monoxide Poisoning
- Exceptional Blood Loss Anaemia
- Crush Injury,
- Compartment Syndrome, and other Acute traumatic Ischemias
- Gas Gangrene
- Thermal Burns
- Cyanide Poisoning
- Necrotizing Soft Tissue Infections
- Decompression Sickness
- Osteomyelitis (Refractory)
- Enhancement of Healing in Selected Problem Wounds.
- Radiation Necrosis:
- Osteoradionecrosis and Soft Tissue Radiation Necrosis.
- Asthma
- Compromised Skin Grafts or flaps
HBO is generally used as an adjunctive therapy. HBO does not compeate with or Replace other treatment methods.
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Effects of Hyperbaric Oxygen Therapy
1. Mechanical effect of increased pressure
Any free gas trapped in the body will decrease in volume as pressure exerted on it increases (Boyle's Law). Reduction in bubble size allow it to pass through the circulation, or at least travel into a smaller vessel which will reduce the size of any resulting infarction. This effect is useful in the management of gas embolism and decompression sickness.
2. Mass Action of gases
Flooding the body with oxygen forces the rapid elimination of other gases, thus reducing damage caused by toxic gases such as carbon monoxide. The elevated pressure used during Hyperbaric oxygen therapy further accelerates the elimination process.
3. Vasoconstriction
Hyperbaric oxygen acts as an alpha-adrenergic drug. Vasoconstriction can result in reduction of oedema following burns or crush injuries. Even with a reduction in blood flow, the blood carries enough extra oxygen so a net increase in tissue oxygen delivery occurs with Hyperbaric oxygen.
4. Antibacterial effect
Anaerobic bacteria do not contain the natural defences to protect them from the superoxides, peroxides and other compounds formed in the presence of high oxygen tensions. More important, many p02 drops too low, effective ingestion and killing by phagocytic leukocytes is tetrad. Reoxygenation of those tissues allows phagocytosis and other host defence mechanisms to come back into play.
5. Anti-ischemic effect
Hyperbaric oxygen physically dissolves extra oxygen into the plasma (Henry's Law) The quantity of oxygen carried and transferred to ischemic tissue by the blood is increased. Relieving the ischemia with this increased oxygenation promotes osteoclastic and osteoblastic activity, collagen matrix formation and the breakdown of many toxins. The extra oxygen also helps the ischemic tissue meet the increased metabolic need required by healing processes.
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