What is Hyperbaric Oxygen Therapy and how is it carried out?
How does Hyperbaric Oxygen Therapy help?
Is there an approved list of conditions where Hyperbaric Oxygen Therapy is used?
Are there any other conditions where HBOT is helpful/used?
How many times & how often should someone enter the hyperbaric chamber for treatment?
Is there enough experience on Hyperbaric Oxygen Therapy and its uses?

  • What is Hyperbaric Oxygen Therapy and how is it carried out?

Hyperbaric Oxygen Therapy (HBOT) is defined as breathing 100% oxygen inside a treatment chamber (hyperbaric or decompression chamber), where ambient pressure is increased to greater than one atmosphere absolute (ATA). Pressure inside the hyperbaric chamber increases with addition of air and Oxygen is delivered to the patients through airtight fitted masks, as they breathe

Pressure in the chamber should be equal or more than 1.4 ATA, according to established standards. Also, breathing 100% oxygen under atmospheric pressure (1 ATA) or exposing isolated body parts to pressurized oxygen DOES NOT constitute HBOT.



  • How does Hyperbaric Oxygen Therapy help?

The following mechanisms have been identified for HBOT that lead to acceleration – optimization of recovery in various conditions

a. Increased Oxygenation Breathing 100% Oxygen under increased ambient pressure increases oxygen content in the blood and available oxygen for the tissues 10 times or more, comparing to air breathing in normal conditions. This way HBOT provides direct support to damaged tissues with marginal perfusion. Increased oxygen also helps in faster elimination of some toxins from the human body, eg carbon monoxide.

b. Direct effects of pressure HBOT reduces size of gas bubbles in the body, resulting in faster elimination as well. This effect makes it invaluable for the treatment of Arterial Gas Embolism and Decompression Sickness

c. Vasoconstriction Increased oxygen available (hyperoxia) during HBOT causes blood vessels constriction and subsequent reduced blood flow, while tissues continue to receive increased oxygen (“Oxygen Paradox”). This unique property of HBOT is particularly beneficial in the management of compartment syndrome, crush injury and thermal burns.

d. Bactericidal / Bacteriostatic Increased tissue oxygenation reduces spread of some toxins and contributes to elimination of bacteria directly and indirectly, by “arming” body’s defense mechanisms that use oxygen for attacking bacteria. This makes HBOT useful for the management of gas gangrene and necrotizing (and other) infections. Additionally, for the treatment of osteomyelitis and soft tissue infections.

e. Angiogenesis – Neovascularization HBOT stimulates new blood vessel formation, resulting in increased tissue perfusion. Very important to the majority of chronic diseases (peripheral vascular disease in Diabetes Mellitus and post-radiation tissue injury). Also, oxygen-dependant collagen production is facilitated. In total, increased oxygenation results in necessary and effective angiogenesis, fibroblast and osteoblast proliferation. Recent studies have reported that number of circulating stem cells increase as well, as a result of HBOT.



  • Is there an approved list of conditions where Hyperbaric Oxygen Therapy is used?

According to the Undersea & Hyperbaric Medical Society (UHMS), the internationally accepted scientific association in the field of Undersea (Diving) and Hyperbaric Medicine, the following indications are approved uses of Hyperbaric Oxygen Therapy (as defined by the Hyperbaric Oxygen Therapy Committee):

  1. Air or Gas Embolism
  2. Carbon Monoxide Poisoning and Carbon Monoxide Poisoning Complicated by Cyanide Poisoning
  3. Clostridal Myositis and Myonecrosis (Gas Gangrene)
  4. Crush Injury, Compartment Syndrome, and other Acute Traumatic Ischemias
  5. Decompression Sickness
  6. Enhancement of Healing in Selected Problem Wounds
  7. Exceptional Blood Loss (Anemia)
  8. Intracranial Abscess
  9. Necrotizing Soft Tissue Infections
  10. Osteomyelitis (Refractory)
  11. Delayed Radiation Injury (Soft Tissue and Bony Necrosis)
  12. Skin Grafts & Flaps (Compromised)
  13. Thermal Burns
  14. Idiopathic Sudden Sensorineural Hearing Loss (Approved on October 8, 2011, by the UHMS Board of Directors)

For a comprehensive list of uses of HBOT, see also link to HBOT-indications



  • Are there any other conditions where HBOT is helpful/used?

There are various other conditions where hyperbaric oxygen is used, considered at the international level as “indications under investigation”. Hyperbaric physicians worldwide treat patients for such conditions although not included in the above list of indications, and a big body of medical literature supports positive results. Long personal experience in treating various cases (reference centre for HBOT for more than half of the country’s population) has shown clearly that it is a unique powerful regimen for many of these. These conditions include:

  • Diabetic foot (included in Enhancement of Healing in Selected Problem Wounds) – contributes to wound healing, treatment of possible underlying osteomyelitis and avoidance of amputation
  • Avascular necrosis (AVN) or aseptic necrosis of the femoral head – avoidance of arthroplasty, resolution of lesions in most cases of stage I & II of AVN
  • Pyoderma Gagrenosum
  • Central Retinal Artery Occlusion
  • Some refractory Fungal Infections: Mucormycosis, Aspergillosis
  • Brown Recluse Spider bite-induced skin lesions
  • Traumatic Brain Injury and other CNS (brain, spinal cord) pathology
  • Nonunion and delayed union of fractures
  • Sickle cell crisis and other hypoxic complications of sickle cell disease (eg chronic ulcers)
  • Sport injuries – rehabilitation and quick return to action and work
  • Neurologic conditions resulting from inflammation and local hypoxia – includes Bell’s palsy and other mononeuropathies
  • Vascular pathology – Buerger’s disease, Raynaud’s syndrome
  • Inflammatory Bowel Disease – Crohn’s disease & Ulcerative Colitis (some cases)
  • Pneumatosis Cystoides Intestinalis
  • In general, conditions where ischemia preserves normal body healing processes leading to insufficient wound healing (including systemic conditions like cortisol treatment for rheumatic diseases, thalasaemia etc), bone formation (cortisol, area of fracture, systemic conditions etc)



  • How many times & how often should someone enter the hyperbaric chamber for treatment?

Various factors determine the precise treatment protocol to be followed and it is usually individualized depending on the condition treated. As a rule, sessions take place on a daily basis, 1 session a day, 5 days a week. Total number of sessions is determined by the disease treated for each patient. However, for the majority of conditions that are chronic, a minimum of 20 sessions (4 weeks) is required for the beneficial effects of HBOT to appear

As a rough rule, acute or emergency conditions require treatment that ranges from just a few to 10 days – 20 at most (sessions). For the HBOT actions on chronic conditions to reveal, initially a minimum of 20 sessions is needed – usually 30 sessions. Chronic conditions may benefit from repetitive sessions of HBOT after initial treatment, which can in total last for a few months



  • Is there enough experience on Hyperbaric Oxygen Therapy and its uses?

Decompression (hyperbaric) chambers have been used for centuries, historically since 1662. Wide use of Hyperbaric Oxygen Therapy in clinical cases started in the middle of the 20th century. Intensive research on HBOT took place for almost 3 decades in UK and also, Germany, USA, France and elsewhere. From that point, Hyperbaric Medicine has become a distinct, appreciated and recognized field in Medicine tested on a large number of conditions through the years. There are 14 universally approved indications for HBOT now, while there is ongoing research for its use in other maladies taking into account evidence and its cost-effectiveness. In some conditions it is the main treatment modality, and in others is an adjunct to established treatment plans contributing to excellent results and resolution in chronic ill-health problems. Specialists in the Department of Hyperbaric & Diving Medicine of the Athens Naval Hospital have extensive experience regarding Hyperbaric Oxygen Therapy and its applications in human disease. This Department acts as the core for all issues concerning not only diving, but HBOT as well, as it serves as centre of reference for more than 60% of the country’s population