Hyperbaric oxygen therapy (HBOT) is the medical use of oxygen at a higher than atmospheric pressure. General Name, Symbol, Number Oxygen, O, 8 Chemical series nonmetals Group, Period, Block 16 (VIA), 2, p Density, Hardness 1. ... Atmospheric pressure is the pressure caused by the weight of air above any area in the Earths atmosphere. ...

Uses

Several therapeutic principles are made use of in HBOT:

• The increased overall pressure is of therapeutic value when HBOT is used in the treatment of decompression sickness.
• For many other conditions, the therapeutic principle of HBOT lies in a drastically increased partial pressure of oxygen in the tissues of the body. The oxygen partial pressures achievable under HBOT are much higher than those under breathing pure oxygen at normobaric conditions (i.e. at normal atmospheric pressure).
• A related effect is the increased oxygen transport capacity of the blood. Under atmospheric pressure, oxygen transport is limited by the oxygen binding capacity of red blood cells and very little oxygen is transported by blood plasma. Because the hemoglobin of the red blood cells is almost saturated with oxygen under atmospheric pressure, this route of transport can not be exploited any further. Oxygen transport by plasma however is significantly increased under HBOT.

The main indications for HBOT are: Pressure (symbol: p or P) is the measure of the force that acts on a unit area. ... Decompression sickness, DCS, the bends, dysbarism, or caisson disease describes a condition characterized by a variety of symptoms resulting from exposure to barometric pressure which is getting lower. ... Approximately, the partial pressure of a gas in atmospheres in a mixture or solution is what would be the pressure of that gas if all other components of the mixture or solution suddenly vanished without its temperature changing. ... Human red blood cells Red blood cells are the most common type of blood cell and are the vertebrate bodys principal means of delivering oxygen to body tissues via the blood. ... Blood plasma is a component of blood. ... 3-dimensional structure of hemoglobin Hemoglobin or haemoglobin is the iron-containing oxygen-transport metalloprotein in the red cells of the blood in mammals and other animals. ...

• Certain nonhealing wounds (post-surgical or diabetic)
• Radiation soft tissue necrosis and radiation osteonecrosis
• Necrotizing fasciitis (flesh eating bacteria)
• Carbon monoxide poisoning
• Decompression sickness
• Severe infection by anaerobic bacteria (such as gas gangrene)
• Air or gas embolism
• Severe uncorrected anemia
• Chronic refractory Osteomyelitis
• Enhancement of healing in problem wounds
• Sports injuries

HBOT is recognized by conventional medicine (in the USA) as an appropriate treatment for about 14 conditions. However, alternative healing advocates of many stripes believe it is useful for many additional conditions. Among the "off label" uses of HBOT are use as a therapy for brain healing (as in stroke, dementia, cerebral palsy), and for some infectious conditions, such as Lyme disease and Post-polio syndrome Carbon monoxide, chemical formula CO, is a colourless, odourless, flammable and highly toxic gas. ... Decompression sickness, DCS, the bends, dysbarism, or caisson disease describes a condition characterized by a variety of symptoms resulting from exposure to barometric pressure which is getting lower. ... An anaerobic organism or anaerobe is any organism that does not require oxygen. ... Description An air embolism, or more generally gas embolism, is a medical condition caused by gas bubbles in the bloodstream. ... Anemia ( American English) or anaemia ( Commonwealth English), which literally means without blood, is a lack of red blood cells and/or hemoglobin. ... In the anatomy of animals, the brain, or encephalon, is the supervisory center of the nervous system. ... A stroke or cerebrovascular accident (CVA) occurs when the blood supply to a part of the brain is suddenly interrupted by occlusion (an ischemic stroke- approximately 90%of strokes) or by hemorrhage (a hemorrhagic stroke - approximately 10% of strokes). ... Dementia (from Latin demens) is progressive decline in cognitive function due to damage or disease in the brain beyond what might be expected from normal aging. ... Cerebral palsy or CP is a group of disorders associated with developmental brain injuries that occur during fetal development, birth, or shortly after birth. ... Lyme disease is an infectious disease, caused by the Borrelia spirochete, a gram-negative microorganism. ... Post-polio syndrome (PPS) (also properly but not commonly called post-polio sequelae) is a condition that can strike polio survivors anywhere from 10 to 40 years after their recovery from polio. ...

HBOT is quite expensive, with a session costing $100 to $600 in the USA.

In the UK most chambers are financed by the National Health Service but there are non-profit HBOT chambers, such as those run by the Multiple Sclerosis Society. The National Health Service (NHS) is the publicly-funded healthcare system of the United Kingdom. ...

The traditional chamber

The traditional type of HBOT chamber is a hard shelled pressure vessel. Such chambers can be run at absolute pressures up to 600 kilopascals, 6 atmospheres, 6 bars or 85 pounds force per square inch. A pressure vessel is a structure designed to contain a fluid at a different pressure to the pressure surrounding the structure without changing volume. ... Pressure (symbol: p or P) is the measure of the force that acts on a unit area. ... The pascal (symbol Pa) is the SI unit of pressure. ... When expressed as a measurement, an atmosphere or standard atmosphere is a unit of pressure roughly equal to the average atmospheric pressure at sea level on the earth. ... The bar is a measurement unit of pressure, equal to 1,000,000 dynes per square centimetre (baryes), or 100,000 newtons per square metre (pascals). ... Psi (Ψ ψ) is a letter of the Greek alphabet. ...

Navies, diving organisations and hospitals typically operate these. They range in size from those that are portable and capable of transporting just one patient to those that are fixed, very heavy and capable of treating eight or more patients.

The chamber may consist of:

• a pressure vessel that is generally made of steel, aluminium, or Plexiglas
• one or more human entry hatches - theses could be small and circular or wheel-in type hatches for patients on trolleys
• an airlock allowing human entry - a separate chamber with two hatches, one to the outside world and one to the main chamber, which can be independently pressurised to allow patients to enter or exit the main chamber while it is still pressurised
• an airlock allowing medicines, instruments and food to enter the main chamber
• glass ports or closed-circuit television allowing the technicians and medical staff outside the chamber to monitor the inside of the chamber
• an intercom allowing two-way communications inside and outside the chamber
• a carbon dioxide scrubber - consisting of a fan that passes the gas inside the chamber through a soda lime canister
• a control panel outside the chamber is used to open and close valves allowing air to enter or leave the chamber and oxygen to be supplied to masks

In larger "multiplace" chambers, both patients and medical staff inside the chamber breathe from individual masks, which supply pure oxygen and remove the exhaled gas from the chamber. During treatment patients breathe oxygen most of the time but have periodic air breaks to minimise the risk of oxygen toxicity. The exhaled gas must be removed from the chamber to prevent the build up of oxygen, which could provoke a fire. Medical staff may also breathe oxygen to reduce the risk of decompression sickness. The masks that are used may simply cover the mouth and nose or they may be a type of flexible, transparent helmet with a seal around the neck. The pressure inside the chamber is increased by opening valves allowing high-pressure air to enter from storage cylinders, similar to diving cylinders. A gas compressor is used to fill these cylinders. A pressure vessel is a structure designed to contain a fluid at a different pressure to the pressure surrounding the structure without changing volume. ... Steel framework Steel is a metal alloy whose major component is iron, with carbon being the primary alloying material. ... General Name, Symbol, Number aluminium, Al, 13 Chemical series poor metals Group, Period, Block 13 (IIIA), 3, p Density, Hardness 2700 kg/m3, 2. ... Structure of PMMA: (C5O2H8)n Structure of methyl methacrylate Polymethyl methacrylate (PMMA) or polymethyl-2-methylpropanoate is the synthetic polymer of methyl methacrylate. ... An airlock is a device which permits the passage of objects, people, etc between a pressure vessel and its surrounding space while minimising the change of pressure in the vessel. ... Carbon dioxide is an atmospheric gas composed of one carbon and two oxygen atoms. ... Soda lime is a mixture of chemicals, used in granular form in closed breathing environments, such as general anaesthesia, submarines, rebreathers and recompression chambers, to remove carbon dioxide from breathing gases to prevent CO2 retention and carbon dioxide poisoning. ... A valve is a mechanical device that regulates the flow of fluids (either gases, fluidised solids, slurries or liquids) by opening, closing, or partially obstructing various passageways. ... This is a disambiguation page — a navigational aid which lists other pages that might otherwise share the same title. ... General Name, Symbol, Number Oxygen, O, 8 Chemical series nonmetals Group, Period, Block 16 (VIA), 2, p Density, Hardness 1. ... General Name, Symbol, Number Oxygen, O, 8 Chemical series nonmetals Group, Period, Block 16 (VIA), 2, p Density, Hardness 1. ... This is a disambiguation page — a navigational aid which lists other pages that might otherwise share the same title. ... Oxygen may cause damage to cells at elevated partial pressures and a condition called oxygen toxicity syndrome can therefore occur whenever the partial pressure of oxygen in the breathing gas is substantially elevated for a prolonged period of time. ... Decompression sickness, DCS, the bends, dysbarism, or caisson disease describes a condition characterized by a variety of symptoms resulting from exposure to barometric pressure which is getting lower. ... 12 litre and 3 litre steel diving cylinders A diving cylinder or SCUBA tank is used to store and transport high pressure breathing gas as a component of an Aqua-Lung. ... A gas compressor is a mechanical device that increases the pressure of a gas by reducing its volume. ...

A recompression chamber for a single diving casualty

Smaller "monoplace" chambers can only accommodate the patient. No medical staff can enter. The chamber is flooded with pure oxygen and the patient does not wear a mask or helmet. Hyperbaric Oxygen Therapy chamber for a single diving casualty I took this photo myself This image has been released into the public domain by the copyright holder, its copyright has expired, or it is ineligible for copyright. ... Hyperbaric Oxygen Therapy chamber for a single diving casualty I took this photo myself This image has been released into the public domain by the copyright holder, its copyright has expired, or it is ineligible for copyright. ...

Patients inside the chamber will notice discomfort inside their ears as a pressure difference develops between their middle ear and the chamber atmosphere. This can be relieved by the Valsalva maneouvre or by "jaw wiggling". As the pressure increase further, mist may form in the air inside the chamber and the air may become warm. When the patient speaks, the tone of the voice may increase to the level that they sound like cartoon characters. For an alternative meaning, see ear (botany). ... A Valsalva maneuver is a forced expiration against the nose and mouth held closed. ... Misty Hill Mist rising from a hill Mist is a phenomenon of a liquid in small droplets floating through air. ... The word tone is used in several different fields with different meanings. ... The word voice can mean: The human voice. ... A cartoon is a form of art with diverse origins and even more diverse modern meanings. ...

To reduce the pressure, a valve is opened to allow gas out of the chamber. As the pressure falls, the patient’s ears may "squeak" as the pressure inside the ear equalises with the chamber. The temperature in the chamber will cool. For an alternative meaning, see ear (botany). ...

Chambers for home treatment

U.S. Federal law requires that HBOT is administered only on the prescription of a physician. Home hyperbaric therapy is not accepted. There are soft sided HBOT chambers, which are sometimes used for self-prescribed home treatment. These are usually referred to as "mild chambers", which is a reference to the lower maximum pressure of soft-sided chambers. Those commercially available in the USA only go up to 1.4 ATM, 1.4 bar or 20 pounds per square inch (about 9 feet under water). These chambers are not useful for diving injuries and deliver only a slight increase in total blood oxygen content. They are of use for high altitude "mountain sickness". Pressure (symbol: p or P) is the measure of the force that acts on a unit area. ...

Historical link to diving

Initially, HBOT was developed as a treatment for diving disorders involving bubbles of gas in the tissues, such as decompression sickness and gas embolism. The chamber cures decompression sickness and gas embolism in several ways: Divers face specific physical and health risks when they go underwater (e. ... Decompression sickness, DCS, the bends, dysbarism, or caisson disease describes a condition characterized by a variety of symptoms resulting from exposure to barometric pressure which is getting lower. ... Description An air embolism, or more generally gas embolism, is a medical condition caused by gas bubbles in the bloodstream. ...

• the increase in pressure in the chamber reduces the size of the gas bubbles improving transport of blood to tissues downstream of the bubbles
• the high concentrations of oxygen breathed by the casualty are beneficial in keeping oxygen-starved tissues alive
• the high concentrations of oxygen in the tissues have the effect of removing the nitrogen from the bubble making it smaller until it consists only of oxygen which is re-adsorbed into the body

Bubbles are eventually eliminated by long exposure to pressure and high oxygen concentrations, allowing a gradual reduction of pressure back to atmospheric levels. Red blood cells (erythrocytes) are present in the blood and help carry oxygen to the rest of the cells in the body Blood is a circulating tissue composed of fluid plasma and cells ( red blood cells, white blood cells, platelets). ... General Name, Symbol, Number Oxygen, O, 8 Chemical series nonmetals Group, Period, Block 16 (VIA), 2, p Density, Hardness 1. ... General Name, Symbol, Number Oxygen, O, 8 Chemical series nonmetals Group, Period, Block 16 (VIA), 2, p Density, Hardness 1. ... General Name, Symbol, Number Nitrogen, N, 7 Chemical series nonmetals Group, Period, Block 15 (VA), 2 , p Density 1. ...

Treatments

The slang term for a cycle of pressurization inside the HBO chamber is "a dive". Slang is the non-standard use of words in a language of a particular social group, and sometimes the creation of new words or importation of words from another language. ...

Emergency HBOT for diving disorders typically follows one of these two forms: Divers face specific physical and health risks when they go underwater (e. ...

• for most cases, a shallow "dive" to a pressure the equivalent of 18 metres / 60 feet of water for 3 to 4.5 hours with the casualty breathing pure oxygen with air breaks every 20 minutes to reduce oxygen toxicity
• for extremely serious cases, a deeper "dive" to a pressure the equivalent of 37 metres / 122 feet of water for 4.5 hours with the casualty breathing air.

An HBOT treatment for longer-term conditions is often a series of 20 to 40 "dives". Oxygen may cause damage to cells at elevated partial pressures and a condition called oxygen toxicity syndrome can therefore occur whenever the partial pressure of oxygen in the breathing gas is substantially elevated for a prolonged period of time. ...

In Canada and the United States, the U.S. Navy Dive Charts are used to determine the duration, pressure and breathing gas of the therapy. The most frequently used tables are Table 5 and Table 6. In the UK the Royal Navy 62 and 67 tables are used. Canada is a sovereign state in northern North America, the northern-most country in the world, and the second largest in total area. ... The United States of America — also referred to as the United States, the U.S.A., the U.S., America, the States, or (archaically) Columbia—is a federal republic of 50 states located primarily in central North America (with the exception of two states: Alaska and Hawaii). ... Air is the most common and only natural breathing gas. ... The United Kingdom of Great Britain and Northern Ireland is a country in western Europe, and member of the Commonwealth of Nations, the G8, the European Union, and NATO. Usually known simply as the United Kingdom, the UK, or (inaccurately) as Great Britain or Britain, the UK has four constituent... Royal Navy Ensign The Royal Navy is the navy of the United Kingdom. ...

Complications

There are risks associated with HBOT, similar to some diving disorders:- Divers face specific physical and health risks when they go underwater (e. ...

• Pressure changes can cause a 'squeeze' or barotrauma in the tissues surrounding trapped air inside the body, such as the lungs, behind the eardrum, inside paranasal sinuses, or even trapped underneath dental fillings.
• Breathing high-pressure oxygen for long periods can causes oxygen toxicity. One of the side effects of oxygen toxicity is a seizure.
• Vision changes (myopia or nearsightedness) caused by swelling of the lens.

The only contraindication to hyperbaric oxygen therapy is untreated pneumothorax. Barotrauma is physical damage to body tissues caused by a difference in pressure between an air space inside or beside the body and the surrounding gas or liquid. ... The heart and lungs (from an older edition of Grays Anatomy) The lung is an organ belonging to the respiratory system and interfacing to the circulatory system of air-breathing vertebrates. ... The tympanum or tympanic membrane, colloquially known as eardrum, is a thin membrane that separates the outer ear from the middle ear. ... The paranasal sinuses are eight (four pairs) air-filled spaces, or sinuses, within the bones of the skull and face. ... Dentals are consonants articulated with either the lower or the upper teeth, or both. ... Oxygen may cause damage to cells at elevated partial pressures and a condition called oxygen toxicity syndrome can therefore occur whenever the partial pressure of oxygen in the breathing gas is substantially elevated for a prolonged period of time. ... This article is about the medical condition. ... Normal vision for a achromatopsic colour-blind person. ... The lens or crystalline lens is a component of the eye. ... In medicine, a contraindication is a condition or factor that increases the risk involved in using a particular drug, carrying out a medical procedure or engaging in a particular activity. ... In medicine (pulmonology), a pneumothorax or collapsed lung is a medical emergency that can result from a penetrating chest wound or barotrauma to the lungs. ...

See also

• Recompression chamber
• Decompression chamber
• In-water recompression

A recompression chamber is a pressure vessel used to treat divers suffering from certain diving disorders such as decompression sickness. ... A decompression chamber is a pressure vessel used in surface supplied diving to allow the divers to complete their decompression stops at the end of a dive on the surface rather than underwater. ... In-water recompression is the emergency treatment of decompression sickness (DCS) by sending the diver back underwater to allow the gas bubbles in the tissues, which are causing the symptoms, to disappear. ...

External links

• Undersea and Hyperbaric Medical Society (http://www.uhms.org/)
• Diving Diseases Research Centre (http://www.DDRC.org/)
• Diving Medicine Online (http://www.scuba-doc.com/)
• HBO evidence (http://www.hboevidence.com/)