HBOT

What is hyperbaric oxygen therapy?
Hyperbaric Oxygen Therapy (HBOT) is a medical treatment where a person is placed in a chamber where they receive 100% oxygen at a pressure greater than the normal atmospheric pressure.

These greater pressures mean that the oxygen administered may be referred to by a number greater than 100%; this indicates the relative pressure of the gases within the chamber. As a comparison, the air we normally breathe is around 21% oxygen. Hyperbaric oxygen therapy encourages red blood cells to carry extra oxygen. This oxygen-saturated blood then perfuses the tissues and encourages healing and improves circulation.

Hyperbaric Oxygen Therapy: How It Works
With HBOT, the body receives a lot more oxygen than normal. This increases the amount of oxygen in the blood that’s carried around the body and delivered to the tissues and organs. Having a higher concentration of oxygen helps the body heal areas that have been damaged by a reduced blood supply and can even encourage the body to grow new blood vessels.

What is hyperbaric oxygen therapy used to treat?
HBOT was originally developed as a treatment for decompression sickness in scuba divers and is still used as an emergency treatment for these complications in people who work in compressed air tunnels or divers. Decompression sickness is a condition where divers rise from the high pressures of the deeper sea to normal atmospheric pressure too quickly. This drop in pressure allows dissolved nitrogen in the blood and tissues to form small bubbles, which causes severe pain and breathing difficulties and can have extremely serious consequences if untreated. Decompression sickness is a medical emergency.

HBOT is now used for a range of conditions, and research into further potential applications is ongoing.

HBOT has some definite uses and good clinical research supports its use for treating several conditions. It also has some potential applications into which research isn’t yet conclusive, or where there isn’t currently a large enough evidence base to be accepted by conventional medicine. This means that the practical use of HBOT can vary from one region to another and from one health authority to another. It also means that health insurance companies may cover HBOT for some conditions but not others – even where HBOT is available and has accepted use for those conditions.

In emergency medicine, HBOT is the first-line treatment for decompression sickness and is often used for severe cases of carbon monoxide poisoning. In an acute or subacute clinical setting, HBOT has been used to treat chronic wounds, particularly diabetic foot ulcers, and non-healing surgical flaps or skin grafts, and has an excellent track record.

Currently, clinical evidence supports the use of HBOT for:

Decompression sickness – ‘the bends’: The original use of HBOT is for divers and people working in high pressure environments who are prone to decompression sickness. Recompression reduces the nitrogen bubbles causing the decompression sickness, perfuses the tissues with oxygen and promotes the normal healthy exchange of gases within the body.
Carbon monoxide poisoning.
Non-healing wounds, such as leg or foot ulcers in persons with diabetes: Improving oxygen perfusion – the amount of oxygen getting to damaged tissues and layers of the skin, subcutaneous fat, and muscle – promotes healing. HBOT can effectively treat wounds even as a last resort – when everything else has failed, and is often successful in treating non-healing wounds.
Supporting skin grafts or surgical flaps: Improving oxygen flow to grafts and skin flaps encourage healing. Tissues that have good blood flow and oxygen supply are much more likely to remain healthy.
Radiation burns: HBOT can be used effectively to treat people with damage to the skin and tissues caused by radiation, such as those undergoing radiation treatment for cancers.
Gangrene or necrosis: Reduced blood flow to certain areas of the body may cause tissue death. Those tissues effectively begin to rot and may need to be surgically removed or amputated. This is called necrosis and is more common in people with diabetes or cardiovascular disease. Although it most commonly affects extremities such as our toes, fingers and lower limbs, areas of the organs or deeper tissues can also become necrotic.
Anaemia: HBOT is not a long-term treatment for chronic anaemia but can be used as an acute phase treatment alongside curative treatments.
Hyperbaric Oxygen Therapy Benefits
HBOT allows much greater than usual oxygen concentrations in the body. In theory, any illness or disorder that is caused by reduced blood flow, or which could be improved by a better oxygen supply could be treated to some degree with HBOT. This means that the potential applications are incredibly widespread, and ongoing research is likely to expand the evidence base behind the use of HBOT for even more medical conditions.

The duration and frequency of HBOT sessions can be restrictive, but it has some compelling benefits: it has extremely good evidence behind its approved uses and is non-invasive, low-risk and painless. In addition, its use is usually much preferable to the alternatives; where nothing else has healed a diabetic leg ulcer or necrotic toe, the alternative may be radical surgical debridement or amputation.

What to expect during hyperbaric oxygen therapy?
How often you have to go for HBOT depends on the need for the treatment and continuous monitoring of the individual's response to the treatment. Acute problems like carbon monoxide poisoning can be treated fairly quickly, whereas treatment for non-healing wounds, for example, may take a longer series of treatments for several hours each time.

There are some conditions that mean that HBOT should be delivered with caution. Your referring physician should consider whether HBOT is the right treatment for you, and the specialists at the HBOT centre will do a full pre-assessment to make sure that there are no issues or concerns before starting treatment.

Before HBOT
A high oxygen environment promotes combustion and a fire which starts in a high oxygen environment is likely to become more widespread in a shorter span of time than in a normal concentration oxygen environment. Precautions are therefore taken to ensure that there’s no chance of a spark or flame in clinical areas. Anything metallic should not be taken into an HBOT chamber – this includes hearing aids, spectacles with metal frames, and dentures with metal parts. People undergoing HBOT may be asked to wear hospital gowns or pyjamas so there’s no risk of metal parts causing sparks. Skincare products containing oils or paraffin wax are flammable and so should not be used prior to receiving HBOT.

Before you have hyperbaric oxygen therapy, your clinician will have let you know what to expect from your treatment, the duration and intended benefits. A nurse may take your blood pressure and other observations before you enter the chamber. If you’re diabetic, your blood sugar may be checked.

It's a good idea to use the bathroom before you enter the chamber to reduce the amount of interruption to the treatment later. Some multi-place chambers have private toilets within them. Your nurse should be able to advise you on what to do if you need to use the toilet while you're having treatment.

During HBOT
As the pressure in the chamber increases, people usually feel pressure in their ears. This can usually be improved by holding your nose and trying to blow out through it – the way people may be advised to manage the feeling of ear pressure changes during an air flight.

During the treatment, you will be able to relax. In a multi-place HBOT chamber you can take in a book or magazine and some chambers even have televisions or DVD players to keep patients entertained for extended therapy sessions.

Whether you're in a multi-place or mono-place chamber, there will be experienced professionals on hand to keep an eye on you and address any concerns.

After HBOT
People don't usually feel particularly different straight after HBOT. The main common side effect that can linger for a short time after the treatment is that feeling of ‘popping’ in the ears; the same kind of feeling many people experience in an aeroplane. You don't usually need to stay for any immediate aftercare as long as you feel well. If you are diabetic, your blood sugar may be checked after the session.

Types of Hyperbaric Oxygen Chambers
Hyperbaric oxygen chambers are divided into two broad categories: mono-place, and multi-place.

Mono-place chambers only fit one person and are often portable. They look like a sealed tube big enough to hold a person lying down, so the whole body is subject to the same pressure and oxygen concentration. There are clear panels so you can see out and the medical staff can monitor you while you have the treatment. Some centres offer home treatment, bringing and setting up a portable mono-place HBOT chamber in your own home. The cost of this is usually considerably higher than attending a centre. 

Multi-place chambers can accommodate several people, which means that more than one person can be treated in the chamber at once. It also means that healthcare workers can attend to patients receiving HBOT without any break in their treatment. This is usually recommended for individuals who may need urgent or ongoing medical assistance without any reduction in the pressure around them. The whole chamber is pressurised and the people receiving treatment wear oxygen masks or hoods.

Any healthcare workers attending to patients within the chamber are also subject to a high-pressure environment so occupational risk assessments are made for healthcare staff working at high pressures.

Risks of Hyperbaric Oxygen Therapy
There are some potential risks with HBOT and the intended benefits should be weighed against the possibility of harm. The possible side effects associated with HBOT are generally short-term and complications are rare. HBOT is generally considered to be very safe.

Damage to the eardrum or middle ear caused by changes in pressure.
Sinus pain – particularly if you're prone to sinus pain when you get a cold or congestion.
Altered vision – a short-term effect caused by pressure.
Damage to the lungs – this is very rare but should be a consideration when planning treatment for people with a history of lung disease or damage.
Unstable blood sugar levels in people with diabetes.
There are always experienced healthcare professionals supervising HBOT sessions, ready to deal with any concerns or issues.

Oxygen itself is not flammable but does promote combustion, so centres offering HBOT take extra precautions to avoid the risk of fire. This usually includes restricting the personal items and clothing you can take with you into the chamber.

Contraindications: Who should NOT undergo HBOT? 
The only absolute contraindication to HBOT is a current pneumothorax – a condition where air is present in the chest cavity outside of the lung.

Certain medical conditions and some medications can be affected by HBOT so you should have a full medical history taken by HBOT specialist physicians before any course of treatment.

If you're pregnant or could be pregnant, you should discuss this with your doctor before any new course of treatment. Pregnancy does not usually mean that you can't have HBOT.

If you're unwell on the day of your treatment, you should discuss your symptoms with the staff there.