Hyperbaric oxygen (HBO) treatment

Some cancer treatments, like radiotherapy, can cause damage to healthy tissue around the area being treated. Usually, that tissue damage heals normally over time. But in some cases, nearby blood vessels lose the ability to supply enough blood to the healing area. When the blood supply is limited, cells don’t get enough oxygen. This slows the healing process even more.

Hyperbaric oxygen (HBO) treatment uses high pressure to increase the amount of oxygen a person can breathe. This puts more oxygen into the bloodstream, which can help the healing process. You stay in a hyperbaric (high-pressure) chamber during the treatment, which can last from 60-90 minutes. Treatments are usually repeated over a number of days or weeks for maximum benefit.

HBO causes few side effects, and these are usually minor.

Hyperbaric oxygen (HBO) treatment

Hyperbaric oxygen treatment (HBO) involves providing the body with extra oxygen. 'Hyper' means increased and 'baric' relates to pressure. Oxygen is one of the gases in the air, and it’s essential for life. Normally, oxygen makes up just over one fifth (21%) of air.

In HBO treatment, people breathe in pure (100%) oxygen. This is done by sitting in a chamber known as a hyperbaric oxygen chamber and using a mask or hood.

What HBO treatment is used for

HBO treatment can help in a number of different situations where body tissues have suffered from a decrease in oxygen levels. These include:

  • decompression illness ('the bends')
  • severe carbon monoxide poisoning
  • smoke inhalation
  • chronic wounds and some infections
  • wound healing after reconstructive surgery 
  • radiation necrosis (body tissue dying off after radiotherapy treatment)
  • acute blood loss where a blood transfusion is not possible (for example, for Jehovah's Witnesses)
  • sports injuries
  • diabetic foot ulcers.

How HBO treatment works

Oxygen is carried around the body by the blood. Breathing in 100% (pure) oxygen under increased pressure, called HBO, allows extra oxygen to be taken up by the bloodstream and dissolved at a far greater rate. This extra oxygen can help where healing is slowed down by infection or where blood supply is limited by damage to the tissues.

HBO treatment:

  • assists healing by raising tissue oxygen levels to normal in areas where they are reduced through illness or injury
  • encourages new blood vessels to grow and carry additional blood
  • increases the ability of the body’s defence mechanisms to fight infection and kill bacteria
  • helps reduce any swelling that may occur around the area.

HBO treatment for people with cancer

The most common use of HBO is in treating the side effects of radiotherapy. Other uses are being investigated.

HBO treatment for radiotherapy side effects

Radiotherapy can cause changes in the oxygen supply to tissues in the treated area. This is because radiotherapy affects normal cells and blood vessels as well as cancer cells.

The small blood vessels in the treated area can be damaged by radiotherapy, causing less blood to be supplied to that area. When this happens, it becomes more difficult for essential oxygen and nutrients to reach the tissues.

Over a period of time, the affected tissues may become fragile and start to break down. They may form areas of open sores (ulceration) and rarely, some tissues may eventually die off completely (radiation necrosis). These radiation injuries can occur very slowly over a number of months or even years.

HBO treatment for radiation injuries works by increasing the oxygen supply to damaged tissue. This encourages new blood vessels to grow and the tissues to heal.

Research has shown that HBO treatment may help treat the following:

Chronic radiation cystitis

Radiotherapy is used as a treatment for some types of pelvic cancer. Sometimes, treatment can lead to chronic cystitis (inflammation of the bladder). Symptoms include needing to pass urine frequently, pain when passing urine and blood in the urine (haematuria). These problems can occur months or years after treatment. Symptoms can be persistent and range from moderate to severe. HBO treatment may help to relieve these symptoms when other forms of treatment have been tried without success.


Radiotherapy is often used for cancers in the head and neck. The tissues around this area are fragile and may break down after radiotherapy, particularly if surgery has been carried out previously. Rarely, the bone itself can be affected by radiotherapy and start to break down and die. This is known as osteoradionecrosis. Osteoradionecrosis can also happen when radiotherapy is given to other areas of the body, such as the chest or pelvis.

A research study called HOPON (hyperbaric oxygen therapy to prevent osteoradionecrosis) is finding out if giving HBO to people with head and neck cancer after radiotherapy prevents damage to the jaw bone.

When the damage has occurred, treatment for osteoradionecrosis includes antibiotics, ‘washing out’ the area with salt water (saline irrigation), and sometimes surgery to remove some or all of the affected bone. Although HBO treatment cannot restore the dead bone, increased oxygen can help the tissues around the area to heal by encouraging blood vessels to grow.

HBO treatment can also be given before reconstructive surgery to help healing, prevent infection and encourage blood vessels to grow and form new bone.

If wounds or tissue are infected, treatment usually consists of medicines or surgery as well as HBO treatment.

Tooth removal

Having a tooth removed shortly before, during or after radiotherapy to the mouth and jaw area may increase the risk of osteoradionecrosis. This is because of the reduced oxygen supply to the healing area. HBO treatment can be given to help prevent this, if used both before and after the tooth extraction, and to stimulate the healing process.

Chronic radiation effects on the bowel

Radiotherapy can be given for bowel cancer. The bowel is very sensitive and, although rare, long-term symptoms due to radiation damage can occur. These include pain, bleeding and irregular bowel habits. If these symptoms don't improve following treatments such as anti-inflammatory medicines; HBO treatment may be helpful.

A research study called HOT II is trying to find out if HBO helps people who have developed bowel complications as a result of radiotherapy to the pelvis. This trial is now closed to new recruits.

How HBO treatment is given

Your hospital specialist can advise you whether HBO treatment is appropriate in your situation. They may refer you for HBO treatment if you have long-term side effects from radiotherapy treatment that have not responded to standard treatments.

There are a number of places where HBO treatment is given. Your doctor will be able to tell you your nearest centre for treatment. Some people may have to travel some distance.

Before having HBO treatment you will be examined by a doctor to make sure that you are fit enough to have it. HBO treatment is suitable for most people. It is given inside a chamber, so if you have a fear of enclosed spaces (claustrophobia), you may need medicines to help calm you.

If you smoke, you'll be asked to stop smoking before and during treatment as this is likely to affect the level of oxygen in your body.

Treatment is usually painless and is carried out in simple chambers. There are two types of chamber: a monoplace chamber and a multiplace chamber.

Monoplace chambers

These are designed to treat one person at a time and treatment involves lying on a 2.1m (7ft) padded stretcher that slides into a clear plastic tube (chamber) about 60cm (2ft) wide. Once you are inside, the door is closed and the chamber is pressurised with oxygen. You will be able to see and talk to a member of staff at all times during the treatment.

Multiplace chambers

These are designed to fit and treat up to 12 people at a time, and are more commonly used than monoplace chambers. These chambers are quite large and you will be able to walk about inside. Once you are sitting or lying inside the chamber, the doors will be closed and air is blown into the chamber to increase the pressure. You will hear a sound similar to that in an aircraft as the air begins to circulate.

In both monoplace and multiplace chambers it is necessary to 'clear' your ears as soon as the pressure begins to increase. You will be shown how to do this. Clearing your ears helps to equalise the pressure in them and prevent any pain in your eardrum.

When the pressure reaches the correct level, you will be asked to put on either a mask or a clear hood to receive 100% oxygen. Monoplace chambers are pressurised using 100% oxygen, so you don’t need to wear a mask or hood. You will be able to relax, read, or listen to music and you can talk to staff who are operating the chamber if you need anything.

Near the end of the treatment the pressure in the chamber is slowly decreased. You may feel 'popping' in your ears during this time. After the decompression phase you can leave the chamber.

The length of each treatment varies depending on what you are being treated for. It can last anywhere from 60–90 minutes at a time. Treatments are usually repeated over a number of days, or several weeks. The entire course should be completed for maximum benefit.

Treatment sessions are likely to be postponed if you have a severe cold or flu, runny nose, vomiting or are generally feeling unwell. You should let your nurse or doctor know if you have any of these symptoms before starting a treatment session.

Possible side effects of HBO treatment

HBO treatment is very safe with few side effects. These are usually minor and short-lived. If you notice any other problems which you think may be due to the treatment, discuss them with your nurse or doctor.

Blurred vision

This can occur after having multiple treatments and is due to the development of short sightedness (myopia). It usually comes on gradually and then gets better slowly when treatment ends. Temporary use of glasses or a change in prescription may be helpful, but the blurred vision only lasts a few weeks at most.


Some people feel light-headed after treatment. This only lasts for a few minutes.


Tiredness is a side effect that can be more of a problem if you have treatment more than once a day. The effect usually wears off after a few days once the treatment sessions are finished.

Less common side effects

Ear problems

Although rare, damage to the eardrum can occur due to the change in pressure. Before treatment you will be shown how to equalise the pressure in your ears, which can help to prevent any ear problems.


The change in pressure may cause discomfort if you have congested sinuses, leading to headaches or facial pain. Usually this can be controlled with decongestant medicine, but occasionally HBO therapy needs to be stopped.

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