Frequently Asked Questions & Information for Patients

What is hyperbaric oxygen therapy?

Hyperbaric oxygen (HBO) therapy is the breathing of 100% oxygen while inside a treatment chamber, at a pressure higher than sea-level pressure (ie greater than 1 atmosphere absolute; ATA). Hyperbaric oxygen therapy has long been accepted as the definitive treatment for decompression illness (the "bends"), a complication of diving and much of the terminology and structure of this therapy reflects that history.

The treatment may be carried out in either a monoplace or multiplace chamber. The former accommodates a single patient and the entire chamber is pressurised with 100% oxygen, which the patient breathes directly. The latter holds two or more people (patients, support personnel, observers) and the chamber is pressurised with air; the patients breathe 100% oxygen by masks, head hoods or endotracheal tube. The purpose of the therapy is to provide increased amounts of oxygen to the body.

According to accepted definition, neither breathing 100% oxygen at 1 ATA pressure (normobaric oxygen) nor exposing discrete parts of the body to 100% oxygen (topical oxygen) constitute hyperbaric oxygen therapy.

What is a hyperbaric chamber?

It is a container / vessel / room built to withstand an increased internal pressure. They are generally cylindrical, spherical or rectangular. Multiplace chambers are usually constructed in steel and monoplace units are mainly acrylic. Multiplace chambers have port-holes or small windows and comfortable seating is provided.

Our large rectangular chamber is approximately 6m x 3m x 2m and is our main treatment room. Access is via a door which is large enough to walk through or wheel a special hyperbaric trolley. It has a toilet available for urgent use. Our smaller chamber is cylindrical measuring 3m long x 2m diameter and is usually reserved for acute diving-related injuries. Both chambers are twin-lock units, which enable personnel to enter or leave while the main treatment continues.

How does it work?

The air we breathe is 21% oxygen, 79% nitrogen and minor amounts of other gases. Our bodies are usually able to heal themselves with a normal oxygen level, but in certain conditions extra oxygen is required. During HBO therapy, the pressure is increased to 2 - 3 times that of sea-level and you breathe 100% oxygen. The breathing of pure oxygen under pressure causes a much larger than normal amount of oxygen to be dissolved in the blood and, subsequently, the rest of the body.

The extra oxygen is used by the body in many ways. Depending on the underlying problem, the actions can include improved wound healing by reduction of swelling, infection control and the stimulation of new blood vessel growth. In dysbaric injuries, there is a reduction in gas bubble size and a reduction in the body’s response to that injury.

About the treatment

The number of treatments you will require varies between patients, depending on your particular problem. Some may only require 2 and others 60 treatments. We treat 6 days a week, Monday - Saturday, with usually one treatment per patient per day. Several patients may participate in each session.

Although you will need to attend regularly, treatment times may vary due to emergency patient treatments. The duration of each treatment is between 1.5 and 2 hours, depending on the condition. Treatment for dysbaric injuries are initially 5 hours. Please ask the medical or nursing staff if you have any queries.

Preparation for your treatment

The following recommendations are made to improve safety, comfort and the benefit you will obtain from the treatment.

• Your fitness for treatment will be assessed by a hyperbaric medicine specialist prior to your first treatment. Subsequent assessments will occur as necessary. It is your responsibility to notify the doctor or nurse of any medications you are taking, as well as any change in your general health. This is very important should you develop a cold, have problems with clearing your ears or have new dental work.
• You will be shown how to "clear" your ears. This is a technique to equalise the pressure on either side of your eardrum to prevent damage to the drum during pressurisation. By holding your nose shut and attempting to blow through it, or simply swallowing, air can enter the middle ear cavity via the Eustachian tube. It is only necessary to do this during the compression or pressurisation phase in first few minutes of a treatment.
• Plenty of rest and a healthy diet are key elements in the healing process. These are recommended during HBO. Diabetic patients will be encouraged to eat prior to a treatment session, as HBO may cause a drop in blood sugar level. The blood sugar level will be checked prior to each session.
• Smoking or the use of other tobacco products reduces the amount of oxygen carried by the blood, as well as causing blood vessels to narrow. The combination reduces the oxygen delivery to healing tissues, counteracting the benefit of HBO therapy. You are encouraged to cease smoking.
• To reduce the risk of fire in the chamber certain precautions are taken. You will be provided with specific clothing to wear and should wear cotton underwear.
• Please refrain from having hair permanents during the course of your treatment.

The following items are not permitted in the chamber:

• lighters, matches, smoking products,
• make-up, perfumes, aftershaves, hair spray / oil
• creams, lotions, linaments, salves
• petroleum or Vaseline products
• wigs or hair-pieces
• battery-operated / electrical devices
• synthetics (rayon, nylon, etc.), including pantyhose
• hard contact lenses
• excessive paper products

Are there any side effects?

Side effects are uncommon. They relate to the increase in pressure (ear or lung barotrauma) or the use of increased amounts of oxygen (CNS or lung oxygen toxicity). Some patients may also experience visual changes that cause them to become more near-sighted (myopia); this is usually temporary and should disappear within 3-4 months of ceasing therapy. Your doctor will discuss these prior to your commencing treatment and at any time you are concerned.

If at any time during the treatment you feel uncomfortable or have any sensation that is not normal for you, please report it to the nurse, immediately.

How will it feel?

The first few minutes of the dive will be quite noisy, due to the pressurised air entering the chamber. It will seem warm at first and then the temperature will be adjusted to a comfortable level. You will feel the change in pressure in your ears, similar to that when descending in an aircraft. With effective equalisation, as coached by the nurse present, you will not have any discomfort. If you do have discomfort, please notify your nurse immediately.

At the end of the treatment, the chamber pressure is reduced to usual atmospheric pressure and the air will feel colder.You will feel your ears "popping" during this phase.

What can I do during the treatment?

It is possible to read, talk, rest, sleep or play cards or other games with the other patients or staff. There will be a short break during the treatment when it may be possible to have some refreshment.

About the staff

A hyperbaric trained attendant, usually a registered nurse, will be inside the chamber during each treatment. The attendant is there to help with the equipment delivering the oxygen, instruct with equalisation of your ears, answer your questions and assist in any way necessary.

For further information

If you have any questions or need further information, please contact us at:

Hyperbaric Medicine Unit
Royal Adelaide Hospital
North Terrace
Adelaide SA 5000
Australia