The science behind hyperbaric oxygen therapy

You have probably read about or heard of hyperbaric oxygen therapy. But have you ever wondered just how it worked?

Hyperbaric oxygen therapy involves breathing 100% pure oxygen whilst sitting in our pressurised chamber. The chamber simulates the pressure at approximately 2 atmospheres (2 ATA) under water. There is, of course, no water involved in this process and the whole process is non-invasive and pain-free.

Due to the increase in pressure, the patient will breathe 10 to 20 times more oxygen into their body. Your blood then carries this oxygen throughout your body and delivers it to areas where it is needed, such as wounds or infected areas.

These areas need more oxygen to survive and heal. The increased level of oxygen in the blood arriving at these areas and result in temporally restoring normal levels of blood gasses and tissue function which help to promote healing and fighting off bacteria by stimulating new capillary growth.

When blood flows normally

The air we normally breathe is made up of 21% oxygen and 79% nitrogen. When breathing the lungs transfer the oxygen to the red blood cells – via hemoglobin. The then oxygen-rich red blood cells are carried throughout the body by plasma, which travels through the blood vessels. The oxygen diffuses into the surrounding tissue and it is delivered where it is needed the most.

When blood flow is restricted

When there is a restriction (occlusion) in the blood flow due to injury or illness, the red blood cells block the blood vessel and are not able to transfer oxygen to the cells on the other side of the blockage. This can cause swelling and the area is starved of oxygen causing hypoxia – a lack of oxygen. When this happens the tissue begins to break down.

Hyperbaric oxygenation effects

Breathing 100% oxygen under pressure causes the oxygen to diffuse into the blood plasma. This oxygen-rich plasma is able to travel past the restriction, diffusing up to four times further into the tissue. The increased pressure helps to reduce swelling and discomfort while providing the body with 10 to 20 times the normal supply of oxygen to help repair tissue damaged by the original occlusion or subsequent hypoxic condition.

Regeneration of blood vessels

Hyperbaric oxygen therapy forces more oxygen into the tissue, which helps stimulate the formation of new blood vessels. These new blood vessels develop, and the oxygenated blood cells start to flow to the affected areas. This then creates the optimal environment for the body’s natural healing processes to repair the damage.

The most common treatments that Wesley Hyperbaric treat are radiation damage to the bone and soft tissue and the treatment of non-healing wounds such as diabetic ulcers or venous leg ulcers. The above process is proven to treat these conditions effectively as well as a range of other conditions.

If you are suffering from any of the conditions that are proven to be treatable with hyperbaric oxygen therapy then do get in touch with us. All you need is a referral from your GP or specialist and you can then come in for an assessment to start treatment straight away.

A brief history of hyperbaric oxygen therapy

A brief history of hyperbaric oxygen therapy

You may not have heard much about hyperbaric oxygen therapy.  You may even think it’s a newly discovered medicine that is untested and unproven. You would certainly be wrong in thinking this as the science and practice behind what we do at Wesley Hyperbaric has been around for centuries.

Looking back as far as the 1600s we can see that the use of chambers to treat conditions by changing air pressure has been practiced. Back then it was a very new science, but a science none the less. As we have had advances in understanding and technology, we have seen how the use of hyperbaric oxygen therapy has become a go-to treatment for certain conditions.

Let’s take a brief journey through the past to understand where hyperbaric oxygen therapy began and how we arrived at where we are today.


The very first steps in hyperbaric oxygen therapy were taken by a British clergyman and physician called Nathaniel Henshaw. He believed that putting a patient under pressurised conditions would leave to therapeutic benefits to certain conditions of the lungs and even to aid better digestion. He created a chamber, which is called his ‘Domicilium’ and the air pressure was driven with organ bellows. At this point in time, this was very simple – there was only a change in pressure within the chamber and no form of pure oxygen was used, in fact at this time air has not been broken down into its constituent gases. With time and further discovery, this initial invention would improve.

1830’s and 40’s

Despite the work of Robert Boyle who gave us Boyle’s Law in the 1600s. There was still much to be understood about decompression and the effects on the human. Robert Boyle had conducted experiments on small animals to understand the behavior of gasses and how the animals reacted to the changes in pressure. But it wasn’t until the 1840’s that we would be affected by decompression illness when workers such as miners, divers and tunnel construction workers were being affected by air pressure in their working conditions.

Diver’s in Portsmouth, England were affected when working to clear the wreck of HMS Royal George which has sunk in 1787 and now was proving to be a hazard to the ever growing English naval fleet. Royal engineer William Pasley decided to test his new equipment – a hard hat diving bell on this project. Men would work underwater in this diving bells and be subject to pressure changes.

Similarly, during the 1830’s bridge construction workers, miners and tunnellers would use a sealed box filled with compressed air, called a caisson, to work underwater or at great depths. This allowed them to work safely with a supply of air. The workers became known as Caisson workers, or just ‘caissons’.

As the amount of work increased and more and more workers were using these Caissons, there was an increase in reports of illnesses such as dizziness, cramping, sharp pains in the joints and abdomen and even death. The understanding for this was not understood and it became known as mysterious malady. One strange mystery to them was that the symptoms seemed to disappear when the worker returned to the pressurised chamber. Of course, we now see these as classic symptoms of decompression illness or as it’s known to divers today ‘the bends’. The term ‘the bends’ was coined later on in the 1700s when similar workers working on the Brooklyn Bridge in New York were suffering from these symptoms, many workers have lost the ability to stand up straight and were left with a permanent bend to their stature.

It was 1878 when Paul Bert proposed that the caisson workers were affected by the pressure changing too quickly which then led to the illness.

Not too long after this understand recompression chambers were built at these construction project sites to help recompress workers suffering from this illness. Effectively creating what we have today in terms of a chamber created to aid suffering patients.


By 1877 the use of hyperbaric chambers was being used in medicine. A French surgeon called Fontaine developed a portable operating theatre which was within a pressured chamber. He believed that the increase in oxygen in the patient’s blood would help with anesthesia. This allowed for a higher level of oxygen to ensure lower rates of death under anesthesia.


By the start of the twentieth century, the Royal Navy has started to take interest in hyperbaric medicine to create a solution for its divers suffering from the bends.

In 1907 Dr. John Scott Haldane was working on experiments using goats and differing depths and helped develop the first dive table for use by divers. These tables are still used today by Wesley Hyperbaric to help safely treat patients.


During the early 1900s Dr. Orval Cunningham has been working with a patient suffering from cardiovascular disease and made a link between patients who lived at higher altitudes suffering more than patients living at sea level. He believed that putting patients under even greater air pressure differences would have great benefits. He created a chamber a 27-metre chamber and started to successfully treat many conditions.

But in 1921 he took a massive step and constructed the world’s largest chamber – a chamber fit for a king! It was built in Kansas City and was 20 metres in diameter and within it there were five floors, a smoking lounge, dining room, private quarters and the décor of a fine hotel.

With claims as big as the chamber itself he was soon under the spotlight of the authorities. With his unproven claims the authorities shut down the ‘hyperbaric hospital’ and it was demolished and sold off for scrap metal for use in the war effort.


The US military began conducting research about survivable pressures.  Using hyperbaric oxygen to treat navy clearance divers with decompression sickness. The US Navy’s research has itself help develop its own dive tables. As the Royal Navy tables, these are used today for treating certain conditions in hyperbaric chambers.


By the 1960s hyperbaric chambers were being used in mainstream medicine. At Boston Children’s Hospital a chamber acquired from Harvard University was being used by Dr William F Bernhard to treat children suffering from cardiac conditions – this included the prematurely arrived son of John F Kennedy. The hospital undertook surgery on 120 infants using the chamber prior to the invention of the bypass machine.

As the research continued and further advancements were made a governing body was formed to help keep this going ­– in 1967 The Undersea and Hyperbaric Medical Society (UHMS) was founded. To this day they continue to add governance to hyperbaric medicine allowing the safe use of the medicine across the world.

UHMS helped develop a list of clinical indicators that have evidence that hyperbaric oxygen therapy can be used. As this is a wholly researched and proven list Medicare in Australia adopted this list to help patients get access to help from registered and accredited practitioners such as Wesley Hyperbaric.


As the years have gone by, the medical research has not stopped and there is an ever increasing list of conditions that hyperbaric oxygen therapy has been proven to benefit. The 1980’s saw research proving that the therapy has a massive impact on problem wounds and radiation tissue damage. These are some of the conditions that we see the most at Wesley Hyperbaric and we see a lot of success in the treatments.

So that brings us up to date on the medicine. As you have read, from the early days we have seen a lot of problems solved from industry being able to build, advances through military research and of course in the medical industry an ability to treat conditions that would have been life-threatening allowing organisations such as the Wesley Hyperbaric to give people a chance of getting over conditions and regaining their life.

But it doesn’t stop there. The most basic and early understood science such as gas laws still today form the basis for hyperbaric oxygen therapy, but as research continues and technology changes the future the medicine will continue to change and grow. Wesley Hyperbaric is playing a major part in this, conducting its own studies into conditions such as Xerostomia and pelvic irradiation damage, and prove how hyperbaric oxygen therapy can help.

HBOT and Idiopathic Sudden Sensorineural Hearing Loss

Idiopathic Sudden Sensorineural Hearing Loss (ISSHL) is defined as hearing loss of at least 30dB occurring within 3 days over at least three contiguous frequencies.1

The most common clinical presentation involves sudden unilateral hearing loss, tinnitus, aural fullness and vertigo. The incidence is estimated at 8-15 per 10,0000 worldwide.2

There are currently over 100 publications available evaluating the use of hyperbaric oxygen therapy (HBOT) for treatment of ISSHL, including eight randomised control trials and a Cochrane meta-analysis.

On average, HBOT has been shown to impart a 19.3dB gain for moderate hearing loss and 37.7dB gain for severe cases. 3 This improvement brings hearing deficits from the moderate/severe range into the slight/no impairment range, a significant gain that can markedly improve a patient’s quality of life.

There is currently no consensus over the aetiology of ISSHL, with suggested mechanisms including vascular occlusion, ischemia, viral infection, labyrinthine membrane breaks, immune associated disease, abnormal cochlear stress response, trauma, abnormal tissue growth, toxins, ototoxic drugs and cochlear membrane damage. 4

The rationale for the mechanism of action for HBOT in ISSHL is likely due to the high metabolism and vascular paucity of the cochlea. Tissue oxygenation of the cochlear structures occurs via diffusion from cochlear capillary networks into the perilymph and cortilymph.

Perilymph oxygen tension has been shown to decrease significantly with ISSHL. 5 Animal studies have shown that compared to room air, normobaric oxygen increases perilymph PO2 3.4 fold, while HBO2 increases perilymph PO2 9.4 fold. 6 However, only HBO2 has been shown to achieve extremely high arterial perilymphatic oxygen concentration gradients in both animals and humans. Other additional postulated benefits include anti-inflammatory effects, blunting of ischemia reperfusion injury and oedema reduction.

When ISSHL is diagnosed, immediate referral to an ENT surgeon should occur. Oral steroids at 1mg/kg/day is a common initial dose tapering over the course of 2-3 weeks.

HBOT has been shown to be most effective if delivered within 2 weeks of hearing loss, with benefit possible up to 3 months post insult.7,8 Patients with a delay of greater than 14 days, advanced age and vertigo are however associated with poorer outcomes. 8

The Cochrane analysis of HBOT for ISSHL has shown a NNT of 5.3.3

A typical treatment regimen is of 10-15 treatments breathing 100% oxygen at 2.4ATA, during which routine pure tune audiometry is undertaken on a weekly basis to track changes in hearing acuity as a response to the treatment.

There is no medicare item number for treatment of ISSHL at this point in time, but the treatment is covered by Alliance health funds so there is no out of pocket expense for their clients.

Our unit will happily asses any referred patient with ISSHL. We can then discuss options and undertake treatment if required.



1 Haberkamp TJ, Tanyeri HM. Management of idiopathic sudden sensorineural hearing Loss. Am J Otol. 1999 Sep;20:587-592
2 Lionello M, Staffieri C, Breda S, Turato C, Giacomelli L, Magnavita P, de Filippis C, Staffieri A, Marioni G Uni- and multivariate models for investigating potential prognostic factors in idiopathic sudden sensorineural hearing loss. Eur Arch Otorhinolaryngol. 2014 Mar 25.
3 Bennett MH, Kertesz T, Matthias P, Yeung P. Hyperbaric oxygen for idiopathic sensorineural hearing lossand tinnitus. Cochrane Database Sys Rev. 2010 Jan 20;(1): CD004739
4 Alimoglu Y, Inci E, Edizer DT, Ozdeilek A, Aslan M. Efficacy comparison of oral steroid, intratympanic steroid, hyperbaric oxygen and oral steroid and hyperbaric oxygen treatments in idiopathic sudden sensorineural hearing loss cases. Eur Arch otorhinology. 2011 Dec;268(12):1735-1741
5 Nagahara K, fisch U, Yagi n. Perilymph oxygenation in sudden and progressive sensorineural hearing loss. Acta Otolarygol. 1983 Jul-Aug; 96(1-2):57-68
6 Lamm C, Walliser U, Schumann K, Lamm K. Oxygen partial pressure measurements in the perilymph and the scala tympani in normo- and hyperbaric conditions. An animal experiment study. HNO. 1988 Sep;36(9):363-366
7 Marchesi G, Valetti TM, Amer M, Ross M, Tibertu R, Ferani R, Ferani R, Mauro G Di. The HBO effect in sudden hearing loss treatment. UHMS Annular Scientific Meeting Abstracts, 2000.
8 Murphy-Lavoie H, Piper S, Moon RE, LeGros T. Hyperbaric oxygen therapy for idiopathic sudden Sensorineural hearing Loss. Undersea Hyperb Med. 2012;39(3):777-792

Read our white paper on treating inflammatory bowel disease with HBOT

With an estimated 75,000 Australian’s living with inflammatory bowel disease and the numbers increasing each year there is good news around findings that hyperbaric oxygen therapy offers a solution.

As Australia’s pioneers in hyperbaric oxygen therapy, we have published a white paper on the topic. It covers the problems faced and offers up a solution complete with case studies to show the success in treating Crohn’s disease and also ulcerative colitis.

To find out more please access our white paper and learn more about how hyperbaric oxygen therapy can treat inflammatory bowel disease.


US Chronic Radiation Proctitis study highly recommends Hyperbaric Oxygen Treatment.

The American Society of Colon and Rectal Surgeons (ASCRS) has recently released a study which looks at the treatments available for people suffering from radiation proctitis which strongly ranked hyperbaric oxygen treatment as a real solution.

Radiation is often successfully used in many types of cancer including anal, cervical, prostate and rectal. Despite the benefits, and often successful removal of tumours, collateral damage can occur to the gastrointestinal tract and the patient can be left suffering from chronic radiation proctitis. Despite advancements in technology which allow for more targeted radiation treatment, it is expected that post radiation injury is still likely to occur in some patients.

The study looked at several medical treatments available and hyperbaric oxygen treatment was one of the strongly recommended treatments based on having a moderate level of evidence. The breakdown of treatments, recommendations and level of supporting evidence is detailed below.

Formalin application is an effective treatment for bleeding in patients with CRP Strong recommendation moderate-quality evidence
Hyperbaric oxygen therapy is an effective treatment modality to reduce bleeding in patients with CRP Strong recommendation moderate-quality evidence
Short chain fatty acid enemas are not effective in preventing or treating chronic hemorrhagic radiation proctitis and are not recommended Weak recommendation moderate-quality evidence
Sucralfate retention enemas are a moderately effective treatment for rectal bleeding resulting from CRP Strong recommendation low-quality evidence
Alternative treatments such as mesalamine, ozone therapy, and metronidazole have not been adequately evaluated in treating radiation proctitis and are not recommended Strong recommendation low-quality evidence
Endoscopic argon beam plasma coagulation is a safe and effective treatment for rectal bleeding induced by CRP Strong recommendation moderate-quality evidence
Endoscopic bipolar electrocoagulation, radiofrequency ablation, Nd-YAG laser, and cryotherapy are alternative treatments of rectal bleeding from CRP that have been insufficiently evaluated and are thus not recommended Strong recommendation low-quality evidence

Wesley Hyperbaric has had proven results for people suffering from radiation proctitis and other radiation injuries. If you would like to find out more about what we do and how we can help, then please contact us.

Doctor’s Education Evening 2018 – Book your seat today!

Our annual RAGCP Doctor’s Education Evening is now open for registrations. Any health professional who has an interest in Hyperbaric Medicine are encouraged to come along to find out how it works and what it can do for patients. Even better, those attending will be eligible to receive CPD points.

The course will be once again facilitated by Wesley Hyperbaric Medical Director Dr. Graeme Kay. You will learn all about the approved medical conditions that are treated at Wesley Hyperbaric as well as having the opportunity to tour the facility and see the chamber up close. There will be informative case studies from recent successful outcomes enabling you to make informed and educated decisions around referring your patients to us for treatment.

Facilitator Dr Graeme Kay

Dr Graeme Kay has been the Medical Director of Wesley Hyperbaric since 2015, serving as the Deputy Director from 2013-2015. Prior to starting at Wesley Hyperbaric he has had a varied medical career wearing many different hats; GP, hyperbaric medicine registrar at The Townsville Hospital, anaesthetic PHO and full-time rural relief doctor serving locations as varied as Hughenden, Ingham, Palm Island and Magnetic Island. He has a very keen interest in medical training and doctor’s welfare since serving as RMO president as a junior doctor in Rockhampton.

He has been a SCUBA diver from the age of 15, started his training in diving medicine in 2003, and holds the qualification of Diploma of Diving and Hyperbaric Medicine awarded by the South Pacific Underwater Medicine Society.

When not working or diving, Graeme can be found enjoying the life of a stay at home dad with his wife and daughters.

The event will take place on Tuesday 27 November and will run for around 2 hours from 6.00pm. The chamber facility is located within the Samford Jackson Building at the Wesley Hospital.

Places are limited so you should register today to ensure you can make this fun and informative event. Please call us on 07 3371 6033 or fill out the below form.

Doctor Education Evening Registration

Please complete to book your place.