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Hyperbaric Therapy and Autism Ranking: Strong negative evidence

Hyperbaric oxygen chamber

Hyperbaric therapy (also known as hyperbaric oxygen therapy or HBOT) is the medical use of oxygen at a pressure which is higher than normal atmospheric pressure.

The oxygen is administered to the individual in a pressurised chamber in order to increase oxygen absorption in bodily tissue.

Hyperbaric therapy is normally used for the treatment of conditions such as embolisms, decompression sickness or carbon monoxide poisoning.

Some people think that hyperbaric therapy can also be used to reduce some of the core symptoms of autism by addressing underlying physiological problems which they believe cause those symptoms.

Please Note

The National Institute of Health and Clinical Excellence (NICE) made the following recommendations:

'Do not use hyperbaric oxygen therapy for the management of core symptoms of autism in adults.' (NICE, 2012)

Our Opinion

Some individuals on the autism spectrum may have one or more physiological problems according to a limited amount of research evidence of sufficiently high quality. However, how many individuals on the autism spectrum have these physiological problems is unclear.

It is also unclear if these problems cause or worsen the features of autism and related issues, if they arise because of the autism, or if they are completely unrelated to the autism.

There are three high quality randomised controlled trials of hyperbaric therapy.  Two of these trials show no benefit and one shows some benefit to participants on the autism spectrum.

There is currently sufficient research evidence to suggest that hyperbaric therapy is ineffective as an intervention for individuals on the autism spectrum.  There is no need for further research.

Disclaimer

Please read our Disclaimer on Autism Interventions


Audience

Hyperbaric therapy is normally used to treat people with medical conditions such as embolisms, decompression sickness or carbon monoxide poisoning.

Some people have suggested that hyperbaric therapy can also be used to treat individuals on the autism spectrum who have underlying physiological conditions such as cerebral hypoperfusion, inflammation, mitochondrial dysfunction and oxidative stress.

Aims and Claims

Aims

Some people think that some individuals on the autism spectrum suffer from a range of physiological problems.

They think that these physiological problems may cause many of the other problems found in people on the autism spectrum, such as poor eye contact, poor socialisation and lack of attention.

They also think that hyperbaric therapy can be used to reduce or overcome the underlying physiological problems and that this can lead to a reduction in the behavioural problems.

Claims

There have been a number of studies which claim that hyperbaric therapy can help reduce physiological problems in some individuals on the autism spectrum.  For example,

  • Rossignol et al (2012) reported "HBOT at the pressures commonly used in children with ASD (up to 1.5 atm/100% oxygen) has been reported to improve cerebral perfusion, decrease markers of inflammation and not worsen oxidative stress markers."

There have been a number of studies which claim that hyperbaric therapy can lead to improvements in behaviour. For example,

  • Bent (2012) reported "Ten children completed 80 sessions of HBOT and all improved by 2 points on the clinician-rated CGI-I scale (much improved) as well as several parent-completed measures of behavior."
  • Chungpaibulpatana J. et al (2008) reported "Improvement was shown in five domains with a significant level. Seventy-five percent of children shown improvement while 25% did not seem to respond to the treatment."

Key Features

Hyperbaric therapy (also known as hyperbaric oxygen therapy or HBOT) is the medical use of oxygen at a pressure higher than normal atmospheric pressure.

The oxygen is delivered to the individual in a pressurised chamber in order to increase oxygen absorption in bodily tissue.

Under these conditions, their lungs can gather more oxygen than would be possible breathing pure oxygen at normal air pressure.

Pressure

Normal atmospheric pressure is described as 1 atmosphere (1 atm).  In hyperbaric therapy the air pressure in the chamber is gradually increased to a higher target level, which is usually between 2.0 and 3.0 atm depending on the treatment.

The air in the chamber may contain a mixture of gasses, with the amount of oxygen varying between 21% to 100% oxygen depending on the treatment and on the type of chamber used.

Each treatment session consists of a compression cycle during which the pressure is increased slowly to allow for equilibration of air pressure in the ears and sinuses, followed by a period where air is delivered at the target pressure, followed by a decompression cycle when the pressure is returned to normal.

Some people have suggested that people on the autism spectrum do not need very high atmospheric pressure.  For example, according to Halepeto et al (2014)

"..., improvements have been observed via treatments with 95 - 100% oxygen and hyperbaric pressures of 1.5 - 2.0 atm for some chronic neurological conditions, including autism. Furthermore, improvements in autism have also been observed with the use of hyperbaric pressures of 1.3 atm and oxygen levels of 21 - 24%."

Chamber

There are various different types of hyperbaric chamber including

  • A monoplace hyperbaric chamber holds one patient at a time. During treatment the entire atmosphere inside the monoplace chamber is pressurised and filled with 100% oxygen.
  • A multiplace hyperbaric chamber can hold more than one patient. In multiplace chambers the ambient pressurised atmosphere is normal air. Patients receive 100% oxygen through a hood or mask.
  • A “mild” hyperbaric chamber is a soft vessel that can only be pressurised to 1.5-1.7 atm.

Cost and Time

Cost

- Hyperbaric Treatment

We have identified a number of organisations in the UK offering hyperbaric treatments, each of which charges different amounts.

According to the OxygenHealing website, accessed on 11 September 2015

"All HBOT chambers have a range of fees per treatment that depend on:

  • how many other patients are being treated at the same time
  • the particular case
  • access to the chamber e.g. lying down patients take more room than sitting and so decrease the amount of others that can be treated at the same time
  • how the oxygen is given- simple hood or mask versus oxygen via tracheostomy
  • how many treatments are given

Fees range from £50 to £300 per treatment [session]. "

We have identified a number of organisations in Canada and the USA offering hyperbaric treatments ranging between $100- $250 (£65-£165)  per session.

In the UK, hyperbaric therapy is not currently provided for people on the autism spectrum via the NHS as it is not accepted as an evidence-based practice.

- Hyperbaric Chamber

The cost of the chamber will depend on the type and size of chamber. Generally speaking smaller portable chambers, soft sided or inflatable chambers, and second hand chambers seem to be less expensive.

We undertook a brief internet search in September 2015 and found chambers that ranged in price from $3,950 to $100,000 [£2,600 to £65,900).

Time

Hyperbaric therapy may require one or more consultations with a specialist, numerous sessions or ‘dives’ in the chamber over several weeks or months, travel to the centre, overnight stays and so on.

The number of dives is usually individualised to each person and the condition that is being treated. So a treatment course can be anything from 3 to 10, 20 or 40 dives, each of which may last between 60 minutes to two hours.

Risks and Safety

Hazards

According to Latham (2016)

"As with any medical therapy, treatment brings both risks and benefits. One of the more frequently seen injuries caused by hyperbaric oxygen therapy (HBOT) is barotrauma (ie, injuries caused by pressure as a result of an inability to equalize pressure from an air-containing space and the surrounding environment)."

According to the Food and Drug Administration (2013)

"Patients receiving HBOT are at risk of suffering an injury that can be mild (such as sinus pain, ear pressure, painful joints) or serious (such as paralysis, air embolism). Since hyperbaric chambers are oxygen rich environments, there is also a risk of fire."

According to Health Canada (2005)

"When used to treat recognized medical conditions, hyperbaric oxygen therapy is generally safe, as long as:

  • the chamber is properly installed according to municipal and provincial regulations;
  • operators and attendants are properly trained; and
  • a certified hyperbaric physician is either on site, or can be reached easily and quickly.

"However, there are risks. Before consenting to treatment, you should consider these factors:

  • Pressure inside the chamber can damage the middle and inner ear, nasal sinuses, lungs and teeth in both adults and children.
  • Some people experience claustrophobia inside the chamber.
  • The therapy may affect your eyes, for example by promoting nearsightedness or cataract growth.
  • Because hyperbaric oxygen therapy affects blood sugar levels, diabetics should have their levels checked before and after treatment.
  • A high concentration of oxygen can cause serious complications in some children who have congenital heart disease.
  • Too much oxygen can sometimes, although rarely, lead to overload that can cause seizures and lung problems. This is usually prevented by having the patient take breaks to breathe normal air instead of pure oxygen.
  • High concentrations of oxygen at elevated pressures can pose a risk of fire.

"There is also a risk the chamber might explode if it has not been properly installed or if the staff is not properly trained. In addition, it may be difficult or impossible for operators to deal with medical emergencies that may come up when patients are isolated inside the closed chamber."

Contraindications

According to Latham (2016)

  • people with untreated pneumothorax (collapsed lung) or who are taking any of the following medications (Bleomycin, Cisplatin, Disulfiram, Doxorubicin or Sulfamylon) should never undertake hyperbaric therapy (Absolute contraindication)
  • people with the following conditions or devices (asthma, claustrophobia, congenital spherocytosis, chronic obstructive pulmonary disease, eustachian tube dysfunction, high fever, pacemakers or epidural pain pump, pregnancy, seizures, upper respiratory infection) should use hyperbaric therapy with extreme caution (Relative contraindication).

Suppliers and Availability

Suppliers

There are a number of suppliers of hyperbaric therapy in the UK, the USA and other countries.

There are approximately 75 organisations providing hyperbaric therapy in the UK. These include NHS hospitals, Multiple Sclerosis National Therapy Centres as well as various organisations affiliated to the British Hyperbaric Association.

There are also a number of manufacturers of hyperbaric chambers in the UK, the USA and other countries. You can buy chambers direct from these manufacturers or via the internet.

Regulation

There are a number of organisations which are responsible for the regulation of hyperbaric therapy organisations and/or devices.

In the UK the Care Quality Commission is responsible for the regulation of organisations which provide hyperbaric chamber services.  This includes for example ensuring the safety, availability and suitability of equipment used.

In addition, the NHS has published guidance on the use of hyperbaric oxygen therapy (2013). This states that any NHS facility providing hyperbaric therapy should meet a number of requirements including

  • be a member of the British Hyperbaric Association (BHA).
  • work in accordance with the BHA publication ‘Health and Safety for Therapeutic Hyperbaric Facilities. A Code of Practice.’
  • be registered with the Care Quality Commission as a Level 1 or Level 2 hyperbaric facility.
  • operate under the clinical responsibility of a suitably qualified and experienced fully registered medical practitioner; the Medical Director as defined by the Cox Report.

In the USA, hyperbaric chambers are medical devices that require clearance by the Food and Drug Administration (FDA). FDA clearance of a device for a specific use means FDA has reviewed valid scientific evidence supporting that use and determined that the device is at least as safe and effective as another legally U.S.-marketed device.

History

The first recorded use of hyperbaric therapy was by a British clergyman named Henshaw in the 1600s. He built a structure called the domicilium that was pressurised and unpressurised with air using bellows.

The French surgeon Fontaine built a pressurized, mobile operating room in 1879 and Orville Cunningham built an entire hospital in 1928 that was 6 stories high and could be pressurised to 3 atmospheres. 

Behnke and Shaw used pressurised chambers to treat patients with decompression sickness in the 1930s.

The first published report of the use of HBOT in an individual on the autism spectrum was in 1994. In this report, treatment with HBOT resulted in improvements in mood and social interactions in a three year old child on the autism spectrum.

Current Research

We have identified nine scientific studies of hyperbaric therapy in peer-reviewed journals published in English.

These trials included more than 200 individuals aged from 3 to 16. These individuals included people with autistic disorder, Asperger syndrome and pervasive developmental disorder - not otherwise specified.

  • Five of the studies (Bent S. et al. (2012); Chungpaibulpatana J. et al. (2008); Rossignol D. A. Rossignol L. W. (2006); Rossignol D. A. et al. (2009); Rossignol D. A. et al. (2007) reported benefits of various kinds. For example, Rossignol D. A. et al. (2009) reported “Children with autism who received hyperbaric treatment at 1.3 atm and 24% oxygen for 40 hourly sessions had significant improvements in overall functioning, receptive language, social interaction, eye contact, and sensory/cognitive awareness compared to children who received slightly pressurized room air.”
  • Four studies (Granpeesheh D. et al. (2010); Jepson B. et al. (2011); Lerman D. C. et al. (2008); Sampanthavivat M. et al. (2012) reported inconsistent effects, suggesting that there were no benefits. For example, (Granpeesheh D. et al. (2010) reported  “The present study demonstrates that HBOT delivered at 24% oxygen at 1.3 atmospheric pressure does not result in a clinically significant improvement of the symptoms of Autistic Disorder. “

Status Research

There are a number of limitations to all of the research studies published to date. For example

Rossignol et al (2012) concluded

“Many of the reviewed studies suffered from limitations, including the lack of control children, an open-label design, a small number of participants, a retrospective design and the use of parent-rated scales. Indeed, there were only two controlled studies that did not suffer from these types of limitations. These limitations may have contributed to inconsistent findings across studies. In addition, some studies used measurements or observational techniques which may not have been sufficient to measure changes in certain areas, such as attention and memory [123]. The reviewed studies also utilized many different standardized and non-standardized instruments, making it difficult to directly compare the results of studies or to know if there are specific areas of behavior in which HBOT is most effective. None of the studies reported measurements of the long-term effects of HBOT beyond the study period, so it is not known if any of the reported improvements were long lasting.”

Halepeto et al (2014) concluded

“Very few controlled and case studies have been reported on HBOT for autistic children. These studies had multiple internal and external validity problems and provided controversial and insufficient evidence to establish a clear relationship between physiologic changes after HBOT sessions, measures of clinical improvement and the risks and benefits of HBOT for children with ASD.”

“It is noted that inadequate attention was paid to measuring and reporting adverse events. While the available evidence did not indicate serious, life threatening adverse effects. Because the existing evidence is insufficient for clinicians and patients to draw conclusions, good quality observational studies, designed to minimize bias present in existing research, should be conducted.“

Despite this, both Rossignol et al and Halepeto et al go on to state that they believe that hyperbaric treatment appears to be safe and a promising treatment for children with autism.

For a comprehensive list of potential flaws in research studies, please see ‘Why some autism research studies are flawed’

Ongoing Research

  • The Center for Autism and Related Disorders and The International Child Development Resource Center are running a trial into the use of hyperbaric oxygenation therapy for people with autism spectrum disorders. Clinical Trials Gov Ref: NCT00404846. For more details, please see 'Effects of hyperbaric oxygenation therapy on adaptive, aberrant and stereotyped behaviors in children with autism.' Full Item (Open in New Window)
  • The International Child Development Resource Center is running a trial on changes taking place in the blood levels of key markers of oxidative stress. Clinical Trials Gov Ref: NCT00263367. For more details please see 'Effect of hyperbaric therapy on markers of oxidative stress in children with autism' Full Item (Open in New Window)
  • Pediatric Partners of Ponte Vedra is running a trial into the effects of hyperbaric oxygen therapy on cognitive function on autistic spectrum disordered children. Clinical Trials Gov Ref: NCT00631215. For more details, please see 'Effects of hyperbaric oxygen therapy on cognitive function on autistic spectrum disordered children.' Full Item (Open in New Window)
  • Thoughtful House is running a trial of Hyperbaric Oxygen Therapy. Clinical Trials Gov Ref: NCT00406159. For more details, please see 'Effects of hyperbaric oxygen therapy on children with autism.' Full Item (Open in New Window)

Future Research

Summary of Existing Research

There is currently sufficient research evidence to suggest that hyperbaric therapy is ineffective as an intervention for individuals on the autism spectrum. 

Recommendations for Future Research

We do not believe that any future studies are required.

Studies and Trials

This section provides details of scientific studies into the effectiveness of this intervention for people with autism which have been published in English-language, peer-reviewed journals. You may be able to find more studies on hyperbaric therapy in our publications database.

If you know of any other studies we should include please email info@researchautism.net with the details. Thank you.

If you are a UK resident you may be able to obtain full copies of some of the items listed here from your local public library, your college library, or the National Autistic Society's Information. Centre. You may also be able to obtain copies from the publisher of the items.

Related Studies and Trials


Other Reading

This section provides details of other publications on hyperbaric therapy. You may be able to find more publications on hyperbaric therapy in our publications database.

If you know of any other publications we should include please email info@researchautism.net with the details. Thank you.

Please note that we are unable to supply publications unless we are listed as the publisher. However, if you are a UK resident you may be able to obtain them from your local public library, your college library or direct from the publisher.

Related Other Reading


Personal Accounts

This section provides details of personal accounts of the use of hyperbaric therapy for people on the autism spectrum.

Personal accounts can be useful sources of information about the intervention but are not as scientifically valid or reliable as research trials. This may be especially true where the accounts are published by an organisation which might gain a financial advantage from the take-up of the intervention.

Please note that the views expressed in these personal accounts do not necessarily represent the views of Research Autism.


Carol Hendrisk, reporting on her patient Ani in the Journal of American Physicians and Surgeons, Volume 15, Number 3, Fall 2010.

"Many other improvements were observed. She speaks more clearly and can be understood by outsiders. She can ‘dance’ now; before she was too rigid and mechanical. She sees more detail at a distance. She has made great strides in self-help. She now attempts all selfcare instead of waiting for her mother to take care of her. She just started brushing her own hair. She manages her own period, and she takes care of her clothing."

Additional Information

Every few years, the European Committee for Hyperbaric Medicine (ECHM) publishes its recommendations concerning the clinical indications for hyperbaric oxygen therapy (HBOT).  According to Kot J. Mathieu D. (2011) who wrote the most recent recommendations:

“Currently there is no clear rationale for HBOT in autism based on clinically proven pathophysiological mechanisms. The few studies on the use of pressurised environments (not always compatible with the definition of ‘hyperbaric oxygen therapy’) for autism have serious methodological limitations. Therefore, autism should remain as a non-accepted indication for HBOT. HBOT should be used only within the framework of an ethically approved clinical trial.”

Related Additional Information


Updated
19 Dec 2017
Last Review
01 Sep 2016
Next Review
01 Sep 2019