SIMSI Position on the use of Low-Pressure Hyperbaric Chambers for Hyperbaric Oxygen Therapy (HBO2)

In Italy, low-pressure monoplace hyperbaric chambers are increasingly being installed in both medical and non-medical facilities.

These facilities advertise the use of such devices as a treatment method for conditions relevant to hyperbaric medicine, often referencing scientific evidence and therapeutic guidelines that support the effectiveness of Hyperbaric Oxygen Therapy (HBOT) administered in multiplace hyperbaric chambers, which are currently the only legally authorized systems in Italy and can reach operating pressures of up to 6 ATA.

The European Committee for Hyperbaric Medicine (ECHM) published the European Code of Good Practice for Hyperbaric Oxygen Therapy, which defines HBOT as the administration of oxygen at a pressure higher than local atmospheric pressure. It specifies that the pressure level, treatment duration, and the partial pressure of oxygen must conform to the current state of the art in the field. It also establishes that three essential elements define HBOT: oxygen partial pressure, environmental pressure, and the use of a hyperbaric chamber.

The Undersea and Hyperbaric Medical Society (UHMS), in the latest 15th Edition of "Hyperbaric Oxygen Therapy Indications", states that therapeutic pressure must not be lower than 2.0 ATA, typically for a period between 90 to 120 minutes.

As such, administering HBOT requires the use of hyperbaric chambers. According to EU regulations, hyperbaric chambers are considered medical devices as well as high-pressure equipment. Previously, they were governed by Directive 93/42/EEC on medical devices, but since May 2021, the new EU Medical Device Regulation (MDR 2017/745) has been in force, which enforces stricter certification criteria for medical devices. The MDR demands scientific evidence for efficacy and safety, which these low-pressure chambers currently lack.

Furthermore, pressure equipment is also subject to Directive 2014/68/EU concerning the harmonization of laws on pressure equipment across EU Member States.

The 7th ECHM Consensus Conference (Lille, 2004) defined HBOT as: "The administration of oxygen at a pressure not lower than 2.0 ATA for a minimum of 60 minutes." This remains the current standard of care.

In 2023, the ECHM published the 2022 revision of the European Code of Good Practice for HBOT, which reaffirmed the consensus that the term "hyperbaric oxygen therapy" can only be used when the oxygen partial pressure exceeds 1.5 ATA for at least 60 minutes (excluding compression and decompression times).

Hyperbaric chambers must meet two sets of technical standards:

• UNI EN 14931:2006, which defines safety and functional requirements for human-occupied hyperbaric chambers.
• UNI EN 16081:2012 - A1:2013, which sets specific requirements for fire suppression systems, installation, and functional testing.

In the United States, the FDA (Food and Drug Administration) authorizes the use of low-pressure hyperbaric bags only for altitude sickness and emergency evacuation using devices such as the Gamow bag.

Oxygen is classified as a drug (CAS No. 7782-44-7; ATC V03AN01). Proper HBOT involves medical-grade oxygen (≥ 99.5%) administered at pressures above atmospheric, in compliance with the official drug data sheet.

Recently, so-called low-pressure hyperbaric chambers have entered the market in several countries, including Italy. These devices typically operate at a maximum pressure of 1.45 ATA (146.92 kPa). They use oxygen concentrators that never reach 100% purity—oxygen concentration decreases from ~93% at 5 L/min to ~90% at 10 L/min, which is their maximum flow rate (as per: Caire Inc.).

Oxygen is administered using non-monitored reservoir masks in continuous-flow, open-circuit systems, unlike multiplace chambers where inspired oxygen concentration is monitored. These chambers also lack internal monitoring or alarms to detect potentially dangerous levels of oxygen (>22.5%)—a risk since excess oxygen is vented into the chamber environment.

To date, scientific literature provides little evidence supporting HBOT at pressures lower than 2.0 ATA. All recognized indications for HBOT require pressures between 2.0 and 2.8 ATA.

The SIMSI considers that these low-pressure chambers do not meet the minimum requirements for safe and effective HBOT as established by international standards. Therefore, it is unacceptable to equate these chambers with certified hyperbaric chambers that comply with the aforementioned regulations.

Due to the unregulated spread, lack of scientific validation, and potential safety risks, multiple scientific societies have expressed their opposition to the use of these low-pressure devices for HBOT.

• In 2010, the South Pacific Underwater Medicine Society, commissioned by the Australian and New Zealand Hyperbaric Medicine Societies, concluded that there was no clinical evidence supporting the therapeutic benefits of these chambers and did not recommend their
• In 2015, the Canadian Undersea and Hyperbaric Medical Association (CUHMA) published guidelines emphasizing the need for continuous oxygen monitoring in hyperbaric chambers and clearly opposed the use of pressures below 1.5 ATA or oxygen concentrations below 100%, except in approved research settings.
• In 2017, the UHMS published a position paper against the use of low-pressure hyperbaric chambers: UHMS Position Statement on LP Chambers (PDF)

In conclusion, SIMSI states that:

1. Low-pressure hyperbaric chambers are currently not suitable for administering HBOT as defined by the current standards of hyperbaric They do not meet the minimum requirements in terms of exposure pressure, structural design, or safety.
2. HBOT should only be administered according to the guidelines outlined by the 10th ECHM Consensus Conference: ECHM Consensus Guidelines
3. Public administrations should implement authorization and accreditation procedures for any type of hyperbaric medical device (regardless of the gas used—air, oxygen, or mixed gases) to ensure user safety.

This represents the current state of the art regarding the use of HBOT, pending future technical and scientific advancements that may validate new devices and treatment protocols.

Presidente SIMSI, Dott. Alfonso Bolognini
Working group SIMSI
Dott. Alfonso Bolognini Presedente SIMSI
Dott. Pasquale Longobardi Vice Presidente SIMSI Dott. Corrado Costanzo consigliere SIMSI
Dott. Luigi Santarella consigliere SIMSI Dott. Massimo Spalletta consigliere SIMSI Dott. Stefano Mancosu consigliere SIMSI
Sig. Gianluca Baroni Tecnico iperbarico Ravenna Sig. Antonio Sanna Tecnico iperbarico Sassari

References

• European Committee for Hyperbaric Medicine (available at www.echm.org)
• European Code of Good Practice for Hyperbaric Oxygen Therapy (available at http://www.echm.org/ECHM-Documents.htm)
• Undersea and Hyperbaric Medical Society (UHMS) (available at www.uhms.org)
• Indications for Hyperbaric Oxygen Therapy. Definition of Hyperbaric Oxygen Therapy (available at www.uhms.org/resources/hbo-indications.html)
• Food and Drug Administration, CFR_Code of Federal Regulations Title 21.
• Kot J, Desola J, Simao AG, Gough-Allen R, Houman R, Meliet J-L, et al. A European code of good practice for hyperbaric oxygen therapy. Int Marit Health [Internet]. 2004;55(1-4):121–30. Available from: http://www.ncbi.nlm.nih.gov/pubmed/15881548
• Hyperbaric Oxygen Therapy Comittee U. Hyperbaric Oxygen Therpy Indications. 13th editi. Weaver L k., editor. Undersea and Hyperbaric Medical Society; 2014. 1-415 p.
• Kot J, Houman R, Müller P. HYPERBARIC CHAMBER AND EQUIPMENT. Multi- and Monoplace Chambers. In: MATHIEU D, editor. Handbook on Hyperbaric Medicine. First. Springer; 2006. p. 611–36.
• Mathieu D. Handbook on hyperbaric medicine. 1st ed. MATHIEU D, editor. Handbook on Hyperbaric Medicine. Dordrecht, The Netherlands: Springer; 2006. 812 p.
• Mathieu D. Recommendations of the 7th European Consensus Conference on Hyperbaric Medicine [Internet]. 2004. Available from http://www.echm.org/documents/ECHM 7th Consensus Conference Lille 2004.pdf
• Committee USC& UOT. Low-Pressure Fabric Hyperbaric Chambers [Internet]. 2017. p. 1–3. Available from https://www.uhms.org/images/Position- Statements/Low_PressureSoft_Chamber_UHMS_Position_Statement_Final_9-30-2017.pdf
• Board of Directors of the Undersea and Hyperbaric Medical society. UHMS position statement on lowpressure, soft-sided hyperbaric chambers. UHM. 2017;44(6):612.
• Canadian Undersea and Hyperbaric Medical Association (CUHMA) Guidelines to the Practice of Clinical Hyperbaric Medicine and Provision of Hyperbaric Oxygen Treatment (2015). Available at https://cuhma.ca/_Library/Documents/CUHMA_Standards_of_Practice_Guidelines_1st_Edition.pd f
• Real Decreto 1277/2003 que regula la autorización de centros y establecimientos sanitarios, (BOE 254/2003, October 10th).
• Mathieu D, Marroni A, Kot J. Tenth European Consensus Conference on Hyperbaric Medicine: recommendations for accepted and non-accepted clinical indications and practice of hyperbaric oxygen treatment. Diving and http://www.eubs.org/?p=583). Hyperbaric Medicine 2017; 47(1):24-32). (available athttp://www.eubs.org/?p=583).