Portable Soft-Shell HBO Chambers

A portable hyperbaric chamber is a pressure chamber that is easily transportable, typically made of durable, flexible materials such as nylon or PVC, and designed to be inflatable or collapsible. These chambers, which are large enough to fit one person and sometimes two, are sealed with a zipper or lock mechanism, and internal pressure is increased by means of a compressor or pump. While fixed HBOT units typically operate in hospital or clinical settings with 100% pure oxygen and at higher pressures, portable chambers generally operate at lower pressures, around 1.3-1.5 ATA, which is why they are referred to as “mild hyperbaric oxygen therapy” (mHBOT). However, the FDA and similar regulatory bodies emphasize that the low-pressure use applied in portable chambers is not as effective as high-pressure clinical HBOT.

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Clinical HBOT protocols are administered at higher pressures than portable chambers allow, and the technical specifications of hard-shell multiplace hyperbaric chambers are engineered accordingly to safely reach these higher treatment pressures; as part of this design, such chambers are generally tested at pressures above 8.5 ATA.

Key Points

• Portable soft-shell hyperbaric chambers are pressurized with air only, typically at 1.3-1.5 ATA.
• The FDA’s 510(k) clearance for soft-shell portable chambers is limited solely to acute mountain sickness, and explicitly prohibits their use with supplemental oxygen.
• Certain commercially marketed low-pressure or soft-sided hyperbaric chambers may operate outside UHMS-defined treatment parameters and may not meet applicable ASME PVHO-1 or NFPA 99 standards required for clinical hyperbaric oxygen treatment. (Owen J. O'Neill, Mathew Kelly, Dag Shapshak. UHMS Position Statement. Standardization of Terminology in Undersea and Hyperbaric Medicine: Adoption of “Hyperbaric Oxygen Treatment”, June 1, 2026)
• UHMS does not endorse the concept of ‘in-home’ hyperbaric therapy under any circumstances.
• Pressure chambers used for treatment purposes are considered medical devices and must comply with standards such as CE certification, the EU Pressure Equipment Directive (EN14931), PVHO-1 and NFPA-99/EN16081.

Henry’s Law

According to Henry’s law, the amount of oxygen physically dissolved in plasma increases as the partial pressure of oxygen increases. Therefore, the combination of elevated ambient pressure and a high inspired oxygen concentration markedly increases the partial pressure of oxygen and, consequently, the amount of oxygen dissolved in plasma. This provides an additional mechanism of oxygen transport beyond hemoglobin-bound oxygen, allowing increased oxygen availability to hypoxic or poorly perfused tissues.

It should be noted, however, that when an oxygen concentrator is used instead of a medical oxygen supply, the delivered oxygen concentration is generally high but does not necessarily reach a true 100% oxygen concentration. In clinical settings, hard-shell hyperbaric oxygen therapy (HBOT) chambers are typically pressurized with compressed air, while oxygen is delivered to the patient through a separate breathing system. The oxygen source may consist of high-pressure medical oxygen cylinders, a centralized medical oxygen supply, or liquid oxygen systems. The patient breathes a high concentration of oxygen, commonly 100% when medical-grade oxygen is used.

Importance of Tissue Oxygenation

According to the Undersea and Hyperbaric Medical Society’s (UHMS) 15th edition Hyperbaric Medicine Indications Manual, hyperbaric oxygen therapy is approved for a total of 15 indications, including carbon monoxide poisoning, decompression sickness, compromised grafts and flaps, gas gangrene, necrotizing soft tissue infections, thermal burns, sudden sensorineural hearing loss, central retinal artery occlusion, and avascular necrosis (Huang, 2023; Tanaka et al., 2024).

Turkey's HBOT indications

1. Decompression sickness
2. Air or gas embolism
3. Carbon monoxide and cyanide poisoning, acute smoke inhalation
4. Gas gangrene
5. Necrotizing soft-tissue infections (subcutaneous, muscle, fascia)
6. Crush injuries, compartment syndrome, and other acute traumatic ischemias
7. Delayed wound healing (diabetic and non-diabetic)
8. Chronic refractory osteomyelitis
9. Severe blood loss
10. Radiation necrosis
11. Compromised skin flaps and grafts
12. Thermal burns
13. Brain abscess
14. Anoxic encephalopathy
15. Sudden hearing loss
16. Retinal artery occlusion
17. Acute osteomyelitis of the skull, sternum, or vertebrae

Hyperbaric oxygen therapy accelerates wound healing by delivering oxygen at high partial pressure, thereby increasing collagen synthesis and angiogenesis, improving endothelial function, reducing ischemic tissue damage, supporting graft/flap viability, reducing edema, and suppressing the inflammatory response.

Tissue oxygen pressure has been found to be 0-15 mmHg in many wounds with healing problems. The critical threshold for wound healing is accepted as 30-40 mmHg. When this value cannot be reached through surgical interventions and other medical treatments, hyperbaric oxygen therapy (HBOT) comes into play. The antihypoxic effect of hyperbaric oxygen (HBO), which cannot be achieved by any other method, is based on the dissolution of oxygen breathed at high pressure within a pressure chamber into the blood and tissues. Thus, in addition to the oxygen carried by hemoglobin, O₂ transported in the liquid phase also reaches problematic tissues (1,2). HBO’s antiedema effect further contributes to tissue oxygenation. The antiedema effect of hyperbaric oxygenation has also been demonstrated experimentally (3,4).

What Does UHMS Say?

Low-pressure fabric (soft) hyperbaric chambers, marketed for sports and alternative medicine purposes, are devices designed to be pressurized with air only and operate below 1.4 ATA; the U.S. Food and Drug Administration (FDA) has granted 510(k) clearance for these devices solely for acute mountain sickness, and their use together with supplemental oxygen is explicitly prohibited by the FDA [1]. The construction, operation, and maintenance requirements for hyperbaric facilities are outlined in the NFPA 101 Life Safety Code and the NFPA 99 Health Care Facilities Code, and accordingly, hyperbaric chamber construction must comply with the ASME-PVHO-1 standard, which applies to any pressure vessel enclosing a human being at an internal or external pressure exceeding 2 psig above ambient (1.14 atmospheres absolute) [2,3,4]. The room housing the chamber must also meet the housing requirements set out in Chapter 14 of NFPA 99 [3]. The Undersea and Hyperbaric Medical Society (UHMS) does not endorse the concept of “in-home” hyperbaric therapy under any circumstances [5].

Mild hyperbaric exposures using air alone deliver no more oxygen to the body than simply breathing oxygen through a mask at sea-level pressure, which is why UHMS does not recommend mild hyperbaric therapy for any medical purpose other than acute mountain sickness.

Can 100% Oxygen Be Used in Soft-Shell Portable Hyperbaric Chambers? If Not, Why?

100% oxygen use in soft-shell portable chambers is not approved. The FDA’s 510(k) clearance for soft-shell portable chambers explicitly prohibits their use with supplemental oxygen, since these devices are designed to be pressurized with air alone.

Excerpts from the Position Statement of the Underwater and Hyperbaric Medicine Society on ‘Low-Pressure (Mild) Hyperbaric Therapy’

Recently, it has been observed that the use of Low-Pressure Hyperbaric Therapy, referred to worldwide as ‘Mild Hyperbaric Therapy,’ has been increasing. In fact, specialized devices have begun to be manufactured for these applications.

Hyperbaric Oxygen (HBO) therapy is a treatment performed by breathing oxygen at pressures higher than 1 atmosphere and at high concentrations, inside a closed device called a pressure chamber. Its mechanism of action is based on the dissolution of the inhaled oxygen into the blood under pressurized conditions. It is used for evidence-based indications recommended by international scientific organizations. The pressure chambers used in HBO therapy must comply with numerous international and national standards, both during the establishment phase and throughout their active use, and they undergo regular inspections at set intervals. Likewise, personnel standards and the precautions taken during application are also subject to national and international regulations. It has been stated that treatments administered at pressures below 1.4 ATA and with oxygen concentrations below 100% are not effective.

HBO therapy’s equipment, application, and personnel standards are regulated by official regulations in our country. All medical applications performed above one atmosphere of pressure are also considered hyperbaric treatment and are subject to these legal regulations.

Patients must undergo a detailed evaluation of indications and contraindications before treatment, and must be carefully monitored for side effects and problems during treatment, all of which must be recorded. The centers where treatments are administered must undergo regular inspections.

Another important issue concerns the pressure chambers in which the treatments are administered. Pressure chambers used for treatment purposes are considered medical devices in our country. As is the case throughout the world, in our country as well, only pressure chambers that comply with certain standards and regulations (such as the CE certificate, the EU Pressure Equipment Directive (EN14931), PVHO-1, and NFPA-99/EN16081) are permitted for use on humans. Recently, some manufacturers in various parts of the world have begun producing devices they call “low-pressure chambers,” used for Low-Pressure Hyperbaric Therapy, in which pressure increases by at most 0.5 bar atmosphere. These devices, too, must comply with the same standards as the pressure chambers used for HBO therapy.

In conclusion, the use of Low-Pressure Hyperbaric Therapy is not recommended for conditions outside the medically approved indications recognized by scientific organizations, as it lacks a scientific basis.

What Are the Safety Concerns With Unsupervised Use?

Regulators in multiple countries have issued specific warnings about soft-shell chamber use outside a supervised medical setting.

• Fire and equipment risk: The FDA has reminded health care providers and facilities that hyperbaric oxygen devices carry a heightened fire risk under high oxygen concentration, and has recommended fire-prevention measures, proper grounding, and continuous patient monitoring following reports of serious injuries and deaths (FDA, 2025).
• Uncertified construction: Many soft-sided chambers sold to consumers are not registered with the FDA and do not meet the ASME PVHO-1 pressure-vessel construction standard used for hard-shell clinical chambers (Melnyczenko, 2025).
• Documented fatality: The UHMS has reported that at least one person died from asphyxia while using an unattended soft-shell chamber at home (Melnyczenko, 2025).
• National restriction: Health Canada has classified unlicensed soft-shelled hyperbaric chambers as a health risk (Health Canada, 2019) and has taken enforcement action against distributors selling them for medical claims (Health Canada, 2020).

These warnings apply specifically to unsupervised or uncertified use, not to hyperbaric oxygen therapy delivered under medical supervision.

How Do the Hyperbaric Oxygen Chamber Types Compare?

Parameter	Portable Soft-Shell	Single-Place Hard-Shell	Multiplace Hard-Shell
Pressure	Up to 1.3–1.5 ATA	Clinical range	Clinical range
Patients per session	One	One	More than one
Staff inside chamber	No	No	Yes
US regulatory status	FDA 510(k)-cleared for acute mountain sickness only; supplemental oxygen use prohibited	FDA-cleared Class II device	FDA-cleared Class II device
Construction standard	Not required to meet ASME PVHO-1	ASME PVHO-1	ASME PVHO-1

Design and Technical Features in Multichambers

In multi-person pressure chambers, there is a front section called the “antechamber” and a second, main section called the “main chamber.” Patients are treated in this main section. The front chamber is left empty for entries and exits into the pressure chamber. A door between the front and main compartments allows the pressure in the two compartments to differ from each other. When necessary, the pressures of the two compartments are equalized and the door between them is opened. (MÇ)

Multi-person chambers can reach higher pressures than single-person ones. For this reason, physiological and clinical research related to deep diving is conducted in this type of chamber. These chambers are also more suitable for treating complex, multisystem diseases. The ability to have doctors, nurses, and other healthcare staff present in the chamber during treatment, or to transfer healthcare personnel or equipment into the chamber using the front compartment when needed, expands the usable space of these chambers. One of the important features of multiplace chambers is that the seating inside the chamber can be rearranged according to the number and condition of patients. When necessary, all the seats can be removed, and a patient can be treated while lying in a hospital bed. (MÇ)

While multi-person chambers used to be operated only manually, today the treatment program is run, patients are monitored via video cameras, the oxygen and carbon dioxide percentages, humidity, temperature, and other values inside the chamber are monitored, patients are entertained during treatment according to their TV, video, and music preferences, ventilation is provided according to the number of patients, and the alarm and sprinkler systems are operated entirely by a computer program. (MÇ)

Multi-person chambers have a small compartment called a “transfer lock” that connects to the main compartment. This compartment, which is essentially a mini pressure chamber on its own, has two hatches — one opening to the outside and one opening into the chamber. By equalizing the internal pressure, this compartment makes it possible to transfer materials, medical equipment, or food from outside into the chamber or from inside out. (MÇ)

Given the fire risk associated with oxygen-enriched, pressurized environments, multiplace chambers are equipped with dedicated fire suppression systems that are integrated with the chamber’s monitoring and alarm systems and designed to activate automatically in accordance with NFPA 99 requirements.

Taken together, these features – continuous medical presence, the transfer lock for passing equipment and supplies without interrupting pressure, the flexibility to treat a patient lying in a hospital bed, and the ability for a patient to exit safely through the antechamber without interrupting treatment for the others still inside – reflect the level of clinical infrastructure that multiplace chambers are designed to support, which in turn relates to how efficacy and safety are maintained during treatment.

Dr. Aslıcan Çakkalkurt, Hyperbaric Medicine Specialist (called Dr. Oxycure by Vera Clinic Patients) says:

Efficacy and safety. These are two important factors. A rigid, hard shelled multiplace chamber holds a pressure that a soft-sided, portable one simply isn't built to reach, and that pressure is what determines how much oxygen actually dissolves into the bloodstream. And the oxygen is pure oxygen, 100% oxygen. A portable soft shelled device isn't a smaller version of the same therapy, it's a different exposure altogether, and that's worth knowing before assuming one can stand in for the other. And since hyperbaric oxygen treatment involves high pressure and pure oxygen, safety is always one of our top priorities. In the chamber we use, we continuously monitor every relevant parameter alongside the treatment itself — including oxygen, carbon dioxide, humidity, and temperature levels, as well as the air and oxygen supply available in our tanks for pressurization. Multi-person hard-shell hyperbaric chambers offer a number of important treatment standards. A healthcare professional accompanies patients during the hyperbaric treatment session, staying present to promptly address any discomfort or concerns that may arise. Should a patient need to exit the chamber early for any reason, a healthcare professional is right there to guide them out safely.

Frequently Asked Questions

References

• Tanaka HL, Rees JR, Zhang Z, Ptak JA, Hannigan PM, Silverman EM, Peacock JL, Buckey JC; Multicenter Registry for Hyperbaric Oxygen Treatment Consortium. Emerging indications for hyperbaric oxygen treatment: registry cohort study. Interact J Med Res. 2024;13:e53821. doi:10.2196/53821
• Huang ET. Hyperbaric Medicine Indications Manual. 15th ed. North Palm Beach, FL: Best Publishing Company; 2023.
• González Flores, J. E., Vázquez Hernández, D. B., Gonzalez Espinosa, A., Sandoval Polito, A., Navalón Calzada, A., & Romero Cázares, E. O. (2026). Hyperbaric oxygen therapy in modern surgical practice: Mechanistic basis and clinical applications across specialties. Cureus, 18(1). https://doi.org/10.7759/cureus.102116
• Food and Drug Administration, CFR_Code of Federal Regulations Title 21.
• National Fire Protection Association, 101 Life Safety Code 2015 edition.
• National Fire Protection Association, 99 Health Care Facilities Code, 2015 edition.
• ASME-PVHO-1- 2012 edition.
• Undersea and Hyperbaric Medical Society Position Statement on the Conduct of Hyperbaric Oxygen Therapy.
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• Dooley J, Chirmer J, Slade B, Folden B. Use of transcutaneous pressure of oxygen in the evaluation of edematous wounds. Undersea Hyperb Med. 1996; 23(3): 167-74.
• Sümen G, Çimşit M, Eroğlu L. Hyperbaric oxygen treatment reduces carrageenan-induced acute inflammation in rats. Eur J Pharmacol. 2001; 431(2): 265-8.
• Çimşit M. Hiperbarik Oksijenin Etki Mekanizması. In: Çimşit M (ed). Hiperbarik Tıp 1. Basım. Ankara, Eflatun Yayınevi, 2009; 17-18.
• Bird N. UHMS Position Statement: Low-Pressure Fabric Hyperbaric Chambers. Undersea and Hyperbaric Medical Society. Published January 22, 2017. Revised July 10, 2018. Available from: https://www.uhms.org/