A question we receive frequently at Extivita is “What is the difference between your chambers, and a soft chamber that zips up?”

Not only is it important to under the difference between the two, it’s also just as important to understand the mandates that the state of North Carolina enforces. Please reference “Why PVHO Mandates are Enforced in 11 States for Hyperbaric Oxygen Therapy” to better understand the mandates surrounding the difference between hard and soft chambers. The referenced page cites W.T. Workman, former Director of Quality Assurance & Regulatory Affairs for the Undersea and Hyperbaric Medical Society, in an article written for Today’s Wound Clinic in May 2022.

None of the low-pressure, portable fabric hyperbaric chambers is compliant with ASME PVHO-1 or NFPA 99. Eleven states have statutes that mandate compliance to ASME PVHO-1 for any clinical hyperbaric chamber in operation in their respective state. They are Arkansas, California, Delaware, Georgia, Hawaii, Minnesota, North Carolina, Oregon, Tennessee, Washington, and Wisconsin. Accordingly, in those states, it is against the law to provide clinical hyperbaric oxygen therapy using a device that does not meet this safety code.



Extivita is a clinic that has multi-place hard shell Hyperbaric Oxygen Therapy chambers. We are a NFPA compliant facility, meeting all necessary safety rules and PVHO (Pressure Vessel for Human Occupancy) mandates required for clinical HBOT operation in North Carolina.

When diving into the difference between hard and soft chambers, the National Hyperbaric Treatment Center published a very insightful article distinguishing the two.  It is cited below:

‍Hard Hyperbaric Oxygen Chambers

In hospitals and clinics, physicians use hard-shell hyperbaric oxygen chambers. These chambers are medical-grade devices and FDA-approved for the treatment of 14 conditions. In addition, they show positive results in studies for many, many more conditions. Hard-shell chambers are steel-enclosed chambers that deliver 100 percent oxygen at atmospheric pressures above 2.0 ATA. Installation of these chambers in a medical facility requires meeting various building regulations, including NFPA-99 from the National Fire Protection Association.

Soft-Sided Hyperbaric Chambers

Soft-sided chambers, known as mild HBOT or mHBOT, are portable chambers that seal with a zipper. They can reach pressure levels around 1.3 ATA and typically deliver 24 percent oxygen levels. Originally designed for divers and mountain climbers to use until they could transport to a hard-sided chamber, the intention was never to use soft-sided chambers for treatment.

The Levels of Oxygen Do Not Compare

The big difference between hard and soft chambers comes when we talk about oxygen concentration into the body. To get a better understanding of this, as you read this, you are breathing in room air with a concentration of 21 percent oxygen. A soft-sided chamber utilizes 24 percent oxygen. In contrast, when you see people transported in an ambulance and hooked up to an oxygen mask, they are receiving 55 percent oxygen. Hard-shell hyperbaric chambers deliver 100 percent oxygen. These numbers don’t even consider the pressure level differences.

To go more in-depth, let’s look at arterial blood gas levels that show oxygen in the blood. In normal air conditions and at normal pressure, your blood oxygen is going to read 157 mmHg. However, in a soft-sided chamber at 1.3 ATA and 24 percent oxygen, your number rises to 230 mmHg. An oxygen mask, like those used in ambulance transport, delivers 55 percent oxygen at normal pressure and gives you 418 mmHg. Of course, the real difference occurs in a hard-shell chamber. With a hard-shell chamber at 2.4 ATA and 100 percent oxygen, your arterial oxygen levels reach 1,824 mmHg.

The idea behind hyperbaric oxygen therapy and its success as a treatment option depend on flooding the body with higher levels of oxygen. Unfortunately, you see that soft-sided chambers don’t really offer much more than the air you naturally breathe. In all honesty, you receive more benefit from a simple oxygen mask.


‍Soft-Sided Chambers Fall Short

While hyperbaric oxygen therapy is FDA-approved for the treatment of 14 conditions currently, many conditions have been treated off-label with great success both in medical clinic environments as well as in numerous clinical studies, showing that flooding the body with high levels of oxygen can heal and, in many cases, return quality of life to many patients. However, in all these studies the administration of oxygen has been at 100 percent and at pressure levels of 2.0 ATA or higher.

To date, no real studies have looked at the benefit of mild hyperbaric, or low oxygen therapy. And given the numbers, the oxygen levels they provide aren’t much different than what you breathe in normally. Soft-sided chambers are not FDA-approved as a medical device for the use in hyperbaric oxygen therapy, except for the use by climbers and divers with altitude sickness during transport to a medical facility with a hyperbaric chamber.

When Your Treatment Causes More Problems

Hyperbaric oxygen therapy treats non-healing wounds as well as bacterial, viral, and fungal infections. Scientific research shows that oxygen becomes bacteriostatic at 1.5 ATA. This means that at levels above 1.5 ATA, the oxygen prevents bacterial and fungal growth. With hard-shell hyperbaric oxygen therapy, pressure levels are typically over 2.0 ATA, making it successful in the suppression of bacterial growth. Unfortunately, with average levels of 1.3 ATA, soft-sided chambers cannot suppress bacterial growth. On the contrary, they enhance the growth of bacteria, mold, and fungus. Exposure to bacteria, mold, and fungus make conditions worse or lead to additional medical complications.

Not all Hyperbaric Oxygen chambers produce the same results, and not all chambers are accepted for use in the state of North Carolina. We hope you now better understand the difference between the two chambers, and the reasons why eleven states have statutes in place that mandate clinics with HBOT chambers comply to PVHO and NFPA-99.

Your safety is always our top priority here at Extivita.

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