Mild vs Hard HBOT Hyperbaric Oxygen Therapy: Proven benefits?

What is the difference between hard and soft hyperbaric oxygen chambers?

• Hard chambers run at higher pressures, typically from 2-3 times atmospheric pressure (ATA)
• Hard chambers are pressurized with 100% oxygen
• Hard chambers are constructed with metal and glass to be able to contain the higer pressures used.
• Hard chambers have a higer risk of fire and require strict safety protocols
• Soft chambers run at lower pressures, 1.3 to 1.5 ATA
• Soft chambers are pressurized with room air, so have a much lower fire risk, but still require safety protocols.
• Soft chambers use a separate oxygen supply for the occupants to breathe via a mask or nasal cannula.

Are soft chambers, using mild hyperbaric oxygen just as effective as hard chambers?

The evidence around this question is mixed, and the answer is probably nuanced. Many proponents of hard chambers will say that mild HBOT at 1.3-1.5 ATA, using only room air, can never have the same benefits as hard chambers at higher pressures of 2-3 ATA (sometimes even higher). The laws of physics will easily show that more oxygen is delivered with the hard chambers, but does this mean that there are no benefits with mild HBOT? Not necessarily. Consider the following:

Studies that support mild HBOT effectiveness:

The question is whether mild hyperbaric oxygen therapy (HBOT) pressures (1.3-1.5 atmospheres absolute, ATA) can deliver results comparable to those of higher pressures found in hard chambers. Let’s consider what insights on this matter can be found in the medical literature.

A systematic review by Harch et al. looked into the effectiveness of HBOT for mild traumatic brain injury persistent postconcussion syndrome (mTBI/PPCS). The study revealed that treatments at 1.5 ATA oxygen yielded statistically significant improvements in symptoms and cognitive function. Encouraging outcomes were also noted at 1.3 ATA air in a particular study, whereas outcomes varied at 1.2 ATA air and were unfavorable at 2.4 ATA oxygen. These findings suggest that lower pressures may prove to be effective and, in certain instances, more reliable than higher pressures.^​1​

Furthermore, Figueroa and Wright pointed out that pressurized air controls at 1.2-1.3 ATA, frequently utilized as placebo controls, actually exhibited therapeutic benefits. This underscores the biological activity of these mild pressures, showcasing their potential to enhance symptoms of mTBI/PPCS.^​2​

Another prospective, randomized, trial involving 565 patients compared the effects of 1.5 and 2.0 ATA for patients with spontaneous intracerebral hemorrhage (ICH). The patients underwent 60 or 90 session and were followed for six months. Investigators found that HBOT at 1.5 and 2.0 ATA had the same beneficial effect and that 1.5 ATA and 60 HBOT sessions was the optimal protocol for improved survival rates and functional measurement. This indicates that the efficacy of 1.5 ATA is on par with that of higher pressures.^​3​

In conclusion, the available evidence suggests that mild HBOT pressure (1.3-1.5 ATA) has the capacity to be just as effective as higher pressures for specific conditions, notably mTBI/PPCS and acute severe intracerebral hemorrhage.

Academic References