There are several types of hyperbaric chambers. Here are the main categories with pros and cons for each + how oxygen is delivered.
Multiplace Chambers
The first type of chamber developed was the mulltiplace chamber. These chambers, as you probably guessed, can treat multiple people all at the same time. There is also typically an attendant in the chamber at the same time that can help people who need it.
These chambers were originally designed to treat patients with decompression illness and go to very, very deep depths (>8 ATA). As a class, they usually are made of steel with port hole windows (just a submarine) to withstand very deep pressures but newer ones are made of more flexible material and only pressurize to 1.3 or 1.5 ATA.
More recently, there are more multiplace chambers outside of hospital, dive, and military settings. The Israelis have clinics across the world that are using the multiplace chamber for their reverse aging protocols. And even smaller clinics around the world use them including in the UK where MS societies make treatment very inexpensive using these decommissioned mulltiplace chambers from the military.
No matter the depth the multiplace is rated to (and operates to), most of these chambers give additional oxygen via a facemask, hood, or possibly by nasal cannula.
There are some mild multiplaces across the world that do not use additional oxygen at all as well, relying on Henry’s law and the increased oxygenation that comes from 1.3 ATA with 21% oxygen.
In any case, however, the full chamber is NEVER fully oxygenated for fire related reasons. Instead, the chamber is pressurized with 21% oxygen (sea-level oxygen).
Benefits of Multiplace Chambers
The benefits outside the critical care side of HBOT are myriad but in essence, the main benefits are cost (in some locations), that you have an attendant in there to help, and there’s the ability actually move around and “do stuff” while you’re in the chamber.
For this latter reason, there has been research on multitasking upgrades in the chamber while under oxygen along with active PT/OT/speech and under therapy under HBOT conditions.
Some clinics also report that when people dive together, they often bond (hey,…you spend a while together) which helps them stay motivated to come for their treatment protocols that can at times be a significant time commitment.
Plus, in milder pressure multiplace chambers across the world especially Japan, they have become popular for holding meetings and creative sessions + group session of all kinds.
Downsides of Multiplace Chambers
The main downside to a multiplace environment is that everyone has to be treated at the same pressure and for the same time. There really is no easy way to individualize treatment. Some of the more cutting-edge academic centers can play with nitrogen/oxygen mixtures in their hoods or masks to simulate a different amount of oxygen infusion at the same pressure. And many of the hyperbaric studies were done doing this.
The other downside is if there are complications for one person in the chamber, it affects the treatment for everyone else. The most common example of this is when one person is having a hard time clearing their ears in the chamber. When this happens, everyone has to wait until that person has cleared their ears to proceed with pressurization.
Another downside is that it just takes longer to corral everyone into the chamber and the scheduling is not as flexible for these types of facilities because everyone has to dive together. Again, there are benefits to diving together but this isn’t one of them.
Monoplace Chambers
These chambers which are mostly for one person at a time (usually) were first developed in the 1960s and come in three major varieties: Hard chambers, hybrid chambers, and soft/inflatable chambers.
The first monoplace or single occupancy chamber developed were medical grade chambers which were initially made out of steel and were basically mini-multiplace chambers with port holes that could pressurize to at least 3 ATA. Quickly, more varieties came on the market that included chambers made of fully translucent acrylic materials where the patient could see out fully 180 degrees. Initially, they were coffin-like small but as the tech has advanced and the population has become much more rotund, the size of the chambers has followed suit.
All outpatient insurance approved indications for HBOT can be treated in a monoplace chamber rated for 3 ATA as well as all the off-label conditions.
Over the last several decades, monoplace chambers have been developed with a mix of materials (hybrids) including aluminum, plexiglass, and others. These chambers typically pressurize in a range of 1.4 to 2.0 ATA. These chambers can treat a smaller subset of conditions including most of the insurance-approved conditions.
The final monoplace type chamber to speak about is the soft, inflatable chambers. Some of these chambers can go to very deep depths (>9ATA) but overall, most pressurize from 1.3 ATA to 1.5 ATA. They are typically made out of an elastic plastic called TPU. TPU is used in many common goods, including inflatable rafts and conveyor belts. These chambers will inflate with air to a certain set of dimensions and internal chamber pressure.
In the US, soft chambers are the only insurance approved for Acute Mountain (Altitude) Sickness. There is also a growing list of investigational indications with the research most promising in neurocognitive recovery (traumatic brain injuries, anoxic brain injury, dementias, etc) cognitive optimization, and day-to-day overall recovery.
Benefits of Monoplace Chambers:
As above, medical grade monoplace chambers can treat all outpatient (stable) insurance approved conditions and all of the investigational ones as well. Having a monoplace unit also gives you the option to personalize treatment which is very difficult to do in the multiplace chambers. This personalization includes rates of descent, rates of ascent, and the actual protocol depth with each treatment.
These units are also much more mobile than their multiplace counterparts. You’ll find some in hospitals but they are the primary chamber used in outpatient HBOT clinics around the world.
The mild sided units are found in clinics around the world as well but are also very popular for home use. There are more and more people getting hard shell chambers for their house as well (or one of their houses for this demographic) to have the versatility of doing all protocols. There are some complications with this but if there’s a will (i.e. money), there is a way.
Downsides of Monoplace Chambers:
Being in a monoplace chamber usually means that you are lying down. There are a few chambers out there that are single occupancy “sit up” varieties (both medical grade and soft sided) but these are far and few between so far (although growing in number). In a mild sided unit you can certainly bring things in there, especially of a non-electrical variety but there is much less room to move and do various types of exercise, PT, etc.
There also isn’t typically room for an attendant to help you so it’s more difficult to do critical care level HBOT in one of these chambers. That being said, it is used in this capacity across the world so it’s definitely possible.
If the patient is disabled and has a hard time w/mobility, the home chambers can be difficult to manage. Typically, however, the medical grade chambers in clinics come w/gurneys to easily slide people but the person will still have to get on the gurney in the first place.
Oxygen in a Monoplace Chamber:
In the monoplace chambers, oxygen is delivered via facemask, hood, nasal cannula, or in some medical grade monos, 100% in the chamber itself. For the medical grade chambers that are pressurizing >1.75 ATA, this requires high flow oxygen that can only be delivered by a high flow oxygen concentrator, regular oxygen concentrators in series, bottled or liquid oxygen. For chambers pressurizing to less than 1.75 ATA, you can usually get away with one to two oxygen concentrators, both working at 10L/minute.
The chamber is under pressure so the concentrator is pumping against the pressure of the chamber to get oxygen in. As a result, there is a significant loss of 02/liter.
