HBAT vs. HBOT - What's the Difference?

When discussing hyperbaric protocols and treatment options with your prescribing physician it is important to know the dosage of oxygen, frequency and duration of the dive(s).  Since hyperbaric treatment is commonly referred out to a specialized clinic or medical supplier, understanding this information could make the difference in the results you achieve.

HBAT is an abbreviation for Hyperbaric Air Therapy.  Essentially, the chamber occupant breathes the same room air used to pressurize the hyperbaric chamber.  No oxygen is used other than the oxygen contained in the normal air we breathe.  Room air, is also referred to as Normoxic Nitrox.  It contains 21% Oxygen, 78% Nitrogen with the 1% balance comprised of inert trace gases that naturally exist is our atmosphere.   For the purposes of these dosage calculations this 1% is factored into the total Nitrogen percentage.

HBOT is an abbreviation for Hyperbaric Oxygen Therapy.  The chamber occupant breathes 100% gaseous oxygen or when oxygen concentrators are used, as a high of a percentage as the equipment is capable of delivering.  The hyperbaric chamber may be completely pressurized with oxygen or the chamber is pressurized with Air (Normoxic Nitrox) and the oxygen is delivered to the patient through a B.I.B.S. (Built in Breathing System.)  Types of BIBS include Non-Rebreather Masks, Demand Masks and Oxygen Hoods

It is important to note that because of cost effectiveness, convenience and safety more hyperbaric chambers pressurize with Air and utilize a BIBS than pressurize with pure oxygen.  US Navy Hyperbaric Protocol is exclusively pressurization with Normoxic Nitrox and Oxygen via BIBS.

The premise for utilizing just HBAT is that the increased pressure of the chamber elevates the partial pressure (percentage) of oxygen being provided to the tissues.  It however overlooks that the partial pressure of nitrogen is significantly elevated as well. This is a result of Dalton's Law of Partial Pressure.  Simply stated, the sum of the whole is equal to all of the parts.  In this case the "parts" are Nitrogen and Oxygen.

21% + 79% = 100%

Another way we could express this is:

.21 + .79 = 1.0

In the case of HBAT at a gauge pressure of 4 psi, which is approximately 1.3 ata:

.27 + 1.03 = 1.3

So yes, HBAT at 4 psig elevates the partial pressure of oxygen to from 21% (.21) to 27% (.27).  It also elevates the partial pressure of nitrogen from 79% (.79) to 103% (1.03). Depending on what you are using HBAT for this may do more harm than good.  The issue here is that while HBAT has been suggested in a small number of clinical trials to be marginally effective for a few conditions, there are other conditions where HBAT is known to be completely ineffective.  There are also some conditions, such as infectious diseases and wound care where HBAT actually creates a negative, potentially harmful ischemic reaction. This is specifically related to the elevated partial pressure of nitrogen also being dissolved into the tissues, etc. An example of a condition where HBAT treatment could potentially cause harm is Lyme Disease.  Not only does that low of a dosage of oxygen do nothing for the auto-immune system it pushes the bacillus further toward protecting itself with its protein coating camouflage.

During HBOT the patient is breathing a much higher partial pressure of oxygen. The actual dosage of oxygen delivered to the tissues, cerebral, synovial and lymphatic fluids is drastically higher but the partial pressure of nitrogen is nominal. Using the same example, HBOT using 100% oxygen at a gauge pressure of 4 psi delivers almost five time more.  This may lead to the question that if some oxygen is good than is more better?  Perhaps, but only to a point and dosage is specific to the exact condition being treated.

If your doctor prescribed HBOT but you were only going to get HBAT would you want to know?  Of course you would and now you do...

How to calculate actual dosage is part of the ANDI Hyperbaric Course Curriculum. HyperbaricsRx offers a variety of seminars, courses and certification programs that greatly elaborate on the general concepts I've discussed here.