Diffusion is the movement of one or more gases down a concentration gradient. In other words... things move from greater concentration to lesser concentration. When working with gases, if more than one gas makes up an atmospheric environment, the partial pressure of any particular gas would be equal to the percentage of the gas multiplied by the total pressure.
Let's look at two more just to be sure we fully understand this component...
What we need to understand from these examples is that the pressure and the gas mixture work together to create a partial pressure differential, resulting in a concentration gradient and the occurrence of diffusion. If you are still confused, don't worry! You still don't have the complete picture as to how all this works and what these numbers mean.
When we talk about concentration gradients in respect to hyperbaric medicine we are speaking of the difference between tissue (don't forget that blood is considered a tissue), and the external atmospheric pressure. Of course, there is always a concentration gradient in the lungs. If there weren't, respiration wouldn't take place. The reason why there is always a concentration gradient in the lungs is due to the fact that venous blood is virtually void of oxygen. The cycle is pretty simple; blood from the body returns to the heart from the tissues via the venous system. This blood is high in carbon dioxide and virtually absent of oxygen. The right ventricle pumps this blood to the lungs where the ppO2 (partial pressure of oxygen) is much higher and carbon dioxide is much lower. As a result of this strong gradient, oxygen dissolves in the plasma and becomes bound to hemoglobin; further, carbon dioxide diffuses out of the blood and is exhaled form the body. This oxygenated blood then travels back to the left side of the heart where it is pumped to the tissues before returning once again. If you haven't figured out where the difference in pressure plays a role... it's in the lungs!
The greater the pressure and the greater the oxygen concentration, the greater the partial pressure of oxygen in a given environment. Diffusion says, "greater concentration to lesser concentration", it could also be stated, "greater partial pressure to lesser partial pressure". After all, we are just talking about concentrations of gases in one environment (inside your body) vs. another environment (outside your body). So, the greater the pressure and oxygen concentration in relation to an individuals normobaric environment (normal everyday atmospheric pressure); the more oxygen that will become dissolved into the bloodstream and secondarily the rest of the tissues of the body.
To calculate the amount of additional oxygen that could potentially become dissolved in the tissues we simply need to know the difference between the partial pressure of oxygen in ones normobaric environment vs. the applied hyperbaric environment.
So, if the oxygen concentration is a constant and the treatment is being applied at sea level, with only the pressure changing; the potential increase in oxygen saturation is easily calculated by subtracting one from the treatment pressure (ata) and then converting that number to a percentage.
Okay, examples 10 and 11 make things pretty simple... but the real world is much different. Let's look at what is really going on when pressure and oxygen concentration are changing and the treatment is being applied at elevations other than sea level.
What this means is that the treatment (oxygen concentration unchanged), although at a lower atmosphere absolute is just as effective at the higher elevation when we actually consider the differential between the treatment and normobaric atmospheric pressure.
So what happens when we add increased oxygen concentrations into the mixture? Let's take a look at whether oxygen concentration plays a changing role in these same two scenarios.
Of course it is a lot easier to just say 1.3 ata rather than figure out your elevation and actually calculate your true treatment pressure. Maybe this is why the industry has fallen into the bad habits that it has. More likely is that people just don't know. Sadly, it is just as easy to say you are undergoing treatment at 4.4 psig; unfortunately the industry is hung up on speaking in absolute terms that it doesn't actually represent. Even if you were representing an absolute pressure, the treatment potential would still vary based on elevation.
Part 5: The Importance of Frequency
About the Author: Greg Harris is the founder of Hyperbaric Options LLC and has spoken publicly about health & wellness in various settings over the past eight years. Greg has a passion for human potential and is a firm believer that nearly all of the health problems we face today, from degenerative neurological conditions to the common cold, are preventable and reversible. As a health professional, Greg has a unique ability to connect the dots where others have left them scattered; it is this ability to integrate disciplines and think outside of the box that give his lectures and written materials a fresh point of view.
Disclaimer: The information and advice published or made available throughout this article is not intended to replace the services of a physician, nor does it constitute a doctor-patient relationship. Information contained within the following and/or preceding pages is provided for informational purposes only and is not a substitute for professional medical advice. The author encourages all readers to further research any topics of interest and reminds the reader that the comments and materials being presented do not necessarily constitute scientific fact and may contain opinions, theories, and third party views not widely accepted. You should not use the information contained in this published material for diagnosing or treating a medical or health condition. You should consult a physician in all matters relating to your health, and particularly in respect to any symptoms that may require diagnosis or medical attention. Any action on your part in response to the information provided throughout the material is at the reader's discretion. Readers should consult their own physicians concerning the information in this material. Hyperbaric Options LLC is not liable for any direct or indirect claim, loss or damage resulting from use of this material.