Oxygen therapy with hyperventilation may be easier to explain and understand if you start with the underlying respiratory physiology.  We upload oxygen and offload CO2 with every inhalation - exhalation cycle...  This brain stem controlled function keeps us alive as our bodies need a balance in oxygen and CO2 blood gasses.

Our bodies are much like the gas driven engine in a car.  If we increase our physical activity we burn (metabolize) more glucose (blood sugar) and in the process generate more heat, energy and CO2.  In comparison, when you step on the gas peddle, your car goes faster as you burn more gas and the carburetor intakes more air.  As a result the engine develops more energy, the engine generates more heat and exhausts more CO2.

As we increase our physical activity we need to breathe faster to inhale the additional  oxygen needed to support the increased metabolism and exhale the additional CO2 generated by the physical activity. Again, this happens without thinking about it.  All you had to do was intentionally increase your physical activity.

The primary physiological function that regulates this process is called a homeostatic process.  The chemoreceptors of the cardiovascular system are located in two places. The carotid bodies are located in the carotid arteries that run through the neck to the brain, and the aortic bodies are found in the aortic arch, an arterial feature near the heart. 

These chemoreceptors sense blood CO2 concentrations and blood pH (a measure of acidity/alkalinity based on hydrogen ion concentrations). These chemorecepters in turn signal control centers in the brain stem that control the rate of heart beat and respiration.  They also control vascular constriction and relaxation to regulate the flow of blood.

When we hyperventilate, (breathe faster than we need to breathe to maintain the homeostatic balance of CO2 and oxygen), we pump more CO2 from the cardiovascular system than normal so blood pH rises (becomes more alkaline).  The chemoreceptors sense these conditions and signal the control centers in the brain stem.  They in turn signal the lungs to breath more slowly, the heart to beat more slowly and the vascular system to constrict.  All these actions slow the flow of blood through the lungs and that slows the release of CO2 in exhaled breath. In short, these homeostatic processes work to lower pH and increase blood CO2 concentrations back to normal.

However, as we are intentionally hyperventilating, we continue to pump CO2 from the blood with each exhalation, we override the control signals to slow the heart beat and rate of respiration.  The only thing we can't override is the vasoconstriction so arteries, arterioles and capillaries continue to constrict.  This is one of the basic cluster headache abort mechanisms.

The other part of the cluster headache abort mechanisms occurs when blood pH rises.  How did that happen?  When CO2 dissolves in water (blood serum) it becomes carbonic acid (more hydrogen ions) so pH drops.  When CO2 is removed from blood serum, the hydrogen ion concentration drops (less acid) so blood pH rises (becomes more alkaline).

When blood pH rises, blood hemoglobin molecules have a greater affinity for oxygen so upload up to 14% more oxygen and offload CO2 more rapidly. This results in oxygenated blood flowing to the brain and body and the returning venous blood carries the CO2 back to the lungs to be exhaled. This is happening every second of every day as long as we're alive. If we're breathing 100% oxygen at this point, we super-oxygenate the blood flowing to the brain and body. This then becomes another important CH abort mechanism.

Now lets look at the breathing procedures I suggest while trying to abort a CH with oxygen.  If we hyperventilate for 30 seconds using maximum forced lung tidal volumes by doing an abdominal crunch at the end of each exhalation cycle, we pump out more CO2 than normal so blood CO2 levels drop and blood pH rises.  If we continue hyperventilating at forced vital capacity tidal volumes for 30 seconds then inhale a lungful of oxygen and hold it for 30 seconds what have we accomplished?  We've lowered the CO2 concentration dissolved in our blood, raised the pH and super-oxygenated the flow of blood to the body and brain...  trigeminovascular system in particular.

Now watch the youtube video of my dear friend Chuck Setzco at the following link.  He's trying to abort a CH with oxygen therapy at an oxygen flow rate of 7 to 9 liters/minute with a non-rebreathing oxygen mask.

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This is painful to watch, but look closely at the 1-liter reservoir bag on the disposable non-rebreathing oxygen mask he's using.  It's collapsed most of the time.  Chuck is trying to breathe faster but the mask and oxygen flow rate will not permit this to happen. 

Although Chuck is receiving an adequate supply of oxygen, the amount of lung ventilation is insufficient to expel the excess CO2 generated through his physical activity fast enough so his blood CO2 levels rise.  This is the worse case scenario and just the opposite of what is needed to abort a CH so the CH pain gets worse rather than better.  This happens as the increased blood CO2 concentration (way above normal) triggers vasodilation which contributes to CH pain and makes an abort with oxygen therapy take much longer than needed.

Chuck was the first CHer to try the oxygen demand valve method of aborting a CH we developed in November of 2007.  This method of oxygen therapy allowed Chuck to hyperventilate with 100% oxygen breathing as fast and as deeply as desired as the oxygen demand valve delivers oxygen on demand much the same as a SCUBA diver's regulator.

Chuck was also the first of seven CHers to take part in a pilot study of the oxygen demand valve method of aborting CH.  We asked him to log his abort times and pain levels using a 15 liter/minute oxygen regulator and the standard disposable non-rebreathing oxygen mask.  The results of that pilot study are illustrated in the following graphic.  In all, the seven CHers collected abort times and pain levels for 8 weeks each resulting in data on 366 aborts with the oxygen demand valve.

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Chuck's aborts with a 15 liter/minute regulator are shown in red.  As you can see his average abort time using an oxygen regulator at a flow rate of 15 liters/minute was over 30 minutes.  Now look at the abort times with the oxygen demand valve that allowed users to hyperventilate with 100% oxygen.  The average abort time was 7 minutes for pain levels 3 through 9 on the Kip Pain Scale.

The latest method of aborting CH by hyperventilating with room air at forced vital capacity tidal volumes for 30 second followed by inhaling a lungful of oxygen and holding it for 30 seconds is just as effective with nearly the same abort times as with the oxygen demand valve.  The biggest benefit of this new method is in the amount of oxygen consumed per abort.  Where this new method results in an average CH abort time of 7 minutes, it consumes roughly 28 liters of oxygen, the demand valve method consumes roughly 280 liters of oxygen per abort.

I hope all this makes sense.

Take care,

V/R, Batch