Question Oxygen Saturation after hyperventilating

[Math147]

Hello,

My question is about the drop of So2 during breathhold after hyperventilating. I've read that hyperventilating only changes that Co2 content of blood, while oxygen saturation is at almost 100 percent anyways, and so is not affected. So far so good. But doesnt lower Co2 also lower the oxygen consumption of the body (and causes the tingling)? That would mean that during breathhold the drop of So2 should come later and be slower. Is that true? It would in a way mean that hyperventilating would have an effect on So2. I tried it out with my oximeter and it seems to be true, but it is lagging more than half a minute so im not sure I can trust it.

Ps: I ask this question out of interest. I do not hyperventilate when in the water.

 

[cdavis]

HV is a bit complicated, but for most divers doing most levels of HV, the 02 level doesn't change to any significant degree at the start of the dive. Lower C02 levels mean dive reflex kicks in later and 02 consumption stays high for longer. Bottom line is lower 02 later in the dive. Since C02 is the prime way the body senses need to breath, the result is a greater tendency to run out of 02 before the C02 level gets high enough to make you surface.

Note: there is minimal dive reflex when doing statics dry, so extreme HV, which can modestly increase 02 level in muscle and plasma, might be useful for dry static. Not my area.

the lag you see on a finger oxymeter is the time it takes for the lowest oxygenated blood to get to your fingertip. That is also strongly affected by DR.

 

[Math147]

HV is a bit complicated, but for most divers doing most levels of HV, the 02 level doesn't change to any significant degree at the start of the dive. Lower C02 levels mean dive reflex kicks in later and 02 consumption stays high for longer. Bottom line is lower 02 later in the dive. Since C02 is the prime way the body senses need to breath, the result is a greater tendency to run out of 02 before the C02 level gets high enough to make you surface.

Note: there is minimal dive reflex when doing statics dry, so extreme HV, which can modestly increase 02 level in muscle and plasma, might be useful for dry static. Not my area.

the lag you see on a finger oxymeter is the time it takes for the lowest oxygenated blood to get to your fingertip. That is also strongly affected by DR.

Ok thanks, but shouldnt the oxygen consumption go down after hv atleast when doing dry statics, because of the Bohr effect. Its the effect that I revered to in my initial question, I didnt know the name. I tried again measuring my So2 with and without hyperventilating, and the So2 seems to go down slower after hv.

 

[Nathan Vinski]

Ok thanks, but shouldnt the oxygen consumption go down after hv atleast when doing dry statics, because of the Bohr effect. Its the effect that I revered to in my initial question, I didnt know the name. I tried again measuring my So2 with and without hyperventilating, and the So2 seems to go down slower after hv.

You need to be careful when measuring O2 with a pulse-ox. Finger blood, is a horrible representation of what's happening in our brain during a hold. The most likely reason that you have 'better' O2 readings after HV is because of increased blood flow to the fingers, or at least decreased potential for vasoconstriction.

I'm not saying that HV isn't possiblely benefiting your STA, as most people are, due to the increased relaxation, since we are working with minutes of contravtions, getting rid of 1-2:00 can be very beneficial in terms of relaxation (at least). Go through the freedive science section and you'll see my other theories on this topic, (actual effects of CO2 thread) should be on the first page