RMV Spinoff from Accident & Incident Discussion - Northernone - aka Cameron Donaldson

[Celt]

Nothing you suggest is really related to oxygen efficiency. I think you are confusing facts with non-scientific opinions.

Its all related to oxygen efficiency and has been proven in the training of athletes using high altitude techniques.

 

[tursiops]

Its all related to oxygen efficiency and has been proven in the training of athletes using high altitude techniques.

Whatever.

 

[Celt]

actually regulator second stage design can be a huge factor, and was very much an issue in reg design 25+ years ago

yeah i can imagine CO2 building up in twin hose single stage regs. or helmet divers but with modern gear and a healthy pair of lungs cant see it

 

[Celt]

Most oxygen in the body is transported in the blood by binding heavily to Hb. Only a small amount is dissolved in the blood.

Mathematically here is the equation: CaO2 = (Hb x 1.39 x SaO2) + (PaO2 x 0.003).
CaO2 is arterial content of oxygen
Hb= Is your Hb levels
SaO2 is your oxygen situation
PaO2 is partial pressure of oxygen

Oxygen is transported by 2 different mechanisms: convection and diffusion

Convection process is a process by which O2 is transported by the blood using hemoglobin as a carrier (i.e. DO2). Oxygen delivery may be calculated as follows:

DO2 = CO x CaO2 x 10. (the number is 10 is used to make the units right).

CO= cardiac output

So you see that Oxygen delivery is dependent on how well your heart pumps (CO) and by the arterial content of oxygen.
The normal CI is 2.5 to 4.0 L/min/m2. The normal oxygen transport 0.6 to 14 L/min.

Now convection is related to VO2 by Fick's law of convection:
More physiology now about the second method of oxygen transport: Diffusion:
Oxygen diffusion from capillary (blood vessels at the end of the arterial system) to cell may be related to VO2 by the Fick law of diffusion:

VO2 = CO x (CaO2 - CvO2) = CO x CaO2. [(CaO2 - CvO2)/CaO2].

VO2I = CI x (CaO2 - CvO2).

where CvO2 is the venous O2 content:

CvO2 = (Hb x 1.39 x SvO2) + (PvO2 x 0.003).


We are getting towards the end:
Oxygen diffusion from capillary to cell is related to VO2 by you guessed it: Fick law of diffusion

VO2 = KO2 x (PcO2 - PmitO2)

where KO2 is a variable which takes into account the capillary surface area, path length from the capillaries to the mitochondria (which uses oxygen to make energy), PcO2 is the mean capillary PO2 and PmitO2 is the PO2 in the tissue surrounding mitochondria. Mitochondria is the structure in the cell that takes oxygen and make energy aerobically (hopefully) with the glucose.You can see then that the greater the pressure gradient and the capillary surface area, the higher will be the total number of molecules to diffuse. The diffusion distance is inversely related to the rate of diffusion.

So now, mathematically I am proving to the inquiring mind how oxygen is transported to where it's needed and why shallow breathing is detrimental to diving.


I tried to keep things simple. @rsingler gave an excellent synopsis above and here is my contribution to the discussion for those interested.

going to have to do some serious study of your post. but just to say my use of the word "shallow" might be misleading as the same word is used to describe some one with poor lung function.

 

[cerich]

yeah i can imagine CO2 building up in twin hose single stage regs. or helmet divers but with modern gear and a healthy pair of lungs cant see it

even single hose regs of the past had CO2 retention issues

 

[Compressor]

going to have to do some serious study of your post. but just to say my use of the word "shallow" might be misleading as the same word is used to describe some one with poor lung function.

Buy the book I recommended by West. It's wonderful and full of pertinent information with great diagrams. Thank you for your interest.

 

[Dan]

Light nasal breathing teaches the body to use oxygen more efficiently. Mouth breathing promotes over breathing which does the opposite. It’s not about the composition of the gas but how efficiently the body can use it. As an example people living at high altitudes use oxygen way more efficiently than people living at sea level.

I don’t know that. Any data or link to a study that support your claim, this more efficient oxygen use through nasal than mouth?

From my understanding of high altitude breathing, people that live in high altitude have either higher density of hemoglobin in their blood as the case of the study on people who live in Andes, "Andeans counter having less oxygen in every breath by having higher hemoglobin concentrations in their blood," as quoted from the article below

https://www.google.com/amp/s/relay....e/2004/02/high-altitude-adaptations-evolution

Or breathe faster, as the case of people who live in Tibet. “Tibetans compensate for low oxygen content much differently. They increase their oxygen intake by taking more breaths per minute than people who live at sea level.”

When I hiked up Kilimanjaro (19,341 feet) I did experience with increase breathing rate. However after 3-4 days high altitude acclimation at around 13,000 to 15,000 feet, before summiting, my breathing rate calmed down to normal level. I was told that my body was adjusting to the low oxygen environment by producing more hemoglobins in the blood.

 

[BRT]

The odds of a diver who is breathing 21% oxygen at depth in an open circuit suffering CO2 retention has to be very small no matter how light they are breathing. But the opposite where a diver over breathing oxygen reduces CO2 to the point of hyperventilating can very easily happen. Has there ever been a case of CO2 poisoning in a healthy diver using air.

I don't know what CO2 poisoning is but it isn't too hard to get a CO2 headache or CO@ narcosis breathing air.

 

[Compressor]

I don’t know that. Any data or link to a study that support your claim, this more efficient oxygen use through nasal than mouth?

From my understanding of high altitude breathing, people that live in high altitude have either higher density of hemoglobin in their blood as the case of the study on people who live in Andes, "Andeans counter having less oxygen in every breath by having higher hemoglobin concentrations in their blood," as quoted from the article below

https://www.google.com/amp/s/relay....e/2004/02/high-altitude-adaptations-evolution

Or breathe faster, as the case of people who live in Tibet. “Tibetans compensate for low oxygen content much differently. They increase their oxygen intake by taking more breaths per minute than people who live at sea level.”

When I hiked up Kilimanjaro (19,341 feet) I did experience with increase breathing rate. However after 3-4 days high altitude acclimation at around 13,000 to 15,000 feet, before summiting, my breathing rate calmed down to normal level. I was told that my body was adjusting to the low oxygen environment by producing more hemoglobins in the blood.

A fascinating topic on its own.

Here is the reference:
Sherpa metabolism and altitude adaptation
James A. Horscroft, et al:
Proceedings of the National Academy of Sciences Jun 2017, 114 (24) 6382-6387; DOI:10.1073/pnas.1700527114

 

[cerich]

I don't know what CO2 poisoning is but it isn't too hard to get a CO2 headache or CO@ narcosis breathing air.

can you provide any studies showing CO2 narcosis from breathing air please?