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

[cerich]

Apart from the fact that no animal other than humans breath through the mouth .

When you predicate your entire premise on wrong information, it fails.

 

[Celt]

When you predicate your entire premise on wrong information, it fails.

what animal uses its mouth as its main means of breathing

 

[BRT]

Apart from the fact that no animal other than humans breath through the mouth the nose warms and filters the air and slow nasal breathing stimulates the production of nitric oxide inside the paranasal sinuses. When we breath through the nose nitric oxide follows the airflow to the lung and increases the oxygen uptake in the blood. Mouth breathing was said to be a curse for a persons health by yoga masters 100 years ago and today science has proved them right. According to Jon Lundberg, professor of pharmacologics at the Karolinska Institute in Stockholm, large amounts of nitric oxide are constantly released in the nasal airways of humans.

You think dogs don't breath through their mouths?

 

[Celt]

Nope. do you believe CO2 doesn't build up when skip breathing or not breathing enough while exercising? Do you believe CO2 is not a narcotic gas? I can be narced relatively shallow while exercising and not breathing deeply enough. No proof it is CO2, but several times this has happened. A few really deep breaths stop the sensation.

Edit:I don't think this has anything to do with air vs nitrox..

Wow....the things one can learn from the internet!

how something is learned is irrelevant, the important thing is to be willing to learn.

 

[Celt]

You think dogs don't breath through their mouths?

dogs breath through their nose, in fact a dogs nose is critical for its survival. they dissipate heat through their mouth.

 

[boulderjohn]

dogs breath through their nose, in fact a dogs nose is critical for its survival. they dissipate heat through their mouth.

Well, it turns out that most animals that normally breathe through the nose have the ability to breathe through the mouths, including dogs. They are very much like humans that way. We can breathe through our mouths indefinitely as well.
Obligate nasal breathing - Wikipedia

 

[BRT]

dogs breath through their nose, in fact a dogs nose is critical for its survival. they dissipate heat through their mouth.

Humans breath through their noses too. Do you think dogs don't breath through their mouths?

 

[markmud]

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.

So in conclusion (take home message): Convection and diffusion are the limiting factors of 0xygen uptake. These are in turn effected by blood flow, and blood oxygenation parameters including oxygen content, arterial oxygen partial pressure and hemoglobin's affinity for its buddy; oxygen. Similarly, factors effecting oxygen convection include blood flow and arterial oxygen content.


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

Thanks Doctor Compressor,

That was beautiful!

Keep it up please.

cheers,
mm

 

[boulderjohn]

Because this is a very common misconception, I want to make sure people reading this are not confused.

If you had two divers on the bottom doing the same workload the diver with greater oxygen efficiency and is breathing slow and light will incur less decompression penalty than the diver who is breathing heavily.

After he wrote that, mac64 was asked to explain why it would impact DCS, and he wrote:

It’s not about the volume it’s about the individuals oxygen transfer efficiency, One diver is using oxygen efficiency and breathing light and the other is breathless, breathing heavily and actually exhaling large amounts of oxygen because of poor breathing habits.

He was then asked what oxygen transfer had to do with DCS, and he did not directly respond. In his following comments, he talked about oxygen and carbon dioxide. If he mentioned nitrogen intake, the primary factor in DCS, I missed it.

A link was provided to another thread dealing with this topic. So that people don't have to work their way through it, I will quote part of a post by Dr. Simon Mitchell, one of the world's foremost authorities on decompression theory:

Breathing more than you need to makes very little change to the alveolar inert gas composition, and would not of itself be expected to materially change gas uptake or the risk of DCS.

In contrast, since it is the blood that carries dissolved gas to the tissues, anything that increases tissue blood flow (perfusion) during the process of gas uptake will result in faster uptake of inert gas into tissues. Thus, if the increase in breathing was precipitated by exercise (which increases cardiac output and tissue perfusion) then it will be associated with faster inert gas uptake and (all other factors like ascent rate etc being equal) greater decompression stress.

As a quick summary, if a diver's increased workload increases perfusion (blood flow through tissues), then that will affect nitrogen loading. It is also likely to increase breathing rates, so an increased breathing rate may be associated with increased nitrogen uptake, but only because of the increase in perfusion. Breathing rate by itself has no real effect on nitrogen loading and has no impact on DCS.

 

[markmud]

Breathing rate by itself has no real effect on nitrogen loading and has no impact on DCS.

Hi Boulderjohn,

Does that include breathing rates that are artificially low (including skip breathing). I believe the Doctors (rslinger and compressor) indicated that it does.

What am I missing?

Or, did I miss your (or their) point?

cheers,
m