Blood donation

[amphipod06]

I'm confused.

As I do understand: Almost all O2 transport is via red blood cells with a very very small O2 component dissolved in the fluid. If I give 1 pint of blood, I have donated 5% of my blood. But a 30% blood loss will cause irreversible shock. Fluid replenishment will not effectively increase O2 transport. And it may take up to 2 months to regenerate my RBC count.

It would seem that with no physical stress issues diving would be OK but perhaps more prudent to wait depending on one's age and overall health and conditioning? But how long to wait?

Unless I had more definitive answers, I'd contact DAN.

Read my post again, Scuba Doc (Dr. Ernest Campbell, who also writes for DAN on occasion) states "if not anemic" on the blurb regarding blood donation. Like Kelly stated a lot more oxygen is also dissolved in the plasma at increased partial pressure, your tissues will utilize this oxygen at rest, they switch to bound oxygen (that oxygen in hemoglobin) during exercise (if I remember my exrecise physiology correctly), so it is important not to be anemic in the first place. Chances are that if you are in good shape, do not have any chronic health issues and eat a well balanced diet, you will not be anemic. Your advise is good too, call DAN and confirm everything, don't believe everything you read in the internet... .

Dive safe,

Celia

[sdalcher]

As I recall hemoglobin is 98% saturated with oxygen at 1 ATA. At higher partial pressures, excess O2 is absorbed directly into the plasma itself...

[amphipod06]

As I recall hemoglobin is 98% saturated with oxygen at 1 ATA. At higher partial pressures, excess O2 is absorbed directly into the plasma itself...

Yes, oxygen content increases significantly until PaO2 is in the normal range, beyond 100 mm Hg, only about 0.3 volumes % of oxygen is added for every 100 mm Hg increase in PaO2. When the PaO2 is six times normal the blood contains just 7.5% more oxygen molecules. There is a major distinction between oxygen pressure and oxygen content in the blood. Oxygen pressure directly reflects the pressure of the inhaled oxygen, and is due solely to the unbound (dissolved) fraction of oxygen in the blood; it is the same value regardless of the hemoglobin content. Oxygen content reflects the actual number of molecules in the blood, both bound to hemoglobin and unbound (dissolved). A low hemoglobin value will not affect a diver's oxygen pressure, but will have a direct effect in reducing oxygen content.

(Reference: Martin, L. Pulmonary Physiology in Clinical Practice. CV Mosby Co., St Louis, 1987.)

Dive safe,

Celia


Edit: corrected mispellings.