Hydration/Dehydration/'Overhydration'.

Mike,

I am not aware of this theory - which does not, in
the least, mean that it does not exist - especially
now that I am no longer current in Medicine.

However, sodium is, predominantly, an extracellular
ion (potassium is predominantly intracellular) - which
makes it relatively easy to lower its plasma concentration
by dilution - rather than depletion.
This occurs frequently in a number of clinical scenarios
- with or without drug interreactions - and, certainly,
miners were notorious for developing cramps in the
hot, underground, conditions in which they worked.

Most UK miners I know (I used to work with them, both
clinically and bureaucratically before I retired) consume
enormous amounts of salt daily - although I do not
know of any sodium (or, indeed, potassium) balance
studies on this group of workers.

Hypoxaemia is not to be ignored - even at relatively
low altitudes - and combined with dehydration is cumulative
in its effects.

However - I had better stop - otherwise I will be accused
of starting up an esoteric and completely irrelevant
thread.

Perhaps some more enlightened practitioner (and there
are bound to be significant numbers of them in gliding
!) - preferably with research experience in this field,
will enlighten us all.

It would be interesting - and important.

Cheers,

Stan.
UK.

Overhydration.

Yes, it is possible. It's rare, but cases have occured in sport pilots
recently.

The trick is to consume large amounts of water while losing salt. You
can get confused, have seizures, or die (more likely of crashing than
of the water intoxication).

The pilots who are most susceptible to this are those with defective
water/salt excretion: older pilots, those with diabetic or
hypertensive kidney disease, those on diuretics for blood pressure,
especially thiazide diuretics.

Rehydrating with sport drinks should help avoid this. Most people
consume far more salt than they need, which helps make this a rare
condition, but not everyone does this.

I am screwed. I work in a deep, hot South African Gold Mine during the
week and fly in hot, high altitude conditions weekends. I must be a
crash waiting to happen if I read this tread.

Clinton
LAK 12