Without actually dying, I recently acquired
some more data on this question, and have come to my own conclusion.
On the fresh water side of things, I've many times had this
experience, as I'd guess you have. You're in the shower, you
bend down to pick up the soap or wash between your toes, and
the water streams down from your chin into your inverted nose.
Not a good feeling, the minor sting that it provides. Most of
us aren't doctors, but we've probably heard that there aren't
many places in the body where the blood comes closer to the
outside world, and we see that illustrated so close to home,
many a morning while the coffee is brewing in the kitchen.
I had the opportunity to compare this with salt water
the other day when I was at the Tri-Counties
Blood Bank for my monthly platelet donation.
When I first started donating platelets, they used small, portable
Haemonetics machines, except for one big Kobe monster that looked
like it belonged in the control room of a power plant.
The smaller machines are less efficient than the Kobe, and usually the
donation process takes longer on one of them, while ending up with
less usable platelets and plasma. Eventually, I asked what the criteria
were for putting a donor on one kind or the other, and was told that the
staff had to learn about each individual, and whether their veins
could stand up to the higher pressure that the Kobe used to return
the mixture of plasma, red cells, saline solution, and anticoagulant
to the donor's circulatory system. They told me of the rare occasions
when the vein couldn't handle it; the word blowout was used.
I think I probably heard more of a horror story than
they intended. After about ten donations, they put me on the Kobe one
day, but then I was back on the Haemonetics after that. Though there
was no problem, I guess I didn't measure up.
I was quite happy with that situation, but the staff didn't like the
smaller machines, and they were being incrementally replaced with new,
incredibly smart units from Baxter. Arriving for my recent
appointment, I found that the TCBB is now a Baxter-only shop, as far
as platelet donation goes.
So I was hooked up, and the first drawing cycle commenced. My whole blood
was diverted out through the needle, around and around the transparent
spiral plastic tubing, and into the heart of the machine which, after
having its way with it, dripped the plasma component into
one bag, the platelets in another, and was ready for the first return
phase. For some reason, there were three technicians huddled around the
status display, including John, the most senior. As the direction of the
flow in the tubing reversed, they asked me "Does that hurt?". I was, and
I assume they were, thinking along the lines of excessive pressure. I
said no, and they seemed suprised at that, as though whatever they were
reading made them think that it should be. "Are you sure?". "Yes". A
few more seconds, and then "Oh — that hurts. Ow!" They jumped into
action, stopping the process, and told me that what I was feeling was
saline solution being pumped into my muscle and other tissues, rather
than into the vein. Despite the blood having been drawn quite without
incident, they were concerned that the needle was badly placed.
I assented to an attempt to use my left arm instead and
they brought out the special machine they use on the rare occasions
when they need to continue a donation in the middle using a new needle.
The tube was hermetically sealed, the needle removed and a new one
emplaced, shortly to be jabbed into another vein, this time by a different
nurse. The return process was resumed, and within seconds I felt the same
pain as before. They stopped the return, and said I was done for the day.
I asked them why it hurt so much. I had always thought of saline
solution as being essentially neutral in the body. I don't remember
their explanation, but I was amused that even while I was talking with
them, I was remembering this node on E2.
Let me tell you, it burns! I was amazed at how much it hurt.
The other writeups here attempt learned speculation based on osmosis
and intracellular pressures and whatnot. I'll leave them to it. But I've
tried both, and if it ever comes to drowning, give me the fresh water!