There is a lot of confusion about saline solutions, even among doctors.  If
one tries to Google for a recipe, all kinds of variations come up.  However,
there can be only one logical formula for approximating normal saline.

From Taber's Medical Cyclopedia:  "A 0.9% solution of sodium chloride is
considered isotonic to the body.  A normal saline solution (one having an
osmolality similar to blood serum) consists of 0.85% salt solution, which is
necessary to maintain osmotic pressure and the stimulation and regulation of
muscular activity."

Taber's gives the formula as 1 [level measuring] teaspoon of salt to 1 pint
[same as two measuring cups] water.  Using normal tap water rather than
distilled will not change the percentage much; obviously one couldn't start
with water with a high sodium level.

A recipe which cuts the salt in half or doubles the salt would be either
hypotonic or hypertonic, and would not support the balance of fluid between
the inside and the outside of the human cell.  Those of us who are healthy
can loll about in a tub, or swim in the ocean or a pool, and the difference
in osmolarity won't matter.  But in a damaged nipple, where the normal
protections have been interrupted, it would be best to approximate the
salinity of blood itself.

One might argue for applying a hypertonic solution to a macerated nipple
(one in which the tissues have become waterlogged through poor management).
But then one would have to take into account the effects of the residual
saline on the infant, or to take care to rinse the hypertonic solution off
before nursing.  I don't know whether anyone has computed a time and
salinity formulation for this type of application, and I've never used it.
I had an NICU nurse once tell me she recommends alcohol for the macerated
nipple (yikes!) but I believe the cellular damage outweighs the dehydrating
effect she's looking for (not to mention the pain).  (She was supporting the
practice of one of our doctors to tell every mother to wipe their nipples
with alcohol 8-12 times/day.)  But back to normal saline:

I use the recipe above exactly as given:  1 tsp to 2 c warm water.  I think
it is safer to stay as close as possible to normal saline.

If anyone has a textbook which gives a different explanation, let me know.

Arly Helm, MS, IBCLC  

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