Dee writes:
<As I understand it, the difference between purchase pumps and the *true*
"hospital-grade pumps" is how closely the suck mimics the suck of a baby
who is
breastfeeding appropriately. . . .  The Lactina and Elite are equivalent
to the purchase pumps, and the sales reps of these companies have
confirmed that to me. >

I confess that understanding the fine points about breast pumps is not
one of my strong suits. I know I need to remedy that shortcoming. I am
interested in learning from the experience from the more "pump-savvy"
lactnetters.

But I will play the devil's advocate here and ask: could the sales reps
of those companies be acting like the sales reps of formula companies we
were discussing here several weeks ago? Breast pumps are products that
must be hyped in advertising to compete with the other hype-rs who are
also trying to make a profit and stay in business.

I thought the word was that the two factors that determined continuing
milk production were the thoroughness and the frequency of milk
removal-period.
I can see a pump mimicking speed, rhythm, etc. but flanges could not
possibly mimic exactly the action of a baby's tongue and jaw. Flanges are
not shaped like a baby's mouth, nor are they at all mobile like a baby's
jaws and tongue (except possibly the Whittlestone), so as I see it, they
cannot compress in the exact same fashion that a baby does, no matter how
much hype is put out to lure us to favor and recommend one pump over
another.

I admit there are some terrible pumps out there at the baby goods
counters in the grocery, drug, department and discount stores. Many of
those are ineffective with either too little vacuum or too much, poor to
no cycling capacity and not much engineering or choice in the form and
size of their flanges. So I am not against well-engineered pumps, but I
just have trouble buying some of the hype.

Catherine writes:

< I suspect it has to do with the peak suction and cycling speed of the
pump, as well as the suction needed by the individual mother in order to
overcome the resistence of the muscles of the nipple-areolar complex.

Pumps work by pulling milk out of the breast by subjecting the nipple to
a vacuum, which increases the pressure differential between inside the
breast and outside.  When the pressure is reached that overcomes the
resistence of the muscles, they let go and the milk sprays or drips out.

For some mothers, the personal double electric breastpumps are enough to
overcome their muscle resistence, and fast enough for her to get milk in
a reasonable time.  For other moms, the resistence is higher, and they
need a higher peak negative pressure (suction) than the small pumps can
provide. >

This is what I see in the pumping process: I do not believe that milk is
"pulled" out of the breast. I think it is extruded from within the breast
by the force of the MER and by compression of the ducts agains the ring
formed by the entrance to the tunnel.

Flesh is the first thing acted upon by vacuum, not milk. It is only when
the milk reaches the surface of the nipple that vacuum effects it
directly. The flesh of the nipple-areolar complex, the areola in
particular, contains only a small percentage of muscle. The subareolar
area is mainly connective tissue (which is more dense in some mothers
than others) with its blood vessels and interstitial fluid, and and
subareolar ducts with the small amount of milk within them.. I agree that
there is more resistance in this area in some mothers than in others, but
I don't believe it is muscle resistance. I think it is actually mainly
connective tissue resistance (including any excess interstitial fluid if
edema and engorgement are present.)

From high school physics I remember something to the effect that a vacuum
is really the absence of atmospheric pressure, and that "Nature abhors a
vacuum."
When the negative pressure that forms the vacuum is low enough, (causing
the pressure differential between inside the breast and outside of the
nipple-areolar complex that Catherine described) the atmospheric pressure
on the tissue beyond the pump flange succeeds in actually pushing the
flesh into the flange to try to fill up the vacuum and try to equalize
the pressure.

In the process, if the fit of the flange matches the location of the
mother's subareolar ducts, the breast is in effect compressing itself
against the inner ring at the entrance of the tunnel at a point well
behind where the ducts narrow at the entrance to the galactophores in the
nipple. I see it as this compression, plus the force of the MER, that
extrudes the milk toward the surface, in much the same way as toothpaste
is extruded from a toothpaste tube by compression applied well behind the
opening to the tube. The vacuum then "invites" the milk in its direction
to help equalize the pressure inside the flange.

If the fit of the flange does not match the location of the mother's
subareolar ducts, the compression may occur in front of them, and the
effect is partly one of stripping milk back up into the ducts (like
squeezing that toothpaste tube as close to the front as possible and
thereby stripping the paste further back in the tube) so that it is at
least partially counteracting the force of the MER.The more vacuum that
is applied, the less milk can get to the surface if the fit of the flange
is not appropriate to the location of the subareolar ducts, (which I
still refer to as lactiferous sinuses.)

Granted, there is a lot I don't understand about the variations in the
strength of the vacuums, but I think the size of the tunnel in the flange
is a more important factor in effective milk transfer than many people
realize. And I believe that teaching the mother that most mothers could
manage their pumping situations better if they were taught at the
beginning that:
there is in fact such a thing as a let-down reflex,
that it is the most important force in milk transfer, and
how to elicit it before pumping and
how massage can help move milk forward
Just my $.02 on the subject.

Jean
*******
K. Jean Cotterman RNC, IBCLC
Dayton, Ohio USA

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