I use such a setup primarily to "test" whether getting some instant
gratification will coax a reluctant nurser to nurse or when
supplementing is going to occur for whatever reason.  In spite of my
concern about product "misuse" there have been a few times when I
have sent parents home using such a device when I feel confident
that they can follow directions appropriately.  In most cases,
however it's only been used for a few feedings.
I think the biggest risk is the person handling the syringe pushing
too much in baby's mouth at one time.  It is essential to
"lubricate" the plunger in the syringe by drawing and pushing on it
a couple times with the tip in whatever liquid baby will be
getting.  If you don't do this, I have found that the plunger may
tend to stick and then give way under the increased pressure being
applied to make it move.  As a result, a lot more liquid is expelled
that one might intend.  Also, by doing such "lubricating" the odds
are greater that baby will be able to draw the plunger down by the
strength of his/her suck.  In most cases, however, I find that a
slight pressure on the plunger is required, then baby can draw it
down with each suck.
Hope this at least in part answers your question.
Winnie Mading RNC, IBCLC

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