Veins have a stress relaxation phenomenon. When the tourniquet has
been left on for a period of time, the vein has dilated. It will
reach it maximum, then the tunica media, smooth muscles of the middle
vein layer, will relax preventing you from feeling the engorged vein.
This is discussed in the A&P chapter of the INS textbook. Lynn
At 8:48 PM -0700 8/11/06, Anna Liang wrote:
I first noticed 'that' in some young adults during
PICC insertion: early twenties, CF. in a couple of
cases the dilator sheath got pushed out of the vein.
When I switched to peds, I noticed more: CF kids
again, teens. Since I am not sure how to 'document'
that 'complication', I just say it is 'venospasm' for
the purpose of data tracking. there was about 4%.
I am not sure if it is related to CF, age, pain, and
or anxiety. By looking at the data, it is true that
teens got less sedation (sometimes we assume they can
cope better than other kids).
I use that data to argue for more sedation for that
population. I try to ask one sedation MD to publish
the data: that the % of venospasm decreases once we
have a real sedation team. well, it seems every one is
busy.
for piv, I have seen veins 'disappear' when the needle
enter the skin but before hitting the vein (I like the
side approach technique). see more among small
kids/infants, not sure why. as you mentioned, it is
very difficult to measure, to track.
Once, entered skin (24g) side of vein; baby cried,
vein 'disappeared'; waited for a few second for the
vein to come back then entered the vein -- the cannula
got pushed out when I tried to thread it in. My
witness then was the attending. It happened so quick,
the only thing I could say was: 'You see what
happened?!"
--- Gwen Irwin <[EMAIL PROTECTED]> wrote:
This may seem to be a weird topic, but with our
years of ultrasound insertion of PICCs, we have
noticed that some patients really react to vein
entry BEFORE we are close to entering the vein,
while observing on ultrasound the location of the
needle in relation to the vein wall. When we
proceed past that point, we are in the vein with
excellent blood return and proceed to successful
PICC insertion. Local anesthesia works only on the
skin entry and doesn't prevent this reaction to vein
entry. They also react differently to vein entry of
the dilator/sheath introducer.
This population of patients are also the ones that
complain of the most pain with IV insertions. Most
staff nurses give up before entering the vein with
an IV catheter, when the patient complains of this
pain. If we are called to do a PIV, we don't give
up at that point, but believe that we are right on
top of the vein and continue past the patient's
complaint to vein entry. We have a successful PIV.
This is so hard to measure for a study, but our
observations have led us to believe that the
innervation of the exterior of the vein is different
for some people. We don't seem to see a large
percentage of our patients that have this type of
reaction, but it is noticeable, when it occurs.
Some of these people call themselves "weenies" for
IV starts. Based on the years of our observations,
we don't believe that they are weenies, but that
they have different innervation that actually gives
them a pain signal before vein entry. We have been
known to tell them that they have bad luck with
their veins, since they feel the stick into the vein
before it actually occurs. These also can be the
patients that have more vasoconstriction observed on
ultrasound, during PICC attempts. We have waited
for as long as 10 minutes to observe the vein stop
its vasospasm, and see the dilation that we
initially saw on our original assessment.
I am wondering if anyone else is noticing this
phenomenon. I am really thinking it would be useful
> information to share, but don't know how to study or
report this subjective observation.
I would love to hear from you, if you think we are
crazy or if we are noticing something that has not
previously reported or discussed. We have seen it
so many times that we don't think we are crazy.
Your responses are always appreciated.
Gwen Irwin
Austin, Texas
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Lynn Hadaway, M.Ed., RNC, CRNI
Lynn Hadaway Associates, Inc.
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