Re: AROM vs. Pitocin
From: james connerth (babydoc@apex.net)
Thu Aug 31 12:03:06 2000
A +FFN may be helpful here??
Steve Raymond wrote:
> Seems to me that a little seminar on the initiation of labour is needed
> here
> with all these different ideas floating around.
>
> If a woman at term has her membranes ruptured and nothing else is done
> then
> 80% will deliver within the next 24 hours. This has been shown by work
> done
> in the late 60's. Several people showed that the use of oxytocin after
> 24
> hours of waiting to see what would happen would ensure delivery of the
> other
> 20% (by whatever route was indicated obstetrically), so it became
> commonplace
> to do an ARM in the evening and, if not in labour in the morning, to
> start
> oxytocin then. With the wide acceptance of active management and the
> realization that the incidence of amnionitis was proportional to the
> length of
> time the membranes were ruptured, people started to realise that it made
> sense
> to start oxytocin at the same time as the ARM to shorten the membrane
> rupture
> to delivery interval. This way you could avoid the wasted time that
> inevitably occurred if contractions didn't establish straight away from
> ARM
> alone.
>
> Prostaglandin metabolism and physiology was extensively studied in the
> early
> 70's and its role in the initiation of labour has been shown to be that
> of
> increasing oxytocin receptors in the myometrium. So it was obvious that
> the
> woman who is approaching term differs from the one in labour by the
> number of
> her oxytocin receptors, as oxytocin levels in the serum don't change a
> great
> deal. The mechanism by which labour starts is thus a process of gradual
>
> increase in the ability of circulating oxytocin to stimulate
> contractions.
> While there is also a direct effect of Prostaglandin on softening of the
>
> cervix its major action is to raise the sensitivity of the myometrium.
> The
> woman who is a long way from the spontaneous onset of labour has low PG
> levels, low oxytocin receptor numbers and an unripe cervix.
>
> If you use exogenous oxytocin you may be able to induce some uterine
> activity
> even in the presence of a cervix with a low Bishop's score, but if you
> increase the sensitivity of the myometrium it will clearly mean that the
>
> uterus will contract sooner and at a lower infusion rate. How to do
> that?
> Obviously administering a prostaglandin is the first thing that springs
> to
> mind, but you can increase endogenous prostaglandin by other means too.
> One
> is to stretch the cervix digitally and sweep the membranes - the good
> old
> fashioned "stretch & sweep". Another means is to rupture the membranes
> - also
> involves a bit of stretching of the cervix.
>
> So the answer to the original question "..does pitocin work with intact
> membranes?" is similar to the answer to the question "How long is a
> piece of
> string?" It all depends on where the woman is on the continuum of
> increasing
> likelihood of going into labour, which is dependent on her oxytocin
> receptors,
> which is dependent on her prostaglandin levels. Of course the woman
> with the
> ripe cervix is easy to induce - she's half way there herself, and may
> need
> only an ARM, but if you want to be sure of success in getting
> contractions you
> need to make sure there is a good bit of PG circulating as well, and
> there's
> nothing like "belt and braces" ARM + Oxytocin. Obviously adding some PG
>
> wouldn't be a bad idea either, but it's difficult to get the same sort
> of
> control as we currently have with oxytocin infusions in concentrated
> dose
> passing through an IVAC pump. Thus we tend to use the various forms of
> Prostaglandin in those patients who are not in the "high receptor"
> stage,
> because it allows the exogenous physiological dose of oxytocin to
> regulate
> itself and it's difficult (but not impossible) to overdose.
>
> If anyone can come up with a reliable method of counting oxytocin
> receptors
> we'd be well on the way to ensuring that the method of induction
> employed is
> tailored exactly to the individual patient
>
> ainsron@msn.com wrote:
>
> > My practice patterns are very similar. I see no benefit using cytotec
>
> > for a patient with a ripe cervix. I'll usually wait 2-4 hours after
> > amniotomy to start pitocin. Sometimes I'll start the pit first then
> do
> > the amniotomy once contractions pickup, usually only if the head is
> > higher than I feel comfortable and not well applied to the cervix.
>
> > >How many initiate induction w/ ARM vs oxytocin (in the presence of a
> > >ripe cervix, of course)?
> > > > >I'm always struck by the fact that once I'm able to AROM someone
> I'm
> > >virtually always able to get them into labor. So I AROM when able.
> When
> > >starting an induction I'll AROM the primips with favorable cervixs
> and
> > >start them right away on pitocin; the multips I AROM and wait one to
> two
> > >hours to start pit. If I MUST induce someone without a favorable
> cervix
> > >I'll use cytotec.
> > > > >--
> > >Cait Cusack
> > >
>
> > > --
> > Ronald E. Ainsworth, MD
>
> --
> Dr. Steve Raymond
> Head of Department of O & G
> Empangeni Hospital
> Empangeni
> SOUTH AFRICA 3880
> Ph:(+27)(035)7721111
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