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Combined Spinal-Epidural (CSE)
for Labor Analgesia: The Walking Epidural
(Originally posted 8 September 1997 on About Anesthesiology)
INTRODUCTION
Walking epidurals originated with the idea that patient satisfaction
is increased when they are allowed or encouraged to ambulate during
their labor. Technically, any form of epidural which allows a
patient to maintain muscular strength while achieving pain relief
can be referred to as a "walking epidural". However,
in the recent literature the term walking epidural has come to
refer more specifically to a technique known as the combined spinal-epidural
technique (CSE).
COMMENTS
In my personal experience most patients find that when they
are actually in labor they do not really want to walk. Others
have had different experiences and feel that most patients do
in fact wish to walk. Whether walking actually occurs or not,
the maintenance of muscular strength is still beneficial in that
it allows the patient to position themselves, sit up if they desire,
use the bathroom with assistance, etc. In addition, the patient
is better able to push when it comes to time of actual delivery.
Epidural anesthesia is generally accepted as the most effective
method of providing pain relief during labor, but it does have
its drawbacks. These include a drop in maternal blood pressure
and muscular weakness as mentioned above. Additionally, usually
approximately 15-20 minutes is required from the beginning of
the procedure until the patient is pain-free. The addition of
a spinal narcotic to the process allows pain relief with more
dilute (i.e. weaker) solutions of local anesthetic which decreases
the occurrence of decreased blood pressure and muscular weakness.
It also takes effect almost immediately after injection which
is a most welcomed effect!
Whether ambulation, or maintenance of muscular strength influences
fetal outcome is debatable. Some studies seem to show a lower
incidence of prolonged labor and instrument-assisted delivery
when the technique of "walking epidural" or so-called
minimal sensory block epidural is utilized. There is some debate
on this matter. Purported benefits from some articles in the literature
include increased intensity or effectiveness of contractions,
decreased frequency of contractions, decreased pain, shorter labor,
less need for augmentation of labor and fewer operative deliveries.
Although the experts may differ on whether there is any benefit,
there has never been shown to be any harmful side effects from
allowing ambulation during labor.
TECHNIQUE
There are a number of steps to prepare a patient for any type
of anesthetic. First, the patient should be seen by the anesthesiologist
and this interaction should include a medical history and physical
examination. During this period of time risks and benefits should
be discussed - although I discuss some of the more common complications
here, a face to face discussion is a more appropriate place for
a thorough explanation of all the possibilities. A prenatal class
or a pre-labor visit with your anesthesiologist is extremely helpful
and can allow a rational discussion and opportunity for the anesthesiologist
to obtain informed consent from the patient. In the "heat
of the moment" most patients usually do not wish to sit through
a long discussion of risks, benefits and options and often consent
to "anything that will take the pain away".
Secondly, all the appropriate equipment and medications should
be arranged. Then the patient should be prepared. Usually this
involves giving the patient additional intravenous fluid to help
prevent a drop in blood pressure after the medication is given
and a small dose of an antacid to decrease the acidity of the
patient's stomach.
When ready to place the epidural and spinal, the patient must
be properly positioned. The patient can be sitting or placed on
their side. Either technique is acceptable but most anesthesiologists
will be more comfortable with one or the other. The patient will
be instructed to arch their back out "in a C shape"
or "like a cat". This separates the vertebral bones
(the bones that make up your spine) in the lower back as much
as possible. This is important because the needle is actually
placed between these bones, and the larger the space between these
bones is, the easier the procedure will be.
Once positioned, the patient will be covered with some sterile
drapes to keep the area as clean as possible and then the back
prepared with antiseptic solution to render it sterile. This is
to reduce the chance of infection to a minimum. Once the back
has been cleaned in this way, the landmarks of the back are identified
by pressing with the fingers. Here the anesthesiologist is looking
for bones and the spaces between them so the needle can be placed
in the proper location.
Some local anesthesia is used to numb the skin prior to the
insertion of the actual epidural needle. This does involve a needle,
but an extremely small needle is used to minimize the discomfort
to the patient. As the local anesthesia used to numb the skin
of the back is injected, it burns a bit until it begins to work.
(I usually describe this to my patients as a "bee sting followed
by some burning, like a sunburn, for about 4 or 5 seconds")
Once the skin is numb, the actual epidural needle is inserted.
This needle is slightly larger to allow placement of a catheter
(a small plastic tube used to deliver medication) but should not
cause any pain since the skin is now numb.
Anesthesiologists use different techniques to identify when
the needle is actually in the correct place - the epidural space
(this is the space just outside a membrane called the dura which
covers the spinal cord and the fluid surrounding it). This part
of the procedure may take some time and requires that the patient
remain still. It is very important that the needle be placed in
the correct location.
Continued... > Page 1,
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