9/4/05njm

**Q. Is repetitive intrathecal anesthesia a good alternative to epidural
anesthesia in labor?**

A. Continuous epidural anesthesia is often the more satisfactory
approach. See details

"....our facility does not provide epidural anesthesia. How about if we
performed repetitive spinal \"intrathecal\" instead? This might avoid
the need for continuous monitoring and make it more feasible for our
anesthesia personnel to provide....."

 

In the United States, intrathecal analgesics are nearly always given as
single dose injections. One assumes complications for intrathecal
injection; including spinal hematoma, meningitis, abscess formation,
leading to cauda equina, or rarely paraplegia, would likely be increased
with multiple repeated injections. On the other hand, there is not a
body of data on this subject, per se, at this point.

An epidural service is more highly recommend.  In many hospitals with
the appropriate nursing support and training, the epidural can be placed
and monitored until stable (15-20")  by the anesthetist, then the OB
nursing staff could monitor vital signs per a protocol while the
infusion is stable. Any changes that need to be made i.e. increases,
decreases, or bolus injections could be restricted to the anesthesia
provider. 

This is a protocol that is followed for epidural infusions at many
community hospitals, as well as some major medical centers. Some
hospitals even allow small changes in the rate to be verbally ordered by
the anesthesiologist from home. Bolus injections always require the
anesthesiologist's presence to treat any potential homodynamic
instability that may occur as a result of the block.

Please see **Prevention and treatment of adverse effects of neuraxial
anesthesia** below

**Background**

Regional anesthetic techniques, such as epidural and spinal anesthesia,
are the most effective modalities for pain relief in labor, which is
likely to be the most severe pain that a woman experiences during her
lifetime. These regional techniques will be reviewed here. Drugs
administered for neuraxial anesthesia, the prevention and treatment of
adverse effects of neuraxial analgesia, and an overview of labor pain
and its management and are discussed separately.

**Intrathecal**

The onset of action for analgesics is more rapid when administered with
a spinal rather than epidural approach. As with single-dose epidural
administration, the duration of analgesia is limited by the duration of
action of the drug(s) used. In the United States, intrathecal analgesics
are nearly always given as single dose injections. Spinal
catheterization techniques were devised to allow for repeated dosing and
circumvent this problem. It is possible to pass a standard epidural
catheter into the intrathecal space, however, the large bore needle (17
or 18 gauge) required is associated with an unacceptably high incidence
of spinal headache. Small gauge \"microcatheters\" (28 to 32 gauge)
introduced more recently are able to pass through small-gauge spinal
needles, permitting catheterization of the spinal space with a low
incidence (approximately 2 percent) of headache.

Continuous spinal techniques with 5 percent hyperbaric lidocaine have
been associated with serious neurotoxicity, such as cauda equina
syndrome, possibly due to pooling of high concentrations of hyperbaric
lidocaine on nerves of the cauda equina. In response to these reports,
the FDA banned the use of spinal microcatheters in 1992, although they
are still available in other countries. There is no evidence that
injection of other types of analgesics (eg, opioids) results in
neurotoxicity, so the FDA is considering the reintroduction of these
catheters. However, the intrathecal route tends to be less forgiving
than the epidural route with regard to neurologic complications.

**Epidural**

Intermittent epidural bolus dosing was the standard technique used for
providing labor analgesia, prior to continuous epidural infusion. An
epidural catheter was sited in the epidural space and doses of local
anesthetic were injected intermittently. Injections were timed to
patient complaints of pain, or at set intervals, based upon the duration
of action of each dose. However, this regimen has two limitations;
first, if injections are not administered until pain returns, the
patient will experience intervals of analgesia after the dose takes
effect alternating with intervals of pain as the analgesia wanes and
second, intermittent dosing requires frequent provider interventions,
especially when using a short-acting agent (e.g., 2-chloroprocaine which
has a short duration of action).

Continuous infusion of analgesics into the epidural space avoids the
peaks and valleys of intermittent administration and results in a
smoother analgesic experience for the parturient with fewer provider
interventions. The infusion may be adjusted to individualize analgesia
and additional rescue doses are given, as needed.

**SINGLE SHOT EPIDURAL VERSUS EPIDURAL CATHETERIZATION** --- A single
shot epidural consists of injecting one dose of medication into the
epidural space before the needle is withdrawn. This technique is not
usually used for labor analgesia because analgesic duration is limited
to the duration of action of a single dose.

For epidural catheterization, a catheter is threaded through the
epidural needle and secured to the skin of the patient\'s back with
adhesive tape so that repeated doses or continuous analgesia can be
administered throughout labor. In theory, a single bolus dose may be
indicated if delivery is anticipated to be imminent. However, as a
practical matter, once the epidural space has been entered, it is
preferable to insert an epidural catheter in case labor continues longer
than the duration of action of a single dose or in case a greater dose
of local anesthetic is needed for instrumental or cesarean delivery.

**CONTINUOUS EPIDURAL INFUSION OF ANALGESICS** --- Continuous infusion
of analgesics into the epidural space avoids the peaks and valleys of
intermittent administration and results in a smoother analgesic
experience for the parturient with fewer provider interventions. The
infusion may be adjusted to individualize analgesia and additional
rescue doses are given, as needed.

**PATIENT-CONTROLLED EPIDURAL ANALGESIA (PCEA)** --- This modality
differs from the continuous infusion technique in that the parturient
herself is given the means to fine-tune the dose of anesthetic she
receives. Patient-controlled technology was initially introduced for
self-administration of intravenous analgesics to decrease the time
required to achieve relief, to maintain the plasma analgesic
concentration in a therapeutic range, and to avoid the inherent
unevenness of intermittent administration. These techniques give
parturients the psychological advantage of being in control of their own
therapy; they are able to titrate the dose to the severity of pain they
are experiencing.

**Resources:**

**Prevention and treatment of adverse effects of neuraxial anesthesia**

[[http://www.uptodateonline.com/application/topic.asp?file=labordel/5857]{.underline}](http://www.uptodateonline.com/application/topic.asp?file=labordel/5857)

**Neuraxial anesthesia for labor and delivery: Techniques**

<http://www.uptodateonline.com/application/topic.asp?file=labordel/6182&type=A&selectedTitle=2~4>

**Neuraxial anesthesia for labor and delivery: Drugs**

<http://www.uptodateonline.com/application/topic.asp?file=labordel/4804>

**Management of pain during labor and delivery**

<http://www.uptodateonline.com/application/topic.asp?file=labordel/5602>

**Anesthesia for cesarean delivery**

<http://www.uptodateonline.com/application/topic.asp?file=labordel/9313>