| |
November 2001
Volume 65 |
Number 11
|
| |
|
| Epidural PCA During
Labor |
Robert D’Angelo, M.D.
The use of epidural patient-controlled analgesia, more commonly
referred to as patient-controlled epidural analgesia (PCEA), is
becoming increasingly popular in treating labor pain because the
technique offers theoretical advantages over intermittent bolus
and continuous infusion techniques. These advantages include the
potential to reduce local anesthetic use and side effects, increase
patient satisfaction and reduce clinician workload.
PCEA theoretically reduces local anesthetic drug use by allowing
patients to self-administer only the amount of local anesthetic
they require to produce labor analgesia. In contrast, infusion
rates with continuous techniques are typically set to produce
analgesia in the majority of patients rather than titrated to
individual patient requirements. Reducing local anesthetic use
with PCEA should lessen the incidence of side effects such as
motor block and hypotension and increase satisfaction since these
patients experience fewer side effects. In addition, the “feeling
of self control” that patients experience with PCEA also
contributes to increased satisfaction.
For the anesthesia care provider, however, the most appealing
aspect of PCEA may be the potential to reduce workforce requirements.
In contrast to continuous infusion techniques that require the
anesthesia care provider to physically increase or decrease the
infusion rate or administer additional local anesthetic boluses
as needed, patients with PCEA simply self-administer additional
local anesthetic as needed. The anesthesia care provider is only
called if multiple self-administered boluses fail to enhance analgesia.
With projections indicating that the number of deliveries and
utilization of epidural analgesia will increase in the future
while the number of anesthesia care providers will decrease, it
is easy to see why the PCEA technique is so appealing.1
|
“[A]dvantages
[of PCEA] include the potential to reduce local anesthetic
use and side effects, increase patient satisfaction and
reduce clinician workload.”
|
Despite the clear theoretical advantages of PCEA, it is unclear
from the literature how best to utilize PCEA in obstetrics. PCEA
devices can be programmed to vary the basal infusion rate, the
on-demand dose, the lockout interval and the hourly dose limit.
However, studies that examine PCEA use during labor vary so significantly
in study design 2 (they measure different endpoints,
utilize a wide range of PCEA settings and usually enroll small
numbers of patients) that using an evidence-based approach to
guide clinical practice is nearly impossible [Table
1]. These studies do, however, collectively suggest that PCEA
offers advantages over both the intermittent bolus and continuous
infusion techniques [Table 2]. The use of
a basal infusion in obstetrics, on the other hand, remains controversial.
The few studies that control for basal infusions generally find
that they increase total drug use without significantly enhancing
analgesia. 3-5 Other important variables such
as patient satisfaction and assessments of manpower requirements,
however, are generally not adequately evaluated in these studies.
Potential disadvantages of PCEA include the risk of the patient
receiving excessive amounts of local anesthetic, leading to a
high block, seizure or cardiac arrest and increased operational
costs. A local anesthetic overdose could theoretically occur from
excessive self-administration in the presence of a “patchy
block” in patients without the mental capacity or language
skills required to understand the technique or from overly helpful
family members pressing the on-demand button. Although toxicity
should always be a concern when administering local anesthetics,
the dilute local anesthetic solutions administered in contemporary
obstetric anesthesia practices reduce the risk of a life-threatening
overdose. In fact, there has not been a reported case of a local
anesthetic-induced cardiac arrest in a laboring patient within
the United States since 1984. Although relatively few parturients
over this time period were administered labor analgesia by PCEA,
our clinical experience with PCEA at Wake Forest University suggests
that the technique is safe in obstetrics. We have utilized PCEA
in approximately 30,000 patients since 1995 and have experienced
no problems with excessively high blocks or local anesthetic overdoses.
Table
1: Studies Examining
PCEA During Labor 2
|
| Number of Studies |
18
|
| Techniques Compared
(# of Studies)* |
|
IB + PCEA
|
3
|
CI + PCEA
|
8
|
CI + IB + PCEA
|
3
|
| PCEA Alone |
4
|
| Used a Basal Rate (# of Studies)
|
7
|
| Basal Rate (Range)
|
0-6 ml/hr
|
| Bolus Dose (Range) |
3-12 ml
|
| Lockout (Range) |
10-24 min
|
| Hourly Limit (Range) |
12-24 ml
|
|
*IB = Intermittent Bolus, CI = Continuous
Infusion, PCEA = Patient-Controlled Epidural Analgesia
|
Utilizing PCEA is, however, generally more expensive than continuous
infusion techniques. A PCEA device costs approximately $300-500
more per unit to purchase than a comparable continuous infusion
device. PCEA devices administer drugs by using either syringes
or plastic collapsible containers (intravenous [I.V.] bags) as
reservoirs. The devices that use I.V. bags generally require expensive
PCEA tubing in order to operate properly, while those that use
syringes save money by operating with standard I.V. extension
tubing. The primary drawback of the PCEA devices that use syringes
is that they are limited to a 60 ml syringe that must be changed
more frequently than the 100-250 ml I.V. bags typically used with
the alternative PCEA devices. Variables such as the location where
the PCEA devices will be utilized (average infusion durations
are longer in the intensive care unit than on a labor suite),
number of cases per year, patient population (pediatrics versus
obstetric), individual staffing constraints as well as cost all
should be considered before purchasing PCEA devices. We utilize
PCEA devices at Wake Forest University with 130 ml reservoirs
that require special tubing to operate. For our practice, we believe
that the benefits of PCEA far outweigh any risks and the increased
cost.
Since no clear recommendations can be made from the literature
on how best to utilize PCEA in obstetrics, two significantly different
clinical regimens will be described that both reportedly produce
excellent labor analgesia and high patient satisfaction while
achieving different clinical endpoints. In Australia, Michael
Paech, M.D., administers 0.0625 percent bupivacaine with fentanyl
2 mg/ml and clonidine 4.5 mg/ml using the following PCEA settings:
no basal infusion, 4 ml on-demand bolus, 15 minute lockout, 16
ml hourly dose limit (from a personal communication). This regimen
primarily uses PCEA to reduce local anesthetic use and side effects.
In contrast, we primarily utilize PCEA at Wake Forest University
to reduce worker requirements. We view PCEA as an advanced continuous
infusion technique that allows the patient to administer additional
local anesthetic boluses when needed. We routinely administer
0.11 percent bupivacaine with fentanyl 2 mg/ml using the following
PCEA settings: 10 ml/hr basal infusion, 5 ml on-demand bolus,
10 minute lockout, 30 ml hourly dose limit. Even with these higher
PCEA settings, it is our clinical opinion that PCEA produces excellent
labor analgesia with minimal side effects, increases patient satisfaction
and significantly reduces workload. It was previously estimated
that PCEA reduces our workload by at least six hours per day,
a considerable savings in time on a busy labor unit. 6
Table
2: Summary of Findings
From 18 Labor PCEA Studies 2
|
| Outcome Associated with PCEA |
Number of Studies*
|
| Reduced Drug Use |
6
|
| Reduced Motor Block |
4
|
| Lower Pain Scores |
2
|
| Increased Maternal Satisfaction
|
5
|
| Reduced Workload |
5
|
| No Differences Found |
4
|
|
* Some studies report multiple benefits
with PCEA.
|
Although both regimens outlined reportedly produce excellent labor
analgesia, the Australian regimen is not likely to satisfy our
primary goal of reducing workload. Although different PCEA regimens
may very well produce equivalent labor analgesia, other factors
such as variations in the drugs administered, patient populations
and patient and physician expectations may also contribute toward
producing labor analgesia. Although these examples illustrate
that “ideal” PCEA settings for laboring patients do
not currently exist, the literature does suggest that the PCEA
technique offers advantages over intermittent and continuous infusion
techniques. Until more definitive PCEA studies are conducted,
clinicians should tailor PCEA settings to suit their own individual
practice needs.
References:
1. Hawkins JL, Gibbs CP, Orleans M, et al. Obstetric
anesthesia workforce survey, 1981 versus 1992. Anesthesiology.
1997; 87:135-143.
2. Tables compiled from 18 studies examining PCEA
during labor. Data obtained via Medline search through the National
Library of Medicine. PubMed Project, National Institutes of Health.
3. Paech MJ. Patient-controlled epidural analgesia
in labour — Is a continuous infusion of benefit? Anaesth
Intensive Care. 1992; 20:15-20.
4. Ferrante FM, Rosinia FA, Gordon C, Datta S.
The role of continuous background infusions in patient-controlled
epidural analgesia for labor and delivery. Anesth Analg. 1994;
79:80-84.
5. Petry J, Vercauteren M, Van Mol I, et al. Epidural
PCA with bupivacaine 0.125 percent, sufentanil 0.75 microgram
and epinephrine 1/800.000 for labor analgesia: Is a background
infusion beneficial? Acta Anaesthesiol Belg. 2000; 51:163-166.
6. Viscomi C, Eisenach JC. Patient-controlled
epidural analgesia during labor. Obstet Gynecol. 1991; 77: 348-351.
return to top
|