THE EFFECT OF EPIDURAL ANALGESIA ON THE OUTCOME OF …

www.wjpps.com Vol 8, Issue 7, 2019.

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Hasan et al. World Journal of Pharmacy and Pharmaceutical Sciences

THE EFFECT OF EPIDURAL ANALGESIA ON THE OUTCOME OF

VAGINAL DELIVERY STUDIES OF 200 CASES

Dr. Selda Bakr Hasan, Dr. Tareva Asadulla Faidhalla and Dr. Maysaa Abdalhussein

Mohammed

Kirkuk General Hospital.

PURPOSE OF REVIEW

Labor is among the most painful experiences that humans encounter.

Neuraxial analgesia is the most effective means of treating this pain. In

this review, we discussed the effect of neuraxial analgesia on the

progress of labor when compared with parenteral opioids. We then

compared initiation of analgesia with a combined spinal–epidural

technique (CSE) to conventional epidural analgesia. Finally we

discussed the impact of neuraxial analgesia, given early in labor,

compared with later administration. Recent findings Compared with

parenteral opioids, neuraxial analgesia does not increase the incidence of cesarean section,

although it is associated with a longer (16 min) second stage of labor. The incidence of

operative vaginal delivery is higher in the epidural group but this may be due to indirect

reasons such as changes in physician behavior. There was no difference in labor outcome

when CSE was compared with low-concentration epidural analgesia, but higher

concentrations may prolong labor. Early administration of neuraxial analgesia does not

increase the incidence of operative delivery or prolong labor. Summary Neuraxial analgesia

does not interfere with the progress or outcome of labor. There is no need to withhold

neuraxial analgesia until the active stage of labor.

KEYWORDS: Labor is among the most painful experiences that humans encounter. From

the earliest times, various forms of analgesia have been used for pain relief. Whereas some

forms of analgesia are more effective than others, the primary concern is for the welfare of

both the mother and baby. In particular, interference with the progress of labor, leading to the

need for operative delivery, is undesirable.

WORLD JOURNAL OF PHARMACY AND PHARMACEUTICAL SCIENCES

SJIF Impact Factor 7.421

Volume 8, Issue 7, 1284-1317 Research Article ISSN 2278 – 4357

*Corresponding Author

Dr. Selda Bakr Hasan

Kirkuk General Hospital.

Article Received on

17 May 2019,

Revised on 08 June 2019,

Accepted on 29 June 2019

DOI: 10.20959/wjpps20197-14251


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There has been considerable debate about whether or not labor analgesia can adversely affect

outcome by increasing the duration of labor or by increasing the incidence of operative

delivery. However, there are many factors that may lead to an adverse outcome. In addition,

many of the factors that lead to painful labor such as fetal malposition, macrosomia or uterine

abnormalities also lead to maternal request for analgesia. This review will primarily be

concerned with new ways of thinking about neuraxial analgesia. We will highlight its effect

on the incidence of cesarean section, instrumental vaginal delivery, and the duration of labor.

We will first examine the effect of neuraxial analgesia compared with parenteral opioid. In

the next section we will examine the effect of initiation of analgesia with combined spinal–

epidural analgesia (CSE) compared with initiation with an epidural. In the final section, we

will discuss the impact of early neuraxial analgesia on the progress of labor. Recently, there

have been many other innovations in delivery of both neuraxial and parenteral labor analgesia

but these do not appear to have an impact on labor outcome. Some of these have been

recently reviewed elsewhere.[1,2]

KEY POINTS

Labour epidurals provide safe, effective analgesia with minimal side effects to mother

and fetus.

Knowledge of anatomy and pain pathways are key to providing epidural analgesia to

labouring parturients.

Consent can be challenging during active labour.

Labour epidurals are beneficial in certain circumstances: high probability of emergency

operative delivery; patients with predictors of a difficult airway; and medical conditions

benefiting from reducing the stress response of labour e.g. pre-eclampsia.

Risk of permanent nerve damage in obstetric epidurals may be as high as 1 in 80,000

Combined spinal-epidurals (CSE), single-shot spinals (SSS), and dural puncture epidurals

(DPE) are alternative neuraxial techniques to epidurals for labour analgesia.

INTRODUCTION

Labour epidurals are popular and safe; they provide effective analgesia for labouring

parturients. Lower dose epidural regimes limit motor block, do not affect progress of labour,

and have minimal side effects to mother and fetus. Labour epidurals can also be used to

provide anaesthesia for assisted vaginal delivery or caesarean section.


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Specific circumstances when labour epidurals may be beneficial1

Pre-eclampsia (without severe thrombocytopenia or coagulopathy)

High Body Mass Index (BMI)

Anticipated difficult airway or other risk factors for general anaesthetic

High risk for assisted vaginal delivery e.g. breech or multiple gestation

Trial of labour after previous caesarean section

Maternal cardiovascular, cerebrovascular or respiratory disease1

Spinal disorders when „urgent‟ neuraxial anaesthesia placement may be difficult, for

example with scoliosis

Contraindications to labour epidurals[1]

Absolute

Patient refusal.

Coagulopathy.

Severe thrombocytopenia.

Hypovolaemia or uncontrolled haemorrhage.

Local infection or systemic sepsis.

Local anaesthetic allergy.

Raised intracranial pressure.

Relative: Fixed cardiac output state Anatomical abnormalities of the vertebral column e.g.

previous spinal surgery, spina bifida and severe spinal deformity Pre-existing central and

peripheral neurological Disease Uncooperative patient.

Consent and risks for labour epidurals[2]

1 in 10 need further attention to help function (e.g. pull catheter back).

1 in 20 need catheter re-siting.

1 in 100 accidental dural puncture.

1 in 24,000 temporary nerve damage, such as temporary motor weakness or paraesthesia

of a limb lasting less than 6 months.

1 in 80,000 permanent nerve damage, such as permanent motor weakness or paraesthesia

of a limb.

Bleeding, including epidural haematoma.

Infection, including epidural abscess.


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Pruritus.

Hypotension.

Increased risk of assisted vaginal delivery.

Informed consent for epidural insertion can be challenging in active labour. The process is

improved if information can be given antenatally, e.g. with information leaflet.1 Retention of

details of the consent discussion may be improved by requesting the parturient sign a written

consent form prior to being in active labour.

Anatomy of the Lumbar Spine and the Epidural Space: Knowledge of lumbar spine

anatomy is the cornerstone of providing safe labour epidural analgesia.

The vertebral column: The vertebral column provides support and protection for the spinal

cord. There are five lumbar vertebrae, which have large vertebral bodies for weight-bearing,

increasing in size from L1 to L5.3 Intervertebral discs separate each vertebral body. The

spinal canal encloses the epidural and subarachnoid spaces. The vertebral bodies are

connected anteriorly by the anterior longitudinal ligament and posteriorly (on the anterior

wall of the vertebral canal) by the posterior longitudinal ligament; both extend from the

occiput to the sacrum. Three ligaments are pierced during epidural insertion: supraspinous,

interspinous, and the ligamentum flavum (Figure 1).


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Figure 1: Anatomy relevant to epidural anaesthesia.

The epidural space: The epidural space is a „potential space‟ that surrounds the dura mater

and extends from the foramen magnum to the sacral hiatus at the level of S2/3.

Boundaries of the epidural space are as follows

Superior fusion of the spinal and periosteal layers of dura mater at the foramen magnum

Inferior sacro-coccygeal membrane

Anterior posterior longitudinal ligament, vertebral bodies and intervertebral discs

Lateral pedicles and intervertebral foramina

Posterior ligamentum flavum and vertebral laminae

The epidural space contains fat, spinal nerve roots, spinal arteries, extra-dural venous

plexuses, connective tissue, lymphatics and the dural sac.4

In adults the spinal cord most commonly ends at L1-L2 (L3 in 10% of adults), the dural sac

ends at S2, continuing below this is the filum terminale, which attaches to the coccygeal

ligament.5

Surface anatomy: Knowledge of surface anatomy is essential in identifying the correct

vertebral level for epidural insertion. An imaginary line is drawn between the top of the iliac

crests, which corresponds to the level of the L4 spinous process or the L4-L5 interspace, and

is known as “Tuffier‟s line”. In parturients, Tuffier‟s line crosses the spine at a higher level

(L3-4) due to the forward rotation of the pelvis.6 As a result anaesthetists are often at a higher

level than anticipated. This is especially pertinent when a CSE technique is being planned.7

Pre- puncture neuraxial ultrasound can help confirm the correct vertebral level, midline and

depth of the epidural space.8


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Pain pathways in labour: During the first stage of labour, afferent nerve impulses from the

lower uterine segment and cervix cause visceral pain, which is poorly localised and diffuse in

nature. These nerve cell bodies are located in the dorsal root ganglia of T10 to L1. During the

second stage of labour, afferent nerves innervating the vagina and perineum cause somatic

pain, which is better localised. These somatic impulses travel primarily via the pudendal

nerve to dorsal root ganglia of S2 to S4.9 The ideal labour epidural block should cover

sensory loss from T10 – S5 dermatomes (with minimal motor block) to provide analgesia for

the first and second stages of labour.

Patient positioning for neuraxial blockade

Insertion of labour epidurals is commonly performed in either the sitting, or the flexed lateral

position. Positioning is governed by maternal comfort and compliance, as well as anaesthetist

preference. Epidural placement in the sitting position has a higher success rate of first-pass

insertion and the procedure can be performed faster compared with the lateral position.10

Equipment and Insertion Technique

The basic equipment required for epidural Insertion is

Scrub Pack: Hibiscrub, surgical hat, mask, gown, gloves

Sterile Pack with swabs and drape

Cleaning solution e.g. Chlorhexidine 0.5%

Local anaesthetic for skin e.g. 1% lignocaine 0.9% saline

Tuohy needle (18 or 16G)

Loss of resistance syringe

Epidural catheter

Epidural filter

Epidural lock/device for securing epidural to skin

A loss of resistance technique for epidural insertion can be performed with either air (LORA)

or saline (LORS). There are case reports of pneumocephalus and an increased incidence of

dural puncture and patchy blocks with LORA, therefore LORS is more commonly practiced.

Regional Analgesia for Vaginal Delivery

Technique of Regional Analgesia

Approximately 60 percent of women, or 2.4 million each year, choose epidural or combined

spinal–epidural analgesia for pain relief during labor.


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Labor pain is transmitted through lower thoracic, lumbar, and sacral nerve roots (Fig. 1 and

2) that are amenable to epidural blockade. Epidural analgesia is achieved by placement of a

catheter into the lumbar epidural space. Solutions of a local anesthetic, opioid, or both can

then be administered as intermittent rapid doses or as a continuous infusion (Fig. 3). The

alternative technique of combined spinal–epidural analgesia has recently gained in

popularity.

With this technique, a single bolus of an opioid, sometimes in combination with local

anesthetic, is injected into the subarachnoid space, in addition to the placement of an epidural

catheter (Fig. 3). The use of a subarachnoid bolus of opioids results in the rapi.

Figure 1: Pathways of Labor Pain.

Labor pain has a visceral component and a somatic component. Uterine contractions may

result in myometrial ischemia, causing the release of potassium, bradykinin, histamine, and

serotonin. In addition, stretching and distention of the lower segments of the uterus and the

cervix stimulate mechanoreceptors. These noxious impulses follow sensory-nerve fibers that

accompany sympathetic nerve endings, traveling through the paracervical region and the

pelvic and hypogastric plexus to enter the lumbar sympathetic chain. Through the white rami

communicantes of the T10, T11, T12, and L1 spinal nerves, they enter the dorsal horn of the

spinal cord. These pathways could be mapped successfully by a demonstration that blockade

at different levels along this path (sacral nerve-root blocks S2 through S4, pudendal block,

paracervical block, low caudal or true saddle block, lumbar sympathetic block, segmental

epidural blocks T10 through L1, and paravertebral blocks T10 through L1) can alleviate the

visceral component of labor pain. id onset of profound relief of pain with virtually no motor


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blockade. In contrast to epidural local anesthetics, spinal opioids do not cause impairment of

balance, giving the parturient woman the option to continue ambulation.

Combined spinal–epidural analgesia is associated with a higher degree of satisfaction

among parturient women than is conventional epidural analgesia.

However, some studies have suggested that there may be an increase in the frequency of

nonreassuring patterns in the fetal heart rate, particularly bradycardia, with combined spinal–

epidural analgesia, and such patterns may necessitate emergency cesarean delivery.[9-11]

Other studies show no difference in the fetal heart rate and no increase in the rate of cesarean

deliveries necessitated by fetal bradycardia.[12,13]

Although there are insufficient data to establish whether there is a causal association, it is

reassuring that no studies suggest that combined spinal–epidural analgesia is associated with

an increase in adverse outcomes for the fetus.

Effect of Epidural Analgesia on the Method of Delivery

The use of epidural analgesia is associated with better pain relief than are systemic

opioids.[14-17]

However, a major concern is whether epidural analgesia may be responsible for an increased

risk of cesarean delivery, vaginal delivery requiring the use of forceps or vacuum extraction,

or prolongation of labor. Both cesarean deliveries and instrument-assisted vaginal deliveries

may be associated with a greater risk of maternal complications than unassisted vaginal de

delivery.

Although the appropriate rate of cesarean delivery remains a matter of de bate 18 (currently

in the United States, the babies of 23 percent of pregnant women are delivered by cesarean

section 19), there is great interest in the effect of epidural analgesia on these rates. In

addition, the rate of instrument-assisted vaginal delivery is of concern because it is

consistently associated with a higher rate of serious perineal laceration, 20 which has been

implicated as a risk factor for later fecal incontinence.[21]

Instrument

Assisted vaginal deliveries have also been linked to higher rates of birth injuries.[22]


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Observational studies: Many studies compare women who selected epidural analgesia with

those who did not. Most such studies show an association between the use of epidural

analgesia and a higher rate of cesarean delivery.

However, women who select epidural analgesia are different from those who do not. They are

more frequently nulliparous, come to the hospital earlier in the course of labor with the fetus

having descended to a lesser degree (a higher fetal station), have slower cervical dilatation,

deliver larger babies, and have smaller pelvic outlets.[23-26]

Observational studies that control for these factors continue to find differences in outcome

between the women who receive epidural analgesia and those who do not.[24,26]

One observational study suggests that women with difficult labor may have more pain early

in labor and require a more potent regimen for pain relief.[27]

However, although the small subgroup of women with exceptionally painful labor may be

more likely to choose epidural analgesia, this is clearly not the main factor contributing to the

choice of a method of pain relief, since many women having a first baby decide before labor

whether to receive epidural analgesia.[28]

Overall, given the possibility of uncontrolled confounding, it is not possible to draw

definitive conclusions from these observational studies.

Randomized trials: Prospective, randomized trials studying the relation between the use of

epidural analgesia and cesarean delivery have shown variable results. A recent metaanalysis

represents the experience of nearly 2400 patients randomly assigned to receive either epidural

analgesia or parenteral opioid analgesia.[17]

Epidural analgesia was associated with a prolongation of the first stage of labor by an average

of 42 minutes and a prolongation of the second stage of labor by an average of 14 minutes.

No significant difference between groups in the rate of cesarean delivery could be

demonstrated by intention-to-treat analysis (8.2 percent of women in the epidural group had

cesarean deliveries, as compared with 5.6 percent in the parenteral-opioid group).

However, in most of the large studies, about 30 percent of women did not receive the

treatment to which they were assigned. Many women assigned to the parenteral-opioid group


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actually received epidural analgesia, and many women assigned to receive epidural analgesia

did not receive it. When such crossover occurs, the proportion of women who receive

epidural analgesia in the two groups becomes much more similar, making it very difficult to

interpret the data on an intention-to-treat basis.

In many trials, a substantial proportion of women did not receive the assigned treatment

because delivery occurred so rapidly that there was no time to administer any analgesia. In

addition, women who agree to be randomly assigned to a certain form of pain relief during

active labor may represent a subgroup of women with less difficult labors or other

characteristics that render them unrepresentative of the general population. This high rate of

noncompliance with the protocols limits our ability to interpret the data.[29]

There have been two randomized trials with essentially no crossover. In the first trial, in

which 93 nulliparous women in spontaneous labor at term were randomly assigned to

epidural analgesia or parenteral meperidine, essentially all women received the assigned

treatment. This study found a large effect of the use of epidural analgesia on the rate of

cesarean deliveries performed because of dystocia (17 percent in the epidural group vs. 2

percent in the meperidine group).[30]

In contrast, a more recent study,[31]

in which 459 nulliparous women in active labor were

randomly assigned to either epi-

A Epidural Analgesia


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B Combined Spinal–Epidural Analgesia


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Dural analgesia or intravenous meperidine and in which 8 percent of the subjects had

protocol violations, found no significant difference in the rate of cesarean deliveries

performed because of dystocia (6 percent in the epidural group vs. 7 percent in the

meperidine group).

It is not clear why these two studies had such different results. It is important to note that the

effect of epidural analgesia on the likelihood of cesarean delivery may vary according to

obstetrical practice and the population studied and that such variations may be the reasons for

the differences between the studies.[32,33]

Studies have clearly demonstrated great variations in physician-specific rates of cesarean

delivery, suggesting that management practices may have an important role. For example, in

a study of 1533 parturient women who were cared for by 11 obstetricians, the rate of cesarean

delivery varied from 19 percent to 41 percent for different caregivers.[33]


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In addition, women enrolled in many of the randomized trials were much younger than the

general population of women delivering babies in the United States.[34]

Studies consistently demonstrate an increase in the rate of cesarean delivery associated with

age,[35]

and the effect of epidural analgesia may vary with age as well. Therefore, the question

of whether the use of epidural analgesia for pain relief during labor increases the rate of

cesarean deliveries performed because of a failure of labor to progress remains unanswered.

Findings with regard to an association between instrument-assisted vaginal delivery and

epidural analgesia are clearer, with a consistent increase in the rates of deliveries involving

forceps and vacuum extraction with epidural analgesia. The metaanalysis of randomized trials

found a doubling of the rate of instrument-assisted vaginal deliveries.[17]

The most recent randomized trial found an increase in the rate of deliveries involving forceps

from 3 percent in the opioid group to 12 percent in the epidural-analgesia group.[31]

However, the reason for this increase with epidural analgesia remains unclear.

One hypothesis is that the motor blockade may prevent the mother from pushing and thereby

necessitate the use of instruments. Epidural analgesia is also associated with a higher

frequency of the occiput posterior position of the fetus at delivery, which, if causal, could

represent a mechanism by which epidural analgesia contributes to the higher rate of

instrument-assisted delivery.[30,36,37]

It is also possible that the presence of an epidural block may sometimes decrease the

obstetrician‟s threshold for performing instrument-assisted deliveries, 17 as well as for

allowing instrument-assisted delivery for the purposes of teaching residents.[37]

studies of sentinel events

A different approach is taken to the question of epidural analgesia and cesarean delivery by

studies comparing the rates of cesarean delivery before and after epidural analgesia was made

available for a certain population of women. The assumption of such studies is that the

population of women, the obstetrical management style, and other confounding variables

change little over time. None of these studies have demonstrated an increase in the rate of

cesarean delivery associated with the sudden availability of epidural analgesia.[38-42]


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A recent meta-analysis of these studies, which included more than 37,000 patients in a variety

of different practice settings and time periods in several countries, showed that the

establishment of a highly utilized epidural-analgesia service had no effect on the overall

incidence of cesarean delivery or the rate of cesarean deliveries performed because of

dystocia.[43]

However, these studies have methodologic limitations. First, it is almost impossible to control

for changes in practice style that may occur when an epidural-analgesia service is introduced;

such changes may be made specifically because providers are aware of the potential

association of epidural analgesia with an increased rate of cesarean deliveries.

Second, there may be secular trends, such as overall changes in the rate of cesarean delivery

between the two periods being studied. Finally, substantial changes may occur in the rate of

cesarean delivery in subgroups of patients (e.g., nulliparous women in spontaneous labor)

without causing a statistically detectable increase in the overall rate of cesarean delivery. It

would be difficult with this type of study design to detect changes even in large subgroups of

women. Therefore, these studies do not provide a conclusive answer to the question of the

effects of epidural analgesia on outcomes of labor for individual women. However, they do

show that the institution of an active anesthesia service providing epidural analgesia need not

lead to an increase in the overall rate of cesarean delivery.

In summary, it appears that epidural analgesia may prolong labor by approximately one hour,

on average. The effect on the rate of cesarean delivery is unclear and may vary with the

practice-related choices of the provider.[29,32,33]

The literature does provide evidence of an increase in the rate of instrument-assisted vaginal

delivery and a decrease in the rate of spontaneous vaginal deliveries with epidural analgesia,

although the reason for this association is not well understood, and the magnitude of the

association may be influenced by the practice style of the obstetrician.

Timing of epidural analgesia

During labor

It has been suggested that the effect of epidural analgesia on labor and the method of delivery

may be greater when such analgesia is administered before a certain degree of cervical


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dilatation or a certain fetal station has been reached. Most observational studies show higher

rates of cesarean delivery with early administration of epidural analgesia.[26,44,45]

In contrast, the three randomized studies specifically comparing the initiation of epidural

analgesia at different degrees of cervical dilatation in nulliparous women found no difference

in the rate of cesarean delivery or instrument-assisted vaginal delivery between women in

whom analgesia was initiated early and those in whom it was initiated late.[46-48]

However, the small degree of difference in cervical dilatation between the early and late

groups (approximately 1 cm) is an important limitation of these trials. There is currently

insufficient evidence to determine whether waiting until a certain degree of cervical dilatation

or a certain fetal station is reached before instituting epidural analgesia will influence the rate

of cesarean or instrument-assisted vagina Leffect of epidural analgesia on maternal

temperature and the newborn Epidural anesthesia in nonobstetrical patients is generally

associated with a decrease in body temperature.

Epidural anesthesia causes vasodilatation in the anesthetized dermatomes, which leads to a

redistribution of heat from the core to the periphery, resulting in a net decrease in body

temperature.[53]

In contrast, observational and randomized studies demonstrate that epidural analgesia during

labor is often associated with an increase in maternal body temperature to over 100.4°F

(38.0°C).[54-56]

For example, in a randomized trial in which fever was reported, an additional 11 percent of

women receiving epidural analgesia became febrile during labor (15 percent, vs. 4 percent of

women who received no epidural analgesia), and the proportion of the population affected

was even greater among nulliparous women (24 percent vs. 5 percent).[55]

An association between the use of epidural analgesia and maternal fever raises some

important questions: Does epidural analgesia cause maternal or neonatal infections? Do

children of mothers who receive epidural analgesia more frequently require evaluation for

sepsis and treatment with antibiotics? The association between the use of epidural analgesia

and maternal fever is complex. Some authors assert that the increase in the frequency of fever

is the result of placental infection, as assessed by neutrophilic infiltration of the placenta,


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possibly associated with the longer duration of labor among women who receive epidural

analgesia.[57]

This explanation seems unlikely to be correct, however, since women with long labors but no

epidural analgesia do not tend to have such high rates of fever.[54]

In addition, if infection were the cause, the incidence of neonatal sepsis would be expected to

be higher among the infants of women who receive epidural analgesia. In fact, the rate of

sepsis among term infants is equally low whether or not the mother receives epidural

analgesia.

Many investigators believe the association of epidural analgesia with fever is probably

attributable to noninfectious causes, such as an alteration in the production and dissipation of

heat resulting from epidural analgesia.[56]

Both randomized and observational studies have demonstrated that infants of women who

receive epidural analgesia are more likely to be evaluated and treated with antibiotics because

of concern about infection.[54,55]

The higher rates of evaluation for sepsis are expected, since fever in labor raises concern

about infection that may be passed to the neonate, and it is not currently possible to

distinguish between fever from infectious causes and fever from noninfectious causes during

labor.[54]

The rates of evaluation for sepsis among infants of afebrile women depend on the criteria by

which pediatricians determine which infants to evaluate.[55,58]

Observational studies have also noted an association between intrapartum maternal fever and

other adverse neonatal outcomes, even when the infant does not have an infection.[59,60]

A more complete understanding of the causes and physiological correlates of fever related to

epidural analgesia and the development of markers to distinguish infectious from

noninfectious causes of fever may provide a means of safely decreasing the number of

evaluations for sepsis that are needed. It seems highly unlikely that such increases in

temperature have an infectious cause, and neonates born to mothers who receive epidural

analgesia do not have an increased risk of sepsis. Further study is needed to determine the


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best criteria for performing workups for sepsis in infants of low-risk women who deliver

infants at term. Additional studies, particularly randomized trials, are also needed to examine

further the reported adverse effects on the neonate of epidural-related fever in the mother

during labor. Other reported complications of regional analgesia Many parturient women are

concerned that epidural analgesia may lead to back pain. A recent randomized trial studied

385 nulliparous parturient women for 12 months after delivery.[61]

No difference in the incidence of backache could be demonstrated women who were

randomly assigned to receive epidural analgesia and those who were not.

The results of several nonrandomized trials are consistent with these findings.[62,63]

Therefore, current data do not support a relation between a new onset of back pain and the

use of epidural analgesia during labor. Inadvertent puncture of the subarachnoid space during

the placement of an epidural catheter occurs in about 3 percent of parturient women, and a

severe headache occurs in up to 70 percent of women with such a puncture.[64]

Postdural puncture headache can be treated with an epidural blood patch, which is effective

in relieving headache in more than 75 percent of women.[65]

If the headache does not have the pathognomonic postural characteristics or persists despite

treatment with an epidural blood patch, other diagnoses should be considered and appropriate

testing performed.[66]

There are a number of other complications that have been reported in connection with

epidural analgesia, including effects on the neonate, for which the available data are

inadequate to allow definitive conclusions to be drawn. In addition, we do not know whether

the use of epidural analgesia influences fetal position at delivery. Although it has been

demonstrated that women who receive epidural analgesia are more likely to have a fetus in

the occiput posterior position at delivery,[30,36,37]

it is not clear whether the use of epidural

analgesia contributes to the persistence of this position or whether women with a fetus in this

position have more painful labors and are therefore more likely to reque request epidural

analgesia.


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Neuraxial Techniques on Labour Ward: what are the options?: There are alternative

neuraxial techniques to the traditional labour epidural. The first choice technique may differ

with anaesthetist experience, institutional preference and the clinical situation.

Labour epidural: Labour epidurals do not increase caesarean section rates, but marginally

prolong the second stage of labour and increase assisted vaginal delivery rates.[12]

Labour

epidurals improve maternal pain and satisfaction scores in comparison to systemic analgesics

and are the most effective analgesic option for labour.

Modern labour epidural dosing regimens (e.g. 0.0625% to 0.1% bupivacaine with 2-4 mcg/ml

fentanyl or 0.4 mcg/ml sufentanil) reduce the total local anaesthetic dose required and motor

block experienced; potentially allowing the parturient to be ambulatory.[13]

There a several different regimes for administering labour epidural analgesia. Current

practices are: intermittent physician or nurse bolus, Patient Controlled Epidural Analgesia

(PCEA), Programmed Intermittent Epidural Boluses (PIEB) or continuous infusions. Labour

epidurals provide safe continuous analgesia throughout labour and can be converted with

higher concentration local anaesthetic top-up to anaesthesia for operative delivery.

Combined Spinal-Epidural (CSE): A CSE combines rapid onset of analgesia from the

spinal component, with the benefit of continuing labour analgesia with the epidural catheter.

A CSE can be performed as an individual single-shot spinal followed by placement of an

epidural catheter as a separate technique (see below), or with a needle-through-needle

technique. For dosing of the CSE‟s spinal component, please see single-shot spinal section

below. When comparing CSEs with labour epidurals, there is no difference in: unintentional

dural puncture; incidence of post Dural Puncture Headache (PDPH); rescue analgesia

requirements; maternal satisfaction scores; and mode of delivery. There is an increased risk

of transient hypotension and fetal bradycardia requiring intervention with CSE compared

with labour epidural.[14]

CSE is a slightly more complicated technique and there is a theoretical risk of having an

untested epidural catheter for labour analgesia and surgery if close to the time of CSE

placement. The 3rd National Audit Project2 in the UK showed there was an increased overall

risk with the use of CSEs compared to epidurals. Both the optimistic and pessimistic

interpretations of the incidence of permanent harm, and paraplegia or death per 100,000 was


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greater for CSEs than epidurals when used perioperatively in the general patient population.

This was not shown in obstetric patients.

Single-shot spinal: Single-shot spinal block for labour analgesia can provide pain relief for

immediate delivery.15 Multiparous parturients are probably the most suitable candidates for

this technique due to rapid labour progression. A dose of 2.5mg bupivacaine and 25mcg

fentanyl has been shown to last up to two hours in duration.[15]

There is greater incidence of

transient hypotension and fetal bradycardia with a single-shot spinal compared with an

epidural.2 The anaesthetist should anticipate this and have phenylephrine, ephedrine, and/or

glyceryl trinitrate (GTN) immediately available. Transient hypotension may contribute to the

fetal bradycardia but it is most likely to be caused by increased uterine tone secondary to the

rapid reduction in circulating catecholamines (especially adrenaline/epinephrine).

Administering GTN (intravenously or sublingually) provides tocolysis improving the fetal

bradycardia.

Single-shot spinal followed by epidural: A single-shot spinal can be immediately followed

with an epidural. This is a useful technique in a distressed parturient to facilitate fast pain

relief and better positioning.

Dural Puncture Epidural (DPE): An alternative for labouring parturients is the DPE

technique. This technique is similar to a CSE, performing an intentional dural puncture with a

spinal needle but without administering intrathecal drugs. DPE avoids the potential

haemodynamic instability caused by intrathecal local anaesthetics and enhances labour

analgesia when compared with standard epidural techniques.16 DPE improves analgesia

compared with epidurals alone by “epidural rent” of the intrathecal space; when there is a

puncture in the dura the anaesthetic can flow from the epidural space into the intrathecal

space. This technique, along with the CSE technique allows partial confirmation of epidural

catheter placement, e.g. cerebrospinal fluid (CSF) is seen in the spinal needle placed through

the epidural needle, and therefore the epidural catheter itself is more likely to be midline.


1303


The DPE technique is not currently widely practised.

Table 1: Advantages and disadvantages of neuraxial techniques for labour analgesia.

Advantages Advantages DIS Advantages

Epidural

Continuous analgesia

Ability to convert from analgesia to anaesthesia

for operative delivery

Longer time to insert compared with spinal

10-15 minutes to establish analgesia

Higher failure rate

Cse

Rapid analgesia

Benefits of spinal and epidural

Continuous analgesia

Ability to convert from analgesia to anaesthesia

for operative delivery

Increased likelihood of functional epidural

catheter due to confirmation of midline on

placement

Initially untested epidural catheter

Potentially longer insertion time than an

epidural or spinal

Risk of fetal bradycardia/ hypotension with

spinal component

Unfamiliarity of labour ward staff with

management of spinal component

Spinal

Rapid analgesia

Fast insertion time

Less risk of epidural haematoma than epidural

Analgesia duration limited, lasting 60-120

minutes

Greater risk of hypotension/ fetal bradycardia

Potential unfamiliarity on labour ward with

management

Dpe

Reduced haemodynamic instability

compared with spinal/ CSE

Increased likelihood of functional epidural

catheter due to confirmation of midline on

placement

Rarely practised – relatively new technique

Test dose: An epidural test dose can identify inadvertent intrathecal or intravascular catheter

placement. Unidentified intrathecal or intravascular epidural catheter placement can lead to a

high or total spinal, or local anaesthetic systemic toxicity (LAST). Historically, 3ml of 1.5%

lidocaine with 1 in 200,000 adrenaline (epinephrine) was used as a „test dose‟: intrathecal

lidocaine would rapidly produce evidence of a spinal block; intravenous adrenaline would

produce transient tachycardia. However, using adrenaline is unreliable (low sensitivity)

because of confusion with transient tachycardia seen with contraction pains.16-17

The current trend is towards using low dose local anaesthetic without adrenaline as a „test

dose‟. This helps reduce motor block, thereby allowing better chance of ambulation. There is

a large variation in drugs/ doses currently used for test doses, with ranges of 3-20 mg

bupivacaine and 15-90 mg lidocaine.18 Every dose administered via an epidural catheter,

whether to initiate a block, or treat breakthrough pain should be treated as a „test dose‟ as

catheters can migrate intrathecally and intravascularly, despite initially being placed correctly

in the epidural space.


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This tutorial is estimated to take 1 hour to complete. Please record time spent and

report this to your accrediting body if you wish to claim CME points

Neuraxial analgesia vs. parenteral opioid

Observational studies have repeatedly shown a strong association between the use of

neuraxial analgesia and operative delivery. In these studies, patients were divided into two

groups based on the type of analgesia chosen by the parturient. Patients who had neuraxial

analgesia had an increased incidence of operative vaginal delivery and cesarean section than

those who did not have neuraxial analgesia. In many of these studies, patients who requested

epidural analgesia were at risk for operative delivery for other reasons. For example, inone

study there were significantly more nulliparous patients in the neuraxial group.[3]

In another,

there were serious imbalances in important demographics such as maternal weight, maternal

height, fetal weight and rate of cervical dilation before analgesia.[4]

Further, patients who

choose neuraxial analgesia may have more pain because of dysfunctional labor[5]

, which may

in turn lead to operative delivery. For these reasons, this study design cannot reliably indicate

whether neuraxial analgesia or other demographic factors cause the excess in operative

deliveries.

Randomized controlled trials take care of the problem of unbalanced demographics but

aremuchmore difficult to perform. In addition to the usual issues of increased time and effort

required for these studies, a comparison of neuraxial and parenteral opioid analgesia has

special problems to resolve. None of the studies can be blinded because of the superior

analgesia obtained using neuraxial techniques. Therefore strict criteria for operative

deliveries must be in place. In addition, patients might not follow their group assignment –

some patients who were assigned parenteral opioids might (after randomization) want to

change their group. In spite of these challenges, 15 studies consisting of 4619 patients, and

two studies with 854 preeclamptic patients have compared epidural analgesia to parenteral

opioid. An additional study with 1223 patients compared CSE to parenteral opioid. The

results of these studies are described in a recent meta-analysis.[6]

As can be seen in Fig. 1, the

incidence of cesarean section is the same in the epidural and parenteral opioid group for

normal and hypertensive patients (odds ratio 1.03, 95% confidence interval 0.86 to 1.22).

However, the incidence of operative vaginal delivery is higher in the neuraxial group [odds

ratio (OR) 1.92, 95% confidence interval (CI) 1.52–2.42]. This may be due to a direct effect

of neuraxial analgesia on labor or it may have been an indirect effect. It should be noted that


1305


the decision to use forceps was not always based on strictly controlled criteria. For example,

one of the investigators noted that forceps were preferentially used in patients in the epidural

group for resident training.[7]

There was no difference in the duration of the first stage of labor

but the second stage was prolonged about 16min (95% CI 10–23 min). Whereas this was

statistically significant, it is not clinically important.

In summary, epidural analgesia is not associated with an increased incidence of cesarean

section when compared with parenteral opioids. It is associated with an increase in

instrumental vaginal delivery. This may be due to the block itself or to changes in physician

behavior. Whereas the duration of the first stage of labor is unaffected, the second stage is

prolonged. The magnitude of the prolongation is not clinically important Epidural analgesia

vs. combined spinal–epidural analgesia The CSE technique, using a long spinal needle

inserted through an epidural needle, has been used for labor analgesia since 1984.[8]

The

technique has the advantage of rapid onset of analgesia with little or no interference with

ambulation. When compared with a standard labor epidural, early studies suggested that

CSEs might reduce the duration of labor.[9]

However, in a study comparing parenteral opioid

to CSE, there appeared to be an excess incidence of severe fetal bradycardia that resulted in

emergency cesarean section for fetal welfare.[10]

In this section, we review the impact of CSE

on labor outcome.

Two large clinical trials compared CSE with epidural analgesia.[11–13]

In addition, a Cochrane

review reported a meta-analysis of 19 trials consisting of 2658 patients.[14]

The 11 trials that

compared CSE with low-dose epidural analgesia were analyzed separately.

Norris et al.[11]

Used a quasi-randomization scheme to enrol 2183 patients in a study that

compared CSE with epidural analgesia for labor. The CSE group received 10mg of

sufentanil, with or without 2.0mg of bupivacaine, depending on the stage of labor. This was

followed by 3 ml of 1.5% lidocaine, given via an epidural catheter.

Parturients in the epidural group received 3 ml of 1.5%. lidocaine followed by 10–20 ml of

0.125% bupivacaine with 10mg of sufentanil via the epidural catheter. Nulliparous and

multiparous parturients were analyzed separately.


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They found no difference in the mode of delivery. In particular, there was no difference in the

incidence of emergency cesarean section within 90 min of initiation of analgesia. There was

no difference in the duration of first or second stage of labor between analgesic techniques.

The COMET study[12,13]

was conducted in the UK between 1999 and 2000 on 1054 patients

randomly assigned to one of three groups: epidural with 0.25% bupivacaine, followed by

intermittent boluses of 0.25% bupivacaine; CSE with 2.5mg bupivacaine and 25mg fentanyl,

followed by boluses of epidural 0.1% bupivacaine with 2mg/ml fentanyl; and initiation with

0.1% bupivacaine with 2mg/ml fentanyl and followed by boluses of the same solution. They

found an increased rate of spontaneous vaginal deliveries, with a reduction in instrumental

deliveries, in those receiving CSE and low-dose epidural infusions compared with 0.25%

bupivacaine. However, there was no difference between the CSE and low-dose group. The

incidence of cesarean section was the same in the three groups and there was no difference in

the incidence of fetal distress. In addition, there was no difference in the length of the first or

second stages of labor[13]

Traditional (0.25% bupivacaine) epidural analgesia was compared

with CSE in the Cochrane review.[14]

Four studies, comprising 925 parturients, met the

inclusion criteria. Whereas there was a small increase in the incidence of instrumental vaginal

delivery in the epidural group (OR 0.82–1.0, P¼0.049), the incidence of cesarean section or

spontaneous vaginal delivery was not statistically different. There were no differences in

mode of delivery when CSE was compared with low-dose epidural analgesia. The review did

not report the reasons for cesarean section or data on the duration of the first or second stage

of labor.

From these data, we conclude that there is no difference in the outcome of labor whether a

CSE or epidural technique is used to initiate analgesia provided dilute concentrations are

used.

Timing of neuraxial analgesia Many parturients want to know the best time to request labor

analgesia without it having a negative impact on labor outcome or duration. In particular,

early practice guidelines suggested that parturients should wait until the cervix was at least 4

cm dilated before initiating neuraxial analgesia to reduce the chance of cesarean section.[15]

The question of early epidural placement has been recently addressed in four large

randomized controlled trials.[16-19]

In the first study, 449 nulliparous patients were randomized

to receive epidural analgesia or parenteral meperidine „early‟ or „late‟ in labor.[16]

The


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investigators included both spontaneous and induced labors, stratifying the randomization on

this parameter.

Patients in the early group received epidural analgesia with 0.1% ropivacaine and 2mg/ml

fentanyl at first request for pain relief. Patients in the late group received parenteral

meperidine until the cervix was 4 cm dilated, followed by an epidural if requested. The

groups were well matched at baseline. Patients received epidural analgesia at a mean of 2.4

and 4.6 cm dilation in the early and late groups, respectively, although about 13.6% of

women in the late group never received epidural analgesia. There was no difference in the

mode of delivery between groups. The total duration of the first stage of labor was slightly

shorter in the early group.

Figure 2: Study design.

Copyright © Lippincott Williams & Wilkins. Unauthorized reproduction of this article is

prohibited (mean_standard deviation, 9.4_3.8 vs. 10.3_4.4 h, P¼0.04) but there was no


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difference in the duration of the second stage. The authors concluded that early epidural

analgesia did not increase the risk of operative delivery in this population of patients.

Wong et al.[17,18]

conducted two studies on nulliparous parturients. The first was in

spontaneously laboring patients[17]

; the second was in nulliparous patients with induced

labor.[18]

In the first study[17]

, 750 spontaneously laboring nulliparous patients in whom the

cervix was less than 4 cm dilated were randomized to receive either parenteral

hydromorphone or intrathecal fentanyl and an epidural test dose of lidocaine. Patients in the

hydromorphone group received a repeated dose of the same drug if the cervix was still less

than 4 cm dilated, whereas the intrathecal fentanyl group received dilute epidural

bupivacaine. Patients in the hydromorphone group received epidural local anesthetic if the

cervix was greater than 4 cm dilated or if they requested analgesia a third time. In this way,

the investigators were able to compare patients who were similar at baseline, but one group

received neuraxial analgesia „early‟ and the other received it later (see Fig. 2). The

investigators found no difference in the incidence of cesarean section or operative vaginal

delivery between groups. Of interest, patients who received intrathecal fentanyl had a shorter

first stage of labor than those who had parenteral hydromophone.

The second study[18]

was conducted on 806 nulliparous patients with induced labors. The

study design was similar to the first study. In this study, the median cervical dilation was 2

cm in the early group and 4 cm in the late group. There was no difference in the incidence of

cesarean section or instrumental vaginal delivery. There was a small reduction in the duration

of labor in patients who received an early epidural. There was no difference in the duration of

the second stage of labor. addition, there was no difference in the length of the first or second

stages of labor.

From these studies, we can conclude that early placement of neuraxial analgesia does not

influence the incidence of operative vaginal delivery. Whereas three of the studies noted a

slightly shorter first stage of labor in parturients who received neuraxial analgesia early, this

was not a consistent finding and is not clinically significant.

2. MATERIALS AND METHODS

This was a retrospective case series of women induced for all indications at term (gestational

age ≥37 weeks) at the Maternity Unit of the Kirkuk general Hospital, between January 2018

and December 2018. women with a normal body mass index (BMI) at booking (<25 kg/m2)


1309


and under the age of 40 years with singleton cephalic presentation deliveries were considered

eligible for the study. Women induced for stillbirths and fetal congenital abnormalities and

with multiple pregnancies were excluded. Data was collected from Medway_ obstetric

electronic database and maternal data, labour/delivery data, and neonatal data were all

recorded.

Maternal data recorded involved age, body mass index at booking, smoking status, and self-

reported. Labour and delivery data included route of birth (normal vaginal delivery,

instrumental vaginal delivery, epidural analgesia use, and liquor appearance (normal,

meconium stained). In our unit, epidural catheters are placed at the L2-L3, L3-L4, or L4-L5

interspace when women have a cervical dilatation of ≥3 cm. Finally, neonatal data recorded

were fetal gender (male, female), birthweight, head circumference, Apgar scores (at 1 and

5minutes), cord gases taken at delivery (arterial/venous pH), and admission to the neonatal

unit (NNU).

Quantitative variableswere expressed as mean values (SD, standard deviation) and qualitative

variables were expressed as absolute and relative frequencies. For the comparison of

proportions Fisher‟s exact tests were used, and Student‟s 𝑡-test was computed for the

comparison of mean values. Multivariable logistic regression analyses in a stepwise method

(𝑝 for entry 0.05, 𝑝 for removal 0.10) were used in order to determine independent factors

that were associated with the odds of an instrumental and caesarean section delivery.

The variables that were entered in the primary analysis were time duration of first and second

stage of labour, age of the mother, smoking, ethnicity, BMI, liquor appearance, use of

epidural, fetal gender, birth weight, and head circumference at birth. Our study included 200

women and, with the current sample size, the study had >95% power to perform a logistic

regression using an alpha of 0.05, large effect sizes, and two-tailed test. Statistical

significance was set at 𝑝 < 0.05 and analyses were conducted using SPSS statistical software

(version 20.0). Ethical approval for collection and analysis of data in our study was obtained

by the.

3. RESULTS

The total sample consisted of 200 eligible women with a mean maternal age at delivery of

25.9 years (SD = 5.7 years). The mean value of BMI was 22 kg/m2 (SD = 1.9 kg/m2) and

87.1% of the participants never smoked. During labour 31.2% of women had an epidural


1310


analgesia for pain relief and the instrumental delivery and overall caesarean section delivery

ratewere 23.1% and 15.1%, respectively. Themean birthweight was 3371 gr (SD= 559 gr)

with 52.5% of the fetuses beingmale.

Meconium stained liquor appearance was identified in 13.3% of the participants and 4% of

all newborns were admitted to the neonatal unit (Tables 1 and 2).

The indications for an instrumental delivery (𝑛 = 242) were prolonged second stage (36.4%),

cardiotocographic (CTG) abnormalities (36.4%), maternal exhaustion (15.2%), abnormal

fetal blood sampling (FBS) (2.9%), fetal malposition (1.3%), and other indications such as

eclampsia (0.8%), and there was a percentage of women with no indication recorded (7%).

The indications for a CS delivery (𝑛 = 158) were failure to progress in labour (38.7%), CT

Gabnormalities (25.9%), failed instrumental delivery (12.7%), failed induction (10.7%),

abnormal FBS (3.1%), and other indications (8.9%) such as chorioamnionitis and placental

abruption.

Those with an epidural analgesia when compared to those without had a significantly greater

maternal age, higher BMI, greater percentage of oxytocin usage, and a longer first and second

stage of labour. Though all women had a normal BMI, the increasing BMI was associated

with a greater use of oxytocin in labour (𝑝 = 0.01). The neonates of women with an epidural

analgesia had a significantly greater birthweight and head circumference, lower Apgar scores

at 1 minute but similar Apgar scores at 5minutes, and higher values of arterial pHin their cord

gases. Women with an epidural analgesia also had a significantly higher instrumental

delivery (37.9% versus 16.4%; 𝑝 < 0.001) and CS delivery rate (26% versus 10.1%; 𝑝 <

0.001) (Tables 1 and 2).

Table 3 shows the results from multivariable stepwise logistic regression analysis with the

dependent variable of presented route of birth (normal vaginal delivery versus instrumental

delivery). The use of an epidural analgesia was independently associated with the odds of an

instrumental vaginal delivery (OR = 3.63; 95% CI: 2.51–5.24, 𝑝 < 0.001).

Additionally, it was found that the increased mother‟s age at delivery, the increased second

stage of labour, and decreasing gestational age were associated with greater odds for an

instrumental delivery.


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Table 3 presents the results from multivariable stepwise logistic regression analysis with the

dependent variable of presented route of birth (vaginal delivery versus CS delivery). The use

of an epidural analgesia was not found to be associated with the odds for a CS delivery. It

was found that the increased birth weight and prolonged second stage were the two factors

that increased the odds for CS delivery.

Table 1: Maternal demographics and labour/delivery characteristics.

𝑝 Epidural, no

(𝑛 = 719)

Epidural, yes

(𝑛 = 327)

Total sample

(𝑛 = 1,046)

0.039† 25.6 (5.6) 26.4 (5.8) 25.9 (5.7) Mothers age at delivery (years),

mean (SD)

0.004† 21.9 (1.9) 22.3 (1.9 22.0 (1.9) BMI, mean (SD)

0.0001‡ 150(73.5%) 50 (36.1%)

200(61.8%)

130 (23.1%158)

60

Route of birth

Normal vaginal delivery

Instrumental vaginal delivery

- - - 10 Caesarean section delivery

0.27† 26 (13) 27 (13) 25 (13) Gestation in days, mean (SD)

0.0001‡ 111 (81.1%)

36 (18.9%)

53 (63.3%)

22 (36.7%)

165 (75.5%)

35 (24.5%)

Use of oxytocin

No

Yes

0.0001‡ 24 (174) 66 (239) 76 (211) First stage of labour (mins), mean

(SD)

0.0001‡ 11 (56) 16(69) 22 (62) Second stage of labour (mins), mean

(SD)

0.63‡ 132 (86.2%)

33 (13.8%)

27 (84.9%)

15 (15.1%)

188 (86.7%)

12 (13.3%)

Liquor appearance

Normal

Meconium stained

† Student‟s 𝑡-test; ‡ Fisher‟s exact test.

Table 2: Results fromstepwisemultivariable logistic regression analysis with the

dependent variable presented route of birth (normal vaginal delivery (𝑁 = 646) versus

instrumental delivery (𝑁 = 242)).

𝑝 OR (95% CI)∗∗ 𝐵 (SE)∗

<0.001 1.38 (1.26–1.51) 0.32 (0.05) Time duration of second stage of

labour (for 30min increase)

<0.001 3.63 (2.51–5.24) 1.29 (0.19) Epidural analgesia

<0.001 0.98 (0.97–0.99) 0.02 (0.01) Gestational age in days

0.001 1.05 (1.02–1.09) 0.05 (0.02) Mother‟s age at delivery (years)

∗Regression coefficient (standard error). ∗∗Odds ratios (95% confidence interval


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Table 3: Results fromstepwisemultivariable logistic regression analysis with the

dependent variable presented route of birth (vaginal delivery (𝑁 = 888) versus CS

delivery (𝑁 = 158)).

𝑝 OR (95% CI)∗∗ 𝐵 (SE)∗

<0.001 1.46 (1.27–1.68) 0.38 (0.07) Birth weight (for 100 g increase)

<0.001 1.17 (1.08–1.27) 0.16 (0.04) Time duration of second stage of labour

(for 30min increase)

∗Regression coefficient (standard error). ∗∗Odds ratios (95% confidence interval).

4. DISCUSSION

We found that women with an epidural analgesia in comparison to those without had a

significantly greater maternal age and a higher BMI. A survey conducted in 2010 showed that

increasing maternal age was a significant factor associated with a woman‟s preference to

have an epidural analgesia during labour.[8]

A more recent, however, large-population based

study in the United States demonstrated that distributions of age were similar between

epidural users and nonusers.[9]

On review of the literature, there are no studies directly

reporting on the finding of increased rates of epidural analgesia in women with a higher BMI.

Nevertheless, there are reports that the increased BMI due to the adipose tissue being

hormonally active predisposes to a reduced response to the induction of labour process

because of the altered metabolic status of these women.[10,11]

In our study we presume that

women with a higher BMI may have also had a reduced response to induced labour, as we

found that the increasing BMI was associated with a greater use of oxytocin in labour (𝑝 =

0.01) which could explain the higher rate of epidural usage due to a more painful labour.

Our study demonstrated that women with induced labour and an epidural analgesia as

compared with those without had a significantly greater percentage of oxytocin usage and a

longer first and second stage of labour. A recent Cochrane review in 2011[4]

reported that

epidural analgesia was associated with an increased rate of oxytocin administration (RR =

1.19; 95% CI: 1.03–1.39). There is evidence that induced labour may be less efficient than

spontaneous labour[12]

and for this reason oxytocin administration may be necessary, thus

rendering labour more painful and therefore requiring the use of pain relief. The Cochrane

review in 2011[4]

also reported that epidural analgesia was associated with a longer second

stage of labour (mean difference = 13.66 mins; 95% CI: 6.67–20.66) but showed no clear

effect on the duration of first stage. On review of the literature there is conflicting evidence

regarding the effect of epidural analgesia with reports of either prolonging[13]

or shortening[14]


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the first stage of labour. In our cohort of women, both first and second stages of labour were

prolonged in those women who had an epidural analgesia.

The neonates of women with epidural analgesia in our study when compared to those without

had significantly lower Apgar scores at 1 minute but similar Apgar scores at 5 minutes. This

is in line with the Cochrane review in 2011[4]

which reported that there were no significant

differences in neonatal Apgar scores at 5 minutes in babies born to women with epidural

analgesia. Our study has also shown that neonates from women with an epidural have

significantly higher values of arterial pH in their cord gases. Higher cord pH values have also

been reported in the past[15]

and this finding could be explained by a recent immune his to

chemical study[16]

that demonstrated that pain-reducing anaesthesia seemed to reduce the

oxidative stress in human termplacenta.

We have found in our study that the use of an epidural analgesia after adjusting formultiple

confounding factors was independently associated with the odds of an instrumental vaginal

delivery (aOR = 3.63; 95%CI: 2.51–5.24). This is in line with the Cochrane review of 2011[4]

indicating an increased risk of assisted vaginal birth in women with an epidural during labour

(RR = 1.42; 95% CI: 1.28–1.57). Previous studies however have shown that the rate of

instrumental vaginal delivery depends on several other confounding factors such as the dose

and concentration of the epidural solution used, the degree of analgesia during second stage,

and obstetric factors.[17,18]

It has been reported that the motor block which is the chief

complication of labour epidural analgesia might result in prolonged labour and therefore

increase the rates of instrument-assisted delivery.[19]

Women with an epidural analgesia in our study when compared to those without had a

significantly higher CS delivery rate (26% versus 10.1%).Nevertheless, after adjusting for

multiple confounding factors, there was no significant difference noted between epidural

users and nonusers. This is in line with the Cochrane review of 2011[4]

indicating that there is

no significant difference in the risk of CS delivery overall. Previous studies have

contemplated that the degree of motor block achieved by an epidural analgesia may result in

a prolonged labour and therefore increase the rates of a CS delivery.[19]

Other studies[17,20]

however have demonstrated that epidural analgesia per se is unlikely to affect the chances of

a normal delivery and there are many other factors that may contribute to a CS delivery such

as the increased birthweight.[17]


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There are certain limitations to be considered about our study. First, data were retrospectively

collected from an electronic database for the study period 2007–2013 where accuracy of data

is dependent on the practitioner recording the information each time on the database. Second,

our electronic database does not have a mandatory field for recording the epidural regimen

that was used. There is literature evidence showing that different epidural analgesia formulas

exhibit a different effect on the course of labour and the delivery outcome.[19,20]

The main

strength of our study includes its large sample size with inclusion of women who were

primigravidae and under 40 years of age and had a normal BMI at booking in order to

account for the significant confounding factors of parity[5]

, age[6]

, and body mass index

(BMI)[7]

on the success of induced labour.

In conclusion we have found that women with an epidural in our cohort have a threefold

increased risk of an instrumental delivery. Our study lends support to the literature reports

that an epidural analgesia is a risk factor for an assisted vaginal birth. It has also added that

there is no effect on the CS delivery rates and the observed increase is due to the presence of

confounding factors.

CONCLUSION

Pain relief in labor is an important aspect of maternity care. Effective pain relief using

neuraxial analgesia with low concentrations of local anesthetic can be offered to parturients

without adversely affecting labor outcome. There is no need to deny parturients adequate

analgesia early in labor if required.

REFERENCES

1. Simpson W. The works of Sir J.Y. Simpson. Edinburgh, Scotland: Adam and Charles

Black, 1871.

2. Bricker L, Lavender T. Parenteral opioids for labor pain relief: a systematic review. Am J

Obstet Gynecol, 2002; 186: Suppl: S94-S109.

3. Simkin PP, O‟Hara M. Nonpharmacologic relief of pain during labor: systematic reviews

of five methods. Am J Obstet Gynecol, 2002; 186: Suppl: S131-S159.

4. Hodnett ED. Pain and women‟s satisfaction with the experience of childbirth: a

systematic review. Am J Obstet Gynecol, 2002; 186: Suppl: S160-S172.

5. Kannan S, Jamison RN, Datta S. Maternal satisfaction and pain control in women electing

natural childbirth. Reg Anesth Pain Med., 2001; 26: 468-72.


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6. Hawkins JL, Beaty BR, Gibbs CP. Update on U.S. OB anesthesia practice.

Anesthesiology, 1999; 91: Suppl: A1060. abstract.

7. Pickering AE, Parry MG, Ousta B, Fernando R. Effect of combined spinal-epidural

ambulatory labor analgesia on balance. Anesthesiology, 1999; 91: 436-41.

8. Collis RE, Davies DW, Aveling W. Randomised comparison of combined spinalepidural

and standard epidural analgesia in labour. Lancet, 1995; 345: 1413-6.

9. Clarke VT, Smiley RM, Finster M. Uterine hyperactivity after intrathecal injection of

fentanyl for analgesia during labor: a cause of fetal bradycardia? Anesthesiology, 1994;

81: 1083.

10. D‟Angelo R, Eisenach JC. Severe maternal hypotension and fetal bradycardia after a

combined spinal epidural anesthetic. Anesthesiology, 1997; 87: 166-8.

11. Gambling DR, Sharma SK, Ramin SM, et al. A randomized study of combined spinal-

epidural analgesia versus intravenous meperidine during labor: impact on cesarean.

12. Regional Anesthesia and Analgesia for Labor and Delivery Holger K. Eltzschig, M.D.,

Ellice S. Lieberman, M.D., Dr.P.H., and William R. Camann, M.D.

13. Research Article The Effect of Epidural Analgesia on the Delivery Outcome of Induced

Labour: A Retrospective Case Series.

14. Department of Health, Statistical Bulletin-NHS Maternity Statistics, England: 2003-2004,

Department of Health, London, UK, 2004.

15. M. J. K. Osterman, J. A. Martin, and F. Menacker, “Expanded health data from the new

birth certificate, 2006,” National Vital Statistics Reports, 2009; 58(5): 1–24.

16. L. Jones, M.Othman, T. Dowswell et al., “Painmanagement for women in labour: an

overview of systematic reviews,” Cochrane Database of Systematic Reviews, no. 3,

Article ID CD009234, 2012.

17. M. Anim-Somuah, R. M. Smyth, and L. Jones, “Epidural versus non-epidural or no

analgesia in labour,” Cochrane Database of Systematic Reviews, vol. 12, Article ID

CD000331, 2011.

18. A. Boyle, U.M. Reddy, H. J. Landy, C.-C.Huang, R.W.Driggers, and S. K. Laughon,

“Primary cesarean delivery in the United States,” Obstetrics and Gynecology, 2013;

122(1): 33–40.

19. G. C. S. Smith, Y. Cordeaux, I. R. White et al., “The effect of delaying childbirth on

primary cesarean section rates,” PLoS Medicine, 2008; 5(7): Article ID e144.


1316


20. N. J. Sebire, M. Jolly, J. P. Harris et al., “Maternal obesity and pregnancy outcome: a

study of 287 213 pregnancies in London,” International Journal of Obesity, 2001; 25(8):

1175–1182.

21. J. Harkins, B. Carvalho, A. Evers, S. Mehta, and E. T. Riley, “Survey of the factors

associated with a woman‟s choice to have an epidural for labor analgesia,”

Anesthesiology Research and Practice, vol. 2010, Article ID 356789, 8 pages, 2010. [9]

S. M. Lancaster, U. M. Schick, M. M. Osman, and D. A. Enquobahrie, “Risk factors

associated with epidural use,” Journal of Clinical Medicine Research, 2001; 4: 119–126.

22. Halpern SH, Carvalho B. Patient-controlled epidural analgesia for labor. Anesth Analg,

2009; 108: 921–928.

23. Hinova A, Fernando R. Systemic remifentanil for labor analgesia. Anesth Analg, 2009;

109: 1925–1929.

24. Niehaus LS, Chaska BW, Nesse RE. The effects of epidural anesthesia on type of

delivery. J Am Board Fam Pract, 1988; 1: 238–244.

25. Lieberman E, Lang JM, Cohen A, et al. Association of epidural analgesia with cesarean

delivery in nulliparas. Obstet Gynecol, 1996; 88: 993–1000.

26. Hess PE, Pratt SD, Soni AK, et al. An association between severe labor pain and cesarean

delivery. Anesth Analg, 2000; 90: 881–886.

27. Leighton BL, Halpern SH. Epidural analgesia and the progress of labor. In: Halpern SH,

Douglas MJ, editors. Evidence-based obstetric anesthesia. Malden, Massachusetts:

Blackwell Publishing, 2005; 10–22.

28. Bofill JA, Vincent RD, Ross EL, et al. Nulliparous active labor, epidural analgesia, and

cesarean delivery for dystocia. Am J Obstet Gynecol, 1997; 177: 1465–1470.

29. Birnbach DJ, Ojea LS. Combined spinal-epidural (CSE) for labor and delivery. Int

Anesthesiol Clin, 2002; 40: 27–48.

30. Tsen LC, Thue B, Datta S, Segal S. Is combined spinal-epidural analgesia associated with

more rapid cervical dilation in nulliparous patients when compared with conventional

epidural analgesia? Anesthesiology, 1999; 91: 920–925.

31. Gambling DR, Sharma SK, Ramin SM, et al. A randomized study of combined spinal-

epidural analgesia versus intravenous meperidine during labor: impact on cesarean

delivery rate. Anesthesiology, 1998; 89: 1336–1344.

32. Norris MC, Fogel ST, Conway-Long C. Combined spinal-epidural versus epidural labor

analgesia. Anesthesiology, 2001; 95: 913–920.


1317


33. Comparative Obstetric Mobile Epidural Trial (COMET) Study Group UK. Effect of low-

dose mobile versus traditional epidural techniques on mode of delivery: a randomised

controlled trial. Lancet, 2001; 358: 19–23.

34. Comparative Obstetric Mobile Epidural Trial Study Group, UK Randomized controlled

trial comparing traditional with two „mobile‟ epidural techniques: anesthetic and

analgesic efficacy. Anesthesiology, 2002; 97: 1567–1575.

35. Simmons SW, Cyna AM, Dennis AT, Hughes D. Combined spinal-epidural versus

epidural analgesia in labour. Cochrane Database Syst Rev., 2007; 3: Art. no.: CD003401.

doi: 10.1002/14651858.CD003401.pub2.

36. Systematic review combines all relevant randomized controlled trials Effect of labor

analgesia on labor outcome Stephen H. Halpern and Faraj W. Abdallah.

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