Obstetrical Anesthesia

Dr. John Snow
born 15 March 1813 in York,
England.Queen Victoria was
given chloroform by John Snow
for the birth of her eighth child
and this did much to popularize
the use of pain relief in labor.
9/3/2013 2BITEW(IESO)

Does Labor Pain Need
Analgesia?

Analgesia for Labor and Delivery
• Always controversial!
• “Birth is a natural process”
• Women should suffer!!
• Concerns for mother’s safety
• Concerns for baby
• Concerns for effects on labor

Why have a Caregiver dedicated to
pain management during
labor and delivery?
9/3/2013 BITEW(IESO) 5

• Labor and delivery result in severe pain for most
women.
• In an attempt to quantify this pain, parturients
were asked to rate their pain during labor.
• These results were then compared to values
obtained from patients in a general pain clinic
and emergency department.
• The pain of childbirth was greater than a
fractured arm and cancer pain.
• Only causalgia and amputation of a digit
exceeded the pain of labor and delivery.
• Parturients described the pain as sharp,
cramping, aching, throbbing, stabbing, hot,
shooting, and tight.

What is the cause of labor pain in
stage 1? What type of pain is it?
• The pain resulting from the first stage of labor is
primarily due to dilatation of the cervix with
consequent distention and stretching.
• As the uterus contracts, the fetal head pushes
against the cervix and causes dilatation.
• Therefore, stage 1 pain generally occurs only during
uterine contraction.

• While the majority of pain during this stage
occurs from the fetal head pushing against the
cervix, there is also pain from pressure and
stretching of the uterine muscles, which activate
the high-threshold mechanoreceptors.
• In the first stage of labor, the pain is visceral.
• It is strong and dull, and occurs over the lower
abdomen between the umbilicus and the
symphysis pubis, laterally over the iliac crest,
and posteriorly in the skin and soft tissue over
the lower lumbar spines.

The location of labor pain in stage 1??
• The location of this pain is explained by the
concept of referred pain.
• The sensory nerves of the uterus and cervix
leave the cervix and join the sympathetic
nerves as they pass through the hypogastric
plexus to the sympathetic chain, synapsing
within the dorsal horn of the spinal cord at T10,
T11, T12, and L1.

• This area of the spinal cord receives not only
these visceral high-threshold afferents, but also
the low-threshold cutaneous afferents of the skin
from T10, T11, T12, and L1.
• With the convergence of both somatic and
visceral fibers within the same area of the spinal
cord, the parturient interprets the uterine pain as
originating from the cutaneous afferents of these
spinal segments. The pain is referred to this area.
9/3/2013 BITEW(IESO) 10

What is the cause of labor pain in stage
2? What type of pain
is it?
9/3/2013 BITEW(IESO) 11

• Second-stage pain occurs as the fetus descends
through the birth canal.
• This results in stretching and tearing of fascia,
skin, and subcutaneous tissue.
• This somatic pain is transmitted primarily through
the pudendal nerve.
• The pudendal nerve is derived from the anterior
primary divisions of sacral nerves, S2 S3 and S4.
• Of note, the fetus often begins to descend during
the first stage of labor.
• During the transitional stage of the first stage, it is
not uncommon for the mother to experience
both visceral and somatic pain
9/3/2013 BITEW(IESO) 12

Labor Pain at different Stages of LaborLabor Pain at different Stages of Labor
Eltzschig, Leiberman, Camann, NEJM 348; 319:2003Eltzschig, Leiberman, Camann, NEJM 348; 319:20039/3/2013 13BITEW(IESO)

The Physiology of Pain in Labor
11stst
stage of laborstage of labor – mostly visceral
◦ Dilation of the cervix and distention of the lower
uterine segment
◦ Dull, aching and poorly localized
◦ Slow conducting, visceral C fibers, enter spinal cord at
T10 to L1
22ndnd
stage of laborstage of labor – mostly somatic
◦ Distention of the pelvic floor, vagina and perineum
◦ Sharp, severe and well localized
◦ Rapidly conducting A-delta fibers, enter spinal cord
at S2 to S4

Pain Pathways of LaborPain Pathways of Labor

LaborLabor
CardiovascularCardiovascular
UrinaryUrinary
Neuro-endocrineNeuro-endocrine
post-traumatic
stress syndrome
post-traumatic
stress syndrome
RespiratoryRespiratory
Gastro-intestinalGastro-intestinal

Potential effects of maternal hyperventilation and subsequent
hypocarbia on oxygen delivery to the fetus9/3/2013 17BITEW(IESO)

Pathways of labor painPathways of labor pain9/3/2013 18BITEW(IESO)

How do psychological factors influence
labor pain?
9/3/2013 BITEW(IESO) 19

While labor is a physiologic process, psychological
factors also affect the pain.
Anxiety is a particularly powerful factor in
reducing pain tolerance.HOW??
Attention, the selective orientation of the
receptor system to one source or pattern of
stimulation to the exclusion of other sources,
either enhances or diminishes the painful
experience.
 Motivation is another psychodynamic
mechanism that can have a marked influence on
the physiologic, behavioral, and affective aspects
of pain.
Breathing exercises divert the mother's attention
from the pain of contractions.
9/3/2013 BITEW(IESO) 20

Introduction
Pain relief in labor presents unique problems.
Labor begins without warning, and obstetrical
anesthesia may be required within minutes of a full
meal.
Vomiting with aspiration of gastric contents is a
constant threat that poses serious maternal
morbidity and mortality.
 Moreover, a host of disorders unique to pregnancy,
such as preeclampsia, placental abruption, and
chorioamnionitis, all superimposed on unique
physiological adaptations of pregnancy, are directly
affected by the choice of analgesia and anesthesia
selected.

Introduction
Anesthesia complications caused 1.6 percent of
pregnancy-related maternal deaths
Several factors likely have contributed to
improved safety of obstetrical anesthesia;
the recent trend toward increased use of
regional analgesia, rather than general
anesthesia, may be the most significant factor.
The increased availability of in-house
anesthesia coverage almost certainly is another
important reason

GENERAL PRINCIPLES
 a woman’s request for labor pain relief is sufficient
medical indication for its provision.
 it is the responsibility of the obstetrician or certified
nurse-midwife, in consultation with an
anesthesiologist, if appropriate, to formulate a suitable
plan for pain relief.
 Identification of any of the risk factors, should prompt
consultation with anesthesia personnel to permit a
joint management plan.
 This plan should include strategies to minimize the
need for emergency anesthesia in women for whom
such anesthesia would be especially hazardous.

Maternal Risk Factors That Should
Prompt Anesthesia Consultation
 Marked obesity
 Severe edema or anatomical abnormalities of face, neck, or
spine, including trauma or surgery
 Abnormal dentition, small mandible, or difficulty opening
mouth
 Extremely short stature, short neck, or arthritis of the neck
 Goiter
 Serious maternal medical problems, such as cardiac,
pulmonary, or neurological disease
 Bleeding disorders
 Severe preeclampsia
 Previous history of anesthetic complications
 Obstetrical complications likely to lead to operative delivery—
e.g., placenta previa or higher-order multiple gestation9/3/2013 25BITEW(IESO)

Goals for optimizing obstetrical
anesthesia services
1. Availability of a licensed practitioner who is credentialed to administer an
appropriate anesthetic whenever necessary and to maintain support of
vital functions in an obstetrical emergency.
2. Availability of anesthesia personnel to permit the start of a cesarean
delivery within 30 minutes of the decision to perform the procedure.
3. Anesthesia personnel immediately available to perform an emergency
cesarean delivery during the active labor of a woman attempting vaginal
birth after cesarean (Candidates for a Trial of Labor).
4. Appointment of a qualified anesthesiologist to be responsible for all
anesthetics administered.
5. Availability of a qualified physician with obstetrical privileges to perform
operative vaginal or cesarean delivery during administration of anesthesia.
6. Availability of equipment, facilities, and support personnel equal to that
provided in the surgical suite.
7. Immediate availability of personnel, other than the surgical team, to
assume responsibility for resuscitation of the depressed newborn (see
Chap. 28, Newborn Resuscitation).

Role of Obstetrician
 Every obstetrician should be proficient in local and
pudendal analgesia.
 Regional analgesia may be administered by the
properly trained obstetrician in appropriately selected
circumstances.
 In general, however, it is preferable for an
anesthesiologist or anesthetist to provide this care so
that the obstetrician can focus attention on the
concerns for the laboring woman and her fetus.
 General anesthesia should be administered only by
those with special training.

Principles of Pain Relief
the experience of labor pain is a highly individual
reflection of variable stimuli that are uniquely received
and interpreted by each woman individually.
These stimuli are modified by emotional, motivational,
cognitive, social, and cultural circumstances.
The complexity and individuality of the experience
suggest that a woman and her caregivers may have a
limited ability to anticipate her pain experience prior to
labor.
Thus, choice among a variety of methods and
individualization of pain relief is desirable.

Goals of Labour Analgesia
• Dramatically reduce pain of labor
• Should allow parturient to participate in
birthing experience
• Minimal motor block to allow ambulation
• Minimal effects on fetus
• Minimal effects on progress of labor

What Are the Types of Labor
Analgesia?
What analgesic options are
available for labor?

Types of Labor Analgesia
1. Non-pharmacological analgesia
2. Pharmacological
3. Regional Anesthesia/Analgesia
4. General Anesthesia

NONPHARMACOLOGICAL METHODS
OF PAIN CONTROL
 Fear and the unknown potentiate pain.
 Make a woman who is free from fear, and develop confidence
in the obstetrical staff that cares for her
 Avoid emotional tension
 Lamaze
 teaching pregnant women relaxed breathing and their labor
partners psychological support techniques.
 Motivatation
 the presence of a supportive spouse

ANALGESIA AND SEDATION DURING
LABOR

ANALGESIA AND SEDATION DURING
LABOR
• When uterine contractions and cervical
dilatation cause discomfort, pain relief with a
narcotic such as meperidine, plus one of the
tranquilizer drugs such as promethazine, is
usually appropriate.
• With a successful program of analgesia and
sedation, the mother should rest quietly
between contractions.
• In this circumstance, discomfort usually is felt at
the acme of an effective uterine contraction, but
the pain is generally not unbearable.9/3/2013 34BITEW(IESO)

Neuraxial Opioids
The following opioids have been used:
Morphine, fentanyl, sufentanil, meperidine,
diamorphine.

Parenteral Agents for Labor Pain
Agent Usual Dose Frequency Onset Neonatal Half-
Life
Meperidine 25–50 mg (IV) 1–2 hr 5 min 13–22.4 hr
50–100 mg (IM) 2–4 hr 30–45 min 63 hr for active
metabolites
Fentanyl 50–100 g (IV) 1 hr 1 min 5.3 hr
Nalbuphine 10 mg (IV or
IM)
3 hr 2–3 min (IV) 4.1 hr
15 min (IM)
Butorphanol 1–2 mg (IV or
IM)
4 hr 1–2 min (IV) Not known
10–30 min (IM) Similar to
nalbuphine in
adults
Morphine 2–5 mg (IV) 4 hr 5 min 7.1 hr
10 mg (IM) 30–40 min9/3/2013 36BITEW(IESO)

NEW DRUGS:
• Clonidine
• Neostigmine
• Midazolam

Parenteral Agents
Meperidine and Promethazine
 Meperidine, 50 to 100 mg, with promethazine, 25
mg, may be administered intramuscularly at intervals
of 2 to 4 hours.
 A more rapid effect is achieved by giving meperidine
intravenously in doses of 25 to 50 mg every 1 to 2
hours.
 Whereas analgesia is maximal about 30 to 45 minutes
after an intramuscular injection, it develops almost
immediately following intravenous administration.
 Meperidine readily crosses the placenta, and the half-
life is approximately 13 hours or longer in the9/3/2013 39BITEW(IESO)

Butorphanol (Stadol)
 This synthetic narcotic, given in 1- to 2-mg doses,
compares favorably with 40 to 60 mg of meperidine.
 The major side effects are somnolence, dizziness, and
dysphoria.
 Neonatal respiratory depression is reported to be less
than with meperidine, but care must be taken that the
two drugs are not given contiguously because
butorphanol antagonizes the narcotic effects of
meperidine
 a sinusoidal fetal heart rate pattern following
butorphanol administration

Fentanyl
This short-acting and potent synthetic opioid
may be given in doses of 50 to 100mcg
intravenously every hour.
Its main disadantage is a short duration of
action, which requires frequent dosing or the
use of a patient-controlled intravenous pump.

Efficacy and Safety of Parenteral Agents
• Meperidine is the most common opioid used worldwide
for pain relief in labor.
• There is no convincing evidence demonstrating that
alternative opioids are better.
• There is no evidence that parenteral opioids influence the
length of labor or need for obstetrical intervention.
• Epidural analgesia provides superior pain relief.
• Intravenous and intramuscular sedation are not without
risks.
 maternal anesthetic-related deaths were from such sedation-
aspiration, inadequate ventilation, and overdosage.
Moreover, meperidine or other narcotics used during labor may cause
newborn respiratory depression.

Narcotic Antagonists
 Naloxone is a narcotic antagonist capable of reversing
respiratory depression induced by opioid narcotics.
 It acts by displacing the narcotic from specific receptors
in the central nervous system.
 Withdrawal symptoms may be precipitated in recipients
who are physically dependent on narcotics.
 For this reason, naloxone is contraindicated in a
newborn of a narcotic-addicted mother.
 Naloxone, along with proper ventilation, may be given
to reverse respiratory depression in a newborn infant
whose mother received narcotics.

Nitrous Oxide
A self-administered mixture of 50-percent
nitrous oxide (N2O) and oxygen provides
satisfactory analgesia during labor for many
women.
Some preparations are premixed in a single
cylinder (Entonox), and in others, a blender
mixes the two gases from separate tanks
(Nitronox).
The gases are connected to a breathing circuit
through a valve that opens only when the patient
inspires.9/3/2013 44BITEW(IESO)

Nitrous Oxide
 The use of intermittent nitrous oxide for labor pain ,the following
technique suggested:
1) Instruct the woman to take slow deep breaths and to begin inhaling 30
seconds before the next anticipated contraction and to cease when the
contraction starts to recede.
2) Remove the mask between contractions and encourage her to breathe
normally. No one but the patient or knowledgeable personnel should
hold the mask.
3) Instruct a caregiver to remain in verbal contact with the patient.
4) Provide the expectation that the pain will likely not be eliminated, but
that the gas should provide some relief.
5) Ensure intravenous access, pulse oximetry, and adequate scavenging of
exhaled gases.
6) Use with additional caution after previous opioid administration
because the combination can more easily render a woman unconscious
and unable to protect her airway.

Regional Analgesia

Regional anesthetic
techniques, were
introduced to obstetrics in
1900, when Oskar Kreis
described the use of spinal
anesthesia.
Unfortunately he was
an obstetrtian

Regional Analgesia
Various nerve blocks have been developed
over the years to provide pain relief during
labor and delivery.
They are correctly referred to as regional
analgesics.

Regional Anesthesia/Analgesia
• Epidural
• Spinal
• Combined Spinal Epidural (CSE)
• Continuous spinal analgesia
• Paracervical block
• Lumbar sympathetic block
• Pudendal block
• Perineal infiltration

Sensory Innervation of the Genital Tract
Uterine Innervation
Pain during the first stage of labor is generated largely
from the uterus.
Visceral sensory fibers from the uterus, cervix, and upper
vagina traverse through the Frankenhäuser ganglion,
which lies just lateral to the cervix, into the pelvic plexus,
and then to the middle and superior internal iliac
plexuses.
From there, the fibers travel in the lumbar and lower
thoracic sympathetic chains to enter the spinal cord
through the white rami communicantes associated with
the T10 through T12 and L1 nerves.
 Early in labor, the pain of uterine contractions is
transmitted predominantly through the T11 and T12
nerves.9/3/2013 50BITEW(IESO)

Pathways of labor painPathways of labor pain9/3/2013 51BITEW(IESO)

Uterine Innervation
The motor pathways to the uterus leave the
spinal cord at the level of the T7 and T8
vertebrae.
Theoretically, any method of sensory block
that does not also block the motor pathways
to the uterus can be used for analgesia during
labor.

Lower Genital Tract Innervation
Pain with vaginal delivery arises from stimuli from the
lower genital tract.
 These are transmitted primarily through the pudendal
nerve, the peripheral branches of which provide
sensory innervation to the perineum, anus, and the
more medial and inferior parts of the vulva and clitoris.
The pudendal nerve passes beneath the posterior
surface of the sacrospinous ligament just as the
ligament attaches to the ischial spine.
The sensory nerve fibers of the pudendal nerve are
derived from the ventral branches of the S2 through S4
nerves.

Anesthetic Agents
• Some preparations that contain dilute epinephrine to prolong
the action of the anesthetic will also cause symptoms when a
test dose is inadvertently given intravenously.
• The dose of each agent varies widely and is dependent on the
particular nerve block and physical status of the woman.
• The onset, duration, and quality of analgesia can be enhanced
by increasing the dose.
• This can be done safely by only incrementally administering
small-volume boluses of the agent and by carefully monitoring
for early warning signs of toxicity.
• Administration of these agents must be followed by appropriate
monitoring for adverse reactions, and equipment and personnel
to manage these reactions must be immediately available.

Most often, serious toxicity follows inadvertent
intravenous injection. For this reason, when
epidural analgesia is initiated, dilute epinephrine
is sometimes added and given as a test dose.
A sudden signiﬁcant rise in the maternal heart
rate or blood pressure immediately after
administration suggests intravenous catheter
placement.
Personnel using these agents must be cognizant
that these agents are manufactured in more than
one concentration and ampule size, which
increases the potential for dosing errors.

Some Local Anesthetic Agents
Used in Obstetrics
Plain Solutions

Anesthetic
Agent
Usual
Concentr
ation (%)
Usual
Volume
(mL)
Usual
Dose
(mg)
Onset Average
Duration
(min)
Clinical Use
Amino-esters
2-
Chloropr
ocaine
1–2 20–30 400–600 Rapid 15–30 Local or
pudendal
block
2–3 15–25 300–750 30–60 Epidural (not
subarachnoid)
for cesarean
delivery
Tetracain
e
0.2 — 4 Slow 75–150 Low spinal
block/6%glucose
0.5 — 7–10 75–150 Spinal for
cesarean
delivery/5%gluco
se9/3/2013 57BITEW(IESO)

Amino-amides
Lidocaine 1 20–30 200–300 Rapid 30–60 Local or
pudendal
block
2 15–30 300–450 60–90 Epidural for
cesarean
delivery
5 1–1.5 50–75 45–60 Spinal for
cesarean
delivery or
puerperal
tubal
ligation/7.5
%glucose
5 0.5–1 25–50 30–60 Spinal for
vaginal
delivery/7.5
%glucose

Bupivacaine 0.5 15–20 50–100 Slow 90–150 Epidural for
cesarean
delivery
0.25 8–10 20–25 60–90 Epidural for
labor
0.75 1–1.5 7.5–11 60–120 Spinal for
cesarean
delivery/8.2
5%glucose
Ropivacain
e
0.5 15–20 75–100 Slow 90–150 Epidural for
cesarean
delivery
0.25 8–10 20–25 60–90 Epidural for
labor

• Addition of glucose to local anesthetics
creates a hyperbaric solution, which is heavier
and denser than cerebrospinal ﬂuid.

Toxicity
• Systemic toxicity from local anesthetics
typically manifests in the central nervous and
cardiovascular systems.

Central Nervous System Toxicity
Early symptoms are those of stimulation but, as
serum levels increase, depression follows.
Symptoms may include light-headedness,
dizziness, tinnitus, metallic taste, and numbness
of the tongue and mouth.
Patients may show bizarre behavior, slurred
speech, muscle fasciculation and excitation,
and ultimately, generalized convulsions,
followed by loss of consciousness.
The convulsions should be controlled, an
airway established, and oxygen delivered.

Succinylcholine abolishes the peripheral
manifestations of the convulsions and allows
tracheal intubation.
Thiopental or diazepam act centrally to inhibit
convulsions.
Magnesium sulfate, administered according to
the regimen for eclampsia, also controls
convulsions.

 Abnormal fetal heart rate patterns, such as late
decelerations or persistent bradycardia, may develop
from maternal hypoxia and lactic acidosis induced by
convulsions.
 With arrest of the convulsions, administration of
oxygen, and application of other supportive measures,
the fetus usually recovers more quickly in utero than
following immediate cesarean delivery.
 Moreover, maternal well-being is usually better served
by waiting until the intensity of the hypoxia and the
metabolic acidosis have diminished.

Cardiovascular Toxicity
• These manifestations generally develop later than
those from cerebral toxicity.
• They do not always follow central nervous system
involvement, because they are induced by higher
drug levels.
• The notable exception is bupivacaine, which is
associated with the development of neurotoxicity
and cardiotoxicity at virtually identical serum drug
levels.
• Because of this risk of systemic toxicity, use of
0.75-percent solution of bupivacaine for epidural
injection was proscribed .

Cardiovascular Toxicity
 Similar to neurotoxicity, cardiovascular toxicity is characterized
first by stimulation and then by depression.
 Accordingly, there is hypertension and tachycardia, which soon
is followed by hypotension and cardiac arrhythmias.
 The latter contribute appreciably to impaired uteroplacental
perfusion and fetal distress.
 Hypotension is managed initially by turning the woman onto
either side to avoid aortocaval compression.
 A crystalloid solution is infused rapidly along with intravenously
administered ephedrine.
 Emergency cesarean delivery should be considered if maternal
vital signs have not been restored within 5 minutes of cardiac
arrest.
 As with convulsions, however, the fetus is likely to recover
more quickly in utero once maternal cardiac output is
reestablished.9/3/2013 66BITEW(IESO)

Pudendal Block
• This block is a relatively safe and simple method of
providing analgesia for spontaneous delivery.
• The end of the introducer is placed against the vaginal
mucosa just beneath the tip of the ischial spine.
• The needle is pushed beyond the tip of the director into
the mucosa and a mucosal wheal is made with 1 mL of
1-percent lidocaine solution or an equivalent dose of
another local anesthetic.
• To guard against intravascular infusion, aspiration is
attempted before this and all subsequent injections.

Pudendal Block
The needle is then advanced until it touches the
sacrospinous ligament, which is infiltrated with 3 mL
of lidocaine.
The needle is advanced farther through the ligament,
and as it pierces the loose areolar tissue behind the
ligament, the resistance of the plunger decreases.
Another 3 mL of the anesthetic solution is injected
into this region.
Next, the needle is withdrawn into the introducer,
which is moved to just above the ischial spine. The
needle is inserted through the mucosa and the rest of
10 mL of solution is deposited. The procedure is then
repeated on the other side.

Pudendal Block
 Within 3 to 4 minutes of the time of injection, the successful
pudendal block will allow pinching of the lower vagina and
posterior vulva bilaterally without pain.
 It is often of benefit before pudendal block to infiltrate the
fourchette, perineum, and adjacent vagina with 5 to 10 mL of
1-percent lidocaine solution directly at the site where the
episiotomy is to be made.
 Then, if delivery occurs before pudendal block becomes
effective, an episiotomy can be made without pain.
 By the time of the repair, the pudendal block usually has
become effective.
 Pudendal block usually does not provide adequate analgesia
when delivery requires extensive obstetrical manipulation.
 Moreover, such analgesia is usually inadequate for women in
whom complete visualization of the cervix and upper vagina,
or manual exploration of the uterine cavity, are indicated.

Complications of Pudendal Block
Central Nervous System Toxicity ,
intravascular injection of a local anesthetic
agent may cause serious systemic toxicity.
Hematoma formation
Rarely, severe infection may originate at the
injection site. The infection may spread
posterior to the hip joint, into the gluteal
musculature, or into the retropsoas space.

Paracervical Block
This block usually provides satisfactory pain relief during
the first stage of labor.
Because the pudendal nerves are not blocked, however,
additional analgesia is required for delivery.
Usually lidocaine or chloroprocaine, 5 to 10 mL of a 1-
percent solution, is injected into the cervix laterally at 3
and 9 o'clock.
 Bupivacaine is contraindicated because of an increased
risk of cardiotoxicity.
Because these anesthetics are relatively short acting,
paracervical block may have to be repeated during
labor.

Complications Of Paracervical Block
Fetal bradycardia(15%)
Bradycardia usually develops within 10 minutes
and may last up to 30 minutes.
The effect may be the consequence of
transplacental transfer of the anesthetic agent or
its metabolites and in turn, a depressant effect
on the fetal heart.
For these reasons, paracervical block should not
be used in situations of potential fetal
compromise.

Spinal (Subarachnoid) Block

Spinal Anesthesia/Analgesia
• Used mainly for very
late in labor because
it has limited
duration of action
• Faster onset than
Epidural
• Amount of local
anesthetic used is
much smaller

Spinal (Subarachnoid) Block
• Introduction of a local anesthetic into the
subarachnoid space to effect analgesia has long
been used for delivery.
• Advantages include a short procedure time, rapid
onset of the block, and high success rate.
• Because of the smaller subarachnoid space
during pregnancy, likely the consequence of
engorgement of the internal vertebral venous
plexus, the same amount of anesthetic agent in
the same volume of solution produces a much
higher blockade in parturients than in
nonpregnant women.

Vaginal Delivery
Low spinal block is a popular form of analgesia
for forceps or vacuum delivery.
 The level of analgesia should extend to the
T10 dermatome, which corresponds to the
level of the umbilicus.
Blockade to this level provides excellent relief
from the pain of uterine contractions.

Vaginal Delivery
• Several local anesthetic agents have been used for
spinal analgesia.
• Addition of glucose to any of these agents creates
a hyperbaric solution, which is heavier and denser
than cerebrospinal ﬂuid.
• A sitting position causes a hyperbaric solution to
settle caudally, whereas a lateral position will have
a greater effect on the dependent side.
• Lidocaine given in a hyperbaric solution produces
excellent analgesia and has the advantage of a
rapid onset and relatively short duration.

Vaginal Delivery
• Bupivacaine in an 8.25-percent dextrose
solution provides satisfactory anesthesia to
the lower vagina and the perineum for more
than 1 hour.
• Neither is administered until the cervix is fully
dilated and all other criteria for safe forceps
delivery have been fulﬁlled.
• Preanalgesic intravenous hydration with 1 L of
crystalloid solution will prevent or minimize
hypotension in many cases.

Cesarean Delivery
• A level of sensory blockade extending to the T4
dermatome is desired for cesarean delivery.
• Depending on maternal size, 10 to 12 mg of
hyperbaric bupivacaine or 50 to 75 mg of
hyperbaric lidocaine are administered.
• The addition of 20 to 25 g of fentanyl increases the
rapidity of the onset of the block and reduces
shivering.
• The addition of 0.2 mg of morphine improves pain
control during delivery and postoperatively.

Complications
• Hypotension
• Postdural puncture headache
• Pruritus
• Failed regional block (need for general
endotracheal anesthesia)
• High spinal block
• Chemical meningitis or epidural abscess or
hematoma
• obese women have significantly impaired
ventilation

Incidence (%) from ACOGa
Incidence (%) from MFMUb
Complication Spinal
(n =
N/A)
Epidural (n =
N/A)
Combined
c
(n =
N/A)
Spinal (n =
27,319)
Epidural (n =
18,697)
Combi
nedc
(n =
5,666)
Hypotensiond
25–67 28–31 — — — —
Postdural puncture
headache
1.5–3 2 1–2.8 0.4 0.3 0.4
Pruritus 41–85 1.3–26 41–85 — — —
Failed regional block
(need for GETA)
— — — 1.7 4.0 1.5
High spinal block — — — 0.05 0.08 0.07
Chemical meningitis
or epidural abscess
or hematoma
— — — 0 0 0

HypotensionHypotension
 may develop soon after injection of the local anesthetic agent
and is the consequence of vasodilatation from sympathetic
blockade compounded by obstructed venous return from
uterine compression of the vena cava and adjacent large veins.
 In the supine position, even in the absence of maternal
hypotension measured in the brachial artery, placental blood
flow may still be significantly reduced.
 Treatment of spinal block hypotension includes uterine
displacement, intravenous hydration, and intravenous bolus
injections of ephedrine or phenylephrine

HypotensionHypotension
 The predominant action of ephedrine is to
raise blood pressure by increasing cardiac
output rather than vasoconstriction.
Phenylephrine is a pure -agonist which, at
least until recently, we have generally
avoided because of concerns about potential
adverse effects on uterine blood flow.

High Spinal Blockade
• Most often, complete spinal blockade is the consequence of
administration of an excessive dose of local anesthetic
agent.
• This is certainly not always the case, because accidental
total spinal block has even occurred following an epidural
test dose.
• In complete spinal block, hypotension and apnea promptly
develop and must be immediately treated to prevent cardiac
arrest.
• In the undelivered woman, (1) the uterus is immediately
displaced laterally to minimize aortocaval compression; (2)
effective ventilation is established, preferably with tracheal
intubation; and (3) intravenous fluids and ephedrine are
given to correct hypotension.

Spinal (Postdural Puncture) Headache
• Leakage of cerebrospinal fluid from the site of puncture of the
meninges is thought to be the major factor in the genesis of
spinal headache.
• Presumably, when the woman sits or stands, the diminished
volume of cerebrospinal fluid allows traction on pain-sensitive
central nervous system structures.
• With severe headache, an epidural blood patch is effective. A
few milliliters of autologous blood are obtained aseptically by
venipuncture without anticoagulant. This is injected into the
epidural space at the site of the dural puncture. Relief is
immediate and complications uncommon.

Convulsions
• In rare instances, postdural puncture
cephalgia is associated with blindness and
convulsions.

Bladder Dysfunction
• With spinal analgesia, bladder sensation is
likely to be obtunded and bladder emptying
impaired for the first few hours after delivery.
• As a consequence, bladder distention is a
frequent postpartum complication, especially
if appreciable volumes of intravenous fluid are
given.

Oxytocics and Hypertension
• Paradoxically, hypertension from
ergonovine or methylergonovine
injected following delivery is more
common in women who have received a
spinal or epidural block.

Arachnoiditis and Meningitis
• Local anesthetics are no longer preserved in
alcohol, formalin, or other toxic solutes, and
disposable equipment is used by most. These
practices, coupled with aseptic technique,
have made meningitis and arachnoiditis
rarities
• Still, these complications are occasionally
occur.

Contraindications to Spinal Analgesia
• Obstetrical complications that are associated
with maternal hypovolemia and hypotension—
such as severe hemorrhage—are
contraindications to the use of spinal block.

Absolute Contraindications toAbsolute Contraindications to
Regional AnalgesiaRegional Analgesia
Refractory maternal hypotension
 Maternal coagulopathy
 Treatment with once-daily dose of low-
molecular-weight heparin within 12 hr
Untreated bacteremia
Skin infection over site of needle placement
Increased intracranial pressure caused by mass
lesion

In addition to refractory maternal hypotension,
disorders of coagulation and defective hemostasis
also preclude the use of spinal analgesia.
Similarly, subarachnoid puncture is
contraindicated when the skin or underlying tissue
at the site of needle entry is infected.
Neurological disorders are considered by many to
be a contraindication, if for no other reason than
that exacerbation of the neurological disease
might be attributed without cause to the
anesthetic agent.
Other maternal conditions, such as significant
aortic stenosis or pulmonary hypertension, are
also relative contraindications to the use of spinal
analgesia

Preeclampsia
As with significant hemorrhage, severe
preeclampsia is another complication in which
markedly decreased blood pressure can be
predicted when subarachnoid analgesia is used.
It has inherent risks of difficult intubation due to
airway edema and cerebrovascular accidents
due to increased blood pressure.
it to be quite controversial, they concluded that
with severe preeclampsia, epidural analgesia is
preferable to a subarachnoid block and
especially preferable to a general anesthetic.9/3/2013 94BITEW(IESO)

Epidural Analgesia
Provides excellent pain relief reducing maternal
catecholamines
Ability to extend the duration of block to match the
duration of labor
Blunts hemodynamic effects of uterine contractions:
beneficial for patients with preeclampsia.

Indications for LEA
PAIN EXPERIENCED BY A WOMAN IN LABORPAIN EXPERIENCED BY A WOMAN IN LABOR
When medically beneficial to reduce the stress of
labor
ACOG and ASA stated
““ in the absence of a medical contraindication,in the absence of a medical contraindication,
maternal request is a sufficient medical indicationmaternal request is a sufficient medical indication
for pain relief…”for pain relief…”

Obstetric conditions where epidural
analgesia is more likely to be
indicated:
•  Pre eclampsia/hypertensive disease
•  Prolonged labour
•  Two or more babies inutero
•  Anticipated instrumental delivery
•  Diabetes Mellitus
•  Breech presentation for vaginal delivery
•  Significant respiratory disease
9/3/2013 BITEW(IESO) 97

Contraindications for LEA
ABSOLUTEABSOLUTE
Patients refusal
Inability to cooperate
Increased intracranial
pressure
Infection
Severe coagulopathy
Severe hypovolemia
Inadequate training
RELATIVERELATIVE
Systemic maternal
infection
Preexisting
neurological deficiency
Mild or isolated
coagulation
abnormalities
Relative (and
correctable)
hypovolemia
9/3/2013 100BITEW(IESO)

We are All Ready…Now What? - Last
Check
• Obstetrician is consulted and confirmed
LEA
• Preanesthetic evaluation is
performed/verified
• Pt’s (and only patient’s) desire to have
LEA is reconfirmed
• Pt’s understanding of risks of LEA is
reconfirmed
9/3/2013 101BITEW(IESO)

Check
• Fetal well-being is assessed and reassured
9/3/2013 102BITEW(IESO)

Check
• Supporting personal is available and
present
9/3/2013 103BITEW(IESO)

Check
• Resuscitation equipment and drugs are
immediately available in the area where
LEA placed
9/3/2013 104BITEW(IESO)

Epidural Analgesia
• Relief from the pain of labor and childbirth, including
cesarean delivery, can be accomplished by injection of a
local anesthetic agent into the epidural or peridural space.
• This potential space contains areolar tissue, fat,
lymphatics, and the internal venous plexus.
• These latter vessels become engorged during pregnancy
such that the volume of the epidural space is appreciably
reduced.
• Entry for obstetrical analgesia is usually through a lumbar
intervertebral space, and less often through the sacral
hiatus and sacral canal for caudal epidural analgesia.
• Although one injection may be used, these usually are
repeated through an indwelling catheter, or they are
given by continuous infusion using a volumetric pump.
9/3/2013 105BITEW(IESO)

Standard Technique of LEA
1. Pre epidural check list is completed
2. Aspiration prophylaxis
3. Intravenous hydration (what? When? How?)
4. Monitoring
– BP every 1 to 2 min for 20 min after injection of drugs
– Continuous maternal HR during induction ( e.g., pulse
oximetry)
– Continuous FHR monitoring
– Continual verbal communication
9/3/2013 106BITEW(IESO)

Standard Technique of LEA
4. Maternal position ( sitting or lateral?)
9/3/2013 107BITEW(IESO)

Comparison of Sitting and Lateral Positions for
Performing Spinal or Epidural Procedures
Sitting Lying (left lateral)
Advantages
• Midline easier to identify in obese
women
• Obese patients may find this position
more comfortable
• Can be left unattended without risk of
fainting.
• No orthostatic hypotension
• Uteroplacental blood flow not reduced
(particularly important in the stressed
fetus)
Disadvantages
• Uteroplacental blood flow decreased
• Orthostatic hypotension may occur
• Increased risk of orthostatic
hypotension if Entonox and pethidine
have been administered
• Assistant (or partner) needed to support
patient
• May he more difficult to find the
midline in obese patient
9/3/2013 108BITEW(IESO)

Influence of epidural analgesia on maternal plasma concentrations of
catecholamines during labor. Modified from Shnider SM et al. Maternal
catecholamines decrease during labor after lumbar epidural analgesia.
Am J Obstet Gynecol 1983;147:13-5.

Continuous Lumbar Epidural Block
Complete analgesia for the pain of labor and
vaginal delivery necessitates a block from the
T10 to the S5 dermatomes.
 For cesarean delivery, a block extending from
the T4 to the S1 dermatomes is desired.
The spread of the anesthetic depends upon the
location of the catheter tip; the dose,
concentration, and volume of anesthetic agent
used; and whether the mother is head-down,
horizontal, or head-up.
9/3/2013 113BITEW(IESO)

Individual variations in the epidural space
anatomy also will affect the block, and in some
cases, synechiae may preclude a completely
satisfactory block.
It also should be recognized that the catheter tip
might move from its original location during the
course of labor.
• Appropriate resuscitation equipment and drugs
must be available during administration of
epidural analgesia.
9/3/2013 114BITEW(IESO)

Technique for Labor Epidural
Analgesia
1. Informed consent is obtained, and the obstetrician consulted.
2. Monitoring includes the following: Blood pressure every 1–2
min for 15 min after giving a bolus of local anesthetic.
Continuous maternal heart rate monitoring during analgesia
induction.
Continuous fetal heart rate monitoring.
Continual verbal communication.
3. Hydration with 500 to 1000 mL of lactated Ringer solution.
4. The woman assumes a lateral decubitus or sitting position.
9/3/2013 115BITEW(IESO)

5. The epidural space is identified with a loss-of-resistance technique.
6. The epidural catheter is threaded 3–5 cm into the epidural space.
7. A test dose of 3 mL of 1.5%lidocaine with 1:200,000 epinephrine or 3 mL of
0.25%bupivacaine with 1:200,000 epinephrine is injected after careful
aspiration and after a uterine contraction—this minimizes the chance of
confusing tachycardia that results from labor pain with tachycardia from
intravenous injection of the test dose.
8. If the test dose is negative, one or two 5-mL doses of 0.25%bupivacaine are
injected to achieve a cephalad sensory T10 level.
9. After 15–20 min, the block is assessed using loss of sensation to cold or
pinprick. If no block is evident, the catheter is replaced. If the block is
asymmetrical, the epidural catheter is withdrawn 0.5–1.0 cm and an
additional 3–5 mL of 0.25%bupivacaine is injected. If the block remains
inadequate, the catheter is replaced. 10. The woman is positioned in the
lateral or semilateral position to avoid aortocaval compression.
11. Subsequently, maternal blood pressure is recorded every 5–15 min. The
fetal heart rate is monitored continuously.
12. The level of analgesia and intensity of motor block are assessed at least
hourly
9/3/2013 116BITEW(IESO)

Complications of epidural analgesia
• Total Spinal Blockade
• Ineffective Analgesia
• Hypotension
• Central Nervous Stimulation
• Maternal Pyrexia
• Back Pain
9/3/2013 117BITEW(IESO)

Effect on Labor
• report that epidural analgesia prolongs labor
and increases the need for oxytocin
stimulation.
• increase the need for instrumental delivery
due to prolonged second-stage labor
9/3/2013 118BITEW(IESO)

Fetal Heart Rate
• Compared with intravenous meperidine, no
deleterious effects were identified.
• In fact, reduced beat-to-beat variability and
fewer accelerations were more common in
fetuses whose mothers received
• Based on their systematic review of eight studies,
Reynolds and co-workers (2002) found that
epidural analgesia was associated with improved
neonatal acid–base status compared with that
with meperidine.
9/3/2013 119BITEW(IESO)

Cesarean Delivery
• These results are consistent with the
belief of many investigators that the
epidural administration of dilute solutions
of local anesthetic is less likely to increase
cesarean delivery rates than concentrated
solutions.
9/3/2013 120BITEW(IESO)

Contraindications
• actual or anticipated serious maternal hemorrhage,actual or anticipated serious maternal hemorrhage,
infection at or near the sites for puncture, and suspicioninfection at or near the sites for puncture, and suspicion
of neurological diseaseof neurological disease
• Rolbin and colleagues (1988) advise against epidural
analgesia if the platelet count is below 100,000/L.
Conversely, Rasmus and associates (1989) found no cases
in which bleeding was caused by regional analgesia in
thrombocytopenic women.
• They recommended consideration of this method if the
patient might be difficult to intubate or ventilate. The
American College of Obstetricians and Gynecologists
(2002b) has concluded that women with platelet counts of
50,000 to 100,000/L may be considered potential
candidates for regional analgesia.
9/3/2013 121BITEW(IESO)

Anticoagulation
• Women receiving anticoagulation therapy who are
given regional analgesia are at increased risk for
spinal cord hematoma and compression.
• The American College of Obstetricians and
Gynecologists (2002b) has recommended the
following for women taking anticoagulants:
• Women receiving unfractionated heparin therapy
should be able to receive regional analgesia if they
have a normal activated partial thromboplastin time
(aPTT).
9/3/2013 122BITEW(IESO)

Cont…
• Women receiving prophylactic doses of unfractionated
heparin or low-dose aspirin are not at increased risk
and can be offered regional analgesia.
• For women receiving once-daily low-dose low-
molecular-weight heparin, regional analgesia should
not be placed until 12 hours after the last injection.
• Low-molecular-weight heparin should be withheld for
at least 2 hours after the removal of an epidural
catheter.
• The safety of regional analgesia in women receiving
twice-daily low-molecular-weight heparin has not been
studied sufficiently.
9/3/2013 123BITEW(IESO)

Severe Preeclampsia–Eclampsia
• As previously discussed, ideal labor analgesia for
women with severe preeclampsia is controversial.
• Obstetrical concerns include hypotension induced by
sympathetic blockade, dangers from pressor agents
given to correct hypotension, and potential for
pulmonary edema following infusion of large volumes
of crystalloid.
• Conversely, general anesthesia with tracheal
intubation may result in severe, sudden hypertension
further complicated by pulmonary or cerebral edema
or intracranial hemorrhage.9/3/2013 124BITEW(IESO)

• Over the past two to three decades, most obstetrical
anesthesiologists have come to favor epidural blockade for
labor and delivery in women with severe preeclampsia.
• There seems to be no argument that epidural analgesia for
women with severe preeclampsia–eclampsia can be safely
used when specially trained anesthesiologists and
obstetricians are responsible for the woman and her fetus
(ACOG)
• Epidural analgesia provided superior pain relief without a
significant increase in maternal or neonatal complications.
9/3/2013 125BITEW(IESO)

Intravenous Fluid Preload
• Women with severe preeclampsia have
remarkably diminished intravascular volume
compared with normal pregnancy.
• And also aggressive volume replacement
increases the risk for pulmonary edema,
especially in the first 72 hours postpartum
• Importantly, this risk can be reduced or
obviated with judicious prehydration—usually
with 500 to 1000 mL of crystalloid solution.
9/3/2013 126BITEW(IESO)

• Moreover, vasodilation produced by epidural blockade
is less abrupt if the analgesia level is achieved slowly
with dilute solutions of local anesthetic agents.
• This allows maintenance of blood pressure while
simultaneously avoiding infusion of large volumes of
crystalloid.
• With vigorous intravenous crystalloid therapy, there is
also concern about development of cerebral edema.
• the majority of cases of pharyngolaryngeal edema
were related to aggressive volume therapy.
9/3/2013 127BITEW(IESO)

Epidural Opiate Analgesia
• Their mechanism of action derives from interaction with
specific receptors in the dorsal horn and dorsal roots.
• Apparently both cerebral and spinal opioid receptors are
stimulated by these narcotics.
• Opiates alone usually will not provide adequate analgesia,
and they most often are given with a local anesthetic agent
such as bupivacaine.
• The major advantages of using such a combination are the
rapid onset of pain relief, a decrease in shivering, and less
dense motor blockade.
9/3/2013 128BITEW(IESO)

Continuous Infusion of Dilute Local
Anesthetic Plus Opioid
• Better pain relief while producing less motor
block.
• Maternal and neonatal drug concentrations
safe.
RegimenRegimen
0.0625% - 0.08% bupivacaine with 2-30.0625% - 0.08% bupivacaine with 2-3
mcg /ml fentanyl, with or withoutmcg /ml fentanyl, with or without
epinephrine, infusing at 10-12 ml/hourepinephrine, infusing at 10-12 ml/hour
9/3/2013 129BITEW(IESO)

Searching For Balanced LaborSearching For Balanced Labor
AnalgesiaAnalgesia
Ambulatory Labor AnalgesiaAmbulatory Labor Analgesia
(CSE)(CSE)
9/3/2013 130BITEW(IESO)

Combined Spinal–epidural Techniques
• may provide rapid and effective analgesia for labor as well
as for cesarean delivery.
• an introducer needle is first placed in the epidural space. A
small-gauge spinal needle is then introduced through the
epidural needle into the subarachnoid space—this is called
the needle-through-needle technique.
• A single bolus of an opioid, sometimes in combination with a
local anesthetic, is injected into the subarachnoid space, the
spinal needle is withdrawn, and an epidural catheter is then
placed. The use of a subarachnoid opioid bolus results in the
rapid onset of profound pain relief with virtually no motor
blockade.
• The epidural catheter permits repeated dosing of analgesia.
9/3/2013 131BITEW(IESO)

Combined spinal epidural (CSE)
Initial reports: two interspace technique-epidural
followed by spinal
Later evolution of CSE in the direction of needle
through needle technique
Postdural puncture headache: 1% or less incidence
for CSE with small bore atraumatic needles.
9/3/2013 132BITEW(IESO)

• combined method produced excellent
immediate pain relief.
9/3/2013 133BITEW(IESO)

Advantages of CSE for Labor Analgesia
Rapid onset of intense analgesia (the patient
loves you immediately!)
Ideal in late or rapidly progressing labor
Very low failure rate
Less need for supplemental boluses
Minimal motor block (“walking epidural”)
9/3/2013 134BITEW(IESO)

Combined Spinal epidural
9/3/2013 136BITEW(IESO)

Espocan CSE Needle (B. Braun)Espocan CSE Needle (B. Braun)
9/3/2013 137BITEW(IESO)

Espocan CSE Needle (B. Braun)Espocan CSE Needle (B. Braun)
9/3/2013 138BITEW(IESO)

Eldor needle
Combined Spinal Epidural for Obstetric Anesthesia.flv
9/3/2013 139BITEW(IESO)

Maintenance of epidural analgesia can beMaintenance of epidural analgesia can be
achieved by:achieved by:
regular top-ups
an epidural infusion
patient-controlled epidural analgesia
(PCEA).
9/3/2013 140BITEW(IESO)

Intermittent bolus injections:
Bupivacaine: 0.125%-0.375%, 5-10 ml,
duration:1-2 hr
Ropivacaine: 0.125%-0.25%, 5-10 ml,
duration: 1-2 hr
Lidocaine: 0.75%-1.5%, 5-10 ml, duration: 1-
1.5 hr
9/3/2013 141BITEW(IESO)

Neuraxial Labor Techniques
9/3/2013 142BITEW(IESO)

Does epidural analgesia affect the
course of labor?
9/3/2013 BITEW(IESO) 143

Local Infiltration for Cesarean
Delivery
9/3/2013 144BITEW(IESO)

Local Infiltration for Cesarean Delivery
• Local block is occasionally useful to augment
an inadequate or "patchy" regional block that
was given in an emergency.
• On more rare occasions, local infiltration may
be used to perform an emergency cesarean to
save the life of the fetus in the absence of any
anesthesia support.
9/3/2013 145BITEW(IESO)

Local anesthetic block for cesarean delivery.Local anesthetic block for cesarean delivery.9/3/2013 147BITEW(IESO)

Local Infiltration for Cesarean Delivery
:Technique
• READING ASSIGNMENT
9/3/2013 148BITEW(IESO)

General Anesthesia
• The increased safety of regional analgesia has increased the
relative risk of general anesthesia.
• The case-fatality rate of general anesthesia for cesarean
delivery is estimated to be approximately 32 per million live
births compared with 1.9 per million for regional anesthesia
• Failed intubation occurs in approximately 1 of every 250
general anesthetics administered to pregnant women, a 10-
fold higher rate than the nonpregnant population.
• The American College of Obstetricians and GynecologistsThe American College of Obstetricians and Gynecologists
(2002b) has concluded that this relative increased morbidity(2002b) has concluded that this relative increased morbidity
and mortality suggest that regional analgesia is the preferredand mortality suggest that regional analgesia is the preferred
method of pain control and should be used unlessmethod of pain control and should be used unless
contraindicatedcontraindicated9/3/2013 149BITEW(IESO)

Patient Preparation
• Prior to anesthesia induction, several steps
should be taken to help minimize the risk of
complications for the mother and fetus. These
include the
use of antacids,
 lateral uterine displacement, and
preoxygenation.
9/3/2013 150BITEW(IESO)

Induction of Anesthesia
Thiopental
Ketamine
9/3/2013 151BITEW(IESO)

Thiopental
• This thiobarbiturate given intravenously is widely
used and offers the advantages of ease and
extreme rapidity of induction as well as prompt
recovery with minimal risk of vomiting.
• Thiopental and similar compounds are poor
analgesic agents, and the administration of
sufficient drug given alone to maintain anesthesia
may cause appreciable newborn depression.
• Thus, thiopental is not used as the sole anesthetic
agent, but rather is administered in a dose that
induces sleep.
9/3/2013 152BITEW(IESO)

Ketamine
• This agent also may be used to render the patient
unconscious.
• Given intravenously in low doses of 0.2 to 0.3 mg/kg,
ketamine may be used to produce analgesia and sedation
just prior to vaginal delivery.
• Doses of 1 mg/kg induce general anesthesia.
• Ketamine may prove useful in women with acute
hemorrhage because, unlike thiopental, it is not associated
with hypotension.
• Conversely, it usually causes a rise in blood pressure, and
thus it generally should be avoided in women who are
already hypertensive.
• Unpleasant delirium and hallucinations are commonly
induced by this agent.
9/3/2013 153BITEW(IESO)

Intubation
• Immediately after the patient is rendered unconscious,
a muscle relaxant is given to facilitate intubation.
• Succinylcholine, a rapid-onset and short-acting agent,
commonly is used.
• Cricoid pressure—the Sellick maneuver—is used to
occlude the esophagus from induction until intubation
is completed by a trained assistant.
• Before the operation begins, proper placement of the
endotracheal tube must be confirmed.
• Such confirmation includes auscultation of bilateral
breath sounds and end-tidal carbon dioxide analysis.
9/3/2013 154BITEW(IESO)

Failed Intubation
Although uncommon, failed intubation is a major
cause of anesthesia-related maternal mortality.
A history of previous difficulties with intubation as
well as a careful assessment of anatomical
features of the neck, maxillofacial, pharyngeal,
and laryngeal structures may help predict a
difficult intubation.
Even in cases where the initial assessment of the
airway was uneventful, edema may develop
intrapartum and present considerable difficulties.
 Morbid obesity is also a major risk factor for
failed or difficult intubation.
9/3/2013 155BITEW(IESO)

Management of failed intubation
 start the operative procedure only after it has been
ascertained that tracheal intubation has been
successful and that adequate ventilation can be
accomplished.
 Even with an abnormal fetal heart rate pattern,
initiation of cesarean delivery will only serve to
complicate matters if there is difficult or failed
intubation.
 Frequently, the woman must be allowed to awaken
and a different technique used, such as an awake
intubation or regional analgesia.9/3/2013 156BITEW(IESO)

• Following failed intubation, the woman is ventilated by
mask and cricoid pressure is applied to reduce the chance
of aspiration.
• Surgery may proceed with mask ventilation or the woman
may be allowed to awaken.
• In those cases where the woman has been paralyzed, and
where ventilation cannot be reestablished by insertion of
an oral airway, laryngeal mask airway, or use of a fiberoptic
laryngoscope to intubate the trachea, a life-threatening
emergency exists.
• To restore ventilation, percutaneous or even open
cricothyrotomy is performed, and jet ventilation begun.
9/3/2013 157BITEW(IESO)

Gas Anesthetics
Once the endotracheal tube is secured, a
50:50 mixture of nitrous oxide and oxygen is
administered to provide analgesia.
 Usually, a volatile halogenated agent is added
to provide amnesia and additional analgesia.
9/3/2013 158BITEW(IESO)

Volatile Anesthetics
 The most commonly used volatile anesthetic in the United States is
isoflurane.
 Both isoflurane and halothane are potent, nonexplosive agents that
produce remarkable uterine relaxation when given in high, inhaled
concentrations.
 Their use in high concentrations is restricted to those uncommon
situations in which uterine relaxation is a requisite rather than a
hazard.
 They are used for internal podalic version of the second twin, breech
decomposition and replacement of the acutely inverted uterus.
 As soon as the maneuver has been completed, anesthetic
administration should be stopped and immediate efforts begun to
promote myometrial contraction to minimize hemorrhage.
 Because of cardiodepressant and hypotensive effects, these agents
may intensify the adverse effects of maternal hypovolemia.
 Halothane and isoflurane occasionally have been associated with
hepatitis and massive hepatic necrosis.9/3/2013 159BITEW(IESO)

Anesthesia Gas Exposure and
Pregnancy Outcome
• Without exception, all anesthetic agents that depress the maternal
central nervous system cross the placenta and depress the fetal
central nervous system. As a result, personnel responsible for the
care of the newborn immediately following delivery with a general
anesthetic should be prepared to provide respiratory support.
• Ideally, induction-to-delivery time should be minimized when general
anesthesia is used.
• In one study, Datta and colleagues (1981) concluded that fetal
exposure of more than 8 minutes was associated with increased
neonatal depression. Kavak and co-workers (2001) randomly assigned
84 women scheduled for elective cesarean delivery to either spinal
analgesia or general anesthesia.
• There were no significant differences in short-term measures of
neonatal outcome, including Apgar scores, umbilical artery blood gas
determinations, or length of stay.
9/3/2013 160BITEW(IESO)

Extubation
• The tracheal tube may be safely removed only
if the woman is conscious to a degree that
enables her to follow commands and is capable
of maintaining oxygen saturation with
spontaneous respiration.
• Typically, the stomach is emptied via a
nasogastric tube prior to extubation.
9/3/2013 161BITEW(IESO)

Aspiration
• Massive gastric acidic inhalation causing
pulmonary insufficiency from aspiration
pneumonitis.
• Such pneumonitis has in the past been the most
common cause of anesthetic deaths in obstetrics
and therefore deserves special attention.
• Procedures mentioned previously that are
important to effective prophylaxis include use of
antacids, skillful intubation accompanied by
cricoid pressure, emptying of the stomach with a
nasogastric tube, and use of regional analgesia
when possible.
9/3/2013 162BITEW(IESO)

Fasting
• Clear liquids such as water, clear tea, black
coffee, carbonated beverages, and fruit juices
without pulp may be allowed in uncomplicated
laboring women.
• Obvious solid foods should be avoided.
• "a fasting period of 8 hours or more is preferable
for uncomplicated parturients undergoing
elective cesarean delivery."
• Despite these precautions, it should be assumed
that any woman in labor has both gastric
particulate matter as well as acidic contents.
9/3/2013 163BITEW(IESO)

Pathophysiology
• if the pH of aspirated fluid was below 2.5,
severe chemical pneumonitis developed.
• The right mainstem bronchus usually offers the
simplest pathway for aspirated material to
reach the lung parenchyma, and therefore the
right lower lobe is most often involved.
• In severe cases, there is bilateral widespread
involvement.
9/3/2013 164BITEW(IESO)

• The woman who aspirates may develop evidence of respiratory distress
immediately or as long as several hours after aspiration, depending in part
on the material aspirated and the severity of the process.
• Aspiration of a large amount of solid material causes obvious signs of
airway obstruction.
• Smaller particles without acidic liquid may lead to patchy atelectasis and
later to bronchopneumonia.
• When highly acidic liquid is inspired, decreased oxygen saturation along
with tachypnea, bronchospasm, rhonchi, rales, atelectasis, cyanosis,
tachycardia, and hypotension are likely to develop. At the sites of injury,
pulmonary capillary leakage results in protein-rich fluid containing
numerous erythrocytes exuding from capillaries into the lung interstitium
and alveoli to cause decreased pulmonary compliance, shunting of blood,
and severe hypoxemia. Radiographic changes may not appear immediately
and they may be quite variable, although the right lobe most often is
affected. Therefore, chest radiographs alone should not be used to exclude
aspiration.
9/3/2013 165BITEW(IESO)

Treatment
 Respiratory rate and oxygen saturation as measured by
pulse oximetry are the most sensitive and earliest
indicators of injury.
• As much of the inhaled fluid as possible should be
immediately wiped out of the mouth and removed
from the pharynx and trachea by suction.
• If large particulate matter is inspired, bronchoscopy
may be indicated to relieve airway obstruction.
• If clinical evidence of infection develops, however, then
vigorous treatment is given.
• When acute respiratory distress syndrome develops,
mechanical ventilation with positive end-expiratory
pressure may prove lifesaving.
9/3/2013 166BITEW(IESO)

What anesthetic options are available for
cesarean delivery?
What options are available for pain control
following cesarean delivery?
What anesthetic risks accompany
preeclampsia?
Is fetal outcome any different between
regional and general anesthesia?
9/3/2013 BITEW(IESO) 167

THANK
YOU!!
9/3/2013 168BITEW(IESO)

Anesthesia for Cesarean
Section
9/3/2013 174BITEW(IESO)

Anesthesia for Cesarean Section
The choice of anesthesia depend on:
• The indication for the CS
• The urgency of the procedure
• The medical condition of the mother and the
fetus
• The desire of the mother
9/3/2013 175BITEW(IESO)

• GA associated with higher risk of airway problems .
• Incidence of failed tracheal intubation in pregnant
women is 1 in 200 to 1 in 300 cases
Anesthesia2000;55:690-4
• Maternal death due to anesthesia is the sixth leading
cause of pregnancy related death in USA
Obstet Gynecol 1996;88:161-7
9/3/2013 176BITEW(IESO)

• The risk of maternal death from complications of GA
is 17 times as high as that associated with Regional
anesthesia
• In USA the shift from GA to RA for CS resulted in
decrease in anesthesia related maternal mortality
from 4.3 to 1.7 per 1 million live birth Anesthsiology
1997;86:277-84
9/3/2013 177BITEW(IESO)

Epidural anesthesia
• AdvantageAdvantage
– Titration (volume dependent, not gravity
dependent), decreased likelihood of
hypotension
– Incremental dose (for longer operation)
• DisadvantageDisadvantage
– Dural puncture :1/200-1/500 in experienced
hands, higher in training institution
– If unintentional dural puncture, PDPH
incidence is 50-85%
– Slower onset
9/3/2013 178BITEW(IESO)

Spinal anaesthesia
• Hyperbaric bupivacaine 0.5% is the drug
most commonly used for spinal
anaesthesia for Caesarean section.
• Pregnant patients require a smaller dose
than the nonpregnant population (why?)
• The dose used via a standard lumbar
approach is typically 2.0–2.75 ml.
no significant correlation between age, height, weight, body
mass index and length of vertebral column and the final
block height achieved
Anesthesiology1990; 72: 478–482.9/3/2013 179BITEW(IESO)

Combined spinal epidural(CSE)
Combines the rapid onset and efficacy of the spinal
technique with the ability to:
Extend anaesthesia if surgery is prolonged
Provide excellent postoperative epidural analgesia.
Combined Spinal Epidural for Obstetric Anesthesia.flv
9/3/2013 180BITEW(IESO)

Medication Spinal Epidural
Local anesthetic Bupivacaine 12 mg
(range 9–15)
Lidocaine 2%;
Fentanyl 15–35 ug 50–100 ug
Morphine 0.1 mg 3.75 mg
Optimal Neuraxial Medication
Combinations for Cesarean Delivery
9/3/2013 181BITEW(IESO)

Complications of Regional
Anesthesia
9/3/2013 182BITEW(IESO)

Complications of regional anesthesia
Post Dural Puncture Headache (PDPH)Post Dural Puncture Headache (PDPH)
severe, disabling fronto-occipital headache
with radiation to the neck and shoulders.
present 12 hours or more after the dural
puncture
worsens on sitting and standing
relieved by lying down and abdominal
compression.
9/3/2013 183BITEW(IESO)

PDPH syndromePDPH syndrome
1. Photophobia
2. Nausea
3. Vomiting
4. Neck stiffness
5. Tinnitus
6. Diplopia
7. Dizziness
9/3/2013 184BITEW(IESO)

Differential diagnosis of post-dural punctureDifferential diagnosis of post-dural puncture
headache in the obstetric patient:headache in the obstetric patient:
11. Non-specific headache
2. Caffeine-withdrawal headache
3. Migraine
4. Meningitis
5. Sinus headache
6. Pre-eclampsia
7. Drugs (amphetamine, cocaine)
8. Pneumocephalus-related headache
9. Intracranial pathology (hemorrhage, venous thrombosis)
9/3/2013 185BITEW(IESO)

Management of PDPHManagement of PDPH
Conservative:Conservative:
Bed rest
Encourage oral fluids and/or intravenous
hydration
Caffeine - either i.v. (e.g. 500mg caffeine in 1litre
of saline) or orally
Regular Analgesia
Reassurance
9/3/2013 186BITEW(IESO)

Management of PDPHManagement of PDPH
OthersOthers
1. Theophylline
3. Sumatriptan
4. Epidural saline
5. Epidural dextran
6. Subarachnoid catheter
7. Epidural blood patch
9/3/2013 187BITEW(IESO)

The new method of prevention of post-duraThe new method of prevention of post-dura
puncture headache (maintaining CSF volume):puncture headache (maintaining CSF volume):
1. Injecting the CSF in the glass syringe back into the
subarachnoid space through the epidural needle
2. Passing the epidural catheter through the dural hole
into the subarachnoid space
3. Injecting of 3-5 ml of preservative free saline into the
subarachnoid space through the intrathecal catheter
4. Administering bolus and then continuous intrathecal
labor analgesia through the intrathecal catheter
5. Leaving the subarachnoid catheter in-situ for a total
of 12-20 h
9/3/2013 188BITEW(IESO)

Cardiovascular complicationsCardiovascular complications
Hypotension (can lead to cord ischaemia)
Bradycardia
Effects on the course of labour and on the fetusEffects on the course of labour and on the fetus
9/3/2013 189BITEW(IESO)

Effect of epidural analgesia on the progress
and outcome of labour
The recently published guidelines on
intrapartum care by the UK national
institute of health and clinical excellence
indicate that epidural analgesia is:
 Not associated with a longer first stage of
labour or an increased chance of a
caesarean birth
Associated with a longer second stage of
labour and an increased chance of an
instrumental birth.
9/3/2013 190BITEW(IESO)

Effect of epidural analgesia on the progress
and outcome of labour
The most important factors determiningThe most important factors determining
labour outcome are:labour outcome are:
• Low concentrations of local anaesthetics
• Oxytocin
• Maternal pushing in the second stage of
labour should, if possible be delayed!
9/3/2013 191BITEW(IESO)

Neurological complicationsNeurological complications
Needle damage to spinal cord, cauda equina
or nerve roots.
Spinal haematoma
Spinal abscess
Meningitis and Arachnoiditis
Neurotoxicity
9/3/2013 192BITEW(IESO)

MiscellaneousMiscellaneous
Venous puncture e.g. of dural veins
Catheter breakage
Extensive block (including unplanned blocks)
Shivering
Backache - Long-term backache is not a
complication of neuraxial techniques although
there will always be some local bruising.
9/3/2013 193BITEW(IESO)

Drug side effectsDrug side effects
Nausea and vomiting (opiates)
Respiratory depression (opiates)
Anaphylaxis
Toxicity (including intravascular injection of
local anaesthetics)
9/3/2013 194BITEW(IESO)

Toxicity of local anaesthetics:
Causes:Causes:
An overdose of local anaesthetic is given,
Large dose of local anaesthetic is inadvertently
given intravenously.
The recommended protocol isThe recommended protocol is
• Take a 500 ml bag of intralipid 20% and
immediately give a 100 ml bolus over 1 minute
9/3/2013 195BITEW(IESO)

Toxicity of local anaesthetics
• Infuse at a rate of 400 ml over 20 minutes
• Give two further boluses of 100 ml at 5-minute
intervals if Circulation is not restored
• Continue infusion at a rate of 400 ml over 10 minutes
until stable circulation is restored.
Airway, ventilatory and cardiovascularAirway, ventilatory and cardiovascular
support should be maintained viasupport should be maintained via
standard protocols. It may be >1 hourstandard protocols. It may be >1 hour
before recoverybefore recovery
9/3/2013 196BITEW(IESO)

Is There Still Place For
General Anesthesia?
9/3/2013 197BITEW(IESO)

Conclusion
“The delivery of the infant into the arms of aThe delivery of the infant into the arms of a
conscious and pain-free mother is one of theconscious and pain-free mother is one of the
most exciting and rewarding moments inmost exciting and rewarding moments in
medicine.”medicine.”
Moir DD. Extradural analgesia for caesarean section. BrMoir DD. Extradural analgesia for caesarean section. Br
J Anaesth 1979; 51: 1093.J Anaesth 1979; 51: 1093.
9/3/2013 198BITEW(IESO)

Obstetrical Anesthesia

Empfohlen

Empfohlen

Weitere ähnliche Inhalte

Was ist angesagt?

Was ist angesagt? (20)

Ähnlich wie Obstetrical Anesthesia

Ähnlich wie Obstetrical Anesthesia (20)

Mehr von Bitew Mekonnen

Mehr von Bitew Mekonnen (8)

Kürzlich hochgeladen

Kürzlich hochgeladen (20)

Obstetrical Anesthesia

Hinweis der Redaktion