الفهرس 
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Abstract
Labor may be the most painful experience many
women ever encounter. The experience is different for each
woman, and the different methods chosen to relieve pain
depend upon the techniques available locally and the
personal choice of the individual.
The pain of labor is severe and many women seek
ways to reduce it. Non-regional techniques include
supportive measures, inhalation of nitrous oxide and
parenteral opioid administration. Neuraxial anesthesia
provides good quality pain relief in labor.
Epidural analgesia effectively relieves labor pain;
however controversy exists as to the effect of epidurals on
the progress of labor, mode of delivery and effects on the
fetus.
Epidural bupivacaine provides excellent sensory
block and has been used for labor analgesia for many years.
However, concerns about its cardiac toxicity and the
intensity of its motor block have led to the investigation of
other agents. The typical dose of bupivacaine is 0.0625%-
0.125% for initiation of epidural analgesia in labor, and
0.05%-0.125% for maintenance of epidural analgesia
(Continuous infusion/PCEA), with 50-100 mcg fentanyl.
Ropivacaine was developed to reduce the incidence
of cardiac toxicity in the event of accidental intravenous
injection. Early reports suggested it was associated with
reduced incidence of operative vaginal delivery and less
motor block when compared with bupivacaine. More recent studies have shown ropivacaine is less
potent than bupivacaine and there is no evidence to support
the view that ropivacaine is superior to bupivacaine for
obstetric or neonatal outcome. Its dose is 0.08%-0.2% for
both initiation and maintenance of epidural labor anesthesia
and 75-125 mg 0.5% for cesarean delivery.
Spinal anesthesia is associated with faster onset of a
dense block, technical ease, minimal maternal systemic
drug absorption, low failure rate and in experienced hands
is almost as fast as general anesthesia. Therefore, it is
suitable for both elective and emergency cases.
Hyperbaric bupivacaine with a lipophilic opioid is
widely used as the drug of choice in spinal anesthesia. Due
to smaller CSF volume and greater nerve fiber sensitivity,
pregnant patients require smaller doses of local anesthetics.
The dose of bupivacaine used for initiation of spinal
analgesia in neuraxial labor analgesia is 1.25-2.5 mg, and if
fentanyl is added, its dose will be 15-25 mcg. However the
dose of bupivacaine for spinal anesthesia in cesarean
section is 7.5-15 mg with 10-25 mcg fentanyl.
CSE provides the advantages of a spinal (speed of
onset) with the ability to prolong labor analgesia with an
epidural catheter. Combination of fentanyl 10-25 mcg or
sufentanil 2.5-10 mcg with bupivacaine 2.5mg can be used.
Pre-eclampsia is a heterogeneous multisystem
disorder of pregnancy. Careful control of the blood
pressure in a high dependency setting is paramount. The
main concerns to the obstetric anesthetist are those of the
potential problems with the airway and the effects of organ dysfunction particularly those of the cardio-respiratory,
cerebral and coagulation systems.
Early epidural analgesia is an ideal form of pain
relief during labor in a pre-eclamptic patient. It helps to
control the exaggerated hypertensive response to pain and
can also improve the placental blood flow in these
patients. A functioning epidural may safely be extended
for caesarean section.
Obesity affects more than a billion people and its
prevalence in pregnancy ranges from 6-28% and is
associated with an increased risk of hypertensive
complications, gestational diabetes mellitus, urinary tract
infection, prolonged labor, cesarean section, postpartum
hemorrhage, neonatal trauma and intensive care admission
and an overall increase in hospital stay.
Regional anesthesia techniques in obese patients are
preferable. But the need for longer spinal and epidural
needles, higher epidural catheter replacement and chances
of accidental dural puncture should be anticipated.
Pregnant patients with diabetes are at risk for
preeclampsia, polyhydramnios, fetal macrosomia, fetal
malformations, and cesarean delivery. Glycemic control
and treatment of hypotension with non-glucose containing
crystalloids and ephedrine or phenylephrine are helpful in
preserving fetal acid-base status. Labor epidural analgesia
for vaginal delivery effectively controls pain and stress
response which predisposes to hyperglycemia. In long
standing DM, presence of autonomic neuropathy and potential for exaggerated hypotension following
sympathectomy should be kept in mind.
Pregnant women with heart disease are markedly
affected by cardiovascular changes associated with
pregnancy, labor, and delivery. Patients with mitral
insufficiency, aortic insufficiency, chronic heart failure, or
congenital lesions with left to right shunting, spinal or
epidural techniques are more preferable to them as they
relieve pulmonary congestion, and increase cardiac output.
Patients with aortic stenosis, congenital lesions with
right to left or bidirectional shunting, or primary pulmonary
hypertension, are better managed with intraspinal opioids
alone, systemic medications and pudendal nerve blocks.