1
Obstetrics
Lec. 4 د. بان عامر موسى
الرابعة
المرحلة
Methods of labor analgesia
pain : defined as unpleasant sensation, subjective sensory and
emotional experience associated with real or potential tissue
damage , although pain may be considered the physiological
consequence of normal labor, it may be the harbinger of
pathological process such as obstructed labor, fetal malposition ,
uterine hyper stimulation and uterine rupture .
Severe pain stimulate sympathetic autonomic response which
is exacerbated by dehydration and exhaustion, it is characterized
by hyperventilation, tachycardia, hypertension, increase 02 and
glucose consumption ,vasoconstriction with decrease blood flow
across the placenta that lead to decrease fetal oxygenation
Non regional analgesia for labor
A -Non pharmacological method of pain relief include: -
Antenatal education, acupuncture , water immersion,
massage and other relaxation techniques .
B -Pharmalogical methods includes:
1) Entonox (50% N20 in 02 )quick onset, short duration of
effect by inhalation
2
2) Systemic opioid : Diamorphin , Pathedin , Remifantanil
Complications: nausea, vomiting, drowsiness, sedation, delayed
gastric empty, shortness of birth, Respiratory depression of the
neonate, interfere with breast feeding .
Regional analgesia:
Epidural analgesia "extradural": is the reliable mean of
providing effective analgesia in labour possible technic include
epidural analgesia, spinal analgesia "interthecal or subarachnoid
or combined.
Uterine contraction and cervical dilatation result in visceral
pain, these pain impulses are transmitted by afferent slow
conducting sympathetic n. and enter spinal cord to a T10 to L1
level, As labor progress, A descent of fetal head and subsequent
pressure on the pelvic floor, vagina and Perineum generate
somatic pain which is transmitted by pudendal n. (S
2-4) these
rapidly conducting somatic pain fibers are relatively difficult to
block .
In obstetric patients , regional analgesia refers to, partial or
complete loss of pain sensation below the T8-T10. In addition a
varying degree of motor block may be present define on the
agent use.
Advantage of regional analgesia include
1) superior pain relief in1st and 2nd stage of labor.
2) Facilitate Patient cooperation during labour and delivery.
3) Provide anasethesia for episiotomy and instrumental
3
delivery.
4) Allow extension of anesthesia for C\S.
5) Avoids opioid-induced maternal and neonatal respiratory
depression from intravenous opioids
6) Besides providing analgesia in labor, regional analgesia
may facilitate a traumatic vaginal delivery of twins,
preterm neonates, and neonates with breech presentation.
-It also helps control blood pressure in women with
preeclampsia by alleviating labor pain, and it blunts the
hemodynamic effects of uterine contractions and the
associated pain response in patients with other medical
complications.
Contraindications
Regional anesthesia is contraindicated in the
-presence of actual or anticipated serious maternal
hemorrhage and refractory maternal hypotension,
-coagulopathy and anticoagulant therapy
-untreated bacteremia,
-raised intracranial pressure,
-skin or soft tissue infection at the site of the epidural or
spinal placement
-Regional analgesia is also contraindicated in cases of patient
refusal or inadequate practitioner training and experience
-As exacerbation of neurological diseases might be attributed
4
without cause to the anesthetic agent, many clinicians avoid
regional anesthesia in its presence
-Other maternal conditions such as aortic stenosis, pulmonary
hypertension, or right-to-left shunts are also relative
contraindications to the use of regional analgesia. Only
opioids.
For extremely obese patients longer needles are available
(12.7 cm / 5 inches).
Spinal anesthesia is the technique of choice for Caesarean
section as it avoids a general anesthetic and the risk of failed
intubation (which is approximately 1 in 250 in pregnant
women). It also means the mother is conscious and the
partner is able to be present at the- birth of the child. The
post-operative' analgesia from intrathecal opioids in addition
to non-steroidal anti-inflammatory drugs is also good.
If surgery allows, spinal anaesthesia is very useful in
patients with severe respiratory disease e.g. COPD as it
avoids intubation and ventilation. It may also be useful in
patients where anatomical abnormalities may make tracheal
intubation very difficult.
Contraindications
Non-availability of patient's consent
Local infection or sepsis at the site of lumbar puncture
thrombocytopenia,
or
systemic
Bleeding
disorders
anticoagulation (secondary to an increased risk of a spinal
5
epidural hematoma).
Space occupying lesions of the brain
Anatomical disorders of the spine
Hypovolaemia
e.g.
following
massive
haemorrhage,
including in obstetric patients could be used for labor
analgesia in these situations, as they do not decrease systemic
vascular resistance.
For patients with mitral stenosis. regional analgesia
(epidural) is the preferred method
In women with severe preeclampsia, analgesia is
controversial due to Obstetrical concerns that regional
analgesia include hypotension induced by sympathetic
blockade, danger from presser 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 cerebral or pulmonary edema or intracranial hemorrhage
Over the past 2-3 decades, most obstetric anesthesiologists
have come to favor epidural blockade for labor analgesia in
women with severe preeclampsia.
Currently, practitioners routinely perform regional
analgesia with platelet counts below 100,000, although few
will instrument the spinal/epidural space if the platelet count
6
is below 50,000. Several studies have reported no
complications in women with platelet counts between 50,000-
100,000
Special precautions are needed for patients taking
anticoagulants to avoid epidural or spinal hematoma
Anesthesia
Spinal anesthesia (or spinal anesthesia), also called spinal
block, subarachnoid block (SAB), intradural block and
intrathecal block, is a form of regional anesthesia involving
injection of a local anaesthetic into the subarachnoid space,
generally through a fine needle, usually 9 cm long (3.5
inches).
Risks/Complications
Can be broadly classified as immediate (on the
operating table) or late (in the ward or in the P.A.C.U.
post-anaesthesia care unit):
Hypotension (Spinal shock) - Due to sympathetic
nervous system blockade. Common but usually easily
treated with intravenous fluid and sympathomimetic
drugs such as Ephedrine, Phenylephrine.
(PDPH) or post spinal head ache - Post dural puncture
head ache Associated with the size and type of spinal
needle used
injury - very rare, due to the insertion site being Cauda
7
equina too high
- very rare, usually related to the underlying Cardiac
arrest medical condition of the patient
Spinal canal haematoma, with or without subsequent
neurological sequelae due to compression of the spinal
nerves. Urgent CT/MRI to confirm the diagnosis
followed by urgent surgical decompression to avoid
permanent neurological damage.
Epidural abscess, again with potential permanent
neurological damage. May present as meningitis or an
abscess with back pain, fever, lower limb neurological
impairment and loss of bladder/bowel function. Urgent
CT/MRI confirms the diagnosis followed by antibiotics
and urgent surgical drainage .
Thanks