23. Obstetric analgesia and anesthesia.

Question 1

At what approximate spinal level do the dural space and the spinal cord, respectively, end

Answer 1

S2, L2

Question 2

motor nerve supply of the uterus supplied by ?

Answer 2

sympathetic and parasympathetic nerve fibre arise from the lower thoracic and upper lumbar segment of spinal cord

parasympathetic - s2-4

Question 3

what are the sensory pathway ?

Answer 3

uterine body - afferent nerve information goes to the t10-12
and 1st lumbar of spinal cord

cervix - the pelvic splanchnic nerves also provides parasympathetic - s2-s4

vagina - pundal nerve (s2-s4)

perineum - from the pudendal nerve (S2 to S4)

labia major -
ilioinguinal - 1st lumbar root

1 and second lumbar root
and genital branch of the genitofemoral nerve

Question 4

what innervates the motor activity of pelvic floor muscles ?

Answer 4

pudendal nerve

Question 5

. Total spinal block does not inhibit uterine activity, provided what?

Answer 5

blood pressure does not work

oxytocin for the posterior pituitary gland

Question 6

what is the cause of pain in labour?

Answer 6

sensory pathways from T10 - L1

other cause of pain -

myometrial hypoxia ,

stretching of peritoneum over fundus ,

stretching of cervix during dilation

Question 7

what are the methods of pain relief ?

Answer 7

psychoprophylaxis - lamaze method , emotional support

sedative and analgesics

regional analgesia
epidural 
paracervical block 
spinal nerve block 
pudendnal nere bock 
perieal infiltration 

general anesthesia

Question 8

the amount of sedative and angesia depends on ?

Answer 8

multiparty - needs less analgesia

Minimal doses of drugs are indicated while the fetus is thought to be premature to avoid neonatal asphyxia.

Question 9

analgesia modes are divided according to what

Answer 9

The first phase is controlled by sedatives and analgesics.
the first phase is up to 8cm dilatation of the cervix in primigravidae and 6 cm in case of multipara.

The second phase corresponds to dilatation of the cervix beyond the above limits up to delivery.
second phase is controlled by inhalation agents.

Question 10

what are the opioid analgesics given during first phase ?

Answer 10

pethidine IM - strong sedative , less analgesia
side effects - vomitting, delayed gastric emptying = ranitidine, metoclopromaide

Meperidine IM or PCA pump (gives you a drug for pain when you press a button)
side effects -Repeated use infants may need naloxone at delivery. Maximum placental transfer and neonatal depression occur 2–3 hours of use.

fentanyl -less neonatal effects and less maternal nausea and vomiting. It needs frequent dosing. It can be used as PCA.

Question 11

what are the inhalation analgesics?

Answer 11

50% nitrous oxide and 50% oxygen mixture

Hyperventilation, dizziness, hypocapnia (resp alkalosis) are the side effects.

taken before contraction occurs and stopped when contractions go

Question 12

describe regional anesthesia in epidural anesthesia ?

Answer 12

lumbar epidural block:

below l2 (after that it is the caudal equina)

detect the l4 and l5 space give

local anesthesia

with an epidural needle tuohy needle enter the epidural space

a plastic catheter is passed through the epidural tuohy needle -owing to the upward tilt at the end of the needle the catheter is directed upwards 4-5cm

for continuous epidural analgesia

the tuohy needle is the removed and analgesics administered

blood pressure constantly checked and after 3-5 mins we see if they are able to move the lower limb if so indicated at the right space - if not then the catheter is between the dura and arachnid space = intrathecal

if positive bolus dose inserted

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For complete analgesia
a block from T10 to the S5 dermatomes is needed.

For cesarean
delivery a block from T4 to S1 is needed.

Question 13

what agents are used for epidural anesthesia?

Answer 13

lidocaine for local anaesthetic

bupivacaine or in combination with fentanyl and morphine

Question 14

when is epidural analgesia given ?

Answer 14

usually only have an epidural during the first stage of labour where contractions well established — but it can be given at any stage of labour

Question 15

what is the clinical management when given regional analgesia / epidural anesthesia is given ?

Answer 15

crystalloid infusion prior commencing the blockade.

The patient’s blood pressure, pulse and the fetal heart rate should be recorded at 15 minutes interval following the induction of analgesia

hypotension, if occurs, should be treated immediately.

The woman is kept in semilateral position to avoid aortocaval compression.

Question 16

what is the complication of epidural anesthesia?

Answer 16

hypotension - that’s why well hydrated before hand

no change in duration of first stage of labor. But second stage of labor appears to be prolonged by 15–30 minutes. This might lead to frequent need of instrumental delivery like forceps or ventouse

Postspinal headache due to leakage of cerebrospinal fluid through the needle hole

Question 17

describe paracervical block in regional anesthesia

Answer 17

for pain relief during the first stage of labor , from 5cm dilation but most useful towards the end of first stage of labour

place a speculum
a long needle is passed into the vagina

inject Iidocaine submucousaly at 12 o clock int he anterioir lip of the cervix
then using a tenaculum at 12o clock grasp the cervix and inject lidocaine at 2 o clock , 4 o clock , 8 o clock and 10 o clock at the cervicovaginal ruction

wait 2 minutes and then pinch the cervix with forceps. If the woman feels the pinch

can only block the pain of uterine contractions

need pudendal nerve block for perineum pain

Question 18

what is the contraindication of paracervical block ?

Answer 18

Bupivacaine is avoided due to its cardiotoxicity

placental insufficiency

Question 19

complication of paracervical block ?

Answer 19

fetal bradycardia - due to decrease placental perfusion

Question 20

when is the regional anesthesia pudendal nerve block used ?

Answer 20

mostly used for forceps and vaginal breech delivery.

or before epstiotomy

Question 21

method of pudendal nerve block ?

Answer 21

A 20 mL syringe, one gauge spinal needle and lignocaine hydrochloride are required.

The index and middle fingers of one hand are introduced into the vagina, the middle finger lays on the ishial spine

The needle is passed along the groove of these two fingers

Place the end of the needle guard 1 cm anteriorly and medial to the ischial spine

guard can then be unhooked and the needle advanced a centimetre into the tissue

pierce the vaginal wall and pierce the sacrospinous ligament

aspiration is done to exclude blood, solution is injected. The similar procedure is adopted to block the nerve of the other side by changing the hands

Question 22

when is local spinal anesthesia used ?

Answer 22

Most women cannot push effectively after a spinal block
so only
often used in emergency c section and assisted delivery such as c section venous and forcep use when no time for epidural
or alleviate the pain during the third stage of labor

Question 23

spinal anesthesia clinical procedure

Answer 23

Spinal anesthesia is obtained by needle going into the subarachnoid space (past the dura mater and arachnoid matter, between the arachnoid matter and pia) containing cerebrospinal fluid which bathes the spinal cord
do it around the the third or fourth lumbar.
Because the spinal cord typically end at the L1 or L2 level of the spine, the needle should be inserted below this between two lumbar vertebrae ( L3 - L5 ) space in order to avoid injury to the spinal cord.

bupivacaine

blood pressure and respiratory rate should be recorded

Question 24

side effects of spinal anesthesia ?

Answer 24

Hypotension

Postspinal headache—due to low or high CSF pressure and leakage of CSF

Meningitis due to faulty asepsis

Transient or permanent paralysis

Toxic reaction of local anesthetic drugs

Paralysis and nerve injury

Question 25

when is perineal infiltration anesthesia used ?

Answer 25

used prior to episiotomy

ventouse and forceps use

Question 26

describe perineal infiltration ?

Answer 26

for epstiotomy

topical anesthesia sprayed

long fine needle syringe with lignocaine hydrochloride is inserted subcutaneously

Two fingers enter the vagina and they are abducted and stretched away from the fetal head to protect it

the are stretched in a way to make to the midline of the fourchetter taut

insert the needle into the middle (downwards) of the fourchette.

aspiration to exclude blood is mandatory.

Release one third of the lidocaine as the syringe is partially withdrawn from the fourchette;

Before the needle is completely removed from the fourchette tilt it so it is at the position where the incision will be made and again inject a third of the lidocaine.

Finally, tilt the syringe to the other side of the proposed incision and give the final dose of lidocaine.

aspirating each time for injecting

wait 3 minutes after procedure

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For outlet forceps or ventouse—Perineal and labial infiltration

topical anestesia sprayed

a long fine needle syringe and about lignocaine hydrochloride are required.

same as epstiotomy and

The needle is then directed anteriorly along each side of the vulva as far as the anterior-third to block the genital branch of the genitofemoral and ilioinguinal nerve. in a fanwise manner

Question 27

what are the preoperative conditions needed for general anesthesia in c section ?

Answer 27

if elective - 6hrs fasting
in high risk preferably not allowed to eat
h2 ranitidine blocker given night before if elective
antacid orally before to neutralise the existing gastric acid

if emergency - reyels tube aspiration of gastric content

metoclopromide IV after minimum of 3 mins preoxygenation to decrease gastric volume and tone of LES

then induction and intubation

left lateral tilt in theatre table with a wedge on back avoid autocaval compression

uterine incision to delivery - U-D =more than 3 mins = low apgar score and neonatal acidosis

Question 28

describe the process of general anethseia in c section ?

Answer 28

Preoxygenation with 100% oxygen is administered by tight mask fit for more than 3 minutes.

Induction of anesthesia by thiopental sodium IV , propofol ,ketamine

Muscle relaxants: Succinylcholine is commonly used immediately after the induction drug to facilitate intubation.

intubation

Anesthesia is maintained with 50% nitrous oxide, 50% oxygen and a trace (0.5%) of halothane.
propofone IV

Relaxation is maintained with nondepolarizing muscle relaxant (vecuronium bromide 4 mg or atracurium 25 mg).

Question 29

what is the complication of general anesthesia ?

Answer 29

gastric content aspiration

Delayed gastric emptying due to high level of serum progesterone, decreased motilin and maternal apprehension during labor is the predisposing factor.

Question 30

what are the contraindications for epidural anaesthesia?

Answer 30

maternal coagulopathy or anticoagulant therapy

supine hypotension

hypovolema

Question 31

regional anesthesia such as epidural than general anesthesia is preferred for c section why is that ?

Answer 31

maintain respiration

Question 32

difference between spinal anesthesia and epidural?

Answer 32

compared to epidural
It has less procedure time and quicker onset

high success rate

last 3-4hrs hours because cannot be ‘topped up’ because there is no catheter put in

affects the spinal cord directly unlike in epidural the
main effect is on the nerve roots leaving the dura matter

An epidural may be given at a cervical, thoracic, or lumbar site,

while a spinal must be injected ONLY below L2 to avoid piercing the spinal cord