obstetric anesthesia and analgesia

8/4/2019 Obstetric Anesthesia and Analgesia

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Obstetric Anesthesia

and Analgesia

By: Edderlyn D. LamarcaSaint John Colleges


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Analgesia

reduces or decreases awareness ofpain

Anesthesia

causes partial or complete loss ofsensation


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Pain During Labor and Delivery

Pain during labor is caused primarily by

uterine muscle contractions and somewhat

by pressure on the cervix. This painmanifests itself as cramping in the

abdomen, groin, and back, as well as a tired,

achy feeling all over. Some womenexperience pain in their sides or thighs as

well.


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I. Analgesics (Narcotic)


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Narcotics may decrease the progress of

labor by reducing the force or rate ofcontractions ( this is dose dependant as well

as dependant on the timing of the dosesBiggest effect is in the latent phase

In the active phase of labor narcotics my

speed up the progress of labor by decreasinganxiety and decreasing catecholamines.


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Meperidine (Demerol)

Most common analgesic in North Americaand Europe

IM up to 100mg-onset 40-50 min

IV up to 50mg-onset5-10 min

Quick placental transfer life 3 hours in mother (up to23 in fetus)

Metabolized to normeperidine


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Morphine

IV 20min onset time

Last 4-6 hours

Very high likelihood on neonatal depression

Not used for pain in Labor

Used for sedation in latent phase10-15mg IM


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Pentazocine (Talwin)

No advantage over other narcotics

Respiratory depression

Weak opiate antagonist, strong opiate agonist


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Butorphanol (Stadol)

Synthetic analgesic like pentazocine (mixedagonist/antagonist

5 times more potent than morphine (40Xmore than Demerol)

Dose 1-2 mg

IM 10min onset, IV 1-2min onset

Duration 2-4 hours


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Butorphanol cont.

Metabolites are inactive

Less nausea and vomiting

Causes drowsiness

Dont give after Demerol


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Alphaprodine (Nisentil)

Rapid onset of action 5-10 min sub Q, 1-2min IV(IM absorbtion is unpredictable)

Short duration 1-2 hoursRepeated doses result in long duration of actionbecause it is accumulated in tissue and slowly released

Maternal respiratory depression is commonDose 10-20mg IV

Dose 30mg sub Q


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Fentanyl (Sublimaze)

Synthetic opoid 1000 times more potent thanmeperidine

Rapid onset

Brief durationRepeated doses result in drug accumulation andlong duration of action

Dose 50-100micrograms IVNot used in labor

Causes sudden and profound respiratory depression


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II. Anesthetic

Anesthetic refers to a technique or

medication that partially or completelyeliminates sensation or feeling


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2 types of nerve-blocking

anestheticsLocal anesthetics block sensory nerve

pathways at the organ level.

Regional anesthetics block sensory nerve

pathways along the course of tissues.


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Level of anesthesia for cesarean

and vaginal delivery.
http://www.brooksidepress.org/Products/Obstetric_and_Newborn_Care_II/images/MD0922_img_29.jpg


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NERVE-BLOCKING

ANESTHETICS USED IN

OBSTETRICS


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produces anesthesia only in the area whereinjected. It is used in the superficial nerves of theperineum to make or repair episiotomy.

Lidocaine1percent drug normally used and isshort acting.

Local anesthetics are used frequently for delivery.

a. Local Anesthetics
http://www.brooksidepress.org/Products/Military_OBGYN/Pharmacy/Lidocainehydrochloride.htmhttp://www.brooksidepress.org/Products/Military_OBGYN/Pharmacy/Lidocainehydrochloride.htm


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b. Regional anesthetics

Regional anesthetics include:

paracervical block

pudendal block saddle block (low spinal)

caudal or lumbar epidural.


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Paracervical block


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Pudendal blockPudendal block is an injection of local anesthetic

on both sides of the vagina. It is administered just

prior to delivery. It numbs the perineal area, vulva,and the vagina. It is used frequently in labor and

delivery in combination with local anesthesia.


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Bilateral blockage of the pudendalnerve will result in complete anesthesia

over the perineum

Pudental Block
http://www.brooksidepress.org/Products/Obstetric_and_Newborn_Care_II/images/Pudendal5.jpghttp://www.brooksidepress.org/Products/Obstetric_and_Newborn_Care_II/images/MD0922_img_32.jpg


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Saddle block (low spinal)is an injection of anesthetic agent directlyinto the spinal canal below the spinalcolumn to cause loss of sensation below

the injection site.patient has to sit up on the table with legscrossed or hanging over the side.

It numbs the abdominal and pelvic areasbelow the umbilicus to include theperineum, legs, and feet.


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The patient will usually feel contractions.Side Effects are severe maternalhypotension due to vasodilation and

decreased oxygen to the fetus as a result ofhypotension.

Cont. Saddle block


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Saddle block
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Caudal or lumbal epidural

is an injection of anesthetic agent in the

peridural space through the sacral hiatus.

is an injection of anesthetic agent on top ofthe dura space through the 3rd and 4th or5th lumbar space.

It numbs the abdominal and pelvic areas

below the umbilicus to the midthigh.


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Cont. Caudal

The patient doesn't feel contractions or

perineal stretching.

The urge to push may be blocked,although the ability is still present.


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Cont. CaudalADVANTAGES:

good pain relief

the patient is alert and cooperative

there is decreased danger of neonatal

depression.


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Cont. Caudal

SIDE EFFECTS:

Hypotension secondary to peripheralvasodilation.

Sensory changes and loss of the ability to move

lower extremities.

Ringing in the ears, lightheadedness, circumoral(around mouth) tingling, numbness, metallic

taste, and seizures.

Burning at the site of injection.


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GENERALANESTHESIA


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General AnesthesiaGeneral anesthesia produces loss ofsensation and loss of consciousness. It is

seldom indicated for uncomplicatedvaginal delivery. It is used in cases of fetal

distress requiring immediate delivery and

used for C-section when spinal anesthesiais contraindicated.


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Cont. G.ADISADVANTAGES:

(1)The patient is unable to participate.

(2) It rapidly crosses the placenta causing fetal

anesthesia, respiratory depression, and possibleanoxia (loss of oxygen).

(3) There is increased risk of maternal aspiration -

- evaluate how recently the patient has eaten.

(4) There is possible hemorrhage since nitrousoxide yields uterine relaxation.


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-End-

Prepared by: Edderlyn D. Lamarca

Saint John Colleges

obstetric anesthesia and analgesia

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