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Clinical ImplicationsAn epidural block limited to T10-L1 will provide excellent pain

relief whilst avoiding neural blockade of sacral segments.

Block may have to be extended to the upper sacral segments

during the last phase of the first stage & the second stage of

labour.

Complete block of the sacral segments need to be perfomed onlywhen the perineal pain becomes severe.

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Consequences Of Pain In Labour

Pain is a noxious & unpleasant stimulus which produces fear &

anxiety.

Unrelieved stress in labourpq uterine blood flow

q foetal heart rate

q foetal oxygenation

o catecholamine & cortisol conc.

Effective pain reliefpq catecholamine conc.q metabolic acidosis-q lactate production

q maternal oxygen consumption by 14%

Epidural prevents pain induced hyperventilation & hypocapnia.

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Requirements Of A Satisfactory

Analgesic Technique

Safety

Effective analgesia throughout painful period

No depressant effect on the maternal resp. or CVS system

No depressant effect on the progress of labour

No depressant effect on the foetus before or after delivery

No unpleasant maternal side-effects

High technical success rate

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History

The first anesthetic used in obstetrics was

chloroform and ether in 1848

1902- Morphine and Scopolamine were

used to induce a twilight sleep.

1924 Barbituates were added for sedation

1940 Dr. Lamaze and Read advocated

natural child birth

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Factors associated with pain in

Labor

Anxiety (reduce fear and reduce pain)

Hx of severe menstral pain Age ( negative correlation)

Socio-economic status (negative

correlation) Education

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Factors that effect the transfer

of a drug to the fetus

Amount of drug

Site of administration Drug distribution in maternal tissue

Maternal metabolism

Renal or liver excretion of the drugs andthere metabolites

Lipid solubility and protein binding

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Factors that effect the transfer

of a drug to the fetus

Spatial configuration

Molecule size Acid base status of the fetus (all narcotics

are weak bases and will become

concentrated in an acidotic fetus, or if the

mother is alkalotic the narcotics will be

concentrated in the fetus

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Factors that effect the transfer

of drugs to the fetus

Uteroplacental blood flow ( if diminished

then less drug is delivered i.e.. PIH, DM as

well as hypovolemia

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Narcotics and the fetus

Fetal metabolism is slower to metabolize

narcotics because of the immature liver,

also the blood brain barrier is very

permeable so the fetuses are more

susceptible to depression from narcotics.

Narcotics can be given IV, IM. Continuousinfusion

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Narcotics and the fetus

IM injections result in a significant delay in

analgesic effect

IM injections can have unpredictable blood

concentrations

IM absorbtion is highly variable from

patient to patient

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Complications of Pudendal

blocks

Systemic toxicity(IV)

Vaginal laceration Vaginal or ischiorectal hematoma

Retro psoas or sub gluteal abscess