obstetric analgesia and anesthesia (copy)
TRANSCRIPT
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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