| Placental Transfer Of Drugs (Narcotics and local anaesthetics) |
Rapid equilibration across placenta (peak leels 15 to 30 mins). |
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Free (non-ionised) fetal drug concentration depends on plasma protein binding and fetal acidosis. |
| Toxic Effects |
Loss of fetal heart rate variability (lignocaine). |
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Large doses cause central nervous system and cardiovascular depression. |
| Neurobehavioural Assessment |
Correlates with neonatal peak local anaesthetic plasma leel. |
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Minimal depressant effect with bupivacaine. |
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Hypotonia & decreased motor reflees with 1.5% lignocaine or mepivacaine. |