Comparison of the effects of general and epidural anaesthesia for caesarean section on the neurobehavioural responses of newborn infants

Fetal Habituation

One aim of obstetric practice is to ensure the wellbeing of the fetus. This is by no means an easy task and recent years have seen the development of a variety of tests, with varying degrees of success, to evaluate fetal health.

Fetal wellbeing may be assessed at a variety of levels: genetic/cellular, physical/structural or functional. Ideally the evaluation of fetal health should provide information about the functional outcome of any particular condition, especially the performance of the central nervous system. Current tests may not do this. Thus, whilst tests of the fetal chromosomal or genetic constitution may determine the presence of particular genetic/chromosomal conditions, they may not predict functional outcome especially the functioning of the cerebral cortices, the ultimate arbiter of excellence in man. For example, Down's syndrome may be accurately diagnosed by analysis of fetal cells to detect the presence of Trisomy 21 but this in itself provides little information on the subsequent functional performance of the individual. The development of tests of fetal heart function such as antenatal cardiotocography have provided a means of assessing cardiac function and, to a certain extent, the functioning of parts of the autonomic nervous system. However such tests can only indirectly assess cortical function.

Perinatal bupivacaine and infant behavior in rhesus monkeys

To assess the effect of perinatal epidural bupivacaine analgesia on infant behavioral development, bupivacaine (1.2 mg/kg) was administered to term-pregnant rhesus monkeys (treated, n = 11, procedural controls, n = 8) and infant behavior was evaluated for 1 year using a test battery including infant neurobehavioral tests, observation of spontaneous behavior, and structured cognitive testing. No adverse effects of bupivacaine were detected for neonatal neurobehavior, early cognitive abilities, or performance of cognitive tasks by older infants. Bupivacaine infants directed more, shorter fixations at visual stimuli during visual novelty preference testing. Observation of behavior maturation patterns showed that the increase in manipulatory activity that normally occurs at 2 months of age was delayed in bupivacaine infants, and the increase in motor disturbance behaviors that normally occurs at 10 months of age was prolonged. These results are interpreted in terms of life-history and brain maturation landmarks that appear at these ages. The data suggest that epidural bupivacaine does not cause neonatal abnormalities or specific cognitive deficits but can alter the normal course of behavioral development.

Risk-benefit assessment of anaesthetic agents in the puerperium

A critical evaluation of anaesthetic agents in the puerperium is difficult because systematic, relevant studies are still lacking. Current knowledge of the effects of different agents used in labour and caesarean section indicates that significant residual effects on the mother and newborn are limited. In the early puerperium, based on physiological and/or hormonal changes, the mother could be more sensitive to inhalational anaesthetic agents and local analgesics. To date there is no evidence that any anaesthetic agent is excreted in breast milk in clinically significant amounts when given as a single dose. The only exception is perhaps in the case of very premature neonates whose mothers have had multidrug therapy before labour. Even then the importance of breast milk should be carefully assessed against possible adverse drug effect. However, repeated administration of long-acting benzodiazepines and continuous epidural administration of pethidine (meperidine) can have adverse effects on the neonate. The essential conclusion of this review is that breast-feeding is best. The different anaesthetic agents are excreted in the milk in amounts so low that detrimental effects on the neonate should not be expected.