Epidural anaesthesia obstetrics

Extradural (epidural) anaesthesia is used in the thoracic, lumbar and sacral (caudal) regions. Lumbar epidurals are used widely in obstetrics and low thoracic epidurals provide excellent analgesia after laparotomy. The drug is injected into the extradural space where it acts on the nerve roots. This technique is less likely to cause hypotension than spinal anaesthesia. Continuous analgesia is achieved if a local anaesthetic, often mixed with an opioid, is infused through an epidural catheter. 

A study on the use of chloroprocaine 3%, bupivacaine 0.5% or a mixture of chloroprocaine 1.5% with bupivacaine 0.375% in obstetric epidural anaesthesia found that time to onset of analgesia, time to maximum analgesia, and effectiveness of analgesia were similar irrespective of the treatment regimen. Bupivacaine 0.5% alone had a longer duration of action than chloroprocaine or the mixture of anaesthetics. Another study found that lidocaine did not affect the pharmacokinetics of bupivacaine. ... 

A total of 3 cases of Homer s syndrome after obstetric epidural anaesthesia have recently been described (17 -, 18 -). In itself, this complication is not dangerous, but it may be a warning sign of an extensive block of serious consequence. Parturient women are more likely to develop this complication than are other patients because epidural injection with the patient in the lithotomy position can promote dissemination to higher levels (18 ). In some cases at least, the complication may be due to dissemination of the anaesthetic by way of the vertebral venous plexus (17 -). In view of the engorgement of the epidural veins during labour, this explanation is by no means improbable. 

An epidurally placed catheter can enter the subarachnoid space in the course of a continuous epidural anaesthesia. In 2 recently reported obstetric cases, repetition of the injection caused a spinal block (19, 20 -). It is therefore advisable to aspirate each time before injecting the local anaesthetic drug. 

Prilocaine is suitable for most types of local anaesthetic block but is not suitable for epidural use in obstetrics because of the need for repeat administration. Its main uses are for infiltration anaesthesia and intravenous regional anaesthesia where its low toxicity makes it the drug of choice. Levobupivacaine... 

When used for spinal anaesthesia, 0.75% ropivacaine produces less intense sensory and motor block than 0.5% bupivacaine. It is suitable for regional, spinal and epidural block but not for regional intravenous anaesthesia. The addition of adrenaline (epinephrine) does not prolong the duration of anaesthesia in brachial plexus or epidural block. Ropivacaine is indistinguishable from bupivacaine when used in obstetric anaesthesia. Its direct myocardial toxicity is somewhat less than that of bupivacaine. 

Foetal depression during spinal and epidural obstetric anaesthesia occurs secondary to maternal hypotension or as a result of placental transfer of the local anaesthetic agent (8, 10 -, 13 ). In this respect, bupivacaine was found to have a low foeto-maternal drug concentration ratio (16 -). When caudal anaesthesia is used, direct injection of the local anaesthetic drug into the foetus is possible (13, Other causes... 

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