When using spinal anaesthesia for caesarean section after the epidural has failed, the normal dose of spinal anaesthetic should be used

Abstract

The safe, effective management of intrathecal anaesthesia for emergency caesarean section in the presence of an epidural block that is inadequate for surgery, remains a clinical challenge, even for the experienced obstetric anaesthetist. The indications to persist with a regional technique are as compelling as in any maternal intervention in labour. Spinal administration following epidural failure, however, may be associated with unpredictable final block height, hence the vigorous debate on the matter of optimum intrathecal dose. In support of using a normal intrathecal dose, I maintain that the evidence for high block with normal doses of intrathecal local anaesthetic is not robust enough to change universal anaesthetic practice. There is persuasive evidence for the safety of spinal anaesthesia with normal intrathecal doses, while reassuring studies demonstrate that any risk can be easily offset with meticulous attention to anaesthetic technique. It is worthwhile considering the causes of inadequate or failed epidural block. It must be carefully defined, since it is pertinent to the conclusions that may be drawn from studies of these mechanisms. For the purposes of the debate, a failed epidural will be considered one that will not provide an adequate height or density of anaesthesia for surgery after an appropriate dose of local anaesthetic has been administered; this is distinct from an epidural that has ceased to function at all. The causes of inadequate block may be broadly cate