Unknowns in the use of remifentanil PCA for labour analgesia

In response to a case report of cardiorespiratory arrest involving remifentanil PCA 1, and referring to other similar cases reported in Anaesthesia 2, 3, an editorial by Muchatuta and Kinsella 4 discusses the risks and benefits of this type of labour analgesia. In addition to concerns about whether preceding or concomitant opioids should be administered, there remain other unknowns concerning the use of remifentanil in labour. Firstly, what are the relative contra-indications to remifentanil PCA? These appear to include morbid obesity, primiparous women who are at risk of prolonged labour and those with signs and symptoms suggestive of chest infection, but may include others. Secondly, the correct dosing regimen remains uncertain 5. Thirdly, the importance of trained midwifery is yet to be quantified, although this would seem to be paramount as suggested by Hughes and Foley's audit data of over 2200 patients receiving remifentanil PCA, of whom only two had apnoea (both of which were managed successfully) 6. Related to the detection of apnoea, no study has yet assessed the importance and cost of apnoea monitoring and/or capnography whilst remifentanil PCA is in use. Finally, the relative risks and levels of satisfaction between remifentanil and pethidine require further study 7. Until these issues are resolved, it may be too early to endorse the use of remifentanil PCA as standard practice, and units would be well advised to monitor the use of remifentanil PCA in their delivery suite very carefully.