CSP (Combined Spinal Parasthesia)

Combined spinal anaesthesia is a popular choice for both labour and caesarean section. I imagine that most anaesthetists think of the needle-through-needle approach when CSE is referred to. This approach is certainly the most marketed approach, although the argued main clinical advantages is the single injection for the patient. However,case reports, commentary from Felicity Reynolds and simple reflection indicate that the long, cephalad pointing spinal needles of theses CSE kits can be a hazardous tool.

Ahn et al in Anaesthesia (July, 2006) present another paper in which the tendency for NTN CSE to aggravate nerve roots is shown. They compared NTN with double space CSE for caesarean and found the spinal needle parasthesia rate to be 20% in the former and 9% in the latter. As they point out, this is usually no big deal apart from an unpleasant experience for the patient, but in the rare event neuropathy occurs after spinal anaesthesia it is often preceded by parasthesia at the time of injection. Thus it seems logical that parasthesia should be avoided rather than be tolerated as a benign and frequent side-effect.

They used the right lateral position for the blocks. Arguably, the lateral position may make intrathecal nerve root contact more likely because the lower CSF pressure means the the dura is slacker and needs more spinal needle length before it is punctured. It may also make extradural nerve root contact more likely because midline direction is more difficult to achieve in the lateral compared to the sitting position. My recent observations are that in Melbourne the sitting position for spinal and CSE, and even epidural are more commonly used.

Of other interest was the successful use (in both groups) of epidural volume extension of the 6.6 mg bupivacaine with sufentanil spinal dose with 10 ml 0.25% bupivacaine 5 minutes later.

Nonetheless, should we consider if a double space technique with an upper lumbar epidural catheter followed by a lower lumbar spinal needle is a more appropriate form of CSE? It has other advantages including the ability to carefully site and if needed, re-site an epidural catheter before a spinal block starts evolving. Ahn’s data indicates their DST took only 30 seconds longer than NTN CSE. Is it worth a mere 30 seconds and a second skin jab of local anaesthetic?