Spinal anaesthesia: an update

Developments in needle design have been driven largely by the need to reduce the incidence of post-dural puncture headache (PDPH). Reduction in needle size reduced significantly the incidence of PDPH, but technical difficulties leading to failure of spinal anaesthesia are common when needles of 29G or smaller are used. However, development of atraumatic ‘pencil-point’ needles also led to a reduction in the incidence of PDPH (0–2%). Although atraumatic needles reduce the incidence of PDPH, they have been shown to increase the likelihood of neurological deficit because of contactwith either the spinal cord or the nerve roots of the cauda equina. The blunt nature of the needle tip and the increased distance that these needles have to be inserted into the subarachnoid space before CSF flow is appreciated are reasons suggested for the increased risk to central nervous system tissue. The introduction of a new 26G Atraucan1 spinal needle with a cutting point and a double bevel (Fig. 1) has been shown to be associated with a higher rate of successful identification of the subarachnoid space at the first attempt, faster CSF backflow and fewer neurological symptoms than a 25G Whitacre needle. Further work is needed to determine whether the incidences of failed spinal anaesthesia and PDPH are less with the new needle design.