Superficial or deep cervical plexus block for carotid endarterectomy: a systematic review of complications

Carotid endarterectomy is commonly conducted under regional(deep, superficial, intermediate, or combined) cervical plexusblock, but it is not known if complication rates differ. Weconducted a systematic review of published papers to assessthe complication rate associated with superficial (or intermediate)and deep (or combined deep plus superficial/intermediate). Thenull hypothesis was that complication rates were equal. Complicationsof interest were: (1) serious complications related to the placementof block, (2) incidence of conversion to general anaesthesia,and (3) serious systemic complications of the surgical-anaestheticprocess. We retrieved 69 papers describing a total of 7558 deep/combinedblocks and 2533 superficial/intermediate blocks. Deep/combinedblock was associated with a higher serious complication raterelated to the injecting needle when compared with the superficial/intermediateblock (odds ratio 2.13, P = 0.006). The conversion rate to generalanaesthesia was also higher with deep/combined block (odds ratio5.15, P < 0.0001), but there was an equivalent incidenceof other systemic serious complications (odds ratio 1.13, P= 0.273; NS). We conclude that superficial/intermediate blockis safer than any method that employs a deep injection. Thehigher rate of conversion to general anaesthesia with the deep/combinedblock may have been influenced by the higher incidence of directcomplications, but may also suggest that the superficial/combinedblock provides better analgesia during surgery.