[Attenuation of phrenic nerve palsy associated with brachial plexus block by modified supra costal approach under fluoroscopic guidance].

Background: Brachial plexus block (BPB) frequently accompanies phrenic nerve palsy (PNP).

Methods: Thirty six patients scheduled for upper-limb surgery were allocated to 2 groups; 14 patients undergoing BPB with the supra costal approach (i. e. placing the needle-tip at the middle of the 1st lib), and 22 patients undergoing BPB with the modified supra costal approach (i. e. placing the needle-tip in the visceral or dorsal area of the 1st lib). We evaluated analgesic effects of the block and changes in forced vital capacity (FVC).

Results: BPB with both approaches provided sufficient analgesia. After BPB with both approaches, a significant reductions in FVC was observed; however, the reduction after BPB with the modified supra costal approach was significantly lower than that with the supra costal approach.

Conclusions: These results suggest that BPB with the modified supra costal approach provides sufficient analgesia with a significantly lower degree of PNP. We suppose that distribution of local anesthetics is altered by changing the location of the needle-tip on the 1st lib. Amounts of local anesthetics distributing around the phrenic nerve can be reduced by the modified supra costal approach, leading to the significantly less reduction in FVC after BPB.