Programmed intermittent peripheral nerve local anesthetic bolus compared with continuous infusions for postoperative...

The role of the programmed intermittent bolus (PIB) technique for infusion of local anesthetics in continuous peripheral nerve blockade (CPNB) remains to be elucidated. Randomized controlled trials (RCTs) on PIB versus continuous infusion for CPNB have demonstrated conflicting results and no systematic review or meta-analysis currently exists. We aimed to delineate via systematic review with meta-analysis if there is any analgesic benefit to performing PIB versus continuous infusion for CPNB.

We conducted a systematic review and random-effects meta-analysis of RCTs.

We searched Medline, Embase, and the Cochrane Library without language restriction from inception to 2-May-2017.

Included RCTs had to compare PIB to continuous infusion in adult surgical patients receiving any upper or lower limb CPNB for postoperative analgesia. VAS pain scores were the primary outcome. The Cochrane Risk of Bias Tool with GRADE methodology was utilized to assess evidence quality.

Nine RCTs (448 patients) met the inclusion criteria. Two studies performed upper limb blocks and the rest lower limb blocks. Five RCTs activated the CPNB with long-acting local anesthetic and only five used multi-modal analgesia. PIB modestly reduced VAS pain scores at 6h (-14.2mm; 95%CI -23.5mm to -5.0mm; I²=82.5%; p=0.003) and 12h (-9.9mm; 95%CI -14.4mm to -5.4mm; I²=12.4%; p<0.001), but not at later time points. There were no other meaningful differences in the rest of the outcomes, apart from more residual motor block with PIB (OR 4.27; 95% CI 1.08-16.9; p=0.04; NNTH=8). GRADE scoring ranged from low to very low.

The existing evidence demonstrates that PIB does not meaningfully reduce VAS pain scores in CPNB. This systematic review provides important information about the limitations of existing studies. Future studies should reflect contemporary practice and focus on more painful operations.