Twenty-one RCTs were included in the review (702 patients). Trial sample size ranged from 16 to 155 patients. Eight trials were considered high quality and 13 were deemed fair quality. There was no evidence of publication bias.
Pain: Compared with single-injection peripheral nerve block, continuous peripheral nerve block was associated with statistically significant lower visual analogue worst pain scores on postoperative day zero (mean difference -1.29, 95% CI -2.19 to -0.40; Ι²=82%; nine RCTs). This significant result was maintained at postoperative day one and two, but it was no longer significant at day three. Visual analogue pain at rest scores showed similar results (full results were presented in the paper).
Satisfaction: Continuous peripheral nerve block was associated with statistically significant greater satisfaction (mean difference 2.04, 95% CI 1.23 to 2.85; Ι²=86%; 11 RCTs) compared with single-injection peripheral nerve block.
Opioid use: Compared with single-injection peripheral nerve block, continuous peripheral nerve block was associated with statistically significant lower opioid use on postoperative day one (mean difference -29.14, 95% CI -43.25 to -15.02; Ι²=95%; eight RCTs). This significant result was maintained at post-operative day two, and over the entire study period. However, the results were not significant at day three.
Complications: Continuous peripheral nerve block was associated with statistically significant lower rates of nausea (RR 0.35, 95% CI 0.17 to 0.70; Ι²=11%; six RCTs) compared with single-injection peripheral nerve block.