Intermittent bolus versus continuous infusion techniques for local anesthetic delivery in peripheral and truncal nerve analgesia: the current state of evidence.

Manually delivered intermittent bolus (MIB) and programmable intermittent bolus (PIB), alternatives to continuous infusion (CI), involve administering a set volume of solution at a set interval of time. The benefits of intermittent bolus techniques in truncal and peripheral nerve blockade (TPNB) are unclear, and studies have largely demonstrated conflicting results. Using MEDLINE, Embase, Google Scholar, and the Cochrane Library, we conducted an evidenced-based review of published randomized controlled trials comparing intermittent bolus and CI methods in TPNB. In total, 13 randomized controlled trials were identified and evaluated. Outcomes data addressed in these studies included assessments of pain, opioid and local anesthetic consumption, patient satisfaction, adverse events, and physical therapy metrics. The overall quality of current evidence was found to be low given the small sample sizes, heterogeneity of data, and the variations in intermittent bolus techniques between studies. At this time, we found limited supportive data to endorse MIB or PIB over CI in TPNB. While unable to provide data-driven conclusions for local anesthetic delivery methods at this time, we propose that future studies and quantitative analysis between techniques should be on an anatomic, site-specific basis, with greater focus on evaluation of opioid use, adverse events, patient satisfaction, and rehabilitative metrics.