Article Text

Download PDFPDF

Intermittent bolus versus continuous infusion techniques for local anesthetic delivery in peripheral and truncal nerve analgesia: the current state of evidence
  1. Ram Jagannathan1,2,
  2. Adam D Niesen1,
  3. Ryan S D'Souza1 and
  4. Rebecca L Johnson1
  1. 1 Department of Anesthesiology and Perioperative Medicine, Mayo Clinic, Rochester, Minnesota, USA
  2. 2 Department of Anesthesiology, Mayo Clinic Health System, Mankato, Minnesota, USA
  1. Correspondence to Dr Ram Jagannathan, Department of Anesthesiology and Perioperative Medicine, Mayo ClinicHealth System, Mankato, MN 56001, USA; jagannathan.ram{at}


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.

  • continuous peripheral techniques
  • regional anesthesia
  • acute pain
  • outcomes

Statistics from

Request Permissions

If you wish to reuse any or all of this article please use the link below which will take you to the Copyright Clearance Center’s RightsLink service. You will be able to get a quick price and instant permission to reuse the content in many different ways.


Truncal and peripheral nerve blockade (TPNB) with continuous infusion (CI) of local anesthesia through perineural catheters is a means of providing analgesia for extended periods of time. Traditionally, medication is administered at a set volume per hour through an electronic infusion delivery system. Manually delivered intermittent bolus (MIB) has been purported to provide more uniform spread of local anesthesia within neuraxial compartments compared with CI.1 More recently, devices with programmable intermittent bolus (PIB) have been developed, allowing for a larger depot of solution to be given at a set interval of time. Although an optimal dose and interval has yet to be clarified, PIB has been shown to be beneficial for labor epidural management,2 3 achieving higher sensory block levels, improving patient satisfaction, and decreasing local anesthetic consumption compared with CI.

However, the benefit of this strategy in TPNB is unclear, as studies have largely demonstrated conflicting results.4–16 Thus, we aimed to examine outcome differences within randomized controlled trials (RCTs) comparing MIB and PIB with CI in TPNB—namely, quality of postoperative analgesia, opioid and local anesthetic consumption, patient satisfaction, side effects, and rehabilitative metrics—in order to ascertain the effect of local anesthesia delivery technique, if any.


Search strategy and selection criteria

MEDLINE, Embase, Google Scholar, and the Cochrane Library were searched from January 4, 2018 through July 14, 2018, using a highly sensitive text word search strategy to find RCTs comparing MIB and PIB directly with CI. Serial searches included the terms “intermittent bolus,” “peripheral nerve catheter,” and “regional anesthesia infusion,” independently and in combination, using Boolean operators.

Each search was limited to TPNB exclusively, including both programmable and manual intermittent bolus techniques, in adult patients undergoing surgical intervention. Studies involving cadavers, volunteers, neuraxial anesthesia, or patient-controlled intervention were excluded from further analysis, as were studies that were non-randomized, quasi-randomized, or not peer-reviewed.

Specific outcomes addressed included quality of postoperative analgesia, opioid and local anesthetic consumption, patient satisfaction, complications, and rehabilitation outcomes. The reference sections of all eligible studies and a previously published systematic review17 were also reviewed to ensure completeness of our search. Two authors (RJ and RSD) independently conducted searches using the aforementioned search strategy, and a third author (RLJ) adjudicated discrepancies (figure 1).

Figure 1

Flow chart of the study selection and inclusion process.

Data extraction

Data extraction of characteristics, validity, and outcomes data was performed by one reviewer (RJ). The following information was extracted from studies meeting the inclusion criteria: name of the first author, year of publication, study design, surgical intervention, block technique, protocol of local anesthetic delivery and use in each group, infusion technique, and a summary of the results of analyzed variables (table 1).

Table 1

Randomized controlled trials comparing intermittent bolus with continuous infusion techniques in peripheral nerve blockade

Assessment of risk of bias

The quality of studies was independently evaluated by two reviewers (RJ and RSD) using the guidelines provided by the Cochrane Collaboration ACROBAT-NRSI (A Cochrane Risk Of Bias Assessment Tool: for Non-Randomized Studies of Interventions).18 Discrepancies were adjudicated by a third reviewer (RLJ). Biases were assessed in the following domains: random sequence generation, allocation concealment, blinding of participants and personnel, blinding of outcome assessment, attrition bias due to missing data, reporting bias, and other biases (including confounding factors and departures from intended interventions such as cross-contamination of groups). The risk of bias in eac domain was assigned at low risk, high risk, or unclear risk (online supplementary appendices 1 and 2).


Tables 1 and 2 show the summary of comparative findings. After abstract screening, 13 publications4–16 were assessed for eligibility, all of which were RCTs comparing MIB or PIB techniques with CI for postoperative analgesia at different anatomic sites. Included studies involved lower extremity blockade (six studies),4–9 upper extremity blockade (three studies),10–12 paravertebral blockade (two studies),13 14 and truncal blockade (two studies)15 16 (online supplementary appendix 3).

Supplemental material

Table 2

Assessment of postoperative analgesia by study

Studies using nerve stimulation4–6 10 11 or ultrasound guidance,6–9 11 12 15 16 alone or in combination, were variable, with two studies using surgical placement14 16 and a single study using fluoroscopic confirmation after landmark-based placement.13 PIB was used in eight studies,4–9 11 12 and MIB was used in five studies.10 13–16 With the exception of two publications,10 13 all studies reviewed were published between 2008 and 2018 (online supplementary appendix 4). The sample size of the selected RCTs ranged from 20 to 120 patients.

Supplemental material

Primary outcome variables in all studies involved at least one assessment of postoperative analgesia, typically by a validated scale, such as the Numeric Rating Scale, Verbal Rating Scale, or Visual Analog Scale (table 2). Other primary variables assessed include frequency of opioid consumption, or in a single study postoperative respiratory function.16 Secondary variables analyzed included patient satisfaction (six studies),5 6 8 11 15 16 consumption of local anesthesia (three studies),5 11 12 and assessment of postoperative rehabilitation and mobility (four studies).6 9 12 16


Effectiveness of intermittent bolus strategies

In our comparative-effectiveness review, we found limited evidence to support the routine use of intermittent bolus techniques, MIB or PIB, for peripheral and truncal nerve analgesia over CI due to the heterogeneity of data between studies.

Intermittent bolus strategies were first described in epidural techniques for labor analgesia. A meta-analysis in obstetric cohorts3 suggests a slightly lower local anesthetic consumption as well as an improvement in maternal satisfaction compared with CI. Similar to TPNB,4–16 data from published studies in obstetrics settings are heterogeneous with regard to specific intervention, particularly in terms of local anesthetic type, dosing, and administration regimen.

For non-obstetrical applications, the benefits of intermittent bolus techniques in TPNB were first shown in popliteal nerve blockade.4 5 These initial studies used nerve stimulation for catheter placement, finding decreases in pain scores and in local anesthetic consumption by a demand type mode. It was theorized that spread around common peroneal and tibial nerve components during bolus delivery was greater because of higher injection pressures and decreased systemic uptake compared with CI, allowing a higher proportion of local anesthetic to reach neural tissue and improve block efficacy.4

More contemporary studies have consistently shown mixed results between bolus techniques compared with CI, including blocks that are compartment-based and more reliant on rostrocaudal spread of local anesthetic (eg, paravertebral blockade). Among other factors, it remains unknown if the advent of ultrasound, compared with nerve stimulator placement, may have mitigated some of the advantages seen when bolus strategies in TPNB were used in earlier studies (eg, decreased distance of catheter tip to perineural structures with ultrasound guidance). Still, select investigations have demonstrated superiority in PIB groups, namely quality of postoperative analgesia,7 8 opioid consumption,6–8 patient satisfaction,8 and rehabilitation metrics.16 The majority of recent studies from 2013 onward, however, have shown no difference between study groups with regard to analyzed variables.9 11 12 14 15

Unlike epidural analgesia for labor, comparative-effectiveness studies of TPNB are often anatomically diverse, which can considerably impact local anesthetic spread, uptake, and the dosing needed for effective analgesia. These factors can differ significantly and must be considered moving forward. This, combined with the small sample sizes of current trials and varying surgical cohorts, makes it a challenge to use meta-analysis to synthesize such data for outcomes specific to local anesthetic delivery methods. Subgroup analysis is likely needed to derive meaningful conclusions, which is not possible at this time.

Recommendations for future research

Overall, there is a paucity of data regarding this important topic. First, perineural catheter management may be occurring less frequently than in the past due to greater use of multimodal analgesia, greater focus on early postoperative mobilization, and presence of adjuvant medications which can prolong single injection regional anesthetic techniques. Second, the mixed use of intermittent bolus techniques (MIB was used in 5 of the 13 studies assessed) added to the heterogeneity across studies in comparison with CI. We postulate that this may reflect a lack of widespread use of electronic delivery systems that have the ability to perform PIB technique, or the resources needed to manage these specialized devices, rather than a technique preference for MIB over PIB. In addition, it remains unknown whether differences in injection pressures between PIB and MIB influence block characteristics and in turn the studied outcomes.19 20 Hence, more comparative-effectiveness studies between MIB and PIB are needed before examining bolus techniques against continuous delivery.


PIB and MIB techniques for TPNB, although effective in providing analgesia, cannot currently be recommended over CI strategies. Perineural infusion outcomes are likely anatomic site-specific, and studies varying local anesthetic delivery should be determined based on the type of blockade. Given the heterogeneity of the current data, the small sample sizes of trials, and the lack of standardized interventions, quantitative analysis to draw meaningful conclusions that affect clinical practice is not possible at this time. Future studies are needed to assess the implications of intermittent bolus techniques in a greater variety of TPNBs within surgical and patient cohorts that can reliably be compared. Lastly, studies involving local anesthetic delivery strategies should further ascertain the effects of bolus methods on opioid-sparing, adverse events of administration, and functional outcomes, which are largely absent in the literature.

Supplemental material

Supplemental material



  • Presented at Presented, in part, at the 2018 World Congress on Regional Anesthesia and Pain Medicine in New York, New York, April 19–21, 2018.

  • Contributors RJ conducted the literary search, and conceived, designed, and drafted the manuscript. ADN edited the manuscript and provided recommendations. RSD conducted the literary search and provided aid in image production and formatting. RLJ edited the manuscript, provided recommendations, and adjudicated discrepancies in the selection of articles.

  • Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.

  • Competing interests None declared.

  • Patient consent for publication Not required.

  • Provenance and peer review Not commissioned; internally peer reviewed.