Continuous peripheral nerve blocks compared to thoracic epidurals or multimodal analgesia for midline laparotomy: a systematic review and meta-analysis

Article information

Korean J Anesthesiol. 2021;74(5):394-408
Publication date (electronic) : 2020 September 23
doi : https://doi.org/10.4097/kja.20304
1Department of Anesthesia, Pain Management and Perioperative Medicine, Dalhousie University, Halifax, Nova Scotia, Canada
2Dalhousie University Faculty of Medicine, Halifax, Nova Scotia, Canada
3Department of Family Medicine, McGill University Faculty of Medicine, Montreal, Quebec, Canada
4Department of Anesthesiology and Pain Medicine, University of Ottawa Faculty of Medicine, Ottawa, Ontario, Canada
Corresponding author: Jonathan G. Bailey, M.D., M.S.c., F.R.C.P.C., E.D.R.A. Department of Anesthesia, Pain Management and Perioperative Medicine, Dalhousie University, 5th floor Halifax Infirmary Site, Rm 5452, 1796 Summer Street, Halifax, Nova Scotia B3H 3A7, Canada Tel: +1-902-473-4326 Fax: +1-902-423-9454 Email: jon.bailey@dal.ca

Previous presentation in conferences: Presented at the Canadian Anesthesiologists’ Society Annual Meeting in Calgary, AB, Canada in June 2019.

Received 2020 June 10; Revised 2020 July 31; Accepted 2020 September 22.

Abstract

Background

Continuous peripheral nerve blocks (CPNBs) have been investigated to control pain for abdominal surgery via midline laparotomy while avoiding the adverse events of opioid or epidural analgesia. The review compiles the evidence comparing CPNBs to multimodal and epidural analgesia.

Methods

We conducted a systematic review using broad search terms in MEDLINE, Embase, Cochrane. Primary outcomes were pain scores and cumulative opioid consumption at 48 hours. Secondary outcomes were length of stay and postoperative nausea and vomiting (PONV). We rated the quality of the evidence using Cochrane and GRADE recommendations. The results were synthesized by meta-analysis using Revman.

Results

Our final selection included 26 studies (1,646 patients). There was no statistically significant difference in pain control comparing CPNBs to either multimodal or epidural analgesia (low quality evidence). Less opioids were consumed when receiving epidural analgesia than CPNBs (mean difference [MD]: –16.13, 95% CI [–32.36, 0.10]), low quality evidence) and less when receiving CPNBs than multimodal analgesia (MD: –31.52, 95% CI [–42.81, –20.22], low quality evidence). The length of hospital stay was shorter when receiving epidural analgesia than CPNBs (MD: –0.78 days, 95% CI [-1.29, -0.27], low quality evidence) and shorter when receiving CPNBs than multimodal analgesia (MD: -1.41 days, 95% CI [-2.45, -0.36], low quality evidence). There was no statistically significant difference in PONV comparing CPNBs to multimodal (high quality evidence) or epidural analgesia (moderate quality evidence).

Conclusions

CPNBs should be considered a viable alternative to epidural analgesia when contraindications to epidural placement exist for patients undergoing midline laparotomies.

Introduction

It is estimated that 43.8% of the North American population will undergo abdominal surgery during their lifetime [1]. These procedures are associated with high rates of complications, particularly for comorbid or older patients [2]. Many physiologic insults are associated with inadequate pain control [3]. Given that pain increases postoperative morbidity, recovery time, duration of opioid use, health care costs, and quality of life impairment, optimizing pain control can help mitigate the negative consequences of surgery [3].

Open laparotomies, particularly those in the upper abdomen, are associated with respiratory complications if pain is not adequately controlled [4]. The incidence of postoperative pulmonary complications can be as high as 39% in high risk abdominal surgery, with increasing incidence each day that patients are not mobilized [5]. Currently, intravenous opioids are the most common medication for postoperative pain control following surgery [6]. Intravenous opioids attenuate the pain response and associated complications; however, in high doses some complications are exacerbated including respiratory depression, pneumonia, and ileus that in turn contribute to longer hospital stays and higher health care costs [7].

The most common regional anesthetic technique used for abdominal surgery is thoracic epidural [8]. Studies have consistently found that patients using thoracic epidural analgesia experience superior pain control and quality of life after laparotomy [9]. Guidelines for ‘Management of Postoperative Pain’ and ‘Enhanced Recovering After Surgery (ERAS) for Gastrointestinal Surgery’ both strongly recommend thoracic epidural analgesia [10,11]. There is reservation regarding the use of epidurals due to potentially devastating complications, such as epidural hematoma and abscesses [12]. In an attempt to avoid complications from systemic opioids or epidural placement, peripheral nerve blocks have been investigated. Initial reports described single shot nerve blocks that were effective at reducing pain; however, most reduction in opioid consumption occurs within the first 24 h [13,14]. Additionally, these studies do not compare the techniques to each other; thus, their relative efficacy and risk remain unclear.

Previous reviews have compared single shot transversus abdominus plane (TAP) blocks to placebo and wound infiltration [14]. Another review compared paravertebral blocks to epidural catheters, with only four of 20 using continuous catheters [15]. One systematic review examined the analgesic efficacy of wound infiltration compared to epidural analgesia [16]. The review included multiple types of incisions increasing the clinical heterogeneity. The purpose of this review is to determine the relative analgesic efficacy of continuous peripheral nerve blocks (CPNBs) compared to (i) multimodal analgesia and (ii) epidural analgesia in patients undergoing abdominal surgery via a midline laparotomy.

Materials and Methods

Search strategy

Our protocol was registered on PROSPERO (2017, https://www.crd.york.ac.uk/PROSPERO, no. CRD42017051770). at the beginning of the review process. Using broad search terms, we conducted a comprehensive search of three databases: Ovid MEDLINE, Embase, and the Cochrane Library. Our search strategy was developed in consultation with an expert medical librarian. We adapted the search terms used in Ovid MEDLINE (Supplementary Table 1) for other databases. We initially completed the search on November 30, 2016 later repeating it on July 1, 2018.

We did not apply language restrictions to this search. We conducted a search of the grey literature using OpenSIGLE (Supplementary Table 2) and conference abstracts. Once studies were selected for inclusion, a reference search and a forward citation search (using Web of Science) were conducted for each included study.

Inclusion criteria

Population

We included randomized controlled trials (RCTs) and cohort studies involving adult patients (aged > 18 years) undergoing elective abdominal surgery via a midline laparotomy. Urology, general surgery, or vascular surgery procedures performed through an open midline laparotomy were included.

Intervention

We included studies using regional anesthesia techniques to block pain transmission from the peripheral nerves of the abdominal wall. To be included, the technique must have blocked pain transmission on a continuous basis either by continuous infusion of a local anesthetic agent via a catheter for > 48 h, intermittent bolus injection of local anesthetic for > 48 h, or by administering liposomal bupivacaine. We included studies that compared these techniques to 1) continuous epidural analgesia covering the abdominal dermatomes and/or 2) multimodal analgesia with systemic opioids.

Outcomes

The primary outcomes of interest were pain control as measured by a visual analog scale (VAS) or a Numerical Rating Scale (NRS) and opioid consumption at 48 h. All VAS pain scores reported on a scale from 0 to 100 mm were converted to NRS pain scores by dividing by 10. Opioid consumption was compared by converting the reported consumption into oral morphine equivalents (OME) [17]. To be included, studies must have reported either pain scores or opioid consumption up to 48 h postoperatively. Secondary outcomes of interest were length of stay (LOS) in hospital and postoperative nausea and vomiting (PONV).

Exclusion criteria

Studies were excluded if they involved obstetrical, gynecologic, or trauma surgery. Studies involving children (< 18 years) or animals were also excluded. Case studies, case series, and reviews were excluded. If > 20% of patients were treated on an urgent or emergent basis, the study was excluded. Likewise, studies involving > 20% laparoscopic procedures were excluded. Patients undergoing procedures via other incisions were excluded.

Selection procedure

Two investigators (JB, CM) independently reviewed the title, abstract, and full text to assess inclusion and exclusion criteria. If consensus could not be reached between the two investigators, then a third investigator (RC, KK) resolved the disagreement.

Risk-of-bias assessment

We critically appraised each cohort study that met the inclusion criteria for potential biases using a modified version of the quality in prognosis studies (QUIPS) tool for cohort studies [18]. Each RCT was assessed using the Cochrane Risk of Bias Tool [19]. Two of the four investigators (JB, CM, RC, or JK) independently rated each domain in every study [19]. We categorized a study as having a high risk of bias in a domain if the bias was likely to change the results significantly [19].

Once all the studies were assessed independently, the reviewers came to a consensus on each domain. If a consensus was not reached, a third reviewer resolved the disagreement. Funnel plots were created for the primary outcomes to assess for publication bias if more than 10 studies reported a particular outcome. The overall certainty of the evidence was rated using the Cochrane handbook risk-of-bias tool and summarized using GRADEpro software (Evidence Prime, Inc., McMaster University, Canada) [19].

Data extraction

One of the four reviewers (JB, CM, RC, or JK) extracted pertinent data points from each included study using a standardized data extraction form. Each data point was then checked for accuracy by a second reviewer (JB, CM, RC, or JK). If further information or clarification was required, we contacted the corresponding author of the study.

Statistical analysis

We synthesized the data using random-effects meta-analysis with Revman 5.3.5 software (The Nordic Cochrane Centre, Denmark). We analyzed continuous data using inverse-variance mean differences and dichotomous data using Mantel–Haenszel odds ratios. Statistical heterogeneity was assessed using an I2 statistic. Forest plots are displayed and interpreted using mean difference (MD) rather than standardized MD since pain scores were all converted to NRS and all opioid consumption was converted to OME in keeping with the Cochrane recommendations [19]. For any study with three comparison groups, the overall means of the shared control group with half the number of patients were used for comparison as per the Cochrane recommendations [19]. Since this review included various CPNBs, forest plots included subgroup analyses for each CPNB separately. These subgroup analyses were planned to evaluate the relative contribution of each technique toward the combined effect, and to evaluate the efficacy of each CPNB separately.

Our PROSPERO registration included two planned sensitivity analyses. First, any study found to have a high risk of bias in one or more categories would be removed. Since 19 of our 26 studies had at least one high risk of bias category, we modified our sensitivity analysis to remove studies with two or more high risk categories. A sensitivity analysis was performed to examine the effect of upper versus lower midline laparotomy (i.e., above or below the umbilicus) on the primary outcomes. In addition to the planned sensitivity analyses, we conducted additional post-hoc sensitivity analyses. We separated the results of those studies using an epidural solution that included opioids. We performed a sensitivity analysis removing cohort studies from the meta-analyses.

Results

Our search strategy yielded 19,889 results. Using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines [20], we generated a flow chart of our selection process (Fig. 1). We contacted 31 authors for additional information. Of these authors, nine responded with the specific data we requested [2129]. One author [30] responded by providing us with the raw anonymized study data. Two authors responded but did not have the data requested. One author declined to provide additional information unless given authorship on this review. Two authors had emails that were not current, and we were unable to reach them.

Fig. 1.

Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) flow chart of included studies.

After title/abstract screening, correspondence with authors, hand-searching, and full-text assessment for eligibility, 26 studies involving 1,646 patients met the final inclusion for this review. Two studies [31,32] were cohort studies, while the rest were RCTs. Two studies [33,34] were divided into two subgroups for a total of 28 comparisons.

Risk of bias

We found that 19 studies had high potential for bias in one domain and, of those, nine had high potential for bias in at least two domains. The most common source of bias was blinding of participants and personnel. Blinding of personnel was considered to be high risk of bias if the study protocol allowed for differential treatment. Random sequence generation was considered to be high risk of bias if the described technique was known to not adequately randomize, whereas studies were rated as moderate or unclear risk of bias if the technique was not adequately described in the paper. Blinding of outcome assessment was deemed high risk of bias if the assessors were aware of the assignment to a study group.

Funnel plots did not suggest publication bias for pain scores or opioid consumption comparing between CPNB and multimodal analgesia (Supplementary Fig. 1). The funnel plots were not created for the comparisons between CPNB and epidural analgesia since there were less than 10 studies.

Multimodal analgesia

The types of multimodal analgesia were not specified a priori in our protocol. Two studies did not describe their multimodal analgesia approach [35,36]. The following agents were used as part of the multimodal analgesia strategy in included studies: Acetaminophen/Paracetamol (20 studies), non-specific NSAIDs (12 studies), COX-2 inhibitors (four studies), gabapentin (three studies), and tramadol (three studies). In two studies, both the intervention and control groups were provided with patient-controlled epidural analgesia [25,37]. These studies were considered multimodal in this review. The intervention group also received epidurals, lessening the potential effect of the CPNB.

Wound catheter

Three studies evaluated the effectiveness of wound catheters on pain management following midline laparotomies [28,34,38]. All three studies compared the use of wound catheters to systemic opioids, while Zheng et al. also compared wound catheters to epidurals. See Table 1 for baseline characteristics, local anesthetic dosing, and comparison groups. The wound catheters were all placed by surgeons.

Characteristics of Included Studies Comparing Continuous Peripheral Nerve Blockade (CPNB) to Multimodal and Epidural Analgesia for Patients Undergoing Midline Laparotomy

Zheng et al. [34] found no difference in pain scores at rest or with movement between groups. Although Zheng et al. displayed these results as figures, exact numbers were not available for meta-analysis. Overall, patients with wound catheters used less opioids over 48 h (MD: -21.46 mg, 95% CI [-40.33, -2.59], P = 0.03, I2 = 94%, three studies, n = 403) (Fig. 2).

Fig. 2.

Cumulative opioid consumption (in oral morphine equivalents) at 48 h comparing between continuous peripheral nerve blocks (CPNB) and multimodal analgesia for patients undergoing midline laparotomy. CPNB: continuous peripheral nerve block, IV: inverse variance, PCA: patient-controlled analgesia, SD: standard deviation, green color: low risk of bias, yellow color: unclear/moderate risk of bias, red color: high risk of bias, bold text: indicates subgroups, subtotal and total effect sizes and weighting.

Wang et al. [28] reported higher rates of PONV among wound catheter participants compared to controls. Zheng et al. [34] recorded lower PONV and sedation scores in the wound catheter group compared to the patient-controlled analgesia (PCA) group, particularly in the first 12 postoperative hours. There was a shorter LOS among participants in the wound catheter group than participants in the PCA group. Rates of PONV and LOS were not significantly different between the wound catheter and epidural groups.

Intraperitoneal catheters

The evidence for intraperitoneal catheters comes from two double-blind placebo-controlled RCTs using the ON-Q® system [37,39]. In the first RCT, Baig et al. [39] studied 66 patients undergoing elective colectomy and found that intraperitoneal catheters decreased the 48-h opioid consumption. There was no significant difference in pain scores except for postoperative day two afternoon. The generalizability of the study is limited by the lack of multimodal analgesia.

The second RCT consists of 60 patients undergoing colectomy, with both groups also receiving thoracic epidurals [37]. This study also found that an intraperitoneal catheter infusion for three days further decreased the pain scores with movement and coughing at multiple time points within the first week postoperatively. However, the data need to be interpreted in the context of overall low pain scores (maximum 4/10) in both groups. We were not able to obtain opioid consumption data from the study authors for meta-analysis.

Preperitoneal catheters

There were 12 studies included involving preperitoneal catheters with seven compared against multimodal analgesia [25,30,31,35,4042] and five compared against epidural catheters [21,24,4345]. In all cases, the catheters were placed by the surgeon during wound closure. In one case, both the preperitoneal and the comparison groups received thoracic epidurals [25]. We considered this study to compare multimodal analgesia with preperitoneal catheters since both groups received epidurals, which we assumed would decrease the overall effect of preperitoneal catheters.

Of the studies comparing preperitoneal catheters to multimodal analgesia, only four of seven reported 48-h pain scores. There was no significant difference in pain at 48 h, either individually or pooled (MD: -0.01, 95% CI [-0.12, 0.10], P = 0.84, I2 = 0%, four studies, 294 patients). The pooled results of six studies showed less cumulative opioid consumption at 48 h in patients with preperitoneal catheters than those receiving multimodal analgesia (Fig. 2). When compared to epidurals, there was no significant difference in pain scores (MD: 0.38, 95% CI [-0.10, 0.86], P = 0.12, I2 = 12%, three studies, 114 patients). The pooled results of these two studies showed less opioid consumption among patients with epidurals (Fig. 3).

Fig. 3.

Cumulative opioid consumption (in oral morphine equivalents) at 48 h comparing between continuous peripheral nerve blocks (CPNB) and epidural analgesia for patients undergoing midline laparotomy. CPNB: continuous peripheral nerve block, IV: inverse variance, SD: standard deviation, green color: low risk of bias, yellow color: unclear/moderate risk of bias, red color: high risk of bias, bold text: indicates subgroups, subtotal and total effect sizes and weighting.

Compared to placebo, preperitoneal catheters reduced LOS in two of four studies reporting hospital stay duration; however, the overall effect was not statistically significant (MD: -1.77 days, 95% CI [-5.04, 1.49], P = 0.29, I2 = 98%, three studies, 192 patients) (Supplementary Fig. 2) [25,35,40,42]. Epidurals reduced LOS compared to preperitoneal catheters in two of three studies (MD: 1.11 days, 95% CI [0.71, 1.51], P < 0.001, I2 = 65%, three studies, 157 patients) (Supplementary Fig. 3) [4345].

TAP catheters

Five studies involving TAP catheters were included, with two comparing to multimodal analgesia [23,32] and three comparing to epidural analgesia [26,36,46]. In one study, the TAP catheters were placed by the surgeon [32], whereas in the other four studies TAP catheters were placed by anesthesiologists under ultrasound guidance [23,26,36,46]. The opioid groups did not have catheters placed and all patients in those studies received PCA pumps.

Kadam and Field [23] found a significant reduction in pain scores during coughing in the first two days for patients with TAP catheters compared to multimodal analgesia. Wahba and Kamal [36] found that the epidural group had significantly lower pain scores at all time points compared to the TAP group. The other three studies found no differences in pain scores. There was no significant difference overall in pain scores compared to multimodal analgesia (MD: -1.32, 95% CI [-2.70, 0.06], P = 0.06, I2 = 52%, two studies, 120 patients) or epidural analgesia (MD: 0.89, 95% CI [-1.10, 2.88], P = 0.38, I2 = 95%, three studies, 133 patients). Both studies comparing with opioid analgesia found a significant reduction in opioid use over 48 h when patients received TAP catheters (Fig. 2) [23,32]. The evidence for comparing TAP catheters to epidurals was conflicting. One study comparing TAP to epidural catheters found no difference in opioid consumption [46], one found a significant reduction in opioid use with epidural analgesia [36], and the other found less opioid use in the TAP group [26] (Fig. 3). It must be noted that the study finding higher opioid use in the epidural group included a converted dose of the epidural opioids in the total opioid consumption [26]. Wahba and Kamal [36], and Rao Kadam et al. [46] did not use opioids in their epidural solution [36,46].

Rectus sheath catheters

Two studies involving rectus sheath block (RSB) catheters were included with one comparing to multimodal analgesia [33] and one comparing to epidural analgesia [29]. Purdy et al. [33] included three groups: RSB with intermittent dosing, RSB with continuous infusion, and a control (opioid analgesia). The catheters were placed by the surgeon in the Purdy et al. [33] study and under ultrasound guidance by an anesthesiologist in the Yassin 2017 study.

Purdy et al. [33] found no differences in the 48-h pain scores between the three groups. The means and standard deviations were not available for meta-analysis. The intermittent dosing group had lower pain at rest at 12 h; all other time points were not significantly different [33]. Similarly, Yassin et al. [27] found no differences in pain scores at any time point [29]. In terms of opioid consumption at 48 h, Purdy et al. [33] found a reduction among both RSB groups compared to multimodal analgesia (Fig. 2), whereas Yassin et al. [27] found opioid consumption to be significantly lower in the epidural group compared to the RSB group (Fig. 3).

Paravertebral catheters

Two randomized trials on paravertebral catheters met the inclusion criteria [22,27]. Hutchins et al. [22] studied 48 patients undergoing open pancreatic surgery randomized to T8 paravetebral catheters or T7-8 epidurals. This trial found that while opioid consumption was decreased within the first 24 h in the epidural group, there was no difference in opioid consumption at other time points (Fig. 3). Moreover, there was no significant difference in pain scores.

In a pragmatic randomized trial of 70 patients comparing bilateral paravertebral versus epidurals, all inserted between T7 and T9, Sondekoppam et al. [27] found that paravertebral catheters provided non-inferior analgesia for the primary outcome of 24-h pain score with movement. Within the follow-up period of 72 h, there was no significant difference in pain scores or opioid consumption. The LOS in hospital was also similar (MD: -1.40 days, 95% CI [-4.31, 1.51], P = 0.34, I2 = 23%, two studies, 116 patients) (Supplementary Fig. 3).

Overall comparison and sensitivity analyses

Primary outcomes

When comparing the combined effects of all CPNB studies, there was no statistically significant difference in pain scores between CPNB and either multimodal analgesia or epidural analgesia (MD: -0.35, 95% CI [-0.77, 0.07], P = 0.10, I2 = 95%, 10 studies, 909 patients; MD: 0.45, 95% CI [-0.13, 1.04], P = 0.13, I2 = 84%, eight studies, 375 patients, respectively) (Tables 2 and 3). Patients receiving CPNB used significantly less opioids than those receiving multimodal analgesia (MD: -31.52, 95% CI [-42.81, -20.22], P < 0.001, I2 = 93%, 13 studies, 970 patients). This was observed for the subgroups receiving continuous wound and preperitoneal catheters (Fig. 2). There was no statistically significant difference in opioid use between CPNB and epidural analgesia in the overall comparison (MD: 16.13, 95% CI [-0.10, 32.36], P = 0.05, I2 = 94%, eight studies, 342 patients); however, opioid consumption was reduced in patients receiving epidural analgesia in the preperitoneal, rectus sheath, and paravertebral subgroups (Fig. 3).

Summary of Findings for Continuous Peripheral Nerve Block (CPNB) Compared to Multimodal for Patients Undergoing Surgery via Midline Laparotomy

Summary of Findings for Continuous Peripheral Nerve Block (CPNB) Compared to Epidural Analgesia for Patients Undergoing Surgery via Midline Laparotomy

Secondary outcomes

Length of hospital stay was significantly shorter for the epidural group compared to the CPNB group (MD: 0.78 days, 95% CI [0.27, 1.29], P = 0.003, I2 = 59%, eight studies, 399 patients, Table 3 & Supplementary Fig. 3) and again less for the CPNB group compared to multimodal analgesia (MD: -1.41 days, 95% CI [-2.45, -0.36], P = 0.008, I2 = 98%, eight studies, 770 patients, Table 2 & Supplementary Fig. 2). PONV was not statistically significantly different between either multimodal or epidural analgesia overall (odds ratio [OR]: 0.89, 95% CI [0.72, 1.10], P = 0.30, I2 = 0%, seven studies, 568 patients; OR: 1.02, 95% CI [0.56, 1.86], P = 0.96, I2 = 36%, five studies, 265 patients), nor for any of the subgroups (Tables 2 and 3).

Sensitivity analyses

We examined the robustness of the main outcomes by conducting a series of sensitivity analyses (Supplementary Table 3). Nine studies had two or more domains that were deemed to have high risk of bias [2123,2628,32,42,46]. In the primary analyses, the difference in opioid consumption between CPNBs and epidurals only bordered on statistical significance. However, there was a significant difference in opioid consumption favoring epidurals once the high risk of bias studies were removed (MD: 16.66, 95% CI [2.48, 30.84], P = 0.02, I2 = 96%, five studies, 205 patients). Removing the high risk of bias studies resulted in the LOS difference becoming non-significant between CPNB and multimodal analgesia (MD: -1.57 days, 95% CI [-3.61, 0.48], P = 0.13, I2 = 88%, six studies, 570 patients). Other outcomes were minimally affected by removing the high risk of bias studies.

The only two studies that included patients with a lower midline incision were removed to examine the effect [30,42]. Removing these studies had minimal effect on the pain scores, PONV, opioid consumption, or LOS. The two cohort studies comparing CPNBs to multimodal analgesia were removed to examine the effect [31,32]. Removing cohort studies had minimal effect on pain scores, PONV, and opioid consumption. However, the difference in LOS became a statistical non-significant result (MD: -1.29 days, 95% CI [-3.16, 0.57], P = 0.17, I2 = 94%, seven studies, 670 patients).

Eight studies [21,22,26,27,34,4345] used opioids in the epidural solution while four studies [24,29,36,46] used only local anesthetics. Removing the studies that did not use opioids in the epidural solution did not change the effect size of pain scores but made the results statistically significant (MD: 0.48, 95% CI [0.34, 0.61], P < 0.001, I2 = 0%, four studies, 216 patients). Only one study explicitly stated that epidural opioids were included in the calculation of cumulative opioid consumption [26]. Removing these studies reduced the effect size of opioid consumption between CPNB and epidural analgesia (MD: 4.48 mg, 95% CI [-14.95, 23.91 mg], P = 0.65, I2 = 93%, four studies, 183 patients). Removing these studies had minimal effect on the LOS and PONV rates.

Discussion

The use of CPNBs, often in the form of fascial plane blocks, is increasingly common [47]. The popularity of these techniques has grown in response to the potential complications and drawbacks of neuraxial analgesia such as hypotension from sympathetic blockade, leg weakness, epidural hematomas, and epidural abscesses [47]. However, many of these techniques are relatively new and their efficacy has not been established relative to epidural analgesia, opioid analgesia, or to one another.

We found that pain scores were not significantly different when comparing the combined effect of all CPNBs to either multimodal or epidural analgesia for abdominal surgery via a midline laparotomy. Our meta-analysis found that opioid consumption was significantly less for CPNBs compared to conventional analgesia with opioids, particularly for wound, preperitoneal, and rectus sheath catheters. There was no significant difference in opioid consumption when comparing CPNBs as a whole to epidural analgesia. However, opioid consumption was significantly less for patients receiving epidural analgesia when compared to preperitoneal, rectus sheath, and paravertebral catheters. In a number of cases, this review states that there are no significant differences between CPNBs and either multimodal or epidural analgesia. This does not necessarily imply equivalency between the two techniques, but rather insufficient data to suggest superiority of one technique over the other. This is particularly true when a small number of studies are used in the comparison. Although meta-analysis seeks to increase statistical power by combining studies, the power may decrease when a small number of studies are included. Because the random-effects model accounts for between-study variation, five or more studies are required to reliably achieve greater power than the primary studies [48].

Overall, the main findings of this review were robust, being only minimally influenced by the sensitivity analyses. Removing studies with procedures using lower midline incisions did not significantly change the results of the meta-analyses. When studies with two or more high risk of bias domains were removed from the opioid consumption, comparison moved from bordering on statistical significance to favoring epidurals; however, the change in effect size between groups was negligible. LOS was the most sensitive to removing high risk studies. When high risk of bias and cohort studies were removed the difference in LOS became not statistically significant with the point estimate moving in the opposite direction.

One area of concern is that we were not able to determine whether most studies included opioids administered via the epidural route in the calculation of total cumulative opioid consumption. This was only explicitly stated in one study. This may have a large impact on whether one technique is favored over another in terms of opioid reduction for a few reasons. Although there is some uncertainty about equianalgesic dose conversion from IV systemic to epidural opioids, the most commonly cited conversion is 10 : 1 for both morphine and hydromorphone [49]. Thus, even low dose opioids added to epidural solutions can contribute to a large proportion of the cumulative opioid consumption. Furthermore, the patients would receive this amount of opioid regardless of whether they needed it. This creates a conflict for pain research because including epidural opioids in the cumulative opioid consumption will favor other techniques, while not including them will favor epidurals. Our recommendation is future studies comparing CPNB to epidural analgesia use only local anesthetic without opioids in the epidural solution if using opioid consumption as an outcome. The next best option is to be very explicit in the method of equianalgesic opioid conversion from the epidural solution to the cumulative opioid consumption.

The majority of studies in this review had at least one domain that was deemed to have high potential for bias. Our ability to draw firm conclusions from this review was hampered by this high risk of bias. However, removing the studies with two or more domains of high risk of bias did not influence the pain score comparison. The finding that epidurals may reduce opioids more than CPNBs was strengthened when removing these studies and the finding that CPNBs may reduce LOS compared to multimodal analgesia was lessened. Overall, if bias was influencing the results of the studies, it seems to exaggerate the benefits of CPNBs in our included studies.

In addition to the risk of bias, our ability to draw conclusions was limited by heterogeneity. There was some clinical heterogeneity between studies due to various types of surgery and practice patterns regarding the type and dose of analgesics and adjuncts. However, pooled results for pain scores and opioid consumption were deemed acceptable by our team since the bulk of postoperative pain originates from the abdominal wall [50]. All included studies involved a midline incision and each intervention was aimed at reducing afferent nociceptive signaling from the thoracoabdominal nerves. There was also statistical heterogeneity found in many of our analyses. This was expected given the practice variation in terms of pain management and uses of adjunct therapies. The heterogeneity seen in terms of pain and opioid consumption also relates strongly to the type of surgery. Despite these differences, the pooled results were deemed acceptable given that in each case the two comparison groups were undergoing the same surgical procedure and were subject to the same pain management practice patterns. Ideally, we would have compared various CPNB techniques to one another using a network meta-analysis. We contemplated this but decided that, given the degree of clinical and statistical heterogeneity described above, the assumptions of transitivity and consistency would not be met.

This review did not find evidence of superior pain scores between CPNBs and either multimodal or epidural analgesia. CPNBs may decrease postoperative opioid consumption and hospital LOS compared to multimodal analgesia. Epidural analgesia may further decrease opioid consumption and LOS when compared to CPNBs. CPNBs should be considered a viable alternative to epidural analgesia when contraindications to epidural placement exist for patients undergoing midline laparotomies. Future studies should directly compare various CPNB techniques to one another. Future systemic reviews should seek to directly or indirectly compare various CPNB techniques once enough high-quality studies allow assumptions to be met.

Notes

Funding

CM received financial assistance from the Dr. Thomas Coonan Anesthesia, Pain & Perioperative Medicine Studentship and JJ Carroll Travel Fund Award through the Dalhousie Medical Research Foundation (Halifax, Canada).

Conflicts of Interest

No potential conflict of interest relevant to this article was reported.

Author Contributions

Jonathan G. Bailey (Conceptualization; Data curation; Formal analysis; Investigation; Methodology; Project administration; Supervision; Writing – original draft)

Catherine W Morgan (Data curation; Formal analysis; Funding acquisition; Project administration; Writing – review & editing)

Russell Christie (Data curation; Formal analysis; Investigation; Writing – review & editing)

Janny Xue Chen Ke (Data curation; Formal analysis; Investigation; Writing – review & editing)

M. Kwesi Kwofie (Conceptualization; Writing – review & editing)

Vishal Uppal (Conceptualization; Formal analysis; Methodology; Writing – review & editing)

Supplementary Materials

Supplementary Table 1.

Search strategy for Embase, Cochrane, and MEDLINE databases

Supplementary Table 2.

OpenGrey search strategy (adapted from the MEDLINE search)

Supplementary Table 3.

Summarized results of sensitivity analyses

Supplementary Fig. 1.

Funnel plot to assess publication bias for studies comparing pain scores and cumulative opioid consumption between continuous peripheral nerve blocks (CPNB) and multimodal analgesia. A: pain scores, B: opioid consumption, MD: mean difference, TAP: transversus abdominus plane, SE: standard error

Supplementary Fig. 2.

Length of stay (LOS) in hospital comparing between continuous peripheral nerve blocks (CPNB) and multimodal analgesia for patients undergoing midline laparotomy. CPNB: continuous peripheral nerve block, IV: inverse variance, PCA: patient-controlled analgesia, SD: standard deviation, green color: low risk of bias, yellow color: unclear/moderate risk of bias, red color: high risk of bias, bold text: indicates subgroups, subtotal and total effect sizes and weighting.

Supplementary Fig. 3.

Length of stay in hospital comparing between continuous peripheral nerve blocks (CPNB) and epidural analgesia for patients undergoing midline laparotomy. CPNB: continuous peripheral nerve block, IV: inverse variance, SD: standard deviation, green color: low risk of bias, yellow color: unclear/moderate risk of bias, red color: high risk of bias, bold text: indicates subgroups, subtotal and total effect sizes and weighting.

References

1. Nunoo-Mensah JW, Rosen M, Chan LS, Wasserberg N, Beart RW. Prevalence of intra-abdominal surgery: what is an individual’s lifetime risk? South Med J 2009;102:25–9.
2. Baker GR, Norton PG, Flintoft V, Blais R, Brown A, Cox J, et al. The Canadian Adverse Events Study: the incidence of adverse events among hospital patients in Canada. CMAJ 2004;170:1678–86.
3. Joshi GP, Ogunnaike BO. Consequences of inadequate postoperative pain relief and chronic persistent postoperative pain. Anesthesiol Clin North Am 2005;23:21–36.
4. Sabaté S, Mazo V, Canet J. Predicting postoperative pulmonary complications: implications for outcomes and costs. Curr Opin Anaesthesiol 2014;27:201–9.
5. Haines KJ, Skinner EH, Berney S, ; Austin Health POST Study Investigators. Association of postoperative pulmonary complications with delayed mobilisation following major abdominal surgery: an observational cohort study. Physiotherapy 2013;99:119–25.
6. Overdyk FJ, Dowling O, Marino J, Qiu J, Chien HL, Erslon M, et al. Association of opioids and sedatives with increased risk of in-hospital cardiopulmonary arrest from an administrative database. PLoS One 2016;11e0150214.
7. Lee LA, Caplan RA, Stephens LS, Posner KL, Terman GW, Voepel-Lewis T, et al. Postoperative opioid-induced respiratory depression: a closed claims analysis. Anesthesiology 2015;122:659–65.
8. Manion SC, Brennan TJ. Thoracic epidural analgesia and acute pain management. Anesthesiology 2011;115:181–8.
9. Nishimori M, Low JH, Zheng H, Ballantyne JC. Epidural pain relief versus systemic opioid-based pain relief for abdominal aortic surgery. Cochrane Database Syst Rev 2012;(7):CD005059.
10. Chou R, Gordon DB, De Leon-Casasola OA, Rosenberg JM, Bickler S, Brennan T, et al. Management of postoperative pain: a clinical practice guideline from the American Pain Society, the American Society of Regional Anesthesia and Pain Medicine, and the American Society of Anesthesiologists’ Committee on Regional Anesthesia, Executive Committee, and Administrative Council. J Pain 2016;17:131–57.
11. Feldheiser A, Aziz O, Baldini G, Cox BP, Fearon KC, Feldman LS, et al. Enhanced Recovery After Surgery (ERAS) for gastrointestinal surgery, part 2: consensus statement for anaesthesia practice. Acta Anaesthesiol Scand 2016;60:289–334.
12. Rawal N. Epidural technique for postoperative pain: gold standard no more? Reg Anesth Pain Med 2012;37:310–7.
13. Bonnet F, Berger J, Aveline C. Transversus abdominis plane block: what is its role in postoperative analgesia? Br J Anaesth 2009;103:468–70.
14. Johns N, O’Neill S, Ventham NT, Barron F, Brady RR, Daniel T. Clinical effectiveness of transversus abdominis plane (TAP) block in abdominal surgery: a systematic review and meta-analysis. Colorectal Dis 2012;14:e635–42.
15. El-Boghdadly K, Madjdpour C, Chin KJ. Thoracic paravertebral blocks in abdominal surgery - a systematic review of randomized controlled trials. Br J Anaesth 2016;117:297–308.
16. Ventham NT, Hughes M, O’Neill S, Johns N, Brady RR, Wigmore SJ. Systematic review and meta-analysis of continuous local anaesthetic wound infiltration versus epidural analgesia for postoperative pain following abdominal surgery. Br J Surg 2013;100:1280–9.
17. Hurley RW, Murphy JD, Wu CL. Acute postoperative pain. In: Miller’s Anesthesia 8th edth ed. In : Miller R, Eriksson L, Fleisher L, Wiener-Kronish J, Young NC, eds. Philadelphia: Elsevier/Saunders; 2015. p. 2974–98.
18. Hayden JA, Cote P, Bombardier C. Evaluation of the quality of prognosis studies in systematic reviews. Ann Intern Med 2006;144:427–37.
19. Higgins JP, Thomas J, Chandler J, Cumpston M, Li T, Page MJ, et al. Cochrane Handbook for Systematic Reviews of Interventions version 6.1 [Internet]. London: Cochrane Training; 2020 Sep [cited 2020 Jun 10]. Available from www.training.cochrane.org/handbook.
20. Moher D, Liberati A, Tetzlaff J, Altman DG, ; PRISMA Group. Preferred reporting items for systematic reviews and meta-analyses: the PRISMA statement. BMJ 2009;339:b2535.
21. Araujo R, Marques C, Fernandes D, Almeida E, Alves J, Rodrigues M, et al. Pain management, local infection, satisfaction, adverse effects and residual pain after major open abdominal surgery: epidural versus continuous wound infusion (PAMA trial). Acta Med Port 2017;30:683–90.
22. Hutchins JL, Grandelis AJ, Kaizer AM, Jensen EH. Thoracic paravertebral block versus thoracic epidural analgesia for post-operative pain control in open pancreatic surgery: a randomized controlled trial. J Clin Anesth 2018;48:41–5.
23. Kadam RV, Field JB. Ultrasound-guided continuous transverse abdominis plane block for abdominal surgery. J Anaesthesiol Clin Pharmacol 2011;27:333–6.
24. Mouawad NJ, Leichtle SW, Kaoutzanis C, Welch K, Winter S, Lampman R, et al. Pain control with continuous infusion preperitoneal wound catheters versus continuous epidural analgesia in colon and rectal surgery: a randomized controlled trial. Am J Surg 2018;215:570–6.
25. Ozturk E, Yilmazlar A, Coskun F, Isik O, Yilmazlar T. The beneficial effects of preperitoneal catheter analgesia following colon and rectal resections: a prospective, randomized, double-blind, placebo-controlled study. Tech Coloproctol 2011;15:331–6.
26. Shaker TM, Carroll JT, Chung MH, Koehler TJ, Lane BR, Wolf AM, et al. Efficacy and safety of transversus abdominis plane blocks versus thoracic epidural anesthesia in patients undergoing major abdominal oncologic resections: a prospective, randomized controlled trial. Am J Surg 2018;215:498–501.
27. Sondekoppam RV, Uppal V, Brookes J, Ganapathy S. Bilateral thoracic paravertebral blocks compared to thoracic epidural analgesia after midline laparotomy: a pragmatic noninferiority clinical trial. Anesth Analg 2019;129:855–63.
28. Wang LW, Wong SW, Crowe PJ, Khor KE, Jastrzab G, Parasyn AD, et al. Wound infusion with local anaesthesia after laparotomy: a randomized controlled trial. ANZ J Surg 2010;80:794–801.
29. Yassin HM, Abd Elmoneim AT, El Moutaz H. The analgesic efficiency of ultrasound-guided rectus sheath analgesia compared with low thoracic epidural analgesia after elective abdominal surgery with a midline incision: a prospective randomized controlled trial. Anesth Pain Med 2017;7e14244.
30. Kristensen BS, Fenger-Eriksen C, Pedersen KV, Felsby S. Wound infusion of bupivacaine following radical retropubic prostatectomy: a randomised placebo-controlled clinical study. Eur J Anaesthesiol 2013;30:124–8.
31. Beaussier M, El'ayoubi H, Rollin M, Parc Y, Atchabahian A, Chanques G, et al. Parietal analgesia decreases postoperative diaphragm dysfunction induced by abdominal surgery: a physiologic study. Reg Anesth Pain Med 2009;34:393–7.
32. Fayezizadeh M, Majumder A, Neupane R, Elliott HL, Novitsky YW. Efficacy of transversus abdominis plane block with liposomal bupivacaine during open abdominal wall reconstruction. Am J Surg 2016;212:399–405.
33. Purdy M, Kinnunen M, Kokki M, Anttila M, Eskelinen M, Hautajärvi H, et al. A prospective, randomized, open label, controlled study investigating the efficiency and safety of 3 different methods of rectus sheath block analgesia following midline laparotomy. Medicine (Baltimore) 2018;97e9968.
34. Zheng X, Feng X, Cai XJ. Effectiveness and safety of continuous wound infiltration for postoperative pain management after open gastrectomy. World J Gastroenterol 2016;22:1902–10.
35. Krishnan S, Morris RG, Hewett PJ, Field J, Karatassas A, Tou S, et al. A randomized double-blind clinical trial of a continuous 96-hour levobupivacaine infiltration after open or laparoscopic colorectal surgery for postoperative pain management--including clinically important changes in protein binding. Ther Drug Monit 2014;36:202–10.
36. Wahba SS, Kamal SM. Analgesic efficacy and outcome of transversus-abdominis plane block versus low thoracic-epidural analgesia after laparotomy in ischemic heart disease patients. J Anesth 2014;28:517–23.
37. Kahokehr A, Sammour T, Zargar Shoshtari K, Taylor M, Hill AG. Intraperitoneal local anesthetic improves recovery after colon resection: a double-blinded randomized controlled trial. Ann Surg 2011;254:28–38.
38. Polglase AL, McMurrick PJ, Simpson PJ, Wale RJ, Carne PW, Johnson W, et al. Continuous wound infusion of local anesthetic for the control of pain after elective abdominal colorectal surgery. Dis Colon Rectum 2007;50:2158–67.
39. Baig MK, Zmora O, Derdemezi J, Weiss EG, Nogueras JJ, Wexner SD. Use of the ON-Q pain management system is associated with decreased postoperative analgesic requirement: double blind randomized placebo pilot study. J Am Coll Surg 2006;202:297–305.
40. Beaussier M, El’Ayoubi H, Schiffer E, Rollin M, Parc Y, Mazoit JX, et al. Continuous preperitoneal infusion of ropivacaine provides effective analgesia and accelerates recovery after colorectal surgery: a randomized, double-blind, placebo-controlled study. Anesthesiology 2007;107:461–8.
41. Dhanapal B, Sistla SC, Badhe AS, Ali SM, Ravichandran NT, Galidevara I. Effectiveness of continuous wound infusion of local anesthetics after abdominal surgeries. J Surg Res 2017;212:94–100.
42. Wu CL, Partin AW, Rowlingson AJ, Kalish MA, Walsh PC, Fleisher LA. Efficacy of continuous local anesthetic infusion for postoperative pain after radical retropubic prostatectomy. Urology 2005;66:366–70.
43. Ball L, Pellerano G, Corsi L, Giudici N, Pellegrino A, Cannata D, et al. Continuous epidural versus wound infusion plus single morphine bolus as postoperative analgesia in open abdominal aortic aneurysm repair: a randomized non-inferiority trial. Minerva Anestesiol 2016;82:1296–305.
44. El-feky EM, El Azez AAA, Amar MS. A comparative study of the postoperative analgesic efficacy of continuous thoracic epidural versus continuous preperitoneal wound infusion during open colorectal surgery. Res Opin Anesth Intensive Care 2014;2:43–51.
45. Jouve P, Bazin JE, Petit A, Minville V, Gerard A, Buc E, et al. Epidural versus continuous preperitoneal analgesia during fast-track open colorectal surgery: a randomized controlled trial. Anesthesiology 2013;118:622–30.
46. Rao Kadam V, Van Wijk RM, Moran JI, Miller D. Epidural versus continuous transversus abdominis plane catheter technique for postoperative analgesia after abdominal surgery. Anaesth Intensive Care 2013;41:476–81.
47. Albrecht E, Chin KJ. Advances in regional anaesthesia and acute pain management: a narrative review. Anaesthesia 2020;75 Suppl 1:e101–10.
48. Jackson D, Turner R. Power analysis for random-effects meta-analysis. Res Synth Methods 2017;8:290–302.
49. Gorlin AW, Rosenfeld DM, Maloney J, Wie CS, McGarvey J, Trentman TL. Survey of pain specialists regarding conversion of high-dose intravenous to neuraxial opioids. J Pain Res 2016;9:693–700.
50. Gebhart GF, Bielefeldt K. Physiology of visceral pain. Compr Physiol 2016;6:1609–33.

Article information Continued

Fig. 1.

Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) flow chart of included studies.

Fig. 2.

Cumulative opioid consumption (in oral morphine equivalents) at 48 h comparing between continuous peripheral nerve blocks (CPNB) and multimodal analgesia for patients undergoing midline laparotomy. CPNB: continuous peripheral nerve block, IV: inverse variance, PCA: patient-controlled analgesia, SD: standard deviation, green color: low risk of bias, yellow color: unclear/moderate risk of bias, red color: high risk of bias, bold text: indicates subgroups, subtotal and total effect sizes and weighting.

Fig. 3.

Cumulative opioid consumption (in oral morphine equivalents) at 48 h comparing between continuous peripheral nerve blocks (CPNB) and epidural analgesia for patients undergoing midline laparotomy. CPNB: continuous peripheral nerve block, IV: inverse variance, SD: standard deviation, green color: low risk of bias, yellow color: unclear/moderate risk of bias, red color: high risk of bias, bold text: indicates subgroups, subtotal and total effect sizes and weighting.

Table 1.

Characteristics of Included Studies Comparing Continuous Peripheral Nerve Blockade (CPNB) to Multimodal and Epidural Analgesia for Patients Undergoing Midline Laparotomy

n
Age
Sex
BMI
Local anesthetic
Author, year Country CPNB Control Mean (SD) years
% (male) Mean (SD) m2/kg
Agent Infusion (ml/h) Intermittent (ml, qh) Surgical procedure
CPNB Control CPNB Control CPNB type Placed by
A. Multimodal
Polglase 2007 Australia 143 167 67 14 65 13 48 53 NR NR NR NR Wound Surgeon Ropi 0.5% 4 n/a Colorectal
Wang 2010 Australia 28 27 65 23 70 22 57 52 NR NR NR NR Wound Surgeon Ropi 0.2% 4 n/a Colorectal
Zheng 2016* China 25 13 62 13 64 10 64 68 23 2 23 4 Wound Surgeon Ropi 0.3% 5 n/a Gastrectomy
Baig 2006 USA 35 35 56 18 59 16 57 77 25 4 27 5 Intraperitoneal Surgeon Ropi 0.5% 4 n/a Colectomy
Kahokehr 2011 New Zealand 30 30 63 15 63 19 33 43 29 5 27 5 Intraperitoneal NR Ropi 0.2% 8 n/a Colectomy
Beaussier 2007 France 21 21 58 10 62 9 67 52 NR NR NR NR Preperitoneal Surgeon Ropi 0.2% 10 n/a Colorectal
Beaussier 2009 France 10 10 57 15 55 15 50 50 NR NR NR NR Preperitoneal Surgeon Ropi 0.2% 10 n/a Colorectal
Dhanapal 2017 India 47 47 53 13 54 11 66 68 21 1 21 1 Preperitoneal Surgeon Bupi 0.25% 6 n/a UGI, Hemicolectomy
Krishnan 2014 Australia 24 6 66 11 65 19 58 67 29 6 28 6 Preperitoneal Surgeon Levobupi 0.25% 10 n/a Colorectal
Kristensen 2013 Denmark 25 25 64 4 66 5 100 100 NR NR NR NR Preperitoneal Surgeon Bupi 0.25% 5 n/a Prostatectomy
Ozturk 2011 Turkey 25 25 59 12 56 12 36 48 27 4 26 4 Preperitoneal Surgeon Levobupi 0.25% n/a 10 ml q12h Colorectal
Wu 2005 USA 50 50 55 7 57 7 100 100 NR NR NR NR Preperitoneal Surgeon Bupi 0.5% 2 n/a Prostatectomy
Purdy 2018 Finland 17 6 58 12 61 14 12 33 25 4 28 3 Rectus Surgeon Levobupi 0.125% 10 n/a Multiple
Purdy 2018 Finland 12 6 62 10 61 14 25 33 25 4 28 3 Rectus Surgeon Levobupi 0.125% n/a 25 mg q4h Multiple
Fayezizadeh 2016 USA 50 50 60 12 59 14 64 28 36 8 36 8 TAP Surgeon LB + Bupi 0.25% n/a n/a Ventral hernia
Kadam 2011 Australia 10 10 NR NR NR NR NR NR NR NR NR NR TAP Anesthesia Ropi 0.2% 8–10 n/a Multiple
B. Epidural
Zheng 2016§ China 25 12 62 13 62 10 64 56 23 2 23 3 Wound Surgeon Ropi 0.3% 5 n/a Gastrectomy
Araujo 2017 Portugal 25 25 68 12 62 18 36 44 NR NR NR NR Preperitoneal Surgeon Ropi 0.2% 10 n/a Colorectal,
UGI, HPB
Ball 2016 Italy 26 25 73 3 74 2 92 84 26 3 27 3 Preperitoneal Surgeon Levobupi 0.25% 4 n/a Open AAA
El Feky 2014 Egypt 28 28 59 4 59 4 64 57 NR NR NR NR Preperitoneal Surgeon Bupi 0.25% 10 n/a Colorectal
Jouve 2013 France 26 24 68 9 63 12 50 54 NR NR NR NR Preperitoneal Surgeon Ropi 0.2% 10 n/a Colorectal
Mouawad 2018 USA 7 6 56 17 60 16 43 67 31 10 32 8 Preperitoneal Surgeon Bupi 0.5% 4–5 n/a Colorectal
Rao Kadam 2013 Australia 22 20 64 10 61 13 64 70 NR NR NR NR TAP Anesthesia Ropi 0.2% 8 n/a Colorectal, urology, UGI
Shaker 2018 USA 24 23 59 13 62 14 NR NR 29 8 28 4 TAP Anesthesia LB + Bupi 0.5% n/a n/a Multiple
Wahba 2014 Egypt 22 22 66 5 66 5 50 45 31 4 31 3 TAP Anesthesia Bupi 0.25% n/a 30 ml q8h Colorectal, UGI, hernia
Yassin 2017 Egypt 29 31 48 9 48 12 23 21 28 2 28 1 Rectus Anesthesia Bupi 0.25% n/a 20 ml q8hr UGI, HPB
Hutchins 2018 USA 25 23 68 12 64 9 48 61 NR NR NR NR Paravertebral Anesthesia Ropi 0.2% 14 n/a Pancreatectomy
Sondekoppam 2019 Canada 34 34 60 14 62 13 65 56 28 6 27 5 Paravertebral Anesthesia Ropi 0.2% 7 n/a Colorectal, HPB
*

Zheng et al. patient-controlled analgesia group.

Purdy et al. continuous group.

Purdy et al. intermittent dosing group.

§

Zheng et al. epidural group.

AAA: aortic abdominal aneurysm, BMI: body mass index, Bupi: bupivacaine, CPNB: continuous peripheral nerve blockade, HPB: hepatobiliary, LB: liposomal bupivacaine, Levobupi: levobupivacaine, n: number, N/a: not applicable, NR: not reported, Ropi: ropivacaine, SD: standard deviation, TAP: transversus abdominus plane, UGI: upper gastrointestinal.

Table 2.

Summary of Findings for Continuous Peripheral Nerve Block (CPNB) Compared to Multimodal for Patients Undergoing Surgery via Midline Laparotomy

Outcomes Anticipated absolute effects (95% CI) Relative effect (95% CI) No. of participants (studies) Certainty of the evidence (GRADE) Comments
Risk with usual care Risk with CPNB
Pain assessed with: Numeric Rating Scale The mean pain score was 2.1 MD 0.35 lower (0.77 lower to 0.07 higher) - 909 (9 RCTs, 1 cohort) ⨁⨁◯◯ The evidence suggests that CPNB results in little to no difference in pain.
Low,
Opioid consumption assessed with: Oral morphine equivalents The mean opioid consumption was 92.9 mg MD 31.52 mg lower (42.81 lower to 20.22 lower) - 970 (11 RCTs, 2 cohorts) ⨁⨁◯◯ The evidence suggests CPNB reduces opioid consumption.
Low,
Length of hospital stay assessed with: days The mean length of hospital stay was 7.2 d MD 1.41 d lower (2.45 lower to 0.36 lower) - 770 (7 RCTs, 1 cohort) ⨁⨁◯◯ The evidence suggests CPNB reduces length of hospital stay.
Low,
Postoperative nausea and vomiting 127 per 1,000 113 per 1,000 (91 to 140) RR 0.89 (0.72 to 1.10) 568 (7 RCTs) ⨁⨁⨁⨁ CPNB results in little to no difference in PONV.
High

The risk in the intervention group (and its 95% CI) is based on the assumed risk in the comparison group and the relative effect of the intervention (and its 95% CI).

The majority of included studies had at least one high risk of bias domain.

There was statistically significant heterogeneity.

CPNB: continuous peripheral nerve block, MD: mean difference, OR: odds ratio; PONV: postoperative nausea and vomiting, RCT: randomized controlled trial, RR: relative risk.

GRADE Working Group grades of evidence

High certainty: We are very confident that the true effect lies close to that of the estimate of the effect. Moderate certainty: We are moderately confident in the effect estimate: the true effect is likely to be close to the estimate of the effect, but there is a possibility that it is substantially different. Low certainty: Our confidence in the effect estimate is limited: the true effect may be substantially different from the estimate of the effect. Very low certainty: We have very little confidence in the effect estimate: the true effect is likely to be substantially different from the estimate of the effect.

Table 3.

Summary of Findings for Continuous Peripheral Nerve Block (CPNB) Compared to Epidural Analgesia for Patients Undergoing Surgery via Midline Laparotomy

Outcomes Anticipated absolute effects* (95% CI)
Relative effect (95% CI) No. of participants (studies) Certainty of the evidence (GRADE) Comments
Risk with epidural analgesia Risk with CPNB
Pain assessed with: Numeric rating scale The mean pain score was 1.8 MD 0.45 higher (0.13 lower to 1.04 higher) - 375 (8 RCTs) ⨁⨁◯◯ The evidence suggests that CPNB results in little to no difference in pain.
Low,
Opioid consumption assessed with: Oral morphine equivalents The mean opioid consumption was 35.4 mg MD 16.13 mg higher (0.10 lower to 32.36 higher) - 342 ⨁⨁◯◯ The evidence suggests epidural analgesia slightly decreases opioid consumption compared to CPNB.
(8 RCTs) Low,
Length of hospital stay assessed with: days The mean length of hospital stay was 5.7 days MD 0.78 days higher (0.27 higher to 1.29 higher) - 399 (8 RCTs) ⨁⨁◯◯ The evidence suggests epidural analgesia decreases length of hospital stay compared to CPNB.
Low,
Postoperative nausea and vomiting 103 per 1,000 104 per 1,000 (60 to 175) OR 1.02 (0.56 to 1.86) 265 (5 RCTs) ⨁⨁⨁◯ CPNB likely results in little to no difference in PONV compared to epidural analgesia.
Moderate
*

The risk in the intervention group (and its 95% CI) is based on the assumed risk in the comparison group and the relative effect of the intervention (and its 95% CI).

The majority of included studies had at least one high risk of bias domain.

There was statistically significant heterogeneity.

CPNB: continuous peripheral nerve block, MD: mean difference, OR: odds ratio, PONV: postoperative nausea and vomiting, RCT: randomized controlled trial, RR: relative risk.

GRADE Working Group grades of evidence

High certainty: We are very confident that the true effect lies close to that of the estimate of the effect. Moderate certainty: We are moderately confident in the effect estimate: the true effect is likely to be close to the estimate of the effect, but there is a possibility that it is substantially different. Low certainty: Our confidence in the effect estimate is limited: the true effect may be substantially different from the estimate of the effect. Very low certainty: We have very little confidence in the effect estimate: the true effect is likely to be substantially different from the estimate of the effect