Continuous delivery of a local anaesthetic around the wound to treat pain after bowel surgery through a vertical cut in the abdomen

Background

People with bowel disease can be treated with surgery to remove a part of the bowel (colorectal resection). A long vertical cut in the abdomen (midline laparotomy) is often required. Recovery after this type of surgery can be slow and painful. Continuous injection of a local anaesthetic (numbing a specific area of the body, e.g. around the wound) may reduce pain after this type of surgery. The local anaesthetic may also reduce the amount of morphine-like pain killers required and side effects related to these medications. This could mean a shorter recovery time for the patient and earlier discharge from the hospital.

Study characteristics

We searched for clinical trials to January 2019 looking at the benefits and harms of continuous injection of a local anaesthetic after surgery to remove the bowel through a vertical cut in the abdomen. We looked for trials comparing local anaesthetic to an inactive substance (placebo) such as salty water (normal saline). We found six clinical trials including 541 participants. Most participants were aged 55 to 65 years, of varying health status from fit and healthy to having a severe systemic disease (a disease that affects the whole body).

Key findings

In people who received a local anaesthetic, pain at rest, pain on movement, and requirement for morphine-like pain killers were reduced on the first day after surgery compared to people who received an inactive substance.

People who received a local anaesthetic also opened their bowels about half a day earlier and were discharged from hospital about a day earlier compared to people who received an inactive substance.

We did not find a difference between people who received a local anaesthetic and those who received an inactive substance in the rates of any serious complications after surgery until hospital discharge.

Certainty of evidence

We rated the certainty of the evidence from studies using four levels: high, moderate, low, very low. Reasons for downgrading the certainty of the evidence included limitations problems with the design of the studies, missing data, differences between trials and how the outcomes were measured, and the small number of participants. We need more high-quality trials to evaluate this treatment, especially its effects on recovery after surgery, side effects and complications.

We rated the certainty of the evidence for pain after surgery at rest and the length of hospital stay as high, meaning that we are very confident in the findings about the effects of the treatment on these outcomes. We rated the certainty of the evidence for the requirement for morphine-like pain killers and the time until the first bowel movement as moderate. This means that we are moderately confident in the findings about the effects of the treatment on these outcomes. We rated the certainty of the evidence for pain after surgery on movement and the rates of any serious complications after surgery until hospital discharge as low, meaning that we have limited confidence in the findings about the effects of the treatment on these outcomes.

Authors' conclusions: 

After elective midline laparotomy for colorectal resection, continuous wound infusion of a local anaesthetic compared to a normal saline placebo reduces postoperative pain at rest and the length of hospital stay, on the basis of high-certainty evidence. This means we are very confident that the effect estimates for these outcomes lie close to the true effects. There is moderate-certainty evidence to indicate that the intervention probably reduces opioid consumption via PCA and the time to first bowel movement. This means we are moderately confident that effect estimates for these outcomes are likely to be close to the true effects, but there is a possibility that they are substantially different. The intervention may reduce postoperative pain on movement, however, this conclusion is based on low-certainty evidence. This means our confidence in the effect estimate is limited. The true effect may be substantially different from the estimate of the effect. There is low-certainty evidence to indicate that the intervention may have little or no effect on the rates of any serious postoperative adverse events until hospital discharge. High-quality randomised controlled trials to evaluate the intervention with a focus on important clinical and patient-centred outcomes are needed.

Read the full abstract...
Background: 

Colorectal resection through a midline laparotomy is a commonly performed surgical procedure to treat various bowel conditions. The typical postoperative hospital stay after this operation is 6 to 10 days. The main factors hindering early recovery and discharge are thought to include postoperative pain and delayed return of bowel function.

Continuous infusion of a local anaesthetic into tissues surrounding the surgical incision via a multi-lumen indwelling wound catheter placed by the surgeon prior to wound closure may reduce postoperative pain, opioid consumption, the time to return of bowel function, and the length of hospital stay.

Objectives: 

To evaluate the efficacy and adverse events of continuous local anaesthetic wound infusion for postoperative pain after midline laparotomy for colorectal resection in adults.

Search strategy: 

We searched the CENTRAL, MEDLINE and Embase databases to January 2019 to identify trials relevant to this review. We also searched reference lists of relevant trials and reviews for eligible trials. Additionally, we searched two clinical trials registers for ongoing trials.

Selection criteria: 

We considered randomised controlled trials (including non-standard designs) or quasi-randomised controlled trials comparing continuous wound infusion of a local anaesthetic versus a placebo or a sham after midline laparotomy for colorectal resection in adults. We did not compare continuous local anaesthetic wound infusion to other techniques, such as transverse abdominis plane block or thoracic epidural analgesia. We allowed non-randomised analgesic co-interventions carried out equally in the intervention and control groups.

Data collection and analysis: 

Two review authors independently identified trials for inclusion and assessed their quality using the Cochrane 'Risk of bias' tool. We extracted data using standardised forms, including pain at rest and on movement (10-point scale), opioid consumption via a patient-controlled analgesia (PCA) system (mg morphine equivalent), postoperative opioid-related adverse events, the time to rescue analgesia, the time to first flatus and to first bowel movement, the time to ambulation, the length of hospital stay, serious postoperative adverse events, and patient satisfaction. We quantitatively synthesised the data by meta-analysis. We summarised and graded the certainty of the evidence for critical outcomes using the GRADEpro tool and created a 'Summary of findings' table.

Main results: 

This review included six randomised controlled trials that enrolled a total of 564 adults undergoing elective midline laparotomy for colorectal resection comparing continuous wound infusion of a local anaesthetic to a normal saline placebo. Due to 23 post-randomisation exclusions, a total of 541 participants contributed data to the analysis of at least one outcome (local anaesthetic 268; control 273). Most participants were aged 55 to 65 years, with normal body mass index and low to moderate anaesthetic risk (American Society of Anesthesiologists class I-III). Random sequence generation, allocation concealment, and blinding were appropriately carried out in most trials. However, we had to downgrade the certainty of the evidence for most outcomes due to serious study limitations (risk of bias), inconsistency, indirectness, imprecision and reporting bias.

Primary outcomes

On postoperative day 1, pain at rest (mean difference (MD) −0.59 (from 3.1), 95% confidence interval (CI) −1.12 to −0.07; 5 studies, 511 participants; high-certainty evidence), pain on movement (MD −1.1 (from 6.1), 95% CI −2.3 to −0.01; 3 studies, 407 participants; low-certainty evidence) and opioid consumption via PCA (MD −12 mg (from 41 mg), 95% CI −20 to −4; 6 studies, 528 participants; moderate-certainty evidence) were reduced in the local anaesthetic group compared to the control group.

Secondary outcomes

There was a reduction in the time to first bowel movement (MD −0.67 from 4.4 days, 95% CI −1.17 to −0.17; 4 studies, 197 participants; moderate-certainty evidence) and the length of hospital stay (MD −1.2 from 7.4 days, 95% CI −2.0 to −0.3; 4 studies, 456 participants; high-certainty evidence) in the local anaesthetic group compared to the control group.

There was no evidence of a difference in any serious postoperative adverse events until hospital discharge (RR 1.04, 95% CI 0.68 to 1.58; 6 studies, 541 participants; low-certainty evidence) between the two study groups.

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