The comparison of epidural fentanyl, epidural lidocaine, and intravenous fentanyl in patients undergoing gastrectomy

Epidural analgesia versus patient-controlled intravenous analgesia for pain following intra-abdominal surgery in adults

BACKGROUND

Intravenous patient-controlled analgesia (IVPCA) with opioids and epidural analgesia (EA) using either continuous epidural administration (CEA) or patient-controlled (PCEA) techniques are popular approaches for analgesia following intra-abdominal surgery. Despite several attempts to compare the risks and benefits, the optimal form of analgesia for these procedures remains the subject of debate.

OBJECTIVES

The objective of this review was to update and expand a previously published Cochrane Review on IVPCA versus CEA for pain after intra-abdominal surgery with the addition of the comparator PCEA. We have compared both forms of EA to IVPCA. Where appropriate we have performed subgroup analysis for CEA versus PCEA.

SEARCH METHODS

We searched the following electronic databases for relevant studies: Cochrane Central Register of Controlled Trials (CENTRAL) (2017; Issue 8), MEDLINE (OvidSP) (1966 to September 2017), and Embase (OvidSP) (1988 to September 2017) using a combination of MeSH and text words. We searched the following trial registries: Australian New Zealand Clinical Trials Registry, ClinicalTrials.gov, and the EU Clinical Trials Register in September 2017, together with reference checking and citation searching to identify additional studies.We included only randomized controlled trials and used no language restrictions.

SELECTION CRITERIA

We included all parallel and cross-over randomized controlled trials (RCTs) comparing CEA or PCEA (or both) with IVPCA for postoperative pain relief in adults following intra-abdominal surgery.

DATA COLLECTION AND ANALYSIS

Two review authors (JS and EY) independently identified studies for eligibility and performed data extraction using a data extraction form. In cases of disagreement (three occasions) a third review author (MB) was consulted. We appraised each included study to assess the risk of bias as outlined in Section 8.5 of the Cochrane Handbook for Systematic Reviews of Interventions. We used GRADE to assess the quality of the evidence.

MAIN RESULTS

We included 32 studies (1716 participants) in our review. There are 10 studies awaiting classification and one ongoing study. A total of 869 participants (51%) received EA and 847 (49%) received IVPCA. The EA trials included 16 trials with CEA (418 participants) and 16 trials with PCEA (451 participants). The studies included a broad range of surgical procedures (including hysterectomies, radical prostatectomies, Caesarean sections, colorectal and upper gastrointestinal procedures), a wide range of adult ages, and were performed in several different countries.Our pooled analyses suggested a benefit with regard to pain scores (using a visual analogue scale between 0 and 100) in favour of EA techniques at rest. The mean pain reduction at rest from waking to six hours after operation was 5.7 points (95% confidence interval (CI) 1.9 to 9.5; 7 trials, 384 participants; moderate-quality evidence). From seven to 24 hours, the mean pain reduction was 9.0 points (95% CI 4.6 to 13.4; 11 trials, 558 participants; moderate-quality evidence). From 24 hours the mean pain reduction was 5.1 points (95% CI 0.9 to 9.4; 7 trials, 393 participants; moderate-quality evidence). Due to high statistical heterogeneity, no pooled analysis was possible for the estimation of pain on movement at any time. Two single studies (one using CEA and one PCEA) reported lower pain scores with EA compared to IVPCA at 0 to 6 hours and 7 to 24 hours. At > 24 hours the results from 2 studies (both CEA) were conflicting.We found no difference in mortality between EA and IVPCA, although the only deaths reported were in the EA group (5/287, 1.7%). The risk ratio (RR) of death with EA compared to using IVPCA was 3.37 (95% CI 0.72 to 15.88; 9 trials, 560 participants; low-quality evidence).A single study suggested that the use of EA may result in fewer episodes of respiratory depression, with an RR of 0.47 (95% CI 0.04 to 5.69; 1 trial; low-quality evidence). The successful placement of an epidural catheter can be technically challenging. The improvements in pain scores above were accompanied by an increase in the risk of failure of the analgesic technique with EA (RR 2.48, 95% CI 1.13 to 5.45; 10 trials, 678 participants; moderate-quality evidence); the occurrence of pruritus (RR 2.36, 95% CI 1.67 to 3.35; 8 trials, 492 participants; moderate-quality evidence); and episodes of hypotension requiring intervention (RR 7.13, 95% CI 2.87 to 17.75; 6 trials, 479 participants; moderate-quality evidence). There was no clear evidence of an advantage of one technique over another for other adverse effects considered in this review (Venous thromboembolism with EA (RR 0.32, 95% CI 0.03 to 2.95; 2 trials, 101 participants; low-quality evidence); nausea and vomiting (RR 0.94, 95% CI 0.69 to 1.27; 10 trials, 645 participants; moderate-quality evidence); sedation requiring intervention (RR 0.87, 95% CI 0.40 to 1.87; 4 trials, 223 participants; moderate-quality evidence); or episodes of desaturation to less than 90% (RR 1.29, 95% CI 0.71 to 2.37; 5 trials, 328 participants; moderate-quality evidence)).

AUTHORS' CONCLUSIONS

The additional pain reduction at rest associated with the use of EA rather than IVPCA is modest and unlikely to be clinically important. Single-trial estimates provide low-quality evidence that there may be an additional reduction in pain on movement, which is clinically important. Any improvement needs to be interpreted with the understanding that the use of EA is also associated with an increased chance of failure to successfully institute analgesia, and an increased likelihood of episodes of hypotension requiring intervention and pruritus. We have rated the evidence as of moderate quality given study limitations in most of the contributing studies. Further large RCTs are required to determine the ideal analgesic technique. The 10 studies awaiting classification may alter the conclusions of the review once assessed.

Epidural local anaesthetics versus opioid-based analgesic regimens for postoperative gastrointestinal paralysis, vomiting and pain after abdominal surgery

BACKGROUND

Gastrointestinal paralysis, nausea and vomiting and pain are major clinical problems following abdominal surgery. Anaesthetic and analgesic techniques that reduce pain and postoperative nausea and vomiting (PONV), while preventing or reducing postoperative ileus, may reduce postoperative morbidity, duration of hospitalization and hospital costs. This review was first published in 2001 and was updated by new review authors in 2016.

OBJECTIVES

To compare effects of postoperative epidural analgesia with local anaesthetics versus postoperative systemic or epidural opioids in terms of return of gastrointestinal transit, postoperative pain control, postoperative vomiting, incidence of anastomotic leak, length of hospital stay and costs after abdominal surgery.

SEARCH METHODS

We identified trials by conducting computerized searches of the Cochrane Central Register of Controlled Trials (CENTRAL) (2014, Issue 12), MEDLINE (from 1950 to December 2014) and EMBASE (from 1974 to December 2014) and by checking the reference lists of trials retained. When we reran the search in February 2016, we added 16 potential new studies of interest to the list of 'Studies awaiting classification' and will incorporate these studies into formal review findings during the next review update.

SELECTION CRITERIA

We included parallel randomized controlled trials comparing effects of postoperative epidural local anaesthetic versus regimens based on systemic or epidural opioids.

DATA COLLECTION AND ANALYSIS

We rated the quality of studies by using the Cochrane 'Risk of bias' tool. Two review authors independently extracted data and judged the quality of evidence according to the GRADE (Grades of Recommendation, Assessment, Development and Evaluation Working Group) scale.

MAIN RESULTS

We included 128 trials with 8754 participants in the review, and 94 trials with 5846 participants in the analysis. Trials included in the review were funded as follows: charity (n = 19), departmental resources (n = 8), governmental sources (n = 15) and industry (in part or in total) (n = 15). The source of funding was not specified for the other studies.Results of 22 trials including 1138 participants show that an epidural containing a local anaesthetic will decrease the time required for return of gastrointestinal transit as measured by time to first flatus after an abdominal surgery (standardized mean difference (SMD) -1.28, 95% confidence interval (CI) -1.71 to -0.86; high quality of evidence; equivalent to 17.5 hours). The effect is proportionate to the concentration of local anaesthetic used. A total of 28 trials including 1559 participants reported a decrease in time to first faeces (stool) (SMD -0.67, 95% CI -0.86 to -0.47; low quality of evidence; equivalent to 22 hours). Thirty-five trials including 2731 participants found that pain on movement at 24 hours after surgery was also reduced (SMD -0.89, 95% CI -1.08 to -0.70; moderate quality of evidence; equivalent to 2.5 on scale from 0 to 10). From findings of 22 trials including 1154 participants we did not find a difference in the incidence of vomiting within 24 hours (risk ratio (RR) 0.84, 95% CI 0.57 to 1.23; low quality of evidence). From investigators in 17 trials including 848 participants we did not find a difference in the incidence of gastrointestinal anastomotic leak (RR 0.74, 95% CI 0.41 to 1.32; low quality of evidence). Researchers in 30 trials including 2598 participants noted that epidural analgesia reduced length of hospital stay for an open surgery (SMD -0.20, 95% CI -0.35 to -0.04; very low quality of evidence; equivalent to one day). Data on costs were very limited.

AUTHORS' CONCLUSIONS

An epidural containing a local anaesthetic, with or without the addition of an opioid, accelerates the return of gastrointestinal transit (high quality of evidence). An epidural containing a local anaesthetic with an opioid decreases pain after abdominal surgery (moderate quality of evidence). We did not find a difference in the incidence of vomiting or anastomotic leak (low quality of evidence). For open surgery, an epidural containing a local anaesthetic would reduce the length of hospital stay (very low quality of evidence).

Recent advances in epidural analgesia

Neuraxial anesthesia is a term that denotes all forms of central blocks, involving the spinal, epidural, and caudal spaces. Epidural anesthesia is a versatile technique widely used in anesthetic practice. Its potential to decrease postoperative morbidity and mortality has been demonstrated by numerous studies. To maximize its perioperative benefits while minimizing potential adverse outcomes, the knowledge of factors affecting successful block placement is essential. This paper will provide an overview of the pertinent anatomical, pharmacological, immunological, and technical aspects of epidural anesthesia in both adult and pediatric populations and will discuss the recent advances, the related rare but potentially devastating complications, and the current recommendations for the use of anticoagulants in the setting of neuraxial block placement.

The site of action of epidurally administered opioids and its relevance to postoperative pain management

The use of epidurally administered opioids to control postoperative pain is a well established and widely accepted technique. However, despite this longstanding use, there is still an ongoing debate concerning the site of action of the opioids used. Some argue that analgesia is mediated by a spinal mechanism and others that a supraspinal mechanism is responsible. On close inspection of the evidence it becomes apparent that epidural opioids act predominantly spinally when administered as a bolus, and predominantly supraspinally when administered as a continuous infusion. A concentration of 10 microg x ml(-1) appears to be the threshold at which epidurally administered fentanyl can elicit segmental analgesia, a value which may have significant clinical applications. The evidence supporting a synergistic relationship between epidural opioids and local anaesthetics is weak and unsupported by a plausible physiological mechanism. Thus the 'threshold concentration' of approximately 10 microg x ml(-1) is unlikely to be lowered by co-administering opioids with local anaesthetics.