Effect of epidural bupivacaine vs combined epidural bupivacaine and morphine on gastrointestinal function and pain after major gynaecological surgery

Authors: H. Jùrgensen¹*, J. S. Fomsgaard¹, J. Dirks¹, J. Wetterslev¹, B. Andreasson², J. B. Dahl¹

Journal Name: British Journal of Anaesthesia

Year: 2001

Volume: 87

Issue: 5

Pages: 727–732

Type of Study: Double-blind randomized controlled trial

DOI/PMID: Not provided

Quick Reference Summary

• The addition of morphine to epidural bupivacaine did not significantly improve pain relief post-major gynaecological surgery compared to bupivacaine alone.
• Patients receiving epidural bupivacaine alone experienced faster gastrointestinal recovery, but required more supplementary analgesics (P<0.05).

Core Clinical Question

Does the addition of epidural morphine to bupivacaine improve postoperative pain management and gastrointestinal function in patients undergoing major gynaecological surgery compared to epidural bupivacaine alone?

Background

Disease Overview: Major gynaecological surgery, such as radical hysterectomy and pelvic lymphadenectomy, is associated with significant postoperative pain and gastrointestinal dysfunction.

Prior Data:

• Epidural opioids may delay gastric emptying and prolong gastrointestinal paralysis.
• Previous randomized studies have shown mixed results regarding the benefits of combined epidural analgesia on gastrointestinal recovery.

Current Standard of Care: Typically involves the use of epidural local anaesthetics for pain relief post-surgery, with or without opioid adjuncts.

Knowledge Gaps Addressed by Study:

• The impact of adding morphine to epidural bupivacaine on both pain relief and gastrointestinal function.
• Balancing analgesic efficacy with potential gastrointestinal side effects.

Study Rationale: To determine whether the combination of bupivacaine and morphine offers superior pain control without compromising gastrointestinal recovery compared to bupivacaine alone.

Methods Summary

Study Design: Double-blind randomized controlled trial

Setting and Time Period: Herlev University Hospital, Copenhagen County, Denmark; published in 2001

Population Characteristics: 40 patients scheduled for radical hysterectomy and pelvic lymphadenectomy

Inclusion/Exclusion Criteria: Not specified

Intervention Details:

• Bupi Group: 0.2% bupivacaine, 8 ml/hour epidural infusion for 48 hours postoperatively
• Bupi/Morph Group: 0.2% bupivacaine with 50 mg morphine at 4 ml/hour epidural infusion for 48 hours postoperatively

Control/Comparison Group Details: Comparison between bupivacaine alone vs. bupivacaine combined with morphine

Primary and Secondary Outcomes:

• Primary Outcomes: Postoperative pain levels, time to first satiety and defaecation
• Secondary Outcomes: Supplementary analgesic requirements, incidence of itching, postoperative nausea and vomiting (PONV), mobilization, time to discharge

Statistical Analysis Approach: Not detailed

Sample Size Calculations: Not provided

Ethics and Funding Information: Not provided

Detailed Results

Participant Flow and Demographics

40 patients randomized evenly into two groups; demographic details Not provided

Primary Outcome Results:

• Pain Levels: No significant differences in pain at rest, during cough, or mobilization between groups.
  Statistical Significance: Not specified, but implied non-significant.
• Supplementary Analgesics: Bupi group requested a significantly greater amount (P<0.05).
• Gastrointestinal Recovery:
  • Bupi Group: Reduced time to first satiety and defaecation compared to Bupi/Morph group.
  • Statistical Significance: P<0.05

Effect Sizes and Confidence Intervals: Not provided

Secondary Outcome Results:

• Itching: More prevalent in the Bupi/Morph group (P<0.05).
• PONV, Mobilization, Time to Discharge: No significant differences between groups.

Subgroup Analyses: Not reported

Adverse Events/Safety Data: Itching was a significant adverse event in the Bupi/Morph group.

Results Tables

Authors' Conclusions

• Primary Conclusions: The addition of morphine to epidural bupivacaine offers only limited improvement in pain relief post-major gynaecological surgery.
• Interpretation of Results: While morphine supplementation does not enhance pain control significantly, it is associated with delayed gastrointestinal recovery and increased incidence of itching.
• Clinical Implications: Combining morphine with bupivacaine may not provide substantial analgesic benefits and could impede gastrointestinal function recovery.
• Future Research Recommendations: Further studies with larger sample sizes are needed to confirm these findings and explore alternative analgesic combinations that optimize pain control without compromising gastrointestinal function.

Critical Analysis

A. Strengths:

• Randomized Controlled Design: Minimizes selection bias and enhances internal validity.
• Double-Blind Methodology: Reduces performance and detection bias.
• Focused Population: Homogeneous group undergoing similar surgical procedures enhances consistency of results.

B. Limitations:

• Small Sample Size: Only 40 patients, limiting the power to detect smaller differences and generalize findings.
• Lack of Detailed Methodological Information: Insufficient details on statistical analyses, inclusion/exclusion criteria, and sample size calculations.
• Short Follow-Up Duration: Observations limited to 96 hours post-surgery may miss long-term outcomes.
• Single-Center Study: Limits external validity and generalizability to other settings or populations.

C. Literature Context

Previous Studies and Meta-Analyses:

• Asantila et al., 1995: Combination of bupivacaine and morphine superior to bupivacaine alone for analgesia after abdominal surgery. Anesth Analg. 1995;80(6):1357-1362.
• Liu et al., 1998: Epidural morphine delays gastric emptying in animal models. Br J Anaesth. 1998;81(3):436-440.

Contrasting Methodological Quality:

• Previous trials had larger sample sizes and multi-center designs, enhancing their applicability.
• This study's smaller size and single-center nature may affect the robustness of its conclusions.

Comparisons with Guidelines:

• The study aligns with guidelines recommending cautious use of epidural opioids due to potential gastrointestinal side effects. Society of Anaesthesiologists Guidelines, 2000.

This Trial's Contribution:

• Provides evidence that adding morphine to epidural bupivacaine may not significantly enhance analgesia while potentially delaying gastrointestinal recovery, contrasting with some earlier studies suggesting analgesic benefits.

Clinical Application

• The findings suggest that epidural bupivacaine alone may be preferable for managing postoperative pain in major gynaecological surgery due to faster gastrointestinal recovery and fewer side effects.
• This approach is most applicable to patients where rapid gastrointestinal function restoration is a priority and where the risk of opioid-related side effects needs to be minimized.

How To Use This Info In Practice

Practitioners should consider using epidural bupivacaine alone for postoperative analgesia in major gynaecological surgeries to optimize pain control while promoting quicker gastrointestinal recovery.