ERAS Protocol for Major Abdominal Surgery: Opioid vs. Non-Opioid Analgesia

What is ERAS?

Core elements of the original ERAS consensus protocol (Fearon et al., Clin Nutr 2005)

Full ERAS Pathway for Major Abdominal Surgery

PREOPERATIVE PHASE

INTRAOPERATIVE PHASE

POSTOPERATIVE PHASE

Analgesia in ERAS: The Central Role

"ERAS protocols focus on opioids as a single component of a comprehensive pain relief strategy, not as the mainstay for treatment. Instead, multimodal analgesia should be emphasized." - Schwartz's Principles of Surgery, 11e

NON-OPIOID ANALGESICS IN ERAS

1. Acetaminophen (Paracetamol)

• Indication: ALL patients without contraindication
• Preoperative: 975-1000 mg IV or PO
• Postoperative: Regular scheduled dosing, max 4 g/24 h
• Mechanism: Central COX inhibition, endocannabinoid modulation
• Advantage: No effect on platelet function, no renal risk, no GI bleeding
• Contraindication: Acute decompensated liver failure

2. NSAIDs / COX-2 Inhibitors

• Indication: ALL patients without contraindication
• Agents: Celecoxib 200-400 mg PO, ibuprofen 400 mg, ketorolac 15-30 mg IV
• Mechanism: Peripheral COX-1/COX-2 inhibition, reduces prostaglandin-mediated sensitization
• Advantage: Anti-inflammatory, synergistic with opioids (reduces opioid requirements by 30-40%)
• Contraindications: Pre-existing renal insufficiency, hypovolemia, major blood loss, hypotension, bleeding/coagulation disorders, GI bleeding history, NSAID hypersensitivity

3. Epidural Analgesia (Gold standard for open abdominal surgery)

• Indication: Major open thoracic and abdominal surgery
• Technique: Mid-thoracic catheter (T6-T9 level), local anesthetic (bupivacaine) ± low-dose opioid
• Advantages:
  • Profound somatic and visceral analgesia
  • Reduces systemic opioid requirements
  • Attenuates surgical stress response
  • Favorable cardiorespiratory effects (reduces pulmonary complications, improves bowel recovery)
  • Epidural local anesthetics independently accelerate return of GI function
• Concerns: Postural hypotension (delays mobilisation), VTE prophylaxis timing conflicts, urinary retention
• Note: Role is decreasing in laparoscopic ERAS due to availability of equivalent alternatives (TAP blocks)

4. IV Lidocaine Infusion

• Indication: Major open abdominal surgery when regional analgesia is not possible
• Dosing: 1.5 mg/kg IBW bolus, then 2 mg/kg/h infusion (can continue postoperatively on monitored floor)
• Mechanism: Sodium channel blockade, anti-inflammatory properties
• Advantages: Opioid-sparing, reduces PONV, hastens return of bowel function (particularly valuable in colorectal ERAS), possible anti-cancer effect
• Contraindications: Cardiac arrhythmias, seizure disorder, electrolyte imbalance, pregnancy; do NOT combine with regional LA blocks (risk of toxicity)

5. Ketamine

• Indication: Opioid-tolerant patients or major painful surgery when non-opioid approaches are insufficient
• Dosing: 0.25 mg/kg IBW bolus + 0.1 mg/kg/h infusion (no role for single bolus doses alone)
• Mechanism: NMDA receptor antagonist
• Advantages:
  • Opioid-sparing
  • May prevent opioid-induced hyperalgesia
  • May prevent chronic post-surgical pain syndromes
• Contraindications: Psychiatric disturbance, cardiovascular or hepatic disease, pregnancy
• Note: Dysphoria and hallucinations at higher doses; subanesthetic doses (0.1-0.35 mg/kg) are well-tolerated

6. Gabapentinoids (Gabapentin / Pregabalin)

• Indication: Preoperative dose for opioid-sparing, especially in opioid-tolerant patients
• Dosing: Gabapentin 300 mg PO (<65 years); 100-300 mg PO (>65 years); adjust for renal function
• Mechanism: Alpha-2-delta calcium channel subunit blockade - reduces central sensitization
• Advantages: Opioid-sparing, reduces postoperative pain, reduces opioid side effects
• Concerns: Visual disturbances, sedation, dizziness; dose reduce in renal impairment; recent debate on routine use due to sedation risk

7. Dexamethasone

• Indication: All patients without contraindication
• Dosing: 8-10 mg IV single intraoperative dose
• Primary role: PONV prophylaxis
• Secondary role: Anti-inflammatory analgesic adjunct
• Contraindications: Poorly controlled diabetes (HbA1c >10%) - transient hyperglycemia

8. Regional/Fascial Plane Blocks

9. Magnesium

• Dosing: Bolus 1-3 g IV, infusion 0.5-1 g/h
• Mechanism: NMDA antagonism (similar to ketamine but weaker), calcium channel effects
• Advantage: Opioid-sparing
• Contraindications: Renal insufficiency, neuromuscular disorders, bradyarrhythmias, hypotension

10. Dexmedetomidine

• Dosing: Bolus 0.5-0.6 mcg/kg; infusion 0.3-1 mcg/kg/h
• Advantage: Opioid-sparing, useful as perineural adjunct for nerve blocks
• Caution: No independent role in pain management in ERAS; concerns of prolonged hypotension and sedation delaying mobilisation

OPIOIDS IN ERAS: Appropriate Use

• Worsen pain scores after they wear off (hyperalgesia)
• Increase postoperative opioid requirements
• PONV (nausea/vomiting)
• Respiratory depression
• Reduced GI motility - major driver of ileus and delayed discharge in abdominal surgery
• Urinary retention
• Endocrine dysfunction (ADH release, immune suppression)
• Cancer growth (immunomodulation)

Opioid-Free vs. Opioid-Sparing: What Does the Evidence Show?

• PONV significantly reduced with opioid-free anesthesia (RR 0.55, 95% CI 0.40-0.74; p<0.001)
• Opioid consumption at 2 hours post-surgery was significantly lower (MD -5.4 mg oral morphine equivalents)
• Pain scores were marginally higher in the opioid-free group but not clinically meaningful
• No difference in PACU length of stay
• Conclusion: Opioid-free anesthesia is a valid alternative for minimally invasive abdominal surgery, especially in patients at high PONV risk - [da Silveira et al., Can J Anaesth 2024, PMID 39500840]

Practical ERAS Analgesic Protocol Summary

Preoperative (1-2 hours before surgery)

• Acetaminophen 1000 mg PO
• Celecoxib 200-400 mg PO (or ibuprofen 400 mg)
• Gabapentin 100-300 mg PO (especially opioid-tolerant patients)
• Place thoracic epidural catheter (for open surgery)

Intraoperative

• Epidural infusion (bupivacaine ± low-dose opioid) OR TAP/ESP blocks
• IV Lidocaine infusion 1.5 mg/kg bolus → 2 mg/kg/h (open abdominal surgery without epidural)
• IV Ketamine 0.1-0.35 mg/kg ± infusion (opioid-tolerant patients)
• Dexamethasone 8-10 mg IV (PONV + analgesic adjunct)
• Magnesium 1-2 g IV
• Minimize/avoid intraoperative fentanyl; if used, low dose only
• Surgical wound infiltration with bupivacaine or liposomal bupivacaine at closure

Postoperative

• Scheduled acetaminophen 1000 mg IV/PO q6h (max 4 g/day)
• Scheduled NSAID (celecoxib 200 mg PO q12h or ketorolac 15-30 mg IV q6h, short course)
• Continue epidural infusion OR IV lidocaine for 24-48 h (open surgery)
• PRN opioid rescue (low-dose oral oxycodone or morphine PCA) only for breakthrough pain
• Early oral analgesic transition (step down from IV to PO as soon as tolerating diet)

Key Principles Summarized

1. Multimodal is mandatory - no single agent provides complete analgesia without excessive dose-dependent side effects
2. Epidural remains gold standard for open major abdominal surgery (colorectal, hepatobiliary, esophageal) but is being replaced by fascial plane blocks in laparoscopic settings
3. IV lidocaine infusion is the preferred systemic non-opioid for open abdominal surgery without epidural - especially valuable for its pro-motility effects
4. Acetaminophen + NSAID scheduled around the clock for all patients forms the analgesic base
5. Ketamine is reserved for opioid-tolerant patients or for prevention of chronic pain
6. Opioids are rescue agents, not scheduled first-line, and should be discontinued as early as possible
7. Regional blocks (TAP, ESP) are the preferred opioid-sparing strategy in laparoscopic surgery
8. Pain management goal in ERAS is to facilitate early mobilization, not simply to achieve a numerical pain score target