Perioperative Pain Management

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Pre-op Pain Plan - Setting the Stage

  • Comprehensive Assessment:
    • Identify risk factors for severe post-op pain (e.g., pre-existing chronic pain, anxiety, young age, type of surgery).
    • Detailed pain history: previous experiences, effective/ineffective analgesics.
    • Screen for substance use (opioids, alcohol, illicit drugs) & adjust plan accordingly.
    • Assess for OSA, renal/hepatic dysfunction.
  • Introduce Multimodal Analgesia (MMA):
    • Explain concept: using different drug classes targeting multiple pain pathways.
    • Goal: ↓ opioid consumption & side effects, ↑ pain relief.
    • Components: NSAIDs, paracetamol, gabapentinoids, regional anesthesia.
  • Patient Education & Expectation Setting:
    • Discuss realistic pain goals.
    • Explain pain assessment tools (e.g., NRS, VAS).
    • Address fears/misconceptions about pain medication.

Multimodal Pain Management Agents

⭐ Pre-emptive analgesia (administering analgesics before surgical incision) is a key component of MMA to reduce central sensitization and improve postoperative pain control. Consider pre-op celecoxib 200-400 mg or gabapentin 300-600 mg if no contraindications exist (📌 CGP - Celecoxib, Gabapentin Pre-op).

Painkiller Toolkit - The Drug Lineup

  • Opioids (μ-agonists): Potent analgesics for moderate-severe pain.
    • Morphine: Gold standard; dose 0.1-0.2 mg/kg IV/IM.
    • Fentanyl: Rapid onset, short duration; 1-2 mcg/kg IV.
    • Tramadol: Weak opioid, SNRI properties; less respiratory depression.
    • Side Effects: Nausea, vomiting, constipation, respiratory depression, sedation.
  • NSAIDs (COX inhibitors): For mild-moderate pain, opioid-sparing.
    • Diclofenac: 50-75 mg BD/TDS.
    • Ketorolac: Potent; max 5 days use.
    • Paracetamol (Acetaminophen): Central analgesic; 1g QDS. Max 4g/day.
    • Side Effects: GI ulcers, renal toxicity, platelet dysfunction.
    • 📌 NSAIDs: No Sympathy For Ailing Inflamed Damaged Kidneys/Stomachs.
  • Adjuvants: Enhance analgesia, target specific pain types.
    • Gabapentinoids (Gabapentin, Pregabalin): Neuropathic pain.
    • Ketamine (low dose): NMDA antagonist; opioid-sparing.
    • Lidocaine infusions: Systemic analgesia, anti-inflammatory. Analgesic Drug Classes for Postoperative Pain Management

⭐ Ketorolac, a potent NSAID, should not be used for more than 5 days due to significant risk of GI bleeding and renal impairment, especially in elderly patients or those with pre-existing renal disease.

Nerve Blocks & Beyond - Precision Numbing

  • Mechanism: Reversible Na+ channel blockade in nerve fibers, halting action potential propagation.
  • Types & Examples:
    • Central Neuraxial: Spinal (intrathecal), Epidural.
    • Peripheral Nerve Blocks (PNBs):
      • Plexus: Brachial (e.g., interscalene, supraclavicular), Lumbar plexus.
      • Single Nerve: Femoral, sciatic, intercostal.
    • Fascial Plane Blocks: Transversus Abdominis Plane (TAP) block, Pectoral nerves (PECS) block.
  • Local Anesthetics (LA):
    • Amides: Lignocaine, Bupivacaine (⚠️ high cardiotoxicity), Ropivacaine.
    • Esters: Procaine (higher allergic potential).
  • Adjuvants (enhance analgesia/duration):
    • Epinephrine: Vasoconstriction → ↓systemic absorption, ↑duration.
    • Opioids (e.g., fentanyl, morphine), Clonidine, Dexamethasone, Ketamine.
  • Complications:
    • LAST (Local Anesthetic Systemic Toxicity): CNS excitation/depression, cardiovascular collapse.
    • Nerve injury, hematoma, infection, block failure.

    ⭐ For LAST management, immediate administration of 20% lipid emulsion (Intralipid) is critical. Initial bolus: 1.5 mL/kg lean body mass over 1 minute, followed by infusion.

  • Beyond Blocks: Cryoanalgesia, Radiofrequency Ablation (RFA) for chronic pain states. Ultrasound-guided nerve block for perioperative pain

Post-op Pain Patrol - Aftercare & Alerts

  • Regular Assessment: Use validated scales (NRS, VAS; BPS for ventilated). Document findings.
  • Monitor Vitals & Side Effects:
    • Sedation (e.g., RASS), RR (⚠️ < 10-12/min), SpO2.
    • PONV: Prophylaxis (ondansetron 4-8 mg).
    • Pruritus, constipation, urinary retention.
  • Managing Inadequate Analgesia:
    • Re-evaluate pain source.
    • Optimize current regimen.
    • Rescue doses (e.g., IV morphine 1-2 mg).
    • Consider multimodal/regional techniques.
  • Special Considerations:
    • Elderly: ↓ dose, ↑ interval.
    • Obese: OSA risk, cautious opioids.
    • Opioid-tolerant: Higher needs, multimodal.
  • Red Flags: Uncontrolled pain, new neuro deficits, compartment syndrome signs, hemodynamic instability.

⭐ Opioid-induced respiratory depression (OIRD) is a critical concern; monitor respiratory rate (RR < 10-12/min is a warning) and sedation levels (e.g., RASS).

High‑Yield Points - ⚡ Biggest Takeaways

  • Multimodal analgesia is standard: combine opioids, NSAIDs, regional blocks.
  • Pre-emptive analgesia before surgery can ↓ postoperative pain intensity.
  • Use NSAIDs cautiously in renal/GI disease; consider COX-2 inhibitors.
  • Monitor opioids closely for respiratory depression; naloxone reverses.
  • Regional techniques (epidural, nerve blocks) markedly reduce systemic opioid needs.
  • PCA empowers patients but demands vigilant monitoring for safety.
  • Gabapentinoids (pregabalin, gabapentin) help manage neuropathic pain and ↓ opioid consumption.

Practice Questions: Perioperative Pain Management

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