Postoperative Pain Management

Pain Assessment - Painful Truths

• Core Principle: Pain is subjective; what the patient says it is.
• Types of Pain:
  • Nociceptive: Somatic (sharp, localized), Visceral (dull, diffuse, deep).
  • Neuropathic: Burning, tingling, shooting (e.g., post-herpetic neuralgia, diabetic neuropathy).
• Assessment Tools:
  • Numeric Rating Scale (NRS): 0-10 (most common).
  • Visual Analog Scale (VAS).
  • Wong-Baker FACES Pain Rating Scale (Children, communication difficulties).
  • 📌 PQRST Mnemonic: Provocation/Palliation, Quality, Region/Radiation, Severity, Timing.
• Key Considerations:
  • Regular, repeated assessment is crucial for effective management.
  • Physiological signs (tachycardia, hypertension) are unreliable indicators alone.

⭐ Self-report is the gold standard for assessing pain intensity whenever possible, superseding observer or physiological data alone.

Pharmacological Management - Pill Power

• WHO Analgesic Ladder:
  • Step 1: Non-opioid ± Adjuvant (Paracetamol, NSAIDs)
  • Step 2: Weak opioid ± Non-opioid ± Adjuvant (Tramadol, Codeine)
  • Step 3: Strong opioid ± Non-opioid ± Adjuvant (Morphine, Fentanyl)
• Non-Opioids:
  • Paracetamol: Max 4g/day. Hepatotoxicity risk.
  • NSAIDs (Diclofenac, Ketorolac): COX inhibitors. GI/Renal risks.
    • Ketorolac: Max 5 days.
• Opioids:
  • Weak: Tramadol, Codeine.
  • Strong: Morphine, Fentanyl, Pethidine (norpethidine toxicity risk).
    • 📌 SE: SCRAP N (Sedation, Constipation, Resp. depression, Addiction, Pruritus, N/V).
    • Antidote: Naloxone 0.4-2mg IV.
• Adjuvants: (Neuropathic/Chronic pain)
  • Gabapentinoids (Gabapentin, Pregabalin).
  • TCAs (Amitriptyline).
  • Ketamine (low-dose).

⭐ Pethidine is contraindicated in patients with renal failure due to accumulation of its neurotoxic metabolite, norpethidine_._

Regional Analgesia Techniques - Nerve Nullifiers

• Epidural Analgesia:
  • Local Anesthetics (LA) ± opioids via catheter in epidural space (lumbar/thoracic).
  • Continuous infusion or Patient-Controlled Epidural Analgesia (PCEA). For major surgeries.
• Spinal (Intrathecal) Analgesia:
  • Single LA ± opioid injection into Cerebrospinal Fluid (CSF).
  • Rapid, dense block. For lower abdominal/limb surgery. Risk: Post-Dural Puncture Headache (PDPH).
• Peripheral Nerve Blocks (PNBs):
  • LA targets specific nerves/plexuses (e.g., brachial, femoral, sciatic).
  • Ultrasound-guided for precision. Single shot or continuous catheter techniques.
• Fascial Plane Blocks (e.g., TAP, Pectoral):
  • LA administered into fascial planes for truncal/abdominal wall analgesia.

⭐ LAST (Local Anesthetic Systemic Toxicity): Life-threatening emergency. Features CNS excitation (e.g., seizures, metallic taste, tinnitus) then depression, and cardiovascular collapse (arrhythmias, arrest). Key management: lipid emulsion (20%).

Multimodal Analgesia - Teamwork Tactics

• Combines diverse analgesic classes & techniques for synergy.
• Goal: ↑ Efficacy, ↓ opioid dose, ↓ side effects, faster recovery.
• Team effort: Surgeon, Anesthesiologist, Nurse, Physiotherapist, Patient.
• Strategy: Proactive, individualized, regularly assessed, dynamic plan.

⭐ Reduces opioid needs by 20-50%, minimizing adverse effects.

High‑Yield Points - ⚡ Biggest Takeaways

• Multimodal analgesia is standard: combine opioids, NSAIDs, paracetamol, and regional techniques.
• Regional techniques (epidural, nerve blocks like TAP) offer superior analgesia and ↓ opioid use.
• PCA (Patient-Controlled Analgesia) with opioids (morphine, fentanyl) improves patient satisfaction.
• NSAIDs (e.g., ketorolac) are crucial for opioid-sparing; watch for renal/GI adverse effects.
• Paracetamol is a fundamental, safe baseline analgesic for most postoperative patients.
• Sub-anesthetic ketamine is a valuable adjunct for severe pain or opioid tolerance_._