Postoperative pain management

Pain Assessment - Gauging the Hurt

• Core Principle: Pain is subjective, the "fifth vital sign." Patient's report is key.
• 📌 PQRST Mnemonic: Provocation/Palliation, Quality, Radiation, Severity, Time.
• Pain Scales: Standardize severity assessment.
  • Numeric Rating Scale (NRS): 0-10 scale, most common.
  • Visual Analog Scale (VAS): 100mm line from "no pain" to "worst pain."
  • Faces Pain Scale-Revised (FPS-R): For children or cognitive impairment.
  • FLACC Scale: For non-verbal patients (Face, Legs, Activity, Cry, Consolability).

⭐ Patient self-report is the gold standard for pain assessment, more reliable than physiologic signs (e.g., tachycardia, hypertension), which can be non-specific.

Analgesic Arsenal - The Drug Cabinet

• Non-opioids: Foundation of multimodal analgesia.
  • Acetaminophen: Central action. Max dose 4g/day. Risk of hepatotoxicity.
  • NSAIDs (e.g., Ibuprofen, Ketorolac): Inhibit COX enzymes. ⚠️ Risk of GI bleeds & renal injury.
• Opioids: For moderate-to-severe pain; use lowest effective dose.
  • Agonists: Morphine, hydromorphone, fentanyl.
  • Delivery: Patient-Controlled Analgesia (PCA) common.
  • Side Effects: ⚠️ Respiratory depression, sedation, constipation.
• Local Anesthetics:
  • Bupivacaine, Ropivacaine for epidurals & nerve blocks.
• Adjuvant Analgesics:
  • Gabapentinoids for neuropathic pain.
  • Low-dose Ketamine as an NMDA antagonist.

⭐ Ketorolac (an NSAID) use is limited to ≤5 days due to significant renal and GI toxicity risk.

Delivery Modalities - Smart Systems

• Patient-Controlled Analgesia (PCA)

  • Patient self-administers small, pre-set opioid doses (e.g., morphine, hydromorphone).
  • Components: On-demand bolus, a lockout interval (5-10 min) to prevent overdose, and an optional basal infusion.
  • Benefit: Empowers patients, leading to better pain control and potentially lower total opioid consumption.
  • 📌 Mnemonic: PCA for Patient Controls Administration.

• Epidural Analgesia

  • Catheter in epidural space delivers local anesthetic + opioid (e.g., bupivacaine + fentanyl).
  • Superior pain control for major abdominal/thoracic surgery.

  ⭐ High-Yield: Epidurals can cause sympathetic blockade, leading to hypotension and bradycardia. Monitor vitals closely.

• Continuous Peripheral Nerve Blocks

  • Catheter placed near a specific nerve/plexus (e.g., femoral, brachial).
  • Infuses local anesthetic for targeted, prolonged analgesia.

Opioid Side Effects - Handling Hazards

• Respiratory Depression: Most severe risk. Monitor RR; if <12/min, consider intervention.
• Constipation: Universal side effect. Begin prophylaxis with stimulant + softener (e.g., Senna + Docusate). 📌 "Mush and Push."
• Nausea & Vomiting: Common. Treat with antiemetics like ondansetron.
• Pruritus: Especially with neuraxial opioids. Manage with antihistamines or low-dose naloxone.
• Sedation: Dose-dependent. Reduce dose or consider opioid rotation.

⭐ Naloxone's half-life (60-90 min) is shorter than most opioids. Patients can re-sedate after naloxone wears off, necessitating vigilant monitoring and potential redosing.

High‑Yield Points - ⚡ Biggest Takeaways

• Multimodal analgesia is the standard, using non-opioid analgesics (NSAIDs, acetaminophen) and regional techniques to reduce opioid requirements.
• The most feared opioid side effect is respiratory depression. Also monitor for sedation, nausea, and postoperative ileus.
• Patient-Controlled Analgesia (PCA) is effective but carries overdose risk, especially with continuous basal rates in opioid-naïve patients.
• Epidural analgesia offers superior pain control for major thoracoabdominal surgery but risks hypotension (sympathectomy) and epidural hematoma.