What are the recommended approaches for postoperative pain management?

Postoperative Pain Management

Build postoperative analgesia on a foundation of multimodal therapy combining acetaminophen 1g every 6 hours with NSAIDs (ibuprofen 400mg or ketorolac 0.5-1mg/kg IV), administered pre-operatively or intra-operatively and continued postoperatively, with opioids strictly reserved as rescue medication only when non-opioid therapy fails. 1, 2

Core Multimodal Analgesic Protocol

Foundation: Non-Opioid Combination Therapy

• Acetaminophen forms the cornerstone and should be initiated first at 1g every 6 hours (IV loading dose 15-20mg/kg, then 10-15mg/kg every 6-8 hours; oral 10-15mg/kg every 6 hours with maximum 60mg/kg/day) 3, 1
• Add NSAIDs when not contraindicated to reduce morphine consumption by approximately 22% and improve pain control 3, 4
  • Ibuprofen 400mg every 8 hours (oral or IV) provides NNT of 2.5 for 50% pain relief 3, 5
  • Ketorolac 0.5-1mg/kg IV (max 30mg single dose; 0.15-0.2mg/kg every 6 hours for maintenance, maximum 48 hours) 3
  • Diclofenac 1mg/kg every 8 hours 3
• Combination therapy of ibuprofen 200mg + paracetamol 500mg produces superior analgesia with NNT of 1.6, outperforming either drug alone 6

Adjunctive Medications

• Dexamethasone 8-10mg IV as a single intra-operative dose provides dual analgesic and anti-emetic effects, reducing pain scores and enabling earlier ambulation 3, 1, 2
• Ketamine at low doses (maximum 0.5mg/kg/h after anesthesia induction) for surgeries with high risk of acute or chronic postoperative pain, or in pain-vulnerable patients 1, 2
• Gabapentinoids can be considered as multimodal components, though systematic preoperative use is not recommended 1, 2

Regional Analgesia Techniques

Use regional anesthesia whenever feasible and when it does not delay emergency procedures 3, 1:

• Single-shot fascia iliaca block or local infiltration analgesia, especially with contraindications to basic analgesics or high expected postoperative pain 3, 2
• Epidural analgesia for major abdominal or thoracic procedures, with adequate monitoring 3, 1
• Caudal blocks with long-acting local anesthetics +/- clonidine for lower extremity/abdominal procedures 3, 2
• Avoid neuraxial administration of magnesium, benzodiazepines, neostigmine, tramadol, and ketamine 1, 2

Opioid Management: Rescue Only

Opioids must be reserved strictly as rescue analgesics, not first-line therapy 3, 1, 2:

• In PACU: IV fentanyl 1-2 micrograms/kg or morphine 25-100 micrograms/kg titrated to effect for breakthrough pain 3, 2
• On ward: Oral/rectal/IV tramadol or IV nalbuphine as rescue 3, 2
• Patient-controlled analgesia (PCA) when IV route needed in cognitively intact patients, starting with bolus injection in opioid-naïve patients (avoid initial infusion) 1, 2

Route of Administration Priority

• Prefer oral route over IV whenever feasible and drug absorption can be reasonably warranted 1
• Avoid intramuscular route entirely in postoperative pain management 1, 2

Assessment and Monitoring Framework

• Use validated pain scales (numeric rating scale 0-10) to assess pain at rest and with movement at regular intervals 1, 2
• Reassess after interventions for both pain control and adverse reactions at appropriate intervals 1, 2
• Sudden increase in pain with tachycardia, hypotension, or hyperthermia requires urgent comprehensive assessment as this may herald complications (bleeding, anastomotic leaks, deep vein thrombosis) 1

Critical Contraindications and Precautions

NSAID Contraindications

• Renal insufficiency (creatinine clearance <50 mL/min) is an absolute contraindication 3, 1
• Colon or rectal anastomoses: Use NSAIDs cautiously due to potential correlation with dehiscence and wound healing inhibition 1, 2
• Atherothrombosis history (peripheral artery disease, stroke, MI): Avoid COX-2 inhibitors entirely and limit non-selective NSAIDs to ≤7 days 7
• Therapeutic anticoagulation: NSAIDs increase bleeding risk 2.5-fold 7
• Never combine coxibs and NSAIDs as this increases myocardial infarction incidence and affects kidney function 1, 2

Special Populations

• Obstructive sleep apnea: Reduce opioid use maximally to prevent cardiopulmonary complications 1, 2
• Liver disease: Use acetaminophen cautiously 2
• Emergency surgery patients: Expect more severe postoperative pain than elective surgery; specific attention required 3, 1

Common Pitfalls to Avoid

• Do not exceed maximum toxic doses of local anesthetics, particularly for peri-prosthetic orthopedic infiltrations 2
• Uncontrolled postoperative pain leads to tachycardia, arterial hypertension, increased abdominal wall and chest muscle rigidity, resulting in altered ventilation, hypoxemia, difficulties coughing, and increased risk of respiratory infectious complications 1
• Inadequate patient education: Provide adequate education for patient and family about surgical and anesthesiologic treatment, options, plan, and aims of pain management whenever possible 3