What medications are recommended for postoperative pain management?

Postoperative Pain Management: Recommended Medications

Build postoperative pain management on a foundation of multimodal analgesia combining acetaminophen with NSAIDs, initiated pre-operatively or intra-operatively and continued postoperatively, with opioids strictly reserved as rescue medication only when non-opioid therapy fails. 1

Core Multimodal Regimen

First-Line: Non-Opioid Combination

• Acetaminophen 1g every 6 hours should be initiated at the beginning of postoperative analgesia as the cornerstone of pain management due to its superior safety profile 1, 2
• NSAIDs or COX-2 selective inhibitors should be added when not contraindicated for moderate pain and to reduce morphine consumption and related side effects 1, 2
  • For dental surgery, NSAIDs are clearly more effective than acetaminophen alone 3
  • For major and orthopedic surgery, NSAIDs and acetaminophen have similar efficacy 3
• Combination therapy (ibuprofen + acetaminophen) provides superior analgesia to either drug alone, with 69-73% of patients achieving at least 50% pain relief over 6 hours (NNT 1.5-1.6) 4
• Single intravenous dose of dexamethasone 8-10 mg intra-operatively is strongly recommended for analgesic and anti-emetic effects 1, 2

Route of Administration

• Prefer oral administration over intravenous route whenever feasible and drug absorption can be reasonably warranted 1
• Avoid intramuscular route completely in postoperative pain management 5, 1, 2

Regional Analgesia Techniques

Neuraxial and Peripheral Nerve Blocks

• Epidural and regional anesthesia is recommended in emergency general surgery whenever feasible and if not delaying emergency procedures 1, 2
• Femoral nerve blocks are recommended based on analgesic efficacy and decreased risk of side-effects compared to neuraxial techniques and parenteral opioids 5
• Continuous infusion via catheter is recommended over single-shot approach for extended duration of analgesia 5
• Single-shot fascia iliaca block or local infiltration analgesia is recommended, especially with contraindications to basic analgesics or in patients with high expected postoperative pain 1, 2

Contraindicated Neuraxial Agents

• Avoid neuraxial administration of magnesium, benzodiazepines, neostigmine, tramadol, and ketamine 1, 2

Opioid Management: Rescue Only

Strict Indications

• Opioids should be reserved strictly as rescue analgesics in the postoperative period, not as first-line therapy 1, 2
• Systemic strong opioids are recommended for managing high-intensity pain (VAS >50/100) following surgery when non-opioid therapy fails 5
• Minimize opioid dose by combining them with other analgesics 5

Administration Method

• Patient-controlled analgesia (PCA) is recommended when IV route is needed in patients with adequate cognitive functions 1, 2
• Start with bolus injection in opioid-naïve patients 1, 2
• Avoid initial infusion of opioids via PCA in opioid-naïve patients 1
• Intravenous PCA or fixed interval intravenous administration titrated for pain intensity is recommended over on-demand or intramuscular administration 5

Weak Opioids

• Weak opioids are not recommended to control high-intensity pain in the early postoperative period (<6 hours) 5
• They are recommended later in the postoperative period, in combination with acetaminophen, when NSAIDs and COX-2 inhibitors are contraindicated or insufficient 5

Adjuvant Medications

Ketamine

• Small doses of ketamine (maximum 0.5 mg/kg/h after anesthesia induction) are recommended in surgeries with high risk of acute pain or chronic postoperative pain, and in patients with vulnerability to pain 1, 2

Gabapentinoids

• Gabapentinoids (pregabalin 75-150 mg every 12 hours or gabapentin 300-600 mg every 8 hours) can be considered as a component in multimodal analgesia 2, 6
• Systematic preoperative use is not recommended 1, 2
• Monitor for sedation and mareos, especially in the first 24-48 hours 6
• Withdraw gradually when no longer necessary 6

COX-2 Inhibitors

• Coxib administration may be considered if there are no contraindications 1, 2
• Injectable COX-2 inhibitor parecoxib remains available for short-term use in treating postoperative pain 5
• Do not combine coxibs and NSAIDs as their combination increases myocardial infarction incidence and affects kidney function 1, 2

Pain Assessment Framework

Monitoring Requirements

• Periodic assessment of pain score is mandatory using validated systems (NRS 0-10, VAS, VRS) to evaluate response to treatments and allow adjustments 5, 1
• Assess pain at rest and on movement 1
• After a pain intervention, reassess patients for both pain control and adverse reactions at appropriate intervals 1, 2

Warning Signs

• A sudden increase in pain, especially with tachycardia, hypotension, or hyperthermia, requires urgent comprehensive assessment as this may herald postoperative complications (bleeding, anastomotic leaks, deep vein thrombosis) 1

Critical Contraindications and Precautions

NSAID Cautions

• Use NSAIDs cautiously in patients with colon or rectal anastomoses due to potential correlation with dehiscence and wound healing inhibition 1, 2
• Renal insufficiency (creatinine clearance <50 mL/min) is a contraindication to NSAIDs 1
• Both COX-2 inhibitors and NSAIDs should be used with care in patients with known cardiovascular disease 5

Acetaminophen Cautions

• Use caution when administering acetaminophen in patients with liver disease 2

Special Population: Obstructive Sleep Apnea

• Reduce opioid use as much as possible to prevent cardiopulmonary complications in patients with obstructive sleep apnea syndrome 1, 2

Procedure-Specific Considerations

Total Hip Replacement

• Acetaminophen in combination with NSAIDs or COX-2 inhibitors is recommended 5, 2
• Single dose of dexamethasone 8-10 mg has shown improved postoperative pain outcomes 2
• Femoral nerve blocks or posterior lumbar plexus blocks are recommended 5

Emergency General Surgery

• Emergency general surgery is associated with more severe postoperative pain than elective surgery; specific attention should be given to this patient group 1

Common Pitfalls to Avoid

• Do not use acetaminophen or NSAIDs as monotherapy for high-intensity pain—always combine them 1
• Do not delay initiation of multimodal analgesia until the postoperative period—start pre-operatively or intra-operatively 1, 2
• Do not use opioids as first-line therapy—they are rescue medications only 1, 2
• 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