What is the recommended approach for postoperative pain management?

Postoperative Pain Management

Postoperative pain management should be built on a foundation of multimodal analgesia combining acetaminophen 1g every 6 hours with NSAIDs (when not contraindicated), administered pre-operatively or intra-operatively and continued postoperatively, with opioids strictly reserved as rescue medication only when non-opioid therapy fails. 1

Core Multimodal Analgesic Regimen

First-Line Non-Opioid Therapy

• Acetaminophen 1g every 6 hours (maximum 4g daily) should be initiated at the beginning of postoperative analgesia as it is safer than other drugs and forms the cornerstone of pain management 1
• NSAIDs should be added when not contraindicated for moderate pain and to reduce morphine consumption and related side effects 1
• A single intra-operative dose of dexamethasone 8-10 mg IV is strongly recommended for its analgesic and anti-emetic effects 1
• The combination of acetaminophen plus NSAIDs provides superior analgesia compared to either drug alone, with 69-73% of patients achieving at least 50% pain relief versus only 7% with placebo 2

Route of Administration Priority

• Oral administration should be preferred over intravenous route whenever feasible and drug absorption can be reasonably warranted 3
• The intramuscular route must be avoided in postoperative pain management 3
• In emergency abdominal surgery where oral absorption is compromised due to postoperative ileus, inflammatory changes, and altered gastric emptying, intravenous routes become necessary 3

Regional Analgesia Techniques

• Epidural and regional anesthesia is recommended in emergency general surgery whenever feasible and if not delaying emergency procedures 1
• 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
• Patients with neuraxial anesthesia must be monitored and assessed adequately 1
• Neuraxial administration of magnesium, benzodiazepines, neostigmine, tramadol, and ketamine should be avoided 1

Opioid Management: Rescue Only

• Opioids should be reserved strictly as rescue analgesics in the postoperative period, not as first-line therapy 1
• Patient-controlled analgesia (PCA) is recommended when IV route is needed in patients with adequate cognitive functions, starting with bolus injection in opioid-naïve patients 1
• Avoid initial infusion of opioids via PCA in opioid-naïve patients 4
• For breakthrough pain in PACU, intravenous fentanyl or other suitable agents can be used 1
• On the ward, consider oral or intravenous tramadol or nalbuphine as rescue medications 1

Adjuvant Medications

• 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
• Gabapentinoids can be considered as a component in multimodal analgesia, though systematic preoperative use is not recommended 1
• Coxib administration may be considered if there are no contraindications 1

Assessment and Monitoring Framework

• Postoperative pain assessment at rest and on movement is strongly recommended using validated pain scales (numeric rating scale 0-10) to improve patient management 3
• After a pain intervention, reassess patients for both pain control and adverse reactions at appropriate intervals 1
• 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) 3
• Regular monitoring of sedation levels, respiratory status, and adverse events is essential in patients receiving systemic opioids 4

Special Population Considerations

Emergency General Surgery Patients

• Emergency general surgery is associated with more severe postoperative pain than elective surgery; specific attention should be given to this patient group 3
• Preemptive analgesia is a viable option in reducing postoperative opioid consumption 3
• Younger age and female gender are risk factors for acute postoperative pain 1

Patients with Obstructive Sleep Apnea

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

Patients with Psychiatric Comorbidities

• Accurate evaluation including dementia and delirium facilitates pain management, as assessment techniques in these conditions are more time-consuming 3
• Special attention should be paid to anxiety, depression, and catastrophizing 3

Critical Contraindications and Precautions

NSAID-Specific Warnings

• NSAIDs should be used cautiously in patients with colon or rectal anastomoses due to potential correlation with dehiscence and wound healing inhibition 1
• Renal insufficiency (creatinine clearance <50 mL/min) is a contraindication to NSAIDs 5
• History of atherothrombosis (peripheral artery disease, stroke, myocardial infarction): avoid COX-2 inhibitors entirely and limit non-selective NSAIDs to ≤7 days 5
• Concurrent therapeutic anticoagulation increases bleeding risk 2.5-fold when combined with NSAIDs 5
• Avoid combining coxibs and NSAIDs as their combination increases myocardial infarction incidence and affects kidney function 1

Other Medication Precautions

• Caution is needed when using acetaminophen in patients with liver disease 1
• Avoid exceeding maximum toxic doses of local anesthetics, particularly for peri-prosthetic orthopedic infiltrations 1

Patient and Family Education

• Adequate education for the patient and family about surgical and anesthesiologic treatment, options, plan, and aims of pain management should be performed whenever possible 3
• Explaining drug choice, properties, effects, and side effects helps reduce acute postoperative pain 3
• Lower educational level has been proven to worsen pain outcomes 3

Clinical Consequences of Inadequate Pain Control

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 3. Enhanced sympathetic stimulation inhibits peristalsis while increasing smooth muscle tone, leading to postoperative paresis 3. Pain prevents early mobilization and contributes to emotional and physical suffering and sleep disturbances 3.