What is the most effective anesthetic regimen for a general adult population undergoing elective surgery, considering optimal pain control and minimal side effects?

Optimal Anesthetic Regimen for Elective Surgery in General Adult Population

For elective surgery in general adults, use multimodal analgesia with acetaminophen 1g IV every 6 hours plus NSAIDs (ibuprofen 600-800mg every 6-8 hours or diclofenac 50-100mg every 8 hours), combined with regional anesthesia techniques when feasible, and reserve opioids strictly as rescue medication. 1, 2

Foundational Multimodal Analgesia

The cornerstone of effective perioperative pain management is multimodal analgesia that minimizes opioid exposure while maximizing pain control 3:

• Acetaminophen 1g IV every 6 hours (maximum 4g daily) should be administered as scheduled medication, not "as needed" 1, 2
• NSAIDs: Either ibuprofen 600-800mg every 6-8 hours OR diclofenac 50-100mg every 8 hours (not exceeding 150mg daily) 2
• Dexamethasone 8-10mg IV at induction reduces postoperative pain and nausea 3
• The combination of acetaminophen plus NSAIDs provides superior analgesia compared to either agent alone 1, 2

This approach ensures predictable plasma concentrations and consistent analgesic effect, particularly when IV formulations are used in acute perioperative settings where oral absorption may be unreliable 1.

Pre-Anesthetic Medication Strategy

Avoid benzodiazepines in patients ≥65 years due to increased risk of cognitive impairment, delirium, and falls 3. Instead:

• Melatonin (tablets or sublingual) provides effective preoperative anxiolysis with minimal side effects and is equally effective to midazolam 3
• Preoperative education ("Surgery School") successfully reduces patient anxiety without pharmacologic intervention 3

Do NOT routinely use gabapentinoids (gabapentin or pregabalin) preoperatively 3. While they demonstrate opioid-sparing effects, they cause clinically significant sedation, dizziness, visual disturbances, and may interfere with early mobilization 3. If gabapentinoids are used in high-risk pain scenarios, limit to a single lowest preoperative dose with dose adjustment in elderly and renally impaired patients 3.

Anesthetic Technique Selection

Neuraxial anesthesia (spinal or epidural) is preferred over general anesthesia when appropriate for the surgical procedure, as it reduces pulmonary complications and may reduce chronic postsurgical pain after major surgery 3, 4:

• Spinal anesthesia provides lower pain scores during the first 24 hours postoperatively compared to general anesthesia when adequate multimodal analgesia is used 3
• Intrathecal morphine 0.1mg provides 24-hour analgesia but carries risks of pruritus and postoperative nausea/vomiting that may delay mobilization; its use remains controversial and should be weighed against optimized multimodal analgesia 3

For general anesthesia:

• Short-acting agents are preferred: propofol for induction, desflurane or sevoflurane for maintenance 3, 5
• Remifentanil 0.5-1 mcg/kg/min provides effective intraoperative analgesia with rapid offset, allowing faster emergence 5
• Volatile anesthetics (particularly sevoflurane) demonstrate cardioprotective effects and are recommended for patients with cardiac disease 4

Regional Anesthesia Techniques

Single-shot peripheral nerve blocks should be incorporated when anatomically appropriate for the surgical site 3:

• Fascia iliaca blocks, femoral nerve blocks, or procedure-specific blocks reduce opioid requirements and improve early mobilization 3, 2
• Local infiltration analgesia (LIA) with bupivacaine 0.5% before incision reduces opioid consumption 3
• Transversus abdominis plane (TAP) blocks decrease pain scores after abdominal surgery 3

Intraoperative Adjuncts

Intravenous lidocaine infusion (bolus 1-2 mg/kg followed by 1-2 mg/kg/h) should be administered during major abdominal, pelvic, or spinal surgery when regional analgesia is not used 3. Lidocaine provides analgesic, anti-hyperalgesic, and anti-inflammatory properties 3.

Low-dose ketamine (maximum 0.5 mg/kg after induction, then 0.125-0.25 mg/kg/h continuous infusion, stopped 30 minutes before end of surgery) is recommended only for:

1. Surgery with high risk of acute or chronic postoperative pain
2. Patients with chronic opioid use or opioid addiction 3

Ketamine reduces 24-hour morphine consumption by approximately 15mg and decreases chronic pain incidence by 30% at 3 months, but routine use is not recommended due to potential psychotropic side effects 3.

Opioid Management

Reserve opioids strictly as rescue medication for breakthrough pain 3, 1, 2:

• Morphine or oxycodone (oral route preferred) should be titrated to minimal effective dose 3
• Avoid long-acting opioids for postoperative pain as they provide no benefit and increase risk of opioid-induced ventilatory impairment 3
• Avoid pethidine (meperidine) in all patients, particularly elderly, due to adverse effects 3
• Limit discharge prescriptions: consensus-built guidelines limiting opioid quantities increased opioid-free discharges from 35.7% to 52.5% without increasing refill requests 3

Most patients require minimal to no opioids by postoperative day 3-4 when multimodal analgesia is optimized 2.

Critical Safety Considerations

Acetaminophen precautions:

• Reduce maximum daily dose to 2-3g in patients with liver disease and monitor liver enzymes 1, 2
• Account for acetaminophen in combination products to avoid exceeding 4g daily maximum 1
• IV acetaminophen may cause hypotension in hemodynamically unstable patients 1

NSAID precautions:

• Use with extreme caution or avoid in renal impairment (creatinine clearance <50 mL/min) 2
• Never combine NSAIDs with therapeutic anticoagulation (enoxaparin, rivaroxaban, warfarin) as this multiplies bleeding risk by 2.5-fold 3
• Limit duration to 48 hours when concerns exist 1

Age-related dosing:

• Reduce induction agent doses in elderly patients 6, 7
• Fentanyl, propofol, thiopental, and isoflurane require 10%, 8%, 6%, and 4% dose reduction per decade of age, respectively, from age of maximum dose to age 80 6
• Elderly patients demonstrate increased sensitivity to opioids requiring careful titration 3

Common Pitfalls to Avoid

• Failing to implement true multimodal analgesia by using acetaminophen or NSAIDs alone when both could be safely combined results in suboptimal pain control and increased opioid requirements 1, 2
• Premature opioid escalation before optimizing non-opioid analgesics increases side effects without improving outcomes 1
• Relying solely on pain scores rather than functional outcomes (ability to ambulate, deep breathe, participate in physical therapy) leads to over-treatment with opioids 3
• Prescribing excessive opioid quantities at discharge contributes to diversion and the opioid epidemic; unused opioids should be disposed of properly 2