What does lidocaine infusion during spinal fusion primarily decrease?

Lidocaine Infusion During Spinal Fusion: Primary Effects

Lidocaine infusion during spinal fusion primarily decreases postoperative pain scores and opioid consumption, with effects extending from the immediate postoperative period through 3 months after surgery. 1, 2, 3

Pain Reduction

Intravenous lidocaine significantly reduces pain intensity at multiple time points:

• Immediate postoperative period (2-6 hours): Pain scores decrease by approximately 1.13 points at 2 hours and 0.79 points at 4-6 hours on the visual analog scale compared to placebo 3
• 24 hours postoperatively: Mean pain reduction of 0.50-0.84 points 2, 3
• 48 hours: Continued pain reduction in adult patients (mean difference of 0.72 points) 3
• Long-term effects: Pain scores remain significantly lower for up to 3 months after a single perioperative infusion 1, 4

The mechanism involves sodium channel blockade, NMDA receptor antagonism, and reduction of circulating inflammatory cytokines, providing analgesic, antihyperalgesic, and anti-inflammatory properties 5

Opioid Consumption Reduction

Lidocaine demonstrates superior opioid-sparing effects compared to other local anesthetics:

• 24-hour morphine consumption: Reduced from approximately 19.85 mg to 4.5 mg (77% reduction) 1
• Comparison to bupivacaine: Lidocaine shows significantly greater opioid reduction (mean difference of -12.25 mg) compared to intrawound or epidural bupivacaine 6
• Time to first analgesic request: Extended from 1.82 hours to 9.56 hours 1
• 48-hour opioid consumption: Sustained reduction in morphine equivalents (55 mg vs 74 mg with placebo) 2

Secondary Benefits

Beyond pain and opioid reduction, lidocaine infusion decreases:

• Postoperative nausea and vomiting: Reduced incidence through decreased opioid requirements 5
• Hospital length of stay: Significantly shorter hospitalization compared to controls 3
• 30-day complications: Slightly fewer complications (odds ratio 0.91) 2
• Anxiety and depression: Improved emotional status up to 3 months postoperatively when combined with magnesium 4

Quality of Life Improvements

Patients receiving lidocaine demonstrate significantly better physical function:

• 1 month postoperatively: SF-12 physical composite scores of 38 vs 33 in placebo group 2
• 3 months postoperatively: Sustained improvement with scores of 39 vs 34 2
• Overall health: Enhanced quality of life measures extending months beyond the single perioperative infusion 4, 2

Clinical Implementation

The recommended dosing protocol based on international consensus:

• Loading dose: 1.5 mg/kg (maximum 2 mg/kg) infused over 10 minutes before skin incision 5
• Maintenance infusion: 1.5-3 mg/kg/hour during surgery and up to 24 hours postoperatively 5, 1
• Duration: Generally should not exceed 24 hours, though may be extended to 48 hours with dose reduction to 50% after consultation 5
• Monitoring: Continuous ECG, pulse oximetry, and blood pressure monitoring required 5

Important Safety Considerations

Common pitfalls to avoid:

• Lidocaine has relatively few side effects when properly dosed, with neurologic symptoms (lightheadedness, dizziness, perioral tingling, tinnitus) appearing before cardiac manifestations 5
• Maintain plasma concentrations below 5 μg/mL to avoid toxicity 5
• Have 20% lipid emulsion immediately available for treatment of local anesthetic systemic toxicity 5
• Use ideal body weight for dosing calculations in patients with BMI >30 kg/m² 5
• Avoid in patients weighing less than 40 kg 5

The evidence consistently demonstrates that lidocaine is superior to bupivacaine for opioid reduction and provides a multimodal approach to pain management with an excellent safety profile when administered according to established protocols 5, 6