What is the recommended intravenous lidocaine infusion dose for analgesia in an adult patient?

Intravenous Lidocaine Infusion Dosing for Analgesia

For adult patients requiring intravenous lidocaine for analgesia, administer a loading dose of 1.5 mg/kg over 10-20 minutes, followed by a continuous infusion of 1.5 mg/kg/hour, with the infusion typically limited to 24 hours. 1

Loading Dose Protocol

• Administer 1.5 mg/kg as an initial bolus over 10-20 minutes at the time of anesthesia induction or when initiating therapy 1, 2
• The loading dose should not exceed 1.5 mg/kg to minimize risk of acute toxicity 1
• An anesthetist or intensivist must be present during the initial loading dose 1
• Complete the loading infusion before surgical incision when used perioperatively 1
• For neuropathic pain management, the NCCN recommends a slightly higher range of 1.5-2 mg/kg over 20-30 minutes (approximately 105-140 mg for a 70 kg adult) 3

Maintenance Infusion

• Start continuous infusion at 1.5 mg/kg/hour after the loading dose 1
• This rate typically maintains plasma concentrations below 5 μg/mL, which is the target therapeutic range 1
• For cancer-related or neuropathic pain, the NCCN recommends 0.5-2 mg/kg/hour with a maximum of 100 mg/hour, titrated to the lowest effective dose 3
• Any adjustment to the infusion rate should be made only by a consultant anesthetist or intensivist 1
• Frequent rate changes are discouraged 1

Duration and Dose Reduction

• Limit infusion duration to 24 hours in most cases 1
• If extension beyond 24 hours is necessary (e.g., for chronic pain patients), reduce the infusion rate to 50% and obtain approval from a consultant anesthetist or intensivist 1
• Most patients achieve adequate analgesia within 24 hours as postoperative pain decreases and other analgesics become effective 1

Critical Dosing Adjustments

• Use ideal body weight for dose calculations in patients with BMI >30 kg/m², not actual body weight 2, 4
• Avoid intravenous lidocaine in patients weighing <40 kg due to increased toxicity risk 2, 3
• Reduce doses in patients with hepatic impairment, age >70 years, cardiac failure, or renal dysfunction 3, 5

Administration Requirements

• Use a dedicated, lockable infusion pump with anti-siphon and anti-reflux mechanisms 1
• Deliver through a separate, dedicated IV cannula with minimum 10 mL/hour sodium chloride 0.9% flush 1
• Install a one-way valve to prevent retrograde tracking into other infusions 1
• Use standardized hospital-wide concentrations (typically 2% w/v lidocaine) 1, 4

Monitoring Protocol

During Loading Dose:

• Continuous ECG and pulse oximetry 1
• Non-invasive blood pressure every 5 minutes during infusion and for 15 minutes after 1

During Maintenance Infusion:

• Observations every 15 minutes for the first hour, then hourly minimum 1
• Continue ECG monitoring in high-dependency areas 1
• Maintain vigilance for early neurological signs of toxicity (see below) 1

Toxicity Recognition and Management

Early Warning Signs (plasma 5-10 μg/mL):

• Perioral tingling or numbness 1, 3
• Tinnitus (ringing in ears) 1, 2, 3
• Facial tingling 1, 3
• Light-headedness and dizziness 1, 3
• Slurred speech 2, 3

Severe Toxicity (plasma >10 μg/mL):

• Muscle twitching or tremor 2, 3
• Loss of consciousness 2, 3
• Seizures 2, 3
• Respiratory arrest 2, 3
• Cardiac arrhythmias and cardiovascular collapse 2, 3

Critical Safety Measures:

• Keep 20% lipid emulsion immediately available wherever lidocaine is infused 1, 3
• Discontinue infusion immediately if any signs of toxicity appear 3
• Staff must be trained to recognize toxicity symptoms 1
• Neurological symptoms appear before cardiovascular signs, making them the most important early indicators 1

Important Contraindications and Precautions

• Do not administer within 4 hours of any other local anesthetic intervention to prevent cumulative toxicity 2, 3
• Calculate total dose of all local anesthetics (any route) before initiating IV lidocaine 2, 3
• Remove any topical 5% lidocaine patches before starting IV infusion 2
• Absolute contraindication: known allergy to amide-type local anesthetics 2
• Contraindicated in advanced liver failure due to decreased clearance 2

Common Pitfalls to Avoid

• Do not use actual body weight in obese patients—this leads to excessive dosing and plasma levels exceeding 10 μg/mL 4
• Do not give repeated 200 mg bolus doses—the NCCN specifically advises against this practice 3
• Do not infuse too rapidly—rapid administration increases toxicity risk 1
• Do not continue on general wards—patients require monitored beds (HDU/level 2 care) outside the operating theater 1, 6
• Do not ignore early symptoms—perioral tingling and tinnitus mandate immediate reassessment even when other explanations seem plausible 1