What is the recommended protocol for administering a 20% Intralipid (lipid emulsion) infusion for local anesthetic toxicity and for parenteral nutrition?

Intralipid Infusion Protocol

For Local Anesthetic Systemic Toxicity (LAST)

Administer 20% Intralipid at 1.5 mL/kg as an intravenous bolus over 1 minute, immediately followed by a continuous infusion at 0.25 mL/kg/min, with the bolus repeatable up to twice at 5-minute intervals for persistent cardiovascular collapse. 1, 2, 1, 3

Initial Bolus Dosing

• Bolus dose: 1.5 mL/kg of 20% lipid emulsion over approximately 1 minute
• For a 70 kg adult: 100 mL bolus
• Repeat bolus: May be given once or twice at 5-minute intervals if cardiovascular collapse persists 1, 2, 1

Continuous Infusion

• Initial infusion rate: 0.25 mL/kg/min (15 mL/kg/hr)
• For a 70 kg adult: 1000 mL/hr
• If inadequate response: Double the infusion rate to 0.5 mL/kg/min (30 mL/kg/hr) after 5 minutes if circulation not restored 2
• Duration: Continue for at least 10 minutes after attaining circulatory stability 1, 3

Maximum Cumulative Dose

• Upper limit: Approximately 10-12 mL/kg total dose 1, 2
• For a 70 kg adult: 840 mL maximum cumulative dose

Critical Context for LAST Management

Stop local anesthetic injection immediately when toxicity is suspected. The lipid emulsion works through a "lipid sink" mechanism, extracting lipophilic local anesthetics from cardiac tissue and plasma, while also counteracting local anesthetic inhibition of myocardial fatty acid oxidation 2.

Concurrent resuscitation measures are mandatory:

• Ventilate with 100% oxygen
• Perform standard ACLS with chest compressions as needed
• Manage seizures with benzodiazepines (midazolam 0.1-0.2 mg/kg IV); avoid propofol if cardiovascular instability present 1, 3
• Reduce epinephrine doses during resuscitation
• Avoid vasopressin, calcium channel blockers, and β-blockers 1, 3

Prolonged resuscitation may be required - potentially over 1 hour - as cardiovascular toxicity from local anesthetics can be very refractory to treatment 2. Alert the nearest facility with cardiopulmonary bypass capability, as mechanical circulatory support (CPB or VA-ECMO) may be necessary if lipid emulsion fails 1, 4.

Pediatric Considerations for LAST

The same weight-based dosing applies: 1.5 mL/kg bolus over 1 minute, followed by 0.25 mL/kg/min infusion 5, 4. The most recent pediatric regional anesthesia guideline (2025) confirms this approach, noting that LAST in children has favorable outcomes with lipid rescue therapy when administered promptly 5.

---

For Parenteral Nutrition

For parenteral nutrition in adults, initiate 20% Intralipid at 0.5 mL/min for 15-30 minutes, then increase to 1 mL/min if tolerated, with a maximum daily dose of 2.5 g fat/kg body weight (12.5 mL/kg of 20% Intralipid) and maximum infusion rate of 0.1 g/kg/hr. 6

Adult Dosing for Parenteral Nutrition

Initial infusion:

• Start at 0.5 mL/min for first 15-30 minutes
• If no adverse reactions occur, increase to 1 mL/min
• Maximum on first day: 500 mL 6

Maintenance dosing:

• Daily dose: 0.7-1.3 g triglycerides/kg body weight (typically 3.5-6.5 mL/kg of 20% Intralipid)
• Maximum daily dose: 2.5 g fat/kg body weight (12.5 mL/kg of 20% Intralipid)
• Maximum infusion rate: 0.1 g/kg/hr (0.5 mL/kg/hr of 20% Intralipid) 6, 7
• Lipids should provide 25-40% of non-protein energy (up to 60% in certain situations like respiratory insufficiency) 6, 7

Pediatric Dosing for Parenteral Nutrition

Premature infants:

• Start at 0.5 g fat/kg/24 hours (2.5 mL/kg of 20% Intralipid)
• Increase gradually based on infant's ability to eliminate fat
• Maximum: 3 g fat/kg/24 hours 6

Older pediatric patients:

• Initial rate: No more than 0.05 mL/min for first 10-15 minutes
• If tolerated, increase to 0.5 mL/kg/hr (equivalent to 0.1 g/kg/hr)
• Maximum daily dose: 3 g fat/kg body weight 6

Critical monitoring for pediatric patients: Perform liver function tests regularly when Intralipid is administered for >2 weeks, as pediatric patients are at risk for parenteral nutrition-associated liver disease (PNALD) 6.

Essential Fatty Acid Deficiency (EFAD)

When correcting EFAD, 8-10% of caloric input should be supplied by 20% Intralipid to provide adequate linoleic and linolenic acids. Administer within 7 days of starting parenteral nutrition to prevent EFAD 6, 7.

Monitoring Requirements for Parenteral Nutrition

• Serum triglycerides: Monitor regularly
• Reduce dosage if triglycerides >400 mg/dL (>4.6 mmol/L)
• Stop infusion if triglycerides >1000 mg/dL (>11.4 mmol/L) 6, 7
• Use 1.2-micron filter; filters <1.2-micron must not be used 6

Administration Considerations

Do not use if oiling out appears on the emulsion surface. Intralipid can be infused into the same vein as carbohydrate/amino acid solutions via Y-connector near the infusion site, or through a separate peripheral site 6. Consider using non-DEHP administration sets, as fat-containing fluids extract DEHP from PVC components 6.

---

Key Distinctions Between Indications

The protocols differ dramatically because the clinical contexts are opposite: LAST requires rapid, high-dose administration to reverse life-threatening cardiotoxicity, while parenteral nutrition requires slow, controlled administration to provide metabolic support. In LAST, you're treating an emergency with bolus dosing up to 12 mL/kg total; in parenteral nutrition, you're providing daily nutrition with maximum 2.5 g/kg/day (12.5 mL/kg) administered slowly over 24 hours.

All cases of lipid rescue for toxicity should be reported to NHS Improvement and the Lipid Rescue registry (www.lipidrescue.org) 2.