Intralipid

A 45-year-old woman presents to the hospital after an acute overdose. The patient has access to buproprion, venlafaxine, propranolol, and clonazepam. She is endotracheally intubated for airway protection. The patient is hypotensive and develops ventricular tachycardia. The physician orders intravenous lipid emulsion therapy…

What is intravenous lipid emulsion (ILE) therapy?

Intravenous lipid emulsion (ILE) is a sterile and non-pyrogenic mixture of medium-chain triglycerides and long chain triglycerides, egg phospholipids and glycerol. After administration, ILE forms chylomicron-like lipid droplets and turns the serum a milky, turbid texture. It is most widely known for its use as part of parenteral nutrition. More recently, ILE is being used as antidotal therapy in acute drug toxicities

 

What are the indications for using ILE?

Traditionally, ILE has been used as antidotal therapy for iatrogenic intravenous local anesthetic toxicity and is widely accepted in the anesthesia literature. In particular it is used for bupivicaine-induced cardiovascular toxicity. There is, however, generalization of this indication for other local anesthetics as well.
re recently, ILE has been advocated for several other lipophilic medications causing cardiovascular collapse. Several case reports and animal models using ILE included propranolol, buproprion, quetiapine, cyclic antidepressants, and calcium channel blockers
　

The use of ILE as an antidote remains a nascent field warranting further preclinical study. The use of traditional resuscitation measures should precede the use of ILE until further studies can establish its early antidotal role.

ILE is ordered as a 20% concentration.

• 1-2 ml/kg IV (lean body mass) administered as a bolus over 1-3 minutes, followed by an infusion of 0.25 ml/kg/minute.
• ILE can be administered through a peripheral intravenous catheter. After the bolus, attach the lipid emulsion bag to an intravenous pump

For non-responders to initial bolus,

• Give 1-2 further 50-100 mL boluses at 5 min intervals (max bolus dose 3 mL/kg)
• Continue infusion until hemo-dynamically stable. Increase the infusion rate to 0.5 ml/kg/minute if blood pressure declines or remains low. Continue infusion for 10–60 minutes after achievement of hemodynamic stability but no more than 1 hour.

There are three proposed mechanisms of action for ILE.

1. Lipid sink : It is postulated that ILE creates fat emulsions that bind lipophilic drugs intravascularly, reducing the free drug concentrations, thereby decreasing serum toxicity.
2. Mass action: Cardiac myocytes use both free fatty acids and carbohydrates as substrate for energy utilization with a preference for free fatty acids. Administration of ILE increases fatty acid serum concentrations that pushes mitochondrial free fatty acid oxidation, thus increasing ATP production and cardiac performance
3. Ion channel activation: long chain unsaturated and saturated fatty acids induce significant increases in voltage dependent calcium currents in cardiac myocytes in a dose dependent fashion. In isolated myocardial cells, free fatty acids increased myocardial contractility, left ventricular systolic pressure, and directly activate voltage-gated calcium channels

Does ILE affect any blood work after administration?

Several laboratory tests, including white blood count, hemoglobin, platelets, and serum electrolytes are unable to be analyzed for up several hours post administration due to the lipidemia in the blood. However, use of ultracentrifugation or point of care lab machines may decrease this post administration delay in labs.