Lipids: Local Anesthetic Systemic Toxicity and Broader Applications

In rare cases (less than 1% of exposures), patients who receive local anesthetics (LA) develop life-threatening systemic toxicity and it’s linked to elevated LA plasma concentrations. Most experts concur that LAs have the greatest potential to cause adverse reactions when prescribers use inappropriate doses or routes, or employ faulty injection techniques. The most common cause of LAST is inadvertent intravascular injection. But unintended reactions are possible even when dose and route are correct. The Journal of Parenteral and Enteral Nutrition published a review article on the go-to rescue intervention when local anesthetic systemic toxicity (LAST) develops: lipid resuscitation.

Lipid resuscitation therapy was identified in 1998 as an effective treatment for LAST. Research has enlightened us about two things.

First, we understand risk factors better. Patients with renal or hepatic impairment, respiratory acidosis, preexisting cardiac block, hypoxia, or ischemic heart disease are at elevated risk for reaction. Patients who are pregnant, very young or very old also are more likely to have adverse reactions to LA.

Second, we also understand the manner in which lipids work, using both dynamic scavenging and direct cardiotonic effects.

When LAST develops, the surgical team moves into crisis mode immediately. The LA is stopped, the patient’s airway secured and ventilation with 100% oxygen initiated. An intravenous (IV) access needs to available or established, since currant recommendations indicate that using an LA Toxicity Kit (20% intralipid emulsion) early is an appropriate and low-risk response.

This review discusses broader applications for lipid rescue in other types of drug overdose. They discuss its use in overdose of illicit drugs, antianxiety, antidepressant, antipsychotics, hypnotics, and veterinary situations.

Most interesting, the review discusses the future of lipids, with a promising area of application that of use as a potential intraperitoneal dialysis agent. This review updates the surgical team on the best approach to LAST, and also offers a wealth of information about overdose management.