Episode 222: Local Anesthetic Systemic Toxicity (LAST)
About this episode
This episode discusses the ominous complication of providing local anesthesia known as Local Anesthetic Systemic Toxicity (LAST).
We discuss this ominous complication of providing local anesthesia. Hosts: Elaine Jonas, MD Brian Gilberti, MD https://media.blubrry.com/coreem/content.blubrry.com/coreem/LAST.mp3 Download Leave a Comment Tags: Critical Care , Toxicology Show Notes I. Pathophysiology & Mechanisms Definition: Systemic toxicity secondary to local anesthetic (LA) via accidental intravascular injection or excessive systemic absorption. Threshold: Occurs when plasma concentration exceeds the safety threshold for cardiac and neural tissue. Agent Profile: Bupivacaine (High Risk) Highly lipophilic with high protein binding. “Fast-on, Slow-off” Kinetics: Strong N a + channel binding with extremely slow dissociation during diastole. Myocardial Depression: Direct inhibition of C a 2+ release from the sarcoplasmic reticulum, impairing contractility. Low CC:CNS Ratio: The dose required for cardiac collapse is very close to the dose that triggers seizures (narrow safety margin). Contributing Factors: Acidosis/Hypercapnia: Increases the fraction of free drug and promotes ion trapping in the brain/heart; shifts the LA-binding curve toward higher toxicity. Hypoxemia: Exacerbates myocardial…
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