LAST: Rx

Advanced, Clinical Sciences: Anesthesia Procedures, Methods, and Techniques

Local Anesthetic Toxicity (LAST) is a relatively rare complication that results from elevated plasma concentrations of local anesthetics most often after accidental intravascular injection.1 The symptoms of local anesthetic toxicity occur in a dose-dependent fashion and result from the systemic sodium channel blockade including in the brain and the heart. 1 CNS symptoms often precede cardiac manifestations causing circumoral numbness, facial tingling, restlessness, vertigo, tinnitus, and slurred speech, culminating in tonic-clonic seizures. 1 Cardiac manifestations include prolonged PR interval and widening of the QRS complex leading to wide range of arrhythmias.1 Mainstay of treatment is the use of 20% Intralipid as described below.

Treatment of LAST:

Stop local anesthetic

CPR/ACLS if pulseless

20% Intralipid IV:

Load 1.5ml/kg

Followed by infusion: 0.25 ml/kg/hr

Propofol should not be administered in place of Intralipid as the volume necessary for lipid therapy would deliver potentially lethal quantities of Propofol

Sodium bicarbonate to maintain pH?7.25 in a prolonged resuscitation

Consider transcutaneous pacing for bradycardic rhythms

Continue CPR for at least 60 min

Adapted from Miller Basics of Anesthesia 1

Below are maximum dosages (subject to variation depending on concentration, location, technique, and whether combined with a vasoconstrictor) of common local anesthetics according to Morgan and Mikhail’s Clinical Anesthesiology.2

Agent

Maximum Dose (mg/kg)

Chloroprocaine

12

Lidocaine

4.5

7 (with Epinephrine)

Mepivacaine

4.5

7 (with Epinephrine)

Bupivacaine

3

Ropivacaine

3

Adapted from Morgan and Mikhail’s Clinical Anesthesiology 2

Additional resources include asra.com and lipidrescue.org

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Answered correctly

2020

Year asked

Author
Cameron Sumner, MD