UMEM Educational Pearls

Category: Toxicology

Title: Local Anesthetic Toxic Doses

Keywords: lidocaine, bupivacaine (PubMed Search)

Posted: 6/5/2014 by Fermin Barrueto, MD (Updated: 9/22/2019)
Click here to contact Fermin Barrueto, MD

This is a must memorize simple table of the toxic doses of local anesthetics. Toxicity of local anesthetics starts with slurred speech, lethargy to seizures and lethal cardiac dysrhythmias. There should be zero tolerance to actual cause toxicity when repairing a laceration or performing a fascia iliaca block.

Remember that a Bupivcaine solution 0.5% = 0.5 g/dL (%=g/dL) so a 70kg person, you can use a  maximum of 2mg/kg x 70kg person. You can inject 140 mg in a 70kg person. This is a maximum volume injection of 28 mL if you were doing a fascia iliaca block. You can double the volume if you use a more dilute solution of 0.25%.

Local Anesthetic mg/kg 
Bupivacaine 2
Ropivacaine 3
Lidocaine 4
Lidocaine with Epinephrine 6
Prilocaine 6

Treatment for cardiac dysrhythmias due to local anesthetics is 20% lipid emulsion therapy - don't follow ACLS protocol as epinephrine or other antidysrhythmics (especially lidocaine) will be lethal.