1. Local Anesthetics P. Orzylowski 6/03/2014

3. Naturally occurring Tetrodotoxin Saxitoxin Menthol Eugenol (cloves)

4. Reversible local anesthesia Decrease rate of depolarization/repolarization of the excitable neural membrane Pain Others Paralysis

5. MOA Inhibit Na influx via Na-specific ion channels in neuronal cell membranes Voltage-gated Na channels Bind intracellular portion of channel and inhibit influx Action potential inhibited

8. 1-2% of LA penetrated nerve fibre Not everything equally blocked Depends on diameter and type of nerve fibres B>C>Adelta(temp)>Agamma(proprio)>Abeta(t ouch&pressure)>Aalpha(motor) B>C?

9. Adjuvants Epinephrine Inc intensity Dec systemic absorption Opiods Steroids – dexa increases duration by 50%

10. Side effects CNS toxicity Cross BBB More common with certain LAs (bupi) Inc: acidosis, Vc, epinephrine Dec: barbiturates.benzos, dec systemic abs (epinephrine) 3/10,000 epidural, 1/10,000 PNB

11. Cardiotoxicity Higher doses required Single isomers – ropi&levo-bupi - decreased affinity for brain and cardiac tissue 1) less lipid-soluble (lido): Hypotension/bradycardia/art hypoxemia 2) more lipid-soluble (bupi): Ventricular cardiac arrhythmias  cardiovascular collapse  resistance to resus (large doses of epi)

12. Bupivacaine has higher affinity for resting and inactive sodium channels. Bind @ systole, dissociate on diastole Dissociates slowly  incomplete recovery L-carnitine def = increased susceptibility

13. Methemoglobinemia Metabolite of prilocaine  o-toluidine Myotoxicity Dysregulation of intracellular Ca concentrion Allergies

14. Uses Regional anesthesia IV regional anesthesia (Bier’s) Peripheral nerve block Topical Systemic?

15. Prophylaxis 1)Aspiration 2)Fractionated doses 3)Slow injection

16. Treatment Mostly supportive Stop LA Supplemental oxygen Ventilatory support and intubation if necessary Treat dysrhythmias  cardioversion/amiodarone Lipid Rescue

17. Weinberg 1998 Published 2006 Still relatively limited literature Removes anesthetic from sight of action

19. 1) IV bolus 20% Lipid emulsion @ 1.5mL/kg 2)continue infusion @ 0.25ml/kg/min after restoration of cardiac function 3)if continues, rpt bolus and increase to 0.5mL/kg/min Upper limit 10mL/kg over 30mins

20. Questions?