Resuscitation with lipid versus epinephrine in a rat model of bupivacaine overdose.
BACKGROUND
Lipid emulsion infusion reverses cardiovascular compromise due to local anesthetic overdose in laboratory and clinical settings. The authors compared resuscitation with lipid, epinephrine, and saline control in a rat model of bupivacaine-induced cardiac toxicity to determine whether lipid provides a benefit over epinephrine.


METHODS
Bupivacaine, 20 mg/kg, was infused in rats anesthetized with isoflurane, producing asystole in all subjects. Ventilation with 100% oxygen and chest compressions were begun immediately, along with intravenous treatment with 30% lipid emulsion or saline (5-ml/kg bolus plus continuous infusion at 0.5 ml . kg . min) or epinephrine (30 microg/kg). Chest compressions were continued and boluses were repeated at 2.5 and 5 min until the native rate-pressure product was greater than 20% baseline. Electrocardiogram and arterial pressure were monitored continuously and at 10 min, arterial blood gas, central venous oxygen saturation, and blood lactate were measured. Effect size (Cohen d) was determined for comparisons at 10 min.


RESULTS
Lipid infusion resulted in higher rate-pressure product (P < 0.001, d = 3.84), pH (P < 0.01, d = 3.78), arterial oxygen tension (P < 0.05, d = 2.8), and central venous oxygen saturation (P < 0.001, d = 4.9) at 10 min than did epinephrine. Epinephrine treatment caused higher lactate (P < 0.01, d = 1.48), persistent ventricular ectopy in all subjects, pulmonary edema in four of five rats, hypoxemia, and a mixed metabolic and respiratory acidosis by 10 min.


CONCLUSIONS
Hemodynamic and metabolic metrics during resuscitation with lipid surpassed those with epinephrine, which were no better than those seen in the saline control group. Further studies are required to optimize the clinical management of systemic local anesthetic toxicity.
Weinberg
Guy L
GL
Department of Anesthesiology, University of Illinois College of Medicine at Chicago and Jesse Brown Veterans Administration Medical Center, Chicago, Illinois 60612, USA. guyw@uic.edu
Di Gregorio
Guido
G
Ripper
Richard
R
Kelly
Kemba
K
Massad
Malek
M
Edelman
Lucas
L
Schwartz
David
D
Shah
Nirali
N
Zheng
Sophie
S
Feinstein
Douglas L
DL
D000779:Anesthetics, Local / Q000627:therapeutic use / Q000633:toxicity; D000818:Animals; D002045:Bupivacaine / Q000008:administration & dosage / Q000627:therapeutic use* / Q000633:toxicity*; D004195:Disease Models, Animal; D062787:Drug Overdose / Q000517:prevention & control*; D004837:Epinephrine / Q000494:pharmacology*; D006321:Heart / Q000187:drug effects; D007262:Infusions, Intravenous; D008055:Lipids / Q000627:therapeutic use*; D008297:Male; D051381:Rats; D017207:Rats, Sprague-Dawley; D012151:Resuscitation / Q000379:methods*
D000779:Anesthetics, Local; D008055:Lipids; D002045:Bupivacaine; D004837:Epinephrine