Pretreatment with Hypertonic Saline Outperforms Sodium Bicarbonate In Rodent Bupivacaine Toxicity

Abstract

Bupivacaine is a commonly used local anesthetic agent with a significant cardiac adverse effect profile. Powerful experimental evidence has recently been published showing an effect for lipid emulsions in bupivacaine toxicity. Other studies have provided evidence of an effect for hypertonic sodium solutions. There is no evidence on whether the effects of lipid emulsion and hypertonic sodium solutions are additive. This preliminary study aims to establish which hypertonic sodium solution is most effective and create a model for future study. 24 female rats were divided into groups and pretreated with gelofusine®(control), hypertonic saline (HS) or sodium bicarbonate (NaBic) solution. Subjects were then infused with bupivacaine 0.75%. Outcomes were time to death and percent QRS duration prolongation two minutes into the infusion. HS pretreated animals survived bupivacaine infusion longer than NaBic (5.3+/-0.7 vs. 4.25+/-1.7 mins, p<0.05). Neither group was significantly different to controls for time to death. A protective effect for HS and NaBic on percent QRS prolongation 2 minutes into infusion occurred (8.8+/6.1%(HS) and 1.2+/-10.1% (NaBic) vs. 22 .8+/-15.0% p<0.05) with no siginificant difference between the 2 solutions. Increased lethal dose of bupivacaine in the HS group versus NaBic made it the most successful pretreatment. While no protective effect was found on time to death for either HS or NaBic, both had a protective effect on QRS duration prolongation 2 minutes into infusion, suggesting benefit. This variable can be included in future studies a priori.