The effect of pretreatment with lipid infusion on ropivacaine cardiotoxicity in rats

SUMMARYThe Effect of Pretreatment with Lipid Infusion on Ropivacaine Cardiotoxicity in RatsGözde Selin Ozdemir, MD, Department of Anesthesiology and Reanimation, Dokuz EylulUniversity Medical School , IZMIR.In this randomized controlled experimental study, the effect of pretreatment with 10%and 20% lipid infusion, on cardiotoxicity of ropivacaine were investigated in anesthetizedrats.Twenty-four male adult Wistar-Albino rats were divided into three groups. Theanesthetized rats were mechanically ventilated using a tracheotomy cannula and invasivelymonitorized. Baseline values for the heart rate, mean arterial pressure and width of QRScomplexes were recorded. The control group (n=8) received 3 mL.kg-1 of 0.9 % saline for 5min. Lipid 1 (n=8) and Lipid 2 (n=8) groups were administered 3 mL.kg-1 of 10 % and 20%lipid solutions respectively for 5 min. After completion of the pretreatment drug infusion,drug infusion was begun with ropivacaine %1 at a rate of 3 mg.kg-1.dk-1 and was continuedtill development of asystole. Ropivacaine infusion was than stopped and resuscitation wasstarted.Times before the first QRS complex change and first dysrhythmia; also times to 50%decrease in heart rate and mean arterial pressure compared to the baseline values and alsotime to asystole, defined as absence of a positive deflection on the arterial pressure trace wererecorded. Variance analysis and Tukey-Kramer tests were used for statistical evaluations. Avalue of P < 0.05 was considered to be statistically significant.Baseline measurements did not differ significantly among the groups. An increase inthe time to 50% decrease in heart rate, and mean arterial pressure values, an increase in theperiod before the development of cardiac arrest and an increase in total ropivacaineconsumption were observed following administration of both 10% and 20% lipid solutions.There was a prolongation in the period before the first QRS complex change and firstdysrhythmia following 20% lipid infusion. It was observed that lipid infusions, did not affectthe period before 50% decrease in mean arterial pressures and results of the resuscitation.These results, suggest that lipid solutions can be effective in prevention of ropivacainecardiotoxicity. Absence of a change in resuscitation results, support further investigation oflipid based resuscitation for treatment of ropivacaine induced cardiotoxicity.Key words: ropivacaine, cardiotoxicity, lipid pretreatment.