Controlled comparison of effects of different lipid forms of propofol on the blood and tissue levels of bupivacaine induced cardiac arrest in rats

In this randomised controlled experimental study, the effect of propofol on bupivacaine cardiotoxicity and also plasma and tissue (heart and brain) levels in anesthetized rats was investigated.Eighteen male Spraque-Dawley rats were randomly divided into 3 groups as intralipid (Propofol, Group P), medialipid (Propofol Lipuro, Group L) and control (Grup K) groups. Rats were monitorized and control heart rate (HRc) values were recorded under ketamin anesthesia (im) followed by surgical tracheostomy, invasive blood pressure monitorization and mechanical ventilation. After invasive procedures HR and mean arterial pressure (HRbv and MAPbv) were recorded. Two tail veins were cannulated for basal intravenous hydration and infusion of study drugs for 20 minutes.During this period MAP and HR values were recorded every 5 minute until on set of bupivacaine infusion. HR and MAP values after 20 minutes were recorded as control before bupivacaine infusion (HRbb and MAPbb).Bupivacaine was infused 2 mg/kg/min in all groups. The first time of dysrythmia occurence, time of reduction of HR and MAP 25 and 50%, cardiac arrest time and total bupivacaine dose were recorded. Intracardiac blood samples were collected following cardiac arrest. Heart and brain tissues were exracted and bupivacaine levels were measured by LC/MSD method.Kruskal-Wallis, Mann-Whitney U and Wilcoxon were used and p< 0.05 was considered as statistically significant.There was no significant difference basal values among groups. The first dysrhytmia time, reduction of HR and MAP 25 and 50% time, time until cardiac arrest was longer in 10% intralipid propofol compared to 10% medialipid propofol group which is consistent with higher bupivacaine dose causing dysrhytmia and bradycardia. Pretreatment decreased plasma and tissue bupivacaine levels in 10% intralipid propofol group and this effect was observed only in tissue levels in 10% medialipid propofol group.These results confirm that 10% intralipid propofol is protective against bupivacaine induced cardiodepressive effects. This effect may be related to decrease of plasma and tissue bupivacaine level. When general anesthesia is needed in addition to regional anesthesia, TIVA with 10% intralipid propofol is recommended.