| Objective:To observe the effects of pretreatment with lipid emulsion on Ropivacaine infusion induced cardiac toxicity in rats and the main mechanisms.Methods:40 SD male rats and weighting about 280-320g, were randomly divided into three groups, control group (A group)(n=8), normal saline treatment group(B group), lipid emulsion pretreatment group(C group), B and C group are further divided into two sub-groups based on the death group and the material group(n=8). The rats were fasted before eight hours, free of water. The rats were anesthetized with 10% chloralic hydrate (0.3ml/100g) that were intraperitoneal injected and Supine fixed on small animals surgery, after that do regular trachea cut and tracheal intubation. After fixation connect the little animal breathing (HX300) machines do mechanical ventilation. Preferences:RR 60times/min, tidal volume (TV) 2ml/100g, oxygen flow0.5L/min. Two-lead ECG being monitored by inserting three acupuncture needles into the both upper limbs and left lower limb subcutaneouly. Exposure to the left common carotid artery in rats, placing 24G casing needle connect pressure sensor for monitoring arterial blood pressure exposure rats right internal jugular vein of femoral vein, placing 24G casing needle (Intravenous needle pre filling 5IU retained/ml heparin sodium saline).Group A, control group,0.9% normal saline(3ml/kg/min)was pumped in intravenous continuously heart was quickly removed after 6 minutes.Group B1, normal saline deadly group,0.9%normal saline (3 ml/kg/min) was pumped in intravenous injection 5 minutes continuously, then 0.5% Ropivacaine lOmg/kg/min was pumped in intravenous injection continuously until cardiac arrest then the heart was quickly removed. Group B2, normal saline materials group,0.9% normal saline (3 ml/kg/min) was pumped in intravenous injection 5 minutes continuously, then 0.5% Ropivacaine 10mg/kg/min was intravenous injection 1 minute continuously then the heart was quickly removed.Group C1, Fat emulsion deadly group,20% fat emulsion (3 ml/kg/min) was pumped in intravenous injection 5 minutes continuously, then 0.5% Ropivacaine 10mg/kg/min was pumped in intravenous injection continuously until cardiac arrest then the heart was quickly removed.Group C2, Fat emulsion materials group,20% fat emulsion (3 ml/kg/min) was pumped in intravenous injection 5 minutes continuously, then 0.5% Ropivacaine 10mg/kg/min was intravenous injection 1 minute continuously then the heart was quickly removed.Mean Arterial Blood Pressure (MAP) was recorded before the drugs were given and the heart rate (HR) were recorded at the same time. Rats MAP reduce 20%, right now for T1. To cardiac arrest, electrocardiogram shown after cardiac arrest observed 1 min no longer appear ECG waveform, right now for T2. On t1 and T2 time points calculated respectively kilogram of body weight of the pump into the local anesthetics dose. Alternately rats open-chest take ventricular muscle, determination of ventricular muscle in Ropivacaine content.Results:1. Weight Five rats, weight comparative differences between groups was statistically significant2. Elementary value of haemodynamics There was no statistic difference on elementary value of haemodynamics (HR,MAP) between five groups. The difference was no significant difference(p>0.05).3. The different time points and dose corresponding to the time in the death group. The time points, Group C1 is appeared later than the group B1 (P<0.05) with statistical significance. The accumulated dose of corresponding Ropivacaine in group C1 is larger than in group B1 (p<0.05) with statistical significance. Ropivacaine content of ventricular muscle in group C2 and B2 was no statistic difference (P>0.05).4. ATP content of ventricular muscle in materials group The ATP content of ventricular muscle in group C2 is higher than in group B2 (p<0.001) with statistical significance.Conclusion:Lipid emulsion pretreatment reduces cardiac toxicity of Ropivacaine and Improves heart toxicity threshold. The mechanism may be the "Lipid pool" effect and "Metabolic theory". |
PDF Full Text Request