Study On The Postmortem Diffusion Of Lidocaine In Dogs After An Epidural Administration

Objective:1.To develop a postmortem diffusion model of lidocaine in dogs after an epidural administration.2.To investigate the postmortem diffusion of lidocaine in dogs.3.To compare postmortem diffusion of lidocaine in dogs with different way of executes and administration times.4.To provide a scientific evidence for the forensic identification of the anesthesia accident caused by lidocaine.Methods:1.Animal models:1.1 Group executed by an aeroembolism:30dogs were executed by an aeroembolism.When the vital signs of dogs disappeared,18dogs were given an epidural anesthesia at an even speed in five minutes with 13mg/kg weight of lidocaine hydrochloride,then sampled in 0,12,24,48,72,96 hours after the administration(n=3 per time-point).The other 12dogs were given an epidural anesthesia with an even speed in five minutes with 13mg/kg weight of lidocaine hydrochloride respectively at 1,3,6,12hours after the vital signs of dogs had disappeared(n=3 per time-point),then collected samples at once.1.2 Group executed by carbon dioxide(18dogs):18dogs were given an epidural anesthesia with an even speed in five minutes with 13mg/kg weight of lidocaine hydrochloride,then respectively collected samples in 0,12,24,48,72,96 hours after administration(n=3 per time-point).2.Record of vital signs:By a biological function system,the vital signs such as electro cardia,blood pressure and respiration from beginning of the execute to the death of dogs were recorded.3.Collection of samples:After administration,the dogs were placed at room temperature(17～21℃),the brain,spinal cord(cervical spinal cord,thoracic spinal cord,lumbar spinal cord,sacrum spinal cord),heart,lung,liver,spleen,kidney,bile,urine,humor vitreous,blood of right ventricle,blood of left ventricle,blood of superior vena,blood of inferior vena,muscle in injection location and temporalis(muscle in no injection location)-were collected and detected immediately.4.Analysis:The samples were extracted with ether.Analysis was performed by a GC equipped with a NPD and a GC-MS.The qualitative analysis was based on retention time in the chromatographic system coupled with the ion fragmentation spectrum in the mass spectrometer. The quantitative analysis was based on an internal standard method.Results:1.Group of executed by aeroembolism:The series of administration when the vital signs of dogs disappeared:In dogs dissected immediately,lidocaine were detected in blood of inferior vena,blood of superior vena,blood of right ventricle,blood of left ventricle and lung.The concentrations of lidocaine in blood of left ventricle were changed obviously,increased from 4.7±3.8gg/ml to 21.0±9.4μg/ml in 72 hours.The concentrations in lung,there was a little decreasing after 24 hours,It indicated that the lidocaine concentrations increased in blood of left ventricle may ascribe to the diffusion from lung.Heart,liver,kidney,urine and muscle in injection location were all affected by the postmortem diffusion.Spleen,tempotal muscle,bile and humor vitreous had not been affected by the postmortem diffusion.The series of administration at 1,3,6,12 hours after the vital signs of dogs disappeared:The postmortem diffusion were similar with dogs administration when the vital signs of dogs disappeared.2. Group of executed by carbon dioxide:Lidocaine were detected in blood of inferior vena at 48,72, 96 hours after administration,It indicated that the postmortem diffusion of lidocaine should be influenced by the method of sacrifice.Conclusion:1.The study has established the postmortem diffusion models of epidural administration with lidocaine,It can be applied to the forensic identification of the epidural anesthesia accident.2.The results of lidocaine sacrificed by aeroembolism showed that,lidocaine detected in heart blood,lung and blood in inferior caval vein in a few minutes after epidural anesthesia,which was related to the physico-chemical property of lidocaine and the path of administration.Lung may be another reservoir in the early stage after death,then with the time lasting,the concentration of lidocaine in heart blood were effected.There was no postmortem diffusion in spleen,tempotal muscle,bile and humor vitreous.Whether lidocaine was detected in the matrix could be regarded as the evidence for the poisoning or postmortem intragastric administration.3.The postmortem diffusion of lidocaine in different time administration groups showed that,it had not significant effect on the postmortem diffusion in the early stage after death.4.The group of sacrificed by carbon dioxide showed that,the cause of death would take an effect on the postmortem diffusion of lidocaine.5.It is important to consider the phenomenon of postmortem diffusion.in the forensic identification of epidural anesthesia accident case.The postmortem diffusion of lidocaine was related to the physico-chemical property of lidocaine,the rate of electro-ionization and the distance to reservoir.With the development of gangrenous, destruction of biological barrier can also facilitate the diffusion of lidocaine hydrochloride.The blood in heart and periph should be discriminated,for lest to pollute each other.