Study On Distribution Of Lidocaine In Dogs Died Of Subarachnoid Anesthesia

AIM: 1. To establish a lidocaine subarachnoid anesthesia death model with dogs, observe the vital sign and pathology of dogs after a lethal dose of lidocaine being injected into subarachnoid space. 2. To set up a thin layer chromatography (TLC) scanning analysis of lidocaine in tissue samples. 3. To study the distribution of lidocaine in dogs died of subarachnoid anesthesia, provide the scientific evidences for forensic medicine identification of the anesthesia accident death case.METHOD: 1. Model: After having been placed a tube in the subarachnoid space, ten dogs were given a lethal dose of lidocaine ( 12.67 mg/kg ) by a slow injection in 5 minutes. 2. Record of vital signs: By an experimental system of biological function, the vital signs alteration of the experiment dogs, such as electro cardiac, respiration and blood pressure, had been recorded. 3. Collection and preservation of samples: As soon as the three vital signs disappeared, the dogs were anatomized, and the heart, liver, kidney, spleen, lung, brain, muscle in the injection location and no injection location, the heart blood, urine, bile, cerebrospinal fluid (CSF) in the lateralventricle and spinal subarachnoid space, spinal cord (medulla oblongata, cervical cord, the upper beast spinal cord, breast spinal cord and waist spinal cord) were taken out, some of which were preserved at -20 for qualitative and quantitative analysis, and the others were fixed with 4% formaldehyde for the pathology observation. 4. Phathology: The fixed tissues were cut into sections and stained with a HE staining for a light microscopic examination. 5. Detection: The samples were extracted with ethyl ether. The lidocaine in the sample was qualitated by Rf and a TLC scanning spectrometry, quantitated by a TLC scanning chromatography and a two points external standard method or a standard curve method.RESULTS: 1. The electro cardiac, blood pressure and respiration of the dogs disappeared within 23.8 16.4 (7~42)min, 16.4 11.5 (7-35) min and 18.6 16.0 (10-47) minafterthe lidocaine was given. The dogs showed the pathology of rapid death cases. The vital sign and pathology of dogs were mostly similar to the signs of an anesthesia accident. 2. The concentrations detected in spinal subarachnoid space CSF, lateral ventricle CSF, the upper beast spinal cord, waist spinal cord, injection location spinal cord, breast spinal cord, cervical spinal cord, medulla oblongata, injection location muscle, brain, blood, bile, urine, lung, liver, kidney, hearts, spleen and no injection location muscle were 485.6 51.5 ug/ml ,464.4 51.6 ug/ml,353.8 44.0 g/g, 353.0 60.1 ug/g, 339.8 52.1 ug/g, 237.0 36.3 ug/g, 235.1 35.2 ug/g, 226.8 35.2 ug/g, 107.6 11.6 ug/g, 44.9 11.5 ug/g, 40.3 6.5 ug/ml, 38.0 9.8 Ug/ml, 37.5 9.5 ug /ml, 28.4 6.8ug/g, 26.3 6.7ug/g, 24.6 7.3ug/g, 23.1 5.5 ug/g, 22.2 4.6ug/g, 13.5 13.7ug/g. Ratios of lidocaine in CSF to in blood and in brain were 12.4 2.7 and 10.8 4.5. Ratios of lidocaine in spinal cord to in blood and in brain were 5.7 0.9-9.0 2.6 5.1 3.1-7.9 5.2. 3. The lidocaine detection curve was linear over the range of 1-200 g/ml, the correlation coefficients were bigger than 0.996. The detection limit in tissues were 0.1-0.5 g /ml. The absolute extraction recoveries of lidocaine in tissues were 79.7%~90.2%.CONCLUSION: The animal model established in this paper can be used for the forensic medicine study on lidocaine anesthesia accident death. The vital signs alteration data and distribution data of lidocaine in dogs died of subarachnoid anesthesia can be used for the forensic medicine identification of the anesthesia accident death case. The TLC scanning analysis can be used for identification and determination of lidocaine in tissue samples.