Prospective Anaylysis of Electrolytic Changes in Vitreous Humour Regarding Estimation of Time Since Death

Abstract

INTRODUCTION: Forensic Medicine deals with the application of medical and paramedical knowledge to aid in administration of justice. Forensic Medicine is a discipline of medicine and natural sciences, dealing with all medical evidence that is relevant for law. It deals with medical evidence not only in practice but also in research. Forensic Medicine have its own research profile and deals with questions and issues that are not found in other disciplines. This includes Thanatology: Post mortem changes, time of death, wound age estimation, distinction between ante and post mortem injuries. AIMS AND OBJECTIVES; 1. To know the relationship between changes in potassium and sodium and chloride concentration with increasing post-mortem interval. 2. To find out up to what time interval the levels of potassium and sodium and chloride change after death. 3. To find out the formula for determining postmortem interval from changes in levels of potassium and sodium and chloride. MATERIALS AND METHODS: Source of data: All medico legal cases and other cases autopsied at mortuary, Department of Forensic Medicine and Toxicology, Madurai Medical College, Tamil Nadu. Method of collection of data: Procedure: Vitreous humour collected by making a puncture 5-6 mm away from the limbus using 10ml sterile syringe and 20 gauze needle. Aspirated vitreous poured in a rubber stopped vial. Normal saline injected into the eye for cosmetic purpose. Specimen forwarded to Department of Biochemistry for biochemical analysis immediately centrifuged for 10 mints 3000 revelation per unit supernatant fluid for Iron Selective Electrode method, Madurai Medical College and reports will be collected for further interpretation. Place of Study: Mortuary, Govt. Rajaji Hospital, Department of Forensic Medicine and Department of Bio chemistry, Madurai Medical College, Madurai. Sample size: The vitreous humour was collected and sampled from 100 cases subjected to autopsy at Madurai Medical college, Madurai. Duration of study: 1 year study from September 2015 to August 2016. Type of study: Prospective analysis study. Sample size: All medico legal cases and other cases autopsied at GRH Madurai Medical College, from September 2015 to August 2016. INCLUSION CRITERIA: All cases male and female aged above 15 to 60 years. Only crystal clear, vitreous humour was used for analysis (with the onset of putrefaction the fluid becomes cloudy and brownish in colour. Cases with known time since death and cause of death alone were included in the study group. EXCLUSION CRITERIA: 1. Murder cases. 2. Custodial death. 3. Dowry death. 4. Decomposed. 5. Bodies with damaged eye balls e.g. assault, trauma and RTA cases. 6. One Eyed Person. 7. Visibly discolored sample to be excluded from the study. RESULTS: 100 cases of known postmortem interval (PMI) were included in this study. Of the 100 cases 71 were male and 29 were female with the age ranging from 16 to 60 years (average age= 38.2) The reported PMI in the present study was in the range of 1.15 hrs to 65 hours. The distribution of cases in different range of PMI is shown in Table No. 3 graph no.3. Deaths due to both natural and unnatural causes were included in this study. The mean value of postmortem vitreous potassium concentration for all the cases was 9.83 ± 2.48 mmol/L (mean ± SD) and the mean time since death for all the cases was 20.42 ± 13.09 hours (mean ± SD). SUMMARY: Time since death estimation is one of the most important aspect of Forensic medicine which is plays important role in crime investigations. This study was carried out 100 cases in which there were 71 males, 29 females, subjected to autopsy at district Rajaji hospital Madurai. Tamil Nadu, South India. The cases included died of RTA, Accidental fall, poison, hanging, burns, snake bites. Natural death, suicide cases at Rajaji hospital Madurai biochemical investigation done by Ion selective Electrode method (NEW METHOD) and prospective analytical study was done. In India PMI / TSD was estimated using vitreous humor electrolytes like Na+ K+Cl_ concentration co-related with PMI, there was linear relationship was obtained upto certain hours. TSD/PMI was estimated using vitreous humor K+ concentration linear association was obtained when mean values of K+ concentration in vitreous humor were plotted against PMI on graph CONCLUSION: Among three electrolytes like Na+ K+ Cl_, estimated from postmortem vitreous humor by Ion selective method, K+ Level concentration serve as potential marker for estimating time since death in early period of postmortem. There is linear relationship between TSD and K+ concentration. External factors like temperature ,humidity has no appreciable effect on vitreous K+ concentration. Age has got no appreciable effect in determining concentration of potassium in vitreous humor. 95% confidence limit of over +/-12 hours limits the usefulness in determining PMI. Concentration of postmortem potassium levels is higher in deaths due to burns, hanging, poisoning ,accidental fall, RTA and natural deaths than snake bite ,electrocution and head injury. The sodium and chloride concentration in vitreous humor has no linear relationship between PMI, Na+, Cl- are little significance when compare with K+ in achieving estimate of postmortem interval, K+, value is most significant there is considerable rise in K+ level in vitreous with increasing PMI. Due to autolysis of vascular choroids and retinal cells, there was rise of K+ and rise of PMI which indicate that rise in K+ level after death has strong correlation with the PMI.