Medicolegal study of determination of time since death from potassium level in vitreous humour

Abstract

Background: From the knowledge of science, various workers have established the methods of determining post mortem interval by the use of physical changes after death. Unfortunately the accuracy was low and margin of error high as evident from the literature available. Trends are now shifting towards the use of various chemical methods like estimation of electrolyte concentration of cerebrospinal fluid, synovial fluid and vitreous humour. Vitreous humour is stable, less contaminated by putrefaction, easily accessible in sufficient quantity. Thus, it is suitable to determine time since death. Methods: The present cross-sectional study was carried out in grant Govt. medical college; Mumbai on 200 cases brought to the mortuary from the period 1st January 2011 to 31st May 2013. Results: It was found that there was linear correlationship between vitreous humour potassium concentration and increasing post-mortem interval irrespective of age, sex, temperature, humidity and mode of death. Conclusions: There was linear relationship between vitreous potassium concentration and post-mortem interval. The accuracy of prediction of PMI can be improved by applying present study formula. The rate of rise of potassium level in vitreous humour was 0.23mEq/L/hr No significant difference in vitreous potassium concentration between the two eyes was noted when samples were drawn at the same PMI. There was no significant effect of age, sex, temperature, humidity and mode of death on vitreous potassium level after death.