Determination of postmortem interval and cause of death: Do the levels of biochemical parameters in vitreous humor provide an additional assistance to medico legal expert?

Abstract

An upward rise has been observed in the pattern of unnatural deaths in the recent years and the same has been found during the post mortem examination. During the trial in the court of law prosecution as well as defense require the time passed death before examination and the cause of death in particular circumstances, as it is mandatory to fix the exact duration either to punish the guilty or NOT to punish the innocent. Vitreous humor is different from other body fluids as it has relative stability in its composition so as also biochemical parameters. It was further hypothesized that postmortem vitreous humor biochemistry closely mimics antemortem serum biochemistry and may be a useful aid in establishing postmortem diagnoses. Various studies have been carried out on vitreous electrolyte concentration changes to arrive at postmortem interval. Many workers found the importance of potassium in the determination of postmortem interval, whereas among all the biochemical parameters, vitreous potassium is found to be more useful to find out time since death. Postmortem biochemical analysis of vitreous humor may be helpful in the establishment of antemortem disease or metabolic disorder. The present study was carried out jointly in department of Forensic Medicine and Toxicology and department of Biochemistry of Surat Municipal Institute of Medical Education & Research (SMIMER), Surat. A total of 100 subjects were taken up for this study. The samples were collected from dead bodies during postmortem examination with all aseptic precautions. A detailed performa was made with all the details of age, sex, length, weight and date and time of admission, date and time of death and manner of death such as suicide, homicide, sudden death and accidents was recorded. Cases below 15 years of age were not considered in this study. Out of 100 cases there were 24 (24%) females and 76 (76%) were males, out of these 56% were between 15-35 years, 32% were of 36-55 years, 9% were of 56-65 years, and 3% were of 66-77 years age group. According to the manner of death 50 subjects were of accident, 26 subjects were of sudden death, 21 subjects were of suicide and 3 subjects were of homicide. According to time interval between sample collection and time of death, 47 subjects were of 0-24 hours, 36 subjects were of 24-48 hours, 11 subjects were of 48-72 hours and 6 subjects were of 72-96 hours. In present study we observed that there is definitive correlation between time of death and changes in level of these biochemical parameters. This was a preliminary study in this region and can be considered as a pilot study. The levels of vitreous Potassium have been found to be significantly altered as the time progresses after death. A progressive decrease in sodium/potassium and increase in potassium/ calcium ratios was also observed.