Medical Journal of Dr. D.Y. Patil Vidyapeeth

ORIGINAL ARTICLE
Year
: 2015  |  Volume : 8  |  Issue : 3  |  Page : 315--318

Vitreous potassium concentration as a predictor of postmortem interval in injury (trauma) cases: A cross-sectional study from a tertiary care center in rural Haryana


Rajesh Duraisamy Rathinam1, Shelesh Goel2, Virender K Chhoker3, Pankaj Chikkara4, Abhishek Singh5, Shwetank Goel6, Nand Kishore Singh5,  
1 Department of Forensic Medicine, Indira Gandhi Medical College and Research Institute, Puducherry, India
2 Department of Community Medicine, GFIMS and R, Ballabhgarh, Faridabad, India
3 Department of Forensic Medicine, Santosh Medical College, Ghaziabad, India
4 Department of Forensic Medicine, PGIMS, Rohtak, Haryana, India
5 Department of Community Medicine, Shaheed Hasan Khan Mewat Govt. Medical College, Nalhar, India
6 Department of Microbiology, Major S D Singh Medical College, Fathehgarh, Uttar Pradesh, India

Correspondence Address:
Abhishek Singh
Department of Community Medicine, Shaheed Hasan Khan Mewat Govt. Medical College, Nalhar, Haryana
India

Abstract

Background: Time since death (TSD) is an important parameter to the forensic expert. Only a fewer studies are available in the literature to determine the relationship between vitreous K + concentration and TSD especially among injury (trauma) cases and thus information on the same is patchy and scanty. Objective: To determine the relationship between changes in vitreous K + concentration with increasing TSD among injury (trauma) cases. An additional objective was to derive a formula for determining TSD from changes in levels of vitreous K + in the study subjects. Materials and Methods: In this study, autopsy cases brought to the mortuary of Department of Forensic Medicine and Toxicology of a tertiary care center, were the subjected for collection of vitreous humor for determination of vitreous potassium. Data of 55 such cases where autopsy confirmed the cause of death as injury (trauma), were included in this study. Determination of potassium level in the collected sample was done using ion-selective electrode method (Biolyte 2000 auto analyzer). Results: A linear relationship was observed between vitreous potassium concentration and TSD in both the eyes. External factors like seasonal variations and temperature, gender difference and age had no appreciable effect on the concentration of vitreous potassium in either eye. In this study, the linear regression equations obtained from potassium concentration (y) verses time (x) for the two groups among injury (trauma) cases were as follows: For right eye: Regression line (y) = −5.040 (x) = +1.989, for left eye: Regression line (y) = −5.223 (x) = +2.005. The potassium levels are found to increase up to 40 h after death. Conclusion: The study highlighted the usefulness of relationship between vitreous potassium concentration and TSD in both the eyes. The formula calculated from the current study could prove to be more appropriate as it is based on a more recent study and more reliable tests.



How to cite this article:
Rathinam RD, Goel S, Chhoker VK, Chikkara P, Singh A, Goel S, Singh NK. Vitreous potassium concentration as a predictor of postmortem interval in injury (trauma) cases: A cross-sectional study from a tertiary care center in rural Haryana.Med J DY Patil Univ 2015;8:315-318


How to cite this URL:
Rathinam RD, Goel S, Chhoker VK, Chikkara P, Singh A, Goel S, Singh NK. Vitreous potassium concentration as a predictor of postmortem interval in injury (trauma) cases: A cross-sectional study from a tertiary care center in rural Haryana. Med J DY Patil Univ [serial online] 2015 [cited 2024 Mar 29 ];8:315-318
Available from: https://journals.lww.com/mjdy/pages/default.aspx/text.asp?2015/8/3/315/157072


Full Text

 Introduction



Time since death (TSD) is an important parameter to the forensic expert and also to the investigating agency, if determined with measurable accuracy. This is an important question asked to every forensic expert appearing in court for evidence. [1] However, determination of accurate TSD is extremely difficult as timings of onset and the rates of post-mortem changes are usually governed by unpredictable endogenous and exogenous factors. [2]

Due to its post-mortem stability, vitreous humor has high utility in forensic pathology. Vitreous humor biochemical constituents, especially K + , have been widely used in the postmortem interval estimations. The time dependent rise of vitreous K + levels in the post-mortem period has been considered to be helpful in post-mortem interval determination. [3]

Only a fewer studies are available in the literature to determine the relationship between vitreous K + concentration and TSD especially among injury (trauma) cases and thus information on the same is patchy and scanty. Therefore, the present study was planned to determine the relationship between changes in vitreous K + concentration with increasing TSD among injury (trauma) cases. An additional objective was to derive a formula for determining TSD from changes in levels of vitreous K + in the study subjects.

 Materials and Methods



In this cross-sectional study, autopsy cases brought to the mortuary of Department of Forensic Medicine and Toxicology of a tertiary care center, were the subjected for collection of vitreous humor for determination of vitreous potassium. Data of 55 such cases, where autopsy confirmed the cause of death as injury (trauma), were included in this study. Vitreous humor was collected at the time of autopsy examination. Most of the vitreous humor potassium analyses were carried out immediately post extraction on the same day of collection.

The information regarding time of death was gathered from police records, hospital records or from eye witnesses, relatives, friends, and attendants of the deceased. The TSD thus obtained was further cross-verified by post-mortem changes like hypostasis, rigor mortis and putrefaction. The data were collected in three groups according to TSD from 0 h to 12 h, 12.01 h to 24 h and above 24 h, respectively, recorded on proforma.

Cases with known or suspected ocular diseases, trauma to head, vitreous fluid cloudy or contaminated with blood, vitreous humor insufficient for the biochemical analyses, and those cases, whose time of death on enquiry from different sources were found to differ by > ±15 min, were excluded from the study. Determination of potassium level in the collected sample was done by ion-selective electrode method (Biolyte 2000 auto analyzer).

The collected data were coded and entered in Statistical Package for Social Sciences, version 17 (IBM, Chicago, USA). Interpretation of the collected data were done using appropriate statistical methods and tests like Chi-square test. Two-tailed P <0.05 was considered as statistically significant. Correlation among variables and regression equation were also derived.

 Results



Data of 55 study subjects belonging to injury (trauma) cases were analyzed in the present study. The mean level of potassium in right eyes was found to be 8.8 ± 3.9 mEq/l (range: 4.60-25.50). On the other hand, mean level of potassium in left eyes was found to be 8.9 ± 3.9 mEq/l (range: 4.50-25.20). This difference in the rise of K + level between right and left eyes was found to be non -significant statistically [Table 1].{Table 1}

There is an evident rise in the potassium (K + ) concentration with the increasing TSD in both the right and left eyes. This pattern was observed in all the three groups of TSD, that is, within 12 h, upto 24 h and more than 24 h. The difference in K + concentration levels among all the 3 TSD groups between right and left eyes, was found to be highly significant statistically [Table 2].{Table 2}

Effect of external factors, gender and age on the concentration of vitreous potassium

It was observed in this study that external factors like seasonal variations and temperature, gender difference and age had no appreciable effect on the concentration of vitreous potassium in either eye.

Following values and linear regression equation obtained from potassium concentration (y) verses time (x) derived from Table 3 for right eye were as follows:

Pearson's correlation co-efficient (r) = +0.946

Co-efficient of determination (r 2 ) = 0.895

Co-efficient of regression equation (R) = 0.946

Regression line (y) = −5.040 x + 1.989

From these above values, the least square regression line is drawn on [Figure 1].{Figure 1}

95% confidence limit of x = Mean ± 2 standard deviation (SD) of x

= Mean ± 16.48

Regression coefficient = r SD of x χ SD of y.

This means that an increase of potassium values of 1 mEq/l will indicate an increase of 1.99 h in the postmortem interval and 95% confidence limit for all cases will be ± 16.48 h.

Following values and linear regression equation obtained from potassium concentration (y) verses time (x) derived from [Table 3] for left eye were as follows:

Pearson's correlation co-efficient (r) = +0.950{Table 3}

Co-efficient of determination (r 2 ) = 0.902

Co-efficient of regression equation (R) = 0.950

Regression line (y) = −5.223 x + 2.005

From these above values, the least square regression line is drawn on [Figure 2].{Figure 2}

95% confidence limit of x = Mean ± 2SD of x

= Mean ± 16.48

Regression coefficient = r SD of x χ SD of y.

This means that an increase of potassium values of 1 mEq/l will indicate an increase of 2.01 h in the postmortem interval and 95% confidence limit for all cases will be ± 16.48 h.

 Discussion



The findings of our study show that with the increase of TSD, the level of potassium in the vitreous humor goes on increasing. Prasad et al. [4] studied correlation of K + level of vitreous and the post-mortem interval, and found that the rise in K + level after death has a strong correlation with the Post-mortem interval's. Mulla [5] hypothesized that the concentration of vitreous biochemical constituents in the same pair of eyes change at the same rate and this change that occurs in a time dependent fashion may be utilized in accurately estimating the post-mortem interval.

Regarding role of age in the changes of K + concentration levels in the vitreous humor after death, it was observed in this study that age has no appreciable role in the changes in the levels of K + concentration in the vitreous humor after death. This observation is consistent with the results of other study by Jashnani et al. [6]

It was observed in this study that there was no effect of temperature on the levels of K + concentration in the vitreous humor after death. Another study by Ahi and Garg [7] is also in concordance with our observations. However, Farmer et al. [8] observed that in warm seasons with higher environmental temperature at the time of death caused marked enhancement of the observed potassium values in the vitreous humor. This study contradicts the observations on this aspect of the study.

In this study, the linear regression equations obtained from potassium concentration (y) verses time (x) for the two groups among injury (trauma) cases were as follows: For right eye: regression line (y) = −5.040 (x) = +1.989, for left eye: Regression line (y) = −5.223 (x) = +2.005. In both study groups, a straight line relationship is found between the vitreous potassium levels and the postmortem interval, which is in confirmation with the observation of made in most of the previous researches. [9],[10] we observed a linear relationship between vitreous potassium concentration and postmortem interval. But Hughes, Coe, Adjutantis and Choo-Kang et al. found this line to be biphasic in which the slope of the first few hours after death is steeper than for more prolonged times after death that is not in agreement with this study. [11],[12],[13],[14] The 95% confidence limit of over ± 17 limits the usefulness of this method in predicting post-mortem interval (95% confidence limits for our study subjects were ± 13.78).

This study has several strengths. First, to our knowledge, assessment of relationship between vitreous K + concentration and TSD especially among injury (trauma) cases in India has not been extensively investigated. Very few similar studies are available in the literature. Second, all the interviews and examinations were conducted by single person, which provided uniformity in data gathering. On the other hand, inclusion of limited number of cases is an evident limitation of this study.

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