Table of Contents  
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


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

Date of Web Publication15-May-2015

Correspondence Address:
Abhishek Singh
Department of Community Medicine, Shaheed Hasan Khan Mewat Govt. Medical College, Nalhar, Haryana
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/0975-2870.157072

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  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.

Keywords: Fracture shaft tibia, Ilizarov ring fixator, wound infection


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;8:315-8

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 2020 May 28];8:315-8. Available from: http://www.mjdrdypu.org/text.asp?2015/8/3/315/157072


  Introduction Top


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 Top


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 Top


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: Comparison of potassium between in right and left eyes among injury (trauma) cases

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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: The levels of potassium depending upon the TSD in both eyes among injury (trauma) cases

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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: Scatter diagram showing correlation between time since death and vitreous K+ concentration in right eye

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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: Correlation between TSD and potassium levels of both the eyes among study subjects

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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: Scatter diagram showing correlation between time since death and vitreous K+ concentration in left eye

Click here to view


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 Top


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.

 
  References Top

1.
Fiddes FS, Patten TD. A percentage method for representing the fall in body temperature after death. J Forensic Med 1958;5:2-15.  Back to cited text no. 1
    
2.
Vij K. Textbook of Forensic Medicine and Toxicology. 2 nd ed. New Delhi: BI Churchill Livingstone; 2002. p. 144.  Back to cited text no. 2
    
3.
Sachdeva N, Rani Y, Singh R, Murari A. Estimation of postmortem interval from the changes in vitreous biochemistry. J Indian Acad Forensic Med 2011;11:171-4.  Back to cited text no. 3
    
4.
Prasad BK, Choudhary A, Sinha JN. A study of correlation between vitreous potassium level and post mortem interval. Kathmandu Univ Med J (KUMJ) 2003;1:132-4.  Back to cited text no. 4
    
5.
Mulla A, Massey KL, Kalra J. Vitreous humor biochemical constituents: Evaluation of between-eye differences. Am J Forensic Med Pathol 2005;26:146-9.  Back to cited text no. 5
    
6.
Jashnani KD, Kale SA, Rupani AB. Vitreous humor: Biochemical constituents in estimation of postmortem interval. J Forensic Sci 2010;55:1523-7.  Back to cited text no. 6
    
7.
Ahi RS, Garg V. Role of vitreous potassium level in estimating postmortem interval and factors affecting it. J Clin Diagn Res 2011;5:13-5.  Back to cited text no. 7
    
8.
Farmer JG, Benomran F, Watson AA, Harland WA. Magnesium, potassium, sodium and calcium in post-mortem vitreous humour from humans. Forensic Sci Int 1985;27:1-13.  Back to cited text no. 8
[PUBMED]    
9.
Sturner WQ, Gantner GE Jr. The postmortem interval. A study of potassium in the vitreous humor. Am J Clin Pathol 1964;42:137-44.  Back to cited text no. 9
[PUBMED]    
10.
Madea B, Henssge C. Eye changes after death. In: Henssge C, Knight B, editor. The Estimation of the Time Since Death in the Early Postmortem Period. London: Arnold Publishers; 1995. p. 106-37.  Back to cited text no. 10
    
11.
Hughes WM. Levels of potassium in the vitreous humour after death. Med Sci Law 1965;5:150-6.  Back to cited text no. 11
[PUBMED]    
12.
Coe JI. Postmortem chemistries on human vitreous humor. Am J Clin Pathol 1969;51:741-50.  Back to cited text no. 12
[PUBMED]    
13.
Adjutantis G, Coutselinis A. Estimation of the time of death by potassium levels in the vitreous humour. Forensic Sci 1972;1:55-60.  Back to cited text no. 13
[PUBMED]    
14.
Choo-Kang E, McKoy C, Escoffery C. Vitreous humor analytes in assessing the postmortem interval and the antemortem clinical status. West Indian Med J 1983;32:23-6.  Back to cited text no. 14
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    Figures

  [Figure 1], [Figure 2]
 
 
    Tables

  [Table 1], [Table 2], [Table 3]



 

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