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ORIGINAL ARTICLE
Year : 2015  |  Volume : 4  |  Issue : 4  |  Page : 214-218

Vitreous potassium concentration as a predictor of postmortem interval: A cross-sectional study among poisoning and burns cases at 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, SHKM Govt. Medical College, Mewat, India
3 ESIC Medical College, Faridabad, Haryana, India
4 Department of Forensic Medicine, Santosh Medical College, Ghaziabad, Uttar Pradesh, India
5 Department of Forensic Medicine, AJ Institute of Medical Sciences, Mangalore, Karnataka, India
6 Department of Microbiology, Major SD Singh Medical College, Fatehgarh, Uttar Pradesh, India
7 Department of Forensic Medicine, PGIMS, Rohtak, Haryana, India

Date of Web Publication14-Dec-2015

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


DOI: 10.4103/2277-8632.171701

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  Abstract 

Background: Time since death (TSD) is an important parameter to the forensic expert. Only a few studies are available in the literature to determine the relationship between vitreous K + concentration and TSD, especially among poisoning and burns cases, and thus information on the same is scant. Therefore the present study was planned.
Objective: The main objective was to determine the relationship between changes in vitreous K + concentration with increasing TSD among poisoning and burns 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 the Department of Forensic Medicine and Toxicology of a tertiary care center were subjected to collection of vitreous humor for the determination of vitreous K + . Data of 36 cases where autopsy confirmed the cause of death as poisoning or burns were included in this study. Determination of K + level in the collected samples was done by the ion-selective electrode method (Biolyte 2000 autoanalyzer).
Results: A linear relationship was observed between vitreous K + concentration and TSD in both the eyes. External factors such as seasonal variations and temperature, gender difference, and age had no appreciable effect on the concentration of vitreous K + in either eye. In this study the linear regression equations obtained from potassium concentration (y) versus time (x) for the two groups among poisoning and burns cases were as follows. For right eye: Regression line (y) = -4.932 x + 1.932; for left eye: Regression line (y) = -5.380 x + 1.990. The K + levels were found to increase up to 40 h after death.
Conclusion: This study highlighted the usefulness of the 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 more reliable tests.

Keywords: Burns cases, poisoning, postmortem interval, vitreous potassium


How to cite this article:
Rathinam RD, Singh A, Goyal P, Chhoker VK, Jayaprakash K, Goel S, Chikkara P. Vitreous potassium concentration as a predictor of postmortem interval: A cross-sectional study among poisoning and burns cases at a tertiary care center in rural Haryana. J NTR Univ Health Sci 2015;4:214-8

How to cite this URL:
Rathinam RD, Singh A, Goyal P, Chhoker VK, Jayaprakash K, Goel S, Chikkara P. Vitreous potassium concentration as a predictor of postmortem interval: A cross-sectional study among poisoning and burns cases at a tertiary care center in rural Haryana. J NTR Univ Health Sci [serial online] 2015 [cited 2020 Jan 27];4:214-8. Available from: http://www.jdrntruhs.org/text.asp?2015/4/4/214/171701


  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 of every forensic expert appearing in court for evidence. [1] But determination of accurate TSD is extremely difficult, as timings of onset and the rates of postmortem changes are usually governed by unpredictable endogenous and exogenous factors. [2]

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

Only a few studies are available in the literature to determine the relationship between vitreous K + concentration and TSD, especially among poisoning and burns cases; in addition, very few studies have made the comparison between the right and left eyes. Thus, information on the same is scant. Therefore the present study was planned to determine the relationship between changes in vitreous K + concentration with increasing TSD among poisoning and burns 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 the Department of Forensic Medicine and Toxicology of a tertiary care center were subjected to collection of vitreous humor for the determination of vitreous potassium. Data of 36 cases where autopsy confirmed the cause of death as poisoning or burns were studied. Vitreous humor from both the eyes was taken at the time of the autopsy examination. Cases with known TSD and cause of death were included in the study. Most of the vitreous humor potassium analyses were carried out immediately after extraction on the same day as collection.

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

Cases with known or suspected ocular diseases, trauma to head, vitreous fluid cloudy or contaminated with blood, or vitreous humor insufficient for the biochemical analyses, and cases in which time of death on enquiry from different sources was found to differ by more than ±15 min were excluded from the study. Determination of potassium level in the collected samples was done by the ion-selective electrode method (Biolyte 2000 autoanalyzer, Biocare, Lujhu Township, Taiwan).

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


  Results Top


Data of 36 study subjects of poisoning and burns cases were analyzed in the present study. The mean level of potassium in right eyes was found to be 8.95 ± 3.10 mEq/L (range 4.6-19.6), while the mean level of potassium in left eyes was found to be 8.95 ± 2.90 mEq/L (range 4.6-19.3). This difference in the rise of K + level between right and left eyes was found to be statistically nonsignificant [Table 1].
Table 1: Comparison of Vitreous Potassium In RT And LT Eyes Among Study Subjects

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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, i.e., within 12 h, up to 24 h, and more than 24 h. The difference in K + concentration levels among all the three TSD groups between the right and left eyes was found to be highly significant statistically [Table 2].
Table 2: Levels of Vitreous Potassium Depending Upon The TSD Among Study Subjects

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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 such as seasonal variations and temperature, gender difference, or age had no appreciable effect on the concentration of vitreous potassium in either eye.

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

Pearson's correlation coefficient (r) = +0.871

Coefficient of determination (r 2 ) = 0.758

Coefficient of regression equation (R) = 0.871
Table 3: Correlation Between TSD And Potassium Levels of Both The Eyes Among Study Subjects

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Regression line (y) = -4.932 x + 1.932

From these above values, the least square regression line is drawn on [Figure 1].
Figure 1: Scatter diagram showing correlation between TSD and vitreous K+ concentration in right eye

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95% confidence limit of x = Mean ± 2SD of x = Mean ± 13.78

Regression coefficient = rSD of x χ SD of y

This means that an increase of potassium values of 1 mEq/l will indicate an increase of 1.93 h in the postmortem interval, and 95% confidence limit for all cases will be ±13.78 h.

The values and linear regression equation obtained from potassium concentration (y) versus time (x) derived from table 3 for left eye were as follows:

Pearson's correlation coefficient (r) = +0.886

Coefficient of determination (r 2 ) = 0.786

Coefficient of regression equation (R) = 0.886

Regression line (y) = -5.380 x + 1.990

From the values given above, the least square regression line is drawn on [Figure 2].
Figure 2: Scatter diagram showing correlation between TSD and vitreous K+ concentration in left eye

Click here to view


95% confidence limit of x = Mean ± 2SD of x = Mean ± 13.78

Regression coefficient = rSD 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 ± 13.78 h.


  Discussion Top


The findings of our study show that with the increase of TSD, the level of potassium in the vitreous humor continues to increase. Prasad et al. [4] studied the correlation of level of vitreous K + and the postmortem interval, and found that the rise in K + level after death has a strong correlation with the postmortem interval. Mulla et al.[5] concluded that the concentration of vitreous biochemical constituents in the same pair of eyes changes at the same rate and this change, which occurs in a time-dependent fashion, may be utilized in accurately estimating the postmortem interval.

Regarding the role of age in changes of K + concentration levels in the vitreous humor after death, it was observed in this study that age played 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 an earlier 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. A study by Ahi et al.[7] is in concordance with our observations. However, Farmer et al. [8] observed that in warm seasons higher environmental temperatures at the time of death caused marked enhancement of the observed potassium values in the vitreous humor. That study contradicts the observations on this aspect of our study.

In this study the linear regression equations obtained from potassium concentration (y) versus time (x) for the two groups among poisoning and burns cases were as follows. For right eye: Regression line (y) = -4.932 x + 1.932; for left eye: Regression line (y) = -5.380 x + 1.990. In both study groups, a straight-line relationship was found between the vitreous potassium levels and the postmortem interval, which confirms the observation made in most of the previous studies. [9],[10] The 95% confidence limit of over ±17 limits the usefulness of this method in predicting the postmortem interval (95% confidence limits for our study subjects were ±13.78).

Regarding difference in vitreous K + concentration between both eyes, our study showed that there was no significant variation in the levels of vitreous K + within a pair of samples when the samples were taken from each eye at the same time. This finding is in agreement with observations made by Tagliaro et al. [11] Results of the current study differ from the observations of Pounder et al., [12] who observed a difference of >10% in the levels of vitreous K + within a pair of samples when samples were taken from each eye at the same time. Recent work has demonstrated that the values of vitreous K + vary with the use of different instruments to measure K + concentration. Determination of serum electrolytes by an autoanalyzer was found to be more efficient, sensitive, and accurate than that by a flame photometer in another study in Mumbai. [13]

This study has several strengths. First, according to our knowledge, difference in the values of vitreous K + between the right and left eyes has not been closely investigated by the experts in the field. Very few similar experiences are available in the literature. Second, we used an autoanalyzer to measure values of vitreous K + , which is a better instrument. Third, all the samples were collected by a single person, which created a sense of uniformity. Determination of serum electrolytes by an auto-analyser was found to be more efficient, sensitive and accurate than flame photometer by another study from Mumbai. [14]


  Conclusion Top


To conclude, the empirical evidences of the current study indicate the usefulness of the relationship between vitreous K + concentration and TSD in both the eyes. The formula calculated from the current study could prove to be increasingly appropriate in the future as it is based on a more recent study and more reliable tests.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

 
  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 postmortem 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 Diag 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 humor from humans. Forensic Sci Int 1985;27:1-13.   Back to cited text no. 8
    
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, editors. 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.
Tagliaro F, Bortolotti F, Manetto G, Cittadini F, Pascali VL, Marigo M. Potassium concentration difference in vitreous humor from the two eyes revisited by microanalysis with capillary electrophoresis. J Chromatogr A 2001;924:493-8.  Back to cited text no. 11
    
12.
Pounder DJ, Carson DO, Johnston K, Orihara Y. Electrolyte concentration difference between left and right vitreous humor samples. J Forensic Sci 1998;43:604-7.  Back to cited text no. 12
    
13.
Raut SC, Chandel RS, Abichandani LG. Study of serum electrolytes by flame photometer and autoanalyser. Sch J App Med Sci 2013;1:972-4.  Back to cited text no. 13
    
14.
Raut SC, Chandel RS, Abichandani LG. Study of Serum Electrolytes by Flame Photometer and Autoanalyser. Sch J App Med Sci 2013;1: 972-4.  Back to cited text no. 14
    


    Figures

  [Figure 1], [Figure 2]
 
 
    Tables

  [Table 1], [Table 2], [Table 3]



 

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