STOMACH EMPTYING AS A MEASURE OF TIME SINCE A

DEATH

With one exception, this controversial topic could be dis- missed summarily as being quite irrelevant. For many years pathologists have argued over the reliability of the state of digestion of gastric contents as an indicator of the time between the last meal and death, the leading case in modern times being that of Truscott in Canada. There is now almost a consensus that with extremely circumscribed exceptions, the method is too uncertain to have much validity.

The original hypothesis was founded on the belief that food spent a fairly uniform time in the stomach before being released into the duodenum. In addition, it was claimed that its physical state was progressively altered by gastric juices and movements so that its appearance and volume was a measure of the time since it had been swallowed. Therefore, if the time of the last meal was known from circumstantial evidence, the time of death could be estimated.

Stomach emptying as a measure of time since a death

FIGURE2.32 Henssge’s nomogram method for estimating the time since death from a single rectal temperature, where the environmental temperature is below 23°C. (From Henssge et al. 2002.)

The nomogram expresses the death time (t) by:

The nomogram is related to the chosen standard, that is, naked body extended lying in still air. Cooling conditions differing from the chosen standard may be proportionally adjusted by corrective factors of the real body weight, giving the corrected body weight by which the death time is to be read off. Factors above 1.0 may correct thermal isolation conditions and factors below 1.0 may correct conditions accelerating the heat loss of a body.

T T

T Bt Bt B

rectum ambient ambient

exp( ) exp(5 ); (kg 625)

37 2 125 0 25 12815 ⁰ 0 0284

. . . . ^. .

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10 20 40 60 80 100 120 160 200 15 30 50 70 90 110 140 180 10

15 20 30 40 50 60 70 80

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10 15 20 24 28

36 40

75 80 5

15 20 24

65 70

2 6 10 12 14 16 18 20 22

55 60

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2,8 2,8

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4,5 7,0

°C

°C 10

20 KILOGRAM

PERMISSIBLE VARIATION OF 95% (±h) TEMPERATURE–TIME OF DEATH RELATING NOMOGRAM For ambient temperatures up to 23°C

Using correctivefactors

Standard(naked–still air)

R E C T U M

A M B I E N T

Stomach emptying as a measure of time since a death

How to read off the time of death

1 Connect the points of the scales by a straight line according to the rectal and ambient temperature. It crosses the diagonal of the nomogram at a special point.

2 Draw a second straight line going through the centre of the circle, below left of the nomogram and the intersection of the first line and the diagonal.

The second line crosses the semicircles, which represent the body weights. At the intersection of the semicircle of the body weight the time of death can be read off. The second line touches a segment of the outermost semicircle. Here can be seen the permissible variation of 95 per cent.

Example: temperature of the rectum 26.4°C; ambient temperature 12°C; body weight 90kg. Result: time of death 161.8h.

Statement: the death occurred within 13.2 and 18.8 (13 and 19) hours before the time of measurement (with a reliability of 95 per cent).

Note: if the values of the ambient temperature and/or the body weight (see ‘corrective factors’) are called into question, repeat the procedure with other values that might be possible. The range of death time can be seen in this way.

Requirements for use

■ No strong radiation (for example, sun, heater, cooling system).

■ No strong fever or general hypothermia.

■ No uncertain* severe changes of the cooling conditions during the period between the time of death and examination (for example, the place of death must be the same as where the body was found).

■ No high thermal conductivity of the surface beneath the body.^†

* Known changes can be taken into account: a change of the ambient temperature can often be evaluation (for example, contact the weather station); use the mean ambient temperature of the period in question. Changes by the operations of the investigators (for example, take any cover off) since finding the body are negligible: take the conditions before into account!

†Measure the temperature of the surface beneath the body also. If there is a significant difference between the temperature of the air and the surface temperature, use the mean.

Empiric corrective factors of the body weight

Wet through

Dry clothing/ Corrective Clothing/covering

covering In air factor wet body surface In air/water

0.35 Naked Flowing water

0.50 Naked Still water

0.70 Naked Moving air

0.70 1–2 thin layers clothing Moving air

Naked Moving 0.75

1–2 thin layers clothing Moving 0.90 2 or more thicker clothing Moving air

Naked Still 1.00

1–2 thin layers clothing Still 1.10 2 thicker layers clothing Still air

2–3 thin layers clothing 1.20 More than 2 thicker layers clothing Still air

1–2 thicker layers clothing Moving or still 1.20

3–4 thin layers clothing 1.30

More thin/thicker layers clothing Without influence 1.40 1.80

Thick bedspreadclothing combined 2.40

Note:for the selection of the corrective factor of any case, only the clothing or covering of the lower trunk is relevant.

Personal experience is needed; nevertheless, this is quickly achieved by consistent use of the method.

FIGURE2.33 Hennsge’s nomogram method for estimating the time since death from a single rectal temperature, where the environmental temperature is above 23°C. (From Henssge et al. 2002.)

The nomogram expresses the death time (t) by:

The difference between this nomogram and that for ambient temperatures up to 23°C concerns only the relative length of the ‘post- mortem plateau’. It is shorter in higher ambient temperatures (above 23°C) than in lower ones (that nomogram: up to 23°C). This nomogram for higher ambient temperatures was developed according to the data from De Saram, which were obtained in ambient temperatures between 27 and 32°C. These data show a relatively shorter length of the ‘post-mortal plateau’ than our own data of body cooling in lower ambient temperatures. Our own practical experience of the cooling of bodies in high ambient temperatures and therefore in using this nomogram, is small. It is recommended that the same permissible variation of 95 per cent as given in the nomogram for lower ambient temperatures is taken.

T T

T Bt Bt B

rectum ambient ambient

exp( ) exp(10 ); (kg 625)

37 2 1 11 011 12815 ⁰ 0 0284

. . . . ^. .

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±2,8 h

37 36 35 34 33 32 31 30 29 28 27 26 25 24 23

23 24 25 26 27 28 29 30 31 32 33 34 35 10

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10 20 40 60 80 100 120 160 200 180 140 110 90 70 50 30 15 60

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KILOGRAM

5 10

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20 25

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25 30 20

20 20 20 20

25 25 25 25

30 30

TEMPERATURE–TIME OF DEATH RELATING NOMOGRAM For ambient temperatures above 23°C PERMISSIBLE VARIATION OF 95% (±h)

A M B I E N T

°C

°C R E C T U M

It was assumed that the physiological process of digestion of an ‘average’ meal lasted some 2–3 hours. This is based on the consumption of a test meal of gruel, however, hardly a representative example of a modern mixed diet. Moreover, the subjects of experimental work were healthy and presum- ably free from sudden stress during the experiments. More elaborate descriptions of digestion times of various foods have been drawn up, but they are of dubious value. As an example of the great variations offered, Modi (1957) gives 4–6 hours for a meat and vegetable meal and 6–7 hours for a farinaceous meal. Adelson (1974) stated that the stomach begins to empty within 10 minutes of swallowing, that a

‘light’ meal leaves the stomach by 2 hours, a ‘medium’ meal takes 3–4 hours and a large, heavy meal takes 4–6 hours. He noted that the head of an ‘ordinary’ meal usually reached the ileocaecal valve between 6 and 8 hours after ingestion. All these values, however, are subject to considerable variation.

More modern methods of investigation have used radioisotope techniques and have shown some interesting facts. When a solid meal is eaten and water drunk with it, the water leaves the stomach quickly irrespective of the nature or calorific content of the solid part. However,

calorific liquids stay longer in the stomach (Brophy et al.

1986). The emptying rate also increases with the weight of the meal, as long as the calorific content remains constant. If the latter is increased, then the pyloric opening is delayed. Further work by Moore et al.(1984) again emphasized the marked variability of emptying times, even in normal circumstances.

The following factors frustrate the use of gastric emptying as a measure of time since death:

■ Digestion may continue for some time after death.

■ The physical nature of a meal has a profound effect on emptying time: the more fluid the consistency, the faster the emptying. Liquids entering an empty stomach pass through without any appreciable pause.

■ The nature of the food modifies emptying time, notably fatty substances, which markedly delay the opening of the pylorus. Strong alcohol, such as spirits and liqueurs, also irritate the mucosa and tend to delay emptying.

■ Importantly, any nervous or systemic shock or stress, mediated through the parasympathetic (vagus) system, can slow or stop gastric motility and digestive juice secretion as well as holding the pylorus firmly closed.

Stomach emptying as a measure of time since a death

Brain

Naked

Covered

Temperature ratio

Covered Covered

Rectum

Naked Naked

Liver

0 5 1.00 0.75 0.50 0.25 0.00 0.25 1.00 0.75 0.50 0.25 0.00 0.25

15 20 25 30

10 0 10 20 30

Hours after death

40 50 60 0 10 20 30 40 50 60

FIGURE2.34 Cooling curves for estimation of the post-mortem interval. In Al-Alousi’s ‘temperature ratio’ method, the graphs above are used as follows. Assume that the body temperature (rectal) is 36.6°C at the time of death (Tb). Measure the environmental and rectal temperatures at the time of examination (T_rand T_e). Then the ‘temperature ratio’ is T_rT_e/T_bT_e. This ratio is then found on the vertical scale of the rectal graph, using either the graph for ‘naked’ or ‘covered’ as appropriate. The time since death is the point on the lower scale where a perpendicular falls from the point on the graph where a horizontal line meets it from the temperature ratio level. The shaded area indicates the limits of a 68 per cent probability at that particular point. For example, if the rectal temperature is 23.4°C and the air temperature 19°C, then the temperature ratio is 0.25. If the body is naked, then this gives 18 hours as the time since death, with a margin of plus 2.5 hours and minus 5 hours. (Reprinted with permission from Al-Alousi LM, Anderson RA. 1986. Microwave thermography in forensic medicine.

Police Surgeon,30:30–42.)

The intestine, as opposed to the stomach, may increase its motility with psychogenic upsets, as noted by De Saram in his autopsies on hanged criminals.

The state of digestion, as opposed to the volume and exit of food from the stomach, is almost impossible to assess.

Variations in the type of food eaten make vast differences to the dissolution rate. Hard objects, such as nuts and seeds, resist digestion and may even be voided intact per rectum, whereas soft carbohydrates can liquefy almost immediately.

The size and dispersion of particles is crucial, including the amount of chewing and admixed saliva. The efficiency of the teeth and gastric acid, enzymes and motility are also of prime importance, as is the amount of liquid either in the original food or drunk during the meal. Fat and oil in the meal slow up pyloric opening, and all these variables make it impossible to time the rate of digestion.

One of the most important factors in the forensic context is the effect of a physical or mental shock or stress during the digestion process. As stated, this can completely inhibit digestion, gastric motility and pyloric opening. The author (BK) recalls a victim of a traffic accident who lived in a coma for a week after a mortal head injury. At eventual autopsy, the large volume of gastric contents looked as fresh as if it had just been swallowed.

Even if one accepts an ‘average’ gastric transit time of an ‘average’ meal as being of the order of 2–3 hours, the assumption that death took place within this time can only be valid if the death was quite sudden and unexpected, with no stressful prodromal event. For example, if an unsuspect- ing person was suddenly shot or run down without warning and died almost immediately, then one can assume that the undisturbed physiological processes of digestion – albeit with its many variables – had taken place. If, however, a domestic dispute or a developing altercation culminated in a strangling or stabbing, the antecedent stresses would almost certainly affect gastric function and render invalid any inter- pretation of the condition of stomach contents at autopsy.

What is valid is the nature of the last meal, which may be helpful in establishing the time of death. If it was known to the investigators that the deceased person ate a certain type of meal at a certain time, whether it be chicken curry or green beans, the identification of such food in the stomach would be persuasive evidence that he died after taking that food and that it was his final meal, before any other sub- stantial food of a different type was taken.

THE USE OF VITREOUS HUMOUR

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