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Chapter: Forensic Medicine: Thermal, electrical, atmospheric pressure and radiation associated deaths

Deaths caused by abnormal temperatures

1. Hypothermia 2. Hyperthermia 3. Thermal wounds (burns)

Deaths caused by abnormal temperatures

These injuries may be due to exposure to cold (hypothermia), high environmental temperatures (hyperthermia) or hot objects coming into contact with the body (burns). All these deaths are unnatural.



Hypothermia or low body temperature is defined as a condition where the central or core body temperature is 35 8C or lower. Hypothermia is a common complication where individuals are exposed to low environmental temperatures. This often occurs amongst mountaineers and other adventurers exposed to the environment. Although the environmental temperature as such plays an important role, it is also important to remember that movement of air (wind) lowers the temperature even further (wind factor).

Exposure to cold water, for instance after shipwrecks, increases the risk of hypothermia. Should an intoxicated person fall into cold water, hypothermia will be worse, as alcohol causes vasodilatation, which increases heat loss (see study unit 11).

The elderly and the young are at greatest risk to develop hypothermia in the domestic situation.

Within certain temperature ranges, hypothermia has a protective effect on certain vital organs, like the brain, as it decreases the energy needs (including oxygen) of the organs. This is one of the reasons why the body temperature is usually lowered during open-heart surgery to protect the brain. Cooling down and rewarming of the body in these circumstances are of course strictly controlled to prevent complications.

Local changes due to hypothermia include frostbite, which can lead to loss of fingers, toes or even parts of the face.

The post-mortem findings are often nonspecific. Typically the hypostasis has a pink to rose-pink discoloration. It tends to be present over the extensor surfaces and large joints. Pulmonary oedema, acute gastric erosions and acute pancreatitis as well as perivascular haemorrhages and small micro-infarcts (small foci of necrosis) may also be present.

Hypothermia can cause confusion and irrational behaviour; sufferers can even take off their clothes due to a false perception that it is hot. This then creates the impression that the person was assaulted or even raped. These people often hide away from sight, the so-called ``hide-and-die'' syndrome.



Hyperthermia is a condition which occurs when the internal body temperature rises above 40,5 8C, and is usually seen in the following two situations:

Exposure to high environmental temperatures. In mines the temperature and humidity are often very high. Physical activity in these circumstances may cause hyperthermia in individuals who have not acclimatised beforehand. It can be aggravated by drugs, that cause constriction of the blood vessels in the skin, for instance drugs that decrease mucus secretion during a common cold (eg ephedrine). The capacity for giving off heat is lost and the patient can become ``overheated''.

The post-mortem findings are often nonspecific, with signs of heart failure (ie pulmonary oedema), internal haemorrhages due to clotting abnormalities, and renal failure.

Malignant hyperthermia. This condition occurs in individuals who are genetically susceptible to certain anaesthetic agents, especially if halothane is used in conjunction with a muscle relaxant (succinylcholine). Professor Harrison of the University of Cape Town developed an antidote, Dantrolene, years ago. This resulted in a significant drop in the mortality rate. In addition to the high body temperature the patient develops an increased potassium level and other metabolic abnormalities. Microscopic examination of the muscles shows myopathy (muscle abnormality) with a moth-eaten appearance and with the nuclei located centrally in the cells.


Thermal wounds (burns)

Strictly speaking frostbite is also a form of thermal injury, but it was discussed under hypothermic injuries. This discussion will therefore focus on the injuries resulting from the application of local heat to the body.

Burns are a common problem in South Africa because the majority of the population use open fires for the preparation of food and heating. As was said in the study unit on carbon monoxide poisoning, these open fires in enclosed spaces are a major cause of death due to the production of carbon monoxide.

Deaths due to thermal injuries can be instantaneous or almost immediate if severe, or can occur later due to complications, for instance infection. The inhalation of smoke and toxic substances found in smoke can also cause death from damage to the airways (heat inhalation syndrome). This may even occur without any external thermal injuries to the body.

Old people and children are especially susceptible to thermal injuries. In elderly people the skin is less sensitive, and they do not realise in time that they are in contact with a hot object. For example hotwater bottles often cause burns. Children sometimes pull containers with boiling water over themselves, as they are inquisitive and cannot see what is happening on the stove.

Deaths due to burns may thus be an accident, a homicide or a suicide.

A post-mortem examination of a severely charred body is often difficult as it might be almost impossible to identify the person.


An important factor to be determined is whether the person was alive at the time the fire started, or whether he or she was already dead at that time (sometimes fires are started to conceal a murder).

These aspects will be discussed later.

Classification of thermal wounds

Burn wounds are classified according to depth

First degree

-   only the epidermis is involved

 -   often painful

 -   sunburn a possible cause

 -   heal without scar tissue formation

Second degree           

 -   the epidermis and part of the dermis are involved

 -   sometimes blisters may be present on the skin

 -   painful

 -   heal without scar tissue  formation, except when complicated by infection

Third degree 

 -   the epidermis and the full thickness of the dermis are involved

 -   usually painless due to the destruction of the nerve-end fibres in the skin

 -   heal with scar tissue formation

Some authors describe fourth-degree burns as charring of part of the body.

Skin burns may further be graded according to the percentage of skin surface involved. In certain areas, for instance the face and perineum (genital region) there is a high risk of complications.

The complications of burns

·              Local complications. The most important is sepsis due to infection of the open wounds containing dead (necrotic) tissue. Over the flexor aspects of joints, for instance the elbow and knee, fibrosis forms scars, which can cause loss of movement. This is also known as a contracture.

·              Systemic complications. This is usually the result of fluid and electrolyte loss through the raw and injured surface of the skin. In addition lung complications can occur due to inhalation of hot air. Pulmonary thrombo-emboli due to immobilisation of the patient, and stasis, may also occur.

The post-mortem findings will depend on the degree of charring. In cases where charring did not occur, open, raw areas are seen. The pathologist must give an estimate of the percentage of the body surface damaged by the burns. In third-degree burns physicians often make incisions in the skin to release the tension of the contracted skin on the underlying soft tissue (escharotomies). This must not be confused with incised wounds.

With inhalation injuries the airways will show signs of damage, and the lungs will be congested in the initial stages. Signs of diffuse alveolar damage or shock lung will be found at a later stage.

In cases of charring the body will be in the so-called pugilistic or boxer stance (see study unit 3) due to shortening of the muscles as the proteins break down and coagulate as result of the heat. The flexor muscles have a larger mass and are therefore stronger than the extensor muscles. The flexor muscles will therefore dominate if all the muscles are shortened. The elbows and knees will bend and the body will assume the stance of a boxer.

The skull bone can fracture and a bloody fluid can ``cook up'' from the bone into the extradural space. This is known as extradural burn haematoma. It must not be confused with injuries of the skull and extradural haemorrhage due to trauma in the ante-mortem period. The skin and soft tissue can also tear, due to shortening of muscles (heat tears). This is not an indication of ante-mortem injuries.

If a body is totally charred, X-rays for identification purposes as well as to locate possible projectiles and other injuries are mandatory. Examination of the teeth is also indicated for identification purposes. In aircraft accidents charring is a common problem and correct identification often depends on dental records (forensic odontology).

The following signs could indicate whether the person was alive when the fire started:

·              the carbon monoxide in the body (by determining the carboxyhaemoglo-bin level [COHB]): a level of more than 5% in a nonsmoker and more than 10% in a smoker indicates that the person was alive when the fire started

·              ash and soot in the airways, stomach and oesophagus

·              fat emboli in the pulmonary vessels (only indicated by some authors)

Boiling water and other hot liquids often cause scald wounds in children. These wounds are characterised by the fact that the intensity of the scalding decreases as the fluid runs over the body and cools. The presence of clothes may also influence the extent and distribution of scald wounds caused by boiling water.


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