Toxic trauma

Many, perhaps most, chemical agents exert their lethal effects because of effects on the respiratory system and thus the provision of breathing support is essential. This is because toxic agents produce effects that cause blockage of the air passages, depression and failure of the respiratory control centres in the brain or paralysis of the muscles of respiration. To overcome these combined effects, the emergency medical response must include the ability to be able to clear and support the airway and also to be able to ventilate the lungs artificially when there is respiratory deficiency or arrest. This support is now part of a standard response for advanced life support in both conventional and toxic trauma and is termed TOXALS (Baker, 1996 Department of Health, 2003) (see Box 3). 

The actions of toxic chemicals on the body can be integrated into the various forms of physical trauma by using the concept of toxic trauma . 

Toxic trauma can be defined broadly as the dismption of somatic systems and their function by exposure to a toxic chemical. Ingested poisoning in its conventional form is only one example of toxic trauma. As we shall see in later chapters, toxic exposure can also arise from inhalation of gases or exposure of the skin to liquids or solids. Like physical trauma, toxic trauma can produce early or late effects with potential fatality at aU stages. 

The deliberate release of chemicals to produce toxic trauma has been familiar in warfare for more than 2000 years. In civil life, although there may have been coincidental exposure (e.g. in siege warfare), most acute toxic trauma up to the twentieth century would have been due to ingested poisonous substances. Since that time, civilians have been increasingly at risk from exposure to both agents of chemical warfare and toxic industrial chemicals. 

The emergence of terrorist use of chemicals over the past two decades, as well as the increasing risk of exposure to accidental release of toxic industrial chemicals, makes the appearance in hospital of casualties with toxic trauma more likely. Emergency medical teams may have to respond quickly to an unfamiliar situation, particularly since the abolition of military service in many countries has produced a generation of civilian doctors and nurses who do not have direct experience of planning and management of such situations as was the case following the two world wars. 

As has been noted, toxic trauma occurs in both the military setting, where the release of chemicals specifically designed to cause harm is a deliberate action or in civil life, where the release is usually accidental and involves toxic industrial chemicals that are used in chemical engineering and have coincidental harmful elfects. The continued development, transport and use of toxic industrial chemicals and the increasing likelihood of accidental and deliberate release make toxic trauma in civilians and their need for pre-hospital and hospital treatment an increasingly likely occurrence. 

With the steady growth of the production, transport and use of toxic chemicals around the world, there has been an increase in the number of casualties with toxic trauma. Although the end of the Cold War reduced the risk of major chemical attacks, the stockpiles of chemical weapons remained and may have fallen into the hands of terrorists. The release of the nerve agent sarin in the Tokyo metro in 1995 confirmed the ability of terrorist organisations not only to use chemical weapons but also to synthesise them. In summary, mass exposure to toxic substances remains a relatively rare but significant event which has importance for emergency medicine and several other specialities. 

Despite their mass disabling actions, CW agents produced the lowest dead-to-wounded ratio of aU the weapons used in World War I (4 % as opposed to over 12 % from artillery). The high proportion of the latter reflects the limited responses to major physical trauma at the time. By the end of the twentieth century and after the application of advanced life-support measures in battle for physical and toxic trauma, both ratios have steadily decreased. 

The increasing use and transportation of toxic industrial chemicals around the world following the Second World War has been accompanied by a rise in the number of small- and large-scale accidental releases causing toxic trauma in the civil setting. The most devastating of this was in Bhopal in India in 1984 where the accidental release of 40 tons of methyl isocyanate, a chemical intermediary in the production of pesticide and other compounds in a densely populated urban area, led to more than 5000 fatalities. The important medical lessons from this incident are considered in Chap. 10. 

Box 2.5 One hundred years of toxic trauma a timeline of events... 

Knowledge of the range and properties of toxic hazards is essential for the management of toxic trauma firstly to understand the presenting and possibly developing conditions in the patient and secondly to assess and understand the potential risks to emergency medical teams from transmission of the hazard. 

Toxic trauma from TIC is usually a result of accidental release, but in recent years, there have been growing concerns that chemicals being transported could be released deliberately as a result of terrorist action. Appendix A lists the properties of a range of TIC which are in common industrial use together with their HAZMAT identification numbers. 

Within the HAZMAT classification, there are five main groups of TIC which cause toxic trauma ... 

While being classified separately, both CW and TIC have many common properties. Although conditions in a battlefield and a civil setting are very different, the principles of management of casualties from CW and TIC are essentially the same, and there is a common approach to management of toxic trauma caused which is determined by the physical and biological properties of the agents. 

Solid agents are those whose physical form conforms to specific dimensions. Solids are usually dispersed in the form of particles which can cause toxic trauma... 

Liquids exist in dynamic equilibrium with vapour that the liquid produces. Toxic trauma may therefore be caused by direct contact with the liquid or by inhalation of the vapour it produces. 

Because toxic trauma may be developing silentiy when the patient is first seen in or before hospital, it is important for physicians to have a basic knowledge of the physical states and properties of the toxic substances that may have been released. This will help predict the development and outcome of toxic injury. 

If a toxic agent has a long persistency, it will be necessary to decontaminate the patient as quickly as possible (1) to reduce further absorption of the agent and (2) to avoid spreading the contamination. Decontamination is a process that can affect the speed and eflhciency of the provision of medical care for toxic trauma. Specific details of the techniques and rationale of decontamination are given in Chap. 5. 

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