Most injuries to motorcyclists are caused by falling from the machine onto the roadway. Many of the injuries can be reduced or prevented by the wearing of suitable protective clothing and a crash helmet.
Abrasions caused by contact with the road surface are almost universal following an accident at speed, and injuries to the limbs and to the chest and spine occur very commonly because of contact with other objects or vehicles, entanglement with the motor bike or direct contact with the road (Figure 14.8).
Despite the introduction of the mandatory wear- ing of crash helmets in the UK, head injuries are still a common cause of morbidity and mortality. In countries where there is no mandatory requirement for motorcycle helmets, the incidence is substan- tially increased. A more unique injury occurs from
‘tail-gating’, where the motorcyclist drives under the rear of a truck, causing severe head injuries or even decapitation. This injury has been reduced by
Box 14.2 The function of seat belts
A seat belt that is correctly installed, and worn, acts in the following ways:
● It spreads the deceleration forces at impact over the whole area of contact between the straps and the body surface so that the force delivered to the body per unit area is reduced.
● It is designed to stretch during deceleration and some belts have a specifi c area for this to occur. This stretching slightly extends the time of deceleration and reduces the force per unit time.
● It restrains the body during deceleration, keeping it away from the windscreen, steering wheel and other obstructions at the front of the vehicle, thus reducing injury potential.
● It prevents ejection into the road through burst doors or windows, which used to be a common cause of severe injury and death.
Figure 14.8 Extensive ‘brush’ abrasion of the left fl ank in a motor cyclist thrown across a rough surface.
1 4 T ransp ortation me dicine
the presence of bars at the sides and rear of trucks to prevent both bikes and cars passing under the vehicle.
Injuries associated with pedal cycles are very common because of the large numbers of cycles in use. Most injuries associated with cycles tend to be of mild or moderate severity because of their low speeds. However, impact by vehicles can result in severe and fatal injuries. Secondary injuries, espe- cially to the head and chest, are common when cyclists fall from their relatively high riding position on such an inherently unstable machine.
Other transportation methods (e.g. the Segway Personal Transporter) may also have their own types and range of risk of injury or fatality.
■ Railway injuries
These are most common in countries with a large railway network, such as India and China, and in countries where rail crossings are unprotected or unmanned. Although mass disasters, such as the derailment of a train, occasionally lead to large numbers of casualties, most deaths and injuries occur as an aggregation of numerous individual incidents, most of which are accidents, such as at level crossings or as a result of children playing on the line. Railway lines are a common site for suicide attempts.
Medically, there is nothing specific about railway injuries except the frequency of very severe mutila- tion. The body may be severed into many pieces and soiled by axle grease and dirt from the wheels and track. Where passengers fall from a train at speed, multiple injuries caused by repeated impacts and rolling may be seen, often with multiple abra- sions from contact with the coarse gravel of the line ballast.
Suicides on railways fall into two main groups:
those that lie on the track (sometimes placing their neck across a rail so that they are beheaded) and those that jump in front of a moving train from a platform, bridge or other structure near to the track.
Jumping from a moving train is much less com- mon. The injuries present will depend on the exact events, but they are usually extensive and severe when there has been contact with a moving train, although they may be localized with black soiling at the crushed decapitation or amputation site if the individual has lain across the track (Figure 14.9).
There is a risk of secondary injury if survival occurs where other factors such as electrified lines are present. On electrified lines, an additional cause of suicidal or accidental injury or death is present in the form of electric shock from either a live rail or overhead power lines. The voltage in these circuits is high, often in region of 600 V. Death is rapid and often associated with severe burns at the points of contact or earthing.
A careful search for unusual injuries inconsist- ent with the setting, and examination for a vital response to the severe blunt force injuries, should be made, as homicides may be concealed by stag- ing the scene, with the deceased being placed on the rail track in an attempt to conceal the true cause of death.
Railway workers may be injured or killed by fall- ing under, or by being struck by, moving rolling stock or by being trapped between the buffers of two trucks while uncoupling or coupling the rolling stock. The injuries associated with the squeezing between rolling stock are often those of a flail chest, with or without evidence of traumatic asphyxia.
■ Aircraft fatalities
Aviation incidents can be divided into two main groups: those that involve the crew and the large numbers of passengers of a modern, commercial aircraft, and those that involve the occupants of small, relatively slow, light aircraft.
Large aircraft are pressurized and, if the integ- rity of the cabin is breached, there can be rapid
Figure 14.9 Amputation of the right arm and bruising of the face and chest in a pedestrian struck by a passing train.
F urther information sourc es
decompression and the passengers may suffer barotrauma. If the defect in the cabin is large enough, victims may exit through the defect and fall to their death. When an aircraft hits the ground, the results will depend on the rapidity of transfer of the forces, and this is dependent on the speed of the aircraft and the angle of impact. If the forces are very severe, all passengers may be killed by decel- eration injuries and by multiple trauma owing to loss of integrity of the fuselage.
In lesser impacts, the results may be similar to those of motor vehicle crashes, although the forces are usually greater and the injuries sustained are proportionately more severe. The usual lap-strap seat belt offers little protection in anything but the most minor accident. Fire is one of the greatest haz- ards in air crashes and accounts for many deaths.
In light aircraft crashes, the velocity, and hence the forces, may be less than in large commercial air- craft, but they are still often fatal. The investigation of air accidents is a task for specialist medical per- sonnel, who are often available from the national air force or from a civil authority. There should always be a full autopsy on the pilot or suspected pilot, with full microscopic and toxicological examination to exclude natural disease, drugs and alcohol.
■ Marine fatalities
Fatalities in the marine setting embrace a range of marine-specific and general injury types. The range of activities include commercial diving, recreational diving, use of powered water sport bikes, sailing, motor cruising and commercial marine transport (e.g. oil tankers, container ships, passenger vessels). The likelihood of dying in a marine environment is enhanced by not wearing appropriate safety gear. In the recreational setting, fatalities occur when individuals fall from vessels and drown, or succumb to hypothermia, or cannot be recovered back on board.
Physical injuries in recreational sailing are widespread and examples include those of suf- fering direct trauma (e.g. head or neck following uncontrolled gybe; Figure 14.10), loss of digits or limbs when caught up in winches or anchor cable, limb fractures or skull fractures from direct impact from flailing blocks and burn injury from uncontrolled rope movement. Drowning may occur from being trapped after inversion of the vessel.
Motor-powered vessels may cause injury from explosion or fire, or those in the water may sustain injury from rotating propellers.
Commercial vessels may cause their own spe- cific problems, such as asphyxiation in storage tanks or falls from heights. Most of these scenarios are of an industrial/occupational nature and may involve potential breaches of health and safety legislation. In the UK The Marine Accident Inves- tigation Branch (MAIB) examines and investigates all types of marine accidents to, or on board, UK ships worldwide, and other ships in UK territorial waters.
■ Further information sources
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Bhatti JA, Razzak JA. Railway associated injuries in Pakistan.
International Journal of Injury Control and Safety Promotion 2010; 17: 41–4.
Boniface K, McKay MP, Lucas R, Shaffer A, Sikka N. Serious injuries related to the Segway® personal transporter: a case series. Annals of Emergency Medicine 2010; [Epub ahead of print].
Chao T-C, Lau G, Eng-Swee Teo C. Falls from a height: the pathology of trauma from vertical deceleration, Chapter 20 In: Mason JK, Purdue BN (eds). The Pathology of Trauma, 3rd edn. London: Arnold, 2000; p. 313–26.
Clark JC, Milroy CM (2000). Injuries and deaths of pedestrians, Chapter 2. In: Mason JK, Purdue BN (eds). The Pathology of Trauma, 3rd edn. London: Arnold, 2000; p. 17–29.
Figure 14.10 Abrasion of neck caused by mainsheet during uncontrolled gybe.
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Conroy C, Hoyt DB, Eastman AB et al. Motor vehicle-related cardiac and aortic injuries differ from other thoracic injuries.
Journal of Trauma 2007; 62: 1462–7.
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Mason JK, Purdue BN (eds). The Pathology of Trauma, 3rd edn. London: Arnold, 2000; p. 300–12.
Deaner RM, Fitchett VH. Motorcycle trauma. Journal of Trauma 1975;15: 678–81.
Graham JW. Fatal motorcycle accidents. Journal of Forensic Sciences 1969; 14: 79–86.
Goonewardene SS, Baloch K, Porter K, Sargeant I, Punchihewa G. Road traffi c collisions-case fatality rate, crash injury rate, and number of motor vehicles: time trends between a developed and developing country.
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Hitusugi M, Takatsu A, Shigeta A. Injuries of motorcyclists and bicyclists examined at autopsy. The American Journal of Forensic Medicine and Pathology 1999; 20: 251–5.
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113: 84–8.
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Asphyxia
■ Introduction
■ Classification of asphyxia
■ Phases and signs of ‘asphyxia’
■ Types of mechanical asphyxial mechanisms
■ Further information sources
15
Chapter
■ Introduction
The literal translation of the word ‘asphyxia’ from the Greek means ‘absence or lack of pulsation’;
quite how this word has came to denote the effects of ‘the lack of oxygen’ is not clear, but it is now a word commonly used to describe a range of con- ditions for which the lack of oxygen, whether it is partial (hypoxia) or complete (anoxia), is considered to be the cause (Table 15.1).
In forensic medicine, asphyxia often describes a situation where there has been a physical
obstruction between the mouth and nose to the alveoli, although other ‘asphyxial mechanisms’
exist, in which there is an inability to utilize oxygen at the cellular level without there being a physical airway obstruction. The term asphyxia is not a term frequently used in clinical medicine and, given the incomplete understanding of the pathophysiology of many deaths occurring following the application of pressure to the chest and neck, for example, its use as a useful descriptive term in such scenarios is perhaps questionable.
Table 15.1 Examples of ‘asphyxial’ conditions
Underlying cause of death Name
Lack of oxygen in the inspired air Suffocation
Blockage of the external orifi ces Suffocation/smothering
Blockage of the internal airways by obstruction Gagging/choking Blockage of the internal airways by external pressure Strangulation/hanging
Restriction of chest movement Traumatic asphyxia
Failure of oxygen transportation (For example carbon monoxide poisoning)
Failure of oxygen utilization (For example cyanide poisoning)
1 5 Asph yxia
■ Classification of asphyxia
Although there are currently moves to develop an internationally agreed classification for asphyxia, for the purposes of exploring what is generally currently broadly agreed in the forensic community as ‘asphyxia’, a simple classification of ‘asphyxial mechanisms’ is described below:
■ Mechanical (Figure 15.1)
• strangulation (pressure applied to the neck by means of a ligature, or by hands etc.)
• hanging (pressure applied to the neck by means of a ligature combined with the weight of the body)
• choking (physical obstruction within the airways)
• compression asphyxia (pressure applied to the chest or abdomen, resulting in a physical interference with the ability to breathe effectively)
• smothering (physical obstruction of the mouth/
nose preventing effective breathing).
■ Non-mechanical
• carbon monoxide poisoning (chemical interfer- ence with respiration at a cellular level – see Chapter 22, p. 212)
• cyanide poisoning (as above).
■ Miscellaneous
• drowning (physical interference with effective respiration; see Chapter 16, p. 164).
Asphyxial insults are not necessarily fatal, the outcome being largely dependent on the nature of the insult, its degree, and its length of time. It is possible for some survivors to suffer no significant adverse long-term health effects, although others may ‘survive’ in a vegetative state following irreversible hypoxic–ischaemic brain injury, depending on the length of time inadequate oxygenation was experienced. In the living, appropriate examination, documenta- tion and investigations will optimize the recov- ery of forensically useful evidence in order to assist subsequent legal proceedings and, if such an individual presents to hospital, it is appro- priate for such an examination to be made by a suitably experienced forensic physician at the earliest opportunity. Where the insult has resulted in death, examination by a forensic pathologist is recommended in order to identify potentially sub- tle evidence of assault.
Blocked pharynx or glottis
Ligature strangulation Inverted posture
Pressure on chest Blocked trachea
Manual strangulation Smothering pad Irrespirable atmosphere Impermeable plastic
(a)
(b)
(c)
Figure 15.1 (a) Examples of the causes of mechanical asphyxia.(b) Grip marks to the neck and jaw following attempted manual strangulation. (c) Ligature mark after attempted garrotting - note congestion ('tide mark') above double ligature.