Traumatic asphyxia and venous compression
2.5.29 In an expert medical opinion provided for the Judicial Review of the Inquests, Dr Iain West, a consultant forensic pathologist, was critical of key aspects of the eight post mortem reports on which he had been invited to comment.
2.5.30 In particular, he stated that a distinction should be drawn between 'classic' traumatic asphyxia, where a sudden rise in venous pressure results in rapid cessation of circulation and a high probability of death, and asphyxia due to suppression of breathing through mechanical compression of the chest wall without venous obstruction.
2.5.31 This takes longer to develop and is associated with a greater likelihood of rescue from mechanical compression of someone partially asphyxiated but still alive. These distinct conditions present different appearances at post mortem. The venous compression characteristic of 'classic' traumatic asphyxia results in intense congestion and a deep purplish-blue skin colouration (cyanosis) with many small (petechial) haemorrhages, occurring over the head, neck and upper chest.
2.5.32 Asphyxia without venous compression may result in cyanosis and a few fine petechial haemorrhages, particularly over the head, neck and extremities, but not the marked pattern restricted to the upper part of the body and associated with congestion that is caused by venous compression.
2.5.33 Dr West found no evidence of 'classic' traumatic asphyxia in three or four of the eight reports that he scrutinised. He concluded that:
it is impossible to state purely from the medical point of view that a number of the young men that I have indicated above could not have been alive at 3.15pm. Those dying as the result of anoxic damage consequent to their chests being crushed could well have survived for a much longer period only to die subsequently from the effects of irreversible anoxia.
Access to post mortem records
2.5.34 Dr West had access to only eight post mortem records. With access to all post mortem records, the Panel was able to review the entire set against these criteria. In 15 of the post mortem records there is a clear description of the findings of 'classic' traumatic asphyxia with venous obstruction, and in a further 25 the description suggests probable venous obstruction.
2.5.35 In 28, however, the findings described clearly do not support the occurrence of 'classic' traumatic asphyxia with venous obstruction, and in a further 16 a significant degree of venous obstruction is unlikely from the description given. (In 11 the appearances were insufficiently clearly described to decide, while in the 96th, death occurred after a prolonged period in hospital by which time the initial changes had reversed.)
2.5.36 The occurrence of a substantial proportion with evidence of this different form of asphyxia calls into question the medical evidence presented to the inquest of a single unvarying pattern of death due to traumatic asphyxia. 'Classic' traumatic asphyxia results in cessation of the blood circulation unless relieved, because the venous obstruction prevents blood returning to the heart. In contrast, those without significant venous obstruction and circulatory arrest are likely to have survived for a significantly longer period.
2.5.37 Had their chest compression been relieved during this period, for example by removal from the pens, resuscitation of a partially asphyxiated individual with a continuing heartbeat would have been a very different proposition from resuscitation of someone who had already suffered cardiac arrest, and significantly more likely to lead to a successful outcome.
2.5.38 Importantly, a person in this condition would also have been vulnerable to further potentially fatal asphyxia from a new cause, such as airway obstruction from being positioned on their back or from inhalation of stomach contents.
 Written opinion of Dr I West, Department of Forensic Medicine, Guy's Hospital, 20 August 1992, SYC000001280001, pp66-71.