Discussion

The Peer Review Panel is an important part of providing assurance to the Chain of Command that the DMS Trauma system is functioning optimally and that Healthcare Governance of the system is in place in that continuous adjustments and improvements are made. As well as immediate feedback to theatre following a post-mortem, comments are passed to clinicians through the Deployed Medical Director (DMD) and at the weekly Joint Theatre Clinical Conference. Feedback can also be passed from the DMD to the Medical Regiment and thus to the Combat Medical Technicians who dealt with the casualty at the point of wounding. This also allows everyone involved in a casualty's care the opportunity to raise questions and receive answers about what happened. Where there has been deviation from standardised procedures, explanations are sought that may result in identification of a training gap and appropriate measures taken.

Further benefits derived from the in-depth review of military operational mortality have been the increased linkages between clinical personnel and those working for other Defence agencies. The review has been used to determine emerging injury and treatment patterns, determine potential areas of clinical research and inform the on-going development of personal and vehicular protective systems and equipment.

There is a potential overlap in the definitions of Killed in Action (KIA) and Died of Wounds (DOW) that are duplicated for Killed by Non-Enemy Action and Died from Non-Enemy Action. Depending on circumstances, a casualty who arrives at hospital in cardiac arrest may receive blood and undergo surgery before resuscitation attempts are ceased and death pronounced. The convention that has been applied in these cases is that if there have been any signs of life at any time after arrival at the hospital then DOW is used, otherwise KIA is the designation. There are 32 cases who received blood in the emergency department and/or theatre but as they did not regain a cardiac output at any stage, are still classified as KIA. In one case, nine units of packed red blood cells and five units of fresh frozen plasma were given. This case and 28 others were S4 when reviewed. The two S2 and five S3 cases all had prolonged evacuation periods as a result of tactical issues. The S4 cases potentially represent failure to recognise futility. In the resource-rich environment of Bastion Role 3, this may not have further ramifications if there are no other casualties requiring immediate treatment. However, as the Armed Forces move to contingency operations, resources will be much more limited. While the final decision to stop resuscitative efforts should always rest with the clinicians at the trolley-side, a further study of these cases will be undertaken to determine if lessons can be drawn and if there is any potential for ‘rules of thumb’ to be developed.

Comparison with the experience of American Forces described by Eastridge et al5 is interesting but no firm conclusions can be drawn as there has been no cross-review or communication on this subject between the reviewers and parameters may have differed. The KIA to DOW ratios of HA casualties are very similar (UK 6.28 vs US 6.87) but the UK review panel rated 93.5% (416 cases) of HA casualties non-salvageable compared with the US figure of 75.7% rated non-survivable. There are many potential explanations for this difference not least a different application of the cut-off between KIA and DOW as described above. The KIA to DOW ratio has in the past been suggested as a measurement of trauma system performance but ‘inevitable’ deaths surviving to reach hospital before dying make it a poorer tool than identifying unexpected outcomes.8

The results of this paper point to the overwhelming severity and nature of military trauma described in other studies14 ,15 especially given the proportion of injuries caused by improvised explosive devices. Data from the Vietnam War and previous modern conflicts showed a preponderance of single life-threatening injuries.16 In the battlefield environment, any AIS score 4 or greater is potentially fatal.17 In this study, 371 cases had AIS 4+ injuries to more than one body region, the highest being six regions, and 80 had AIS 6 injuries to two or more regions (highest 4). Of those killed by an AIS 4+ injury to a single body region, the head (72 cases) and thorax (46) were most often involved.

A further finding is the necessity to apply a clinical dimension to the review process as well as using the different trauma scoring methods especially when considering individual cases. As was observed when analysing survivors over 18 months between 2006 and 2008,4 there is not necessarily agreement between the methods themselves or between them and experienced clinical opinion. In total, 17 cases were identified by ASCOT and/or TRISS as ‘expected survivors’ (one TRISS only, eight ASCOT only and eight by both). Of these, clinical review graded 10 as S4, three S3, one S2 and two S1; three further cases had an ISS of <15 thus not reaching the threshold for ‘major trauma’. All three were expected deaths on TRISS and ASCOT due to their physiological status on arrival at hospital and peer review award one each to S2, S3 and S4. In all three, tactical aspects caused a delayed evacuation.

The members of the review panel have not been identical throughout the period of this paper due in particular to deployments. This is a source of weakness but it is also a potential strength as it has meant that all the military members of the panel have had recent operational experience. Regardless, the membership has been relatively stable with the personnel listed in acknowledgements attending over two-thirds of meetings and three of whom have attended all but one or two. Judgements have as a result been consistent to the standard of the best practice available at the time of that particular meeting. However, over time the parameters within which those judgements have been made have been shifting on a regular basis as advances in trauma treatment in the DMS developed. An injury pattern illustrating this is multiple amputations following an improvised explosive device strike. This has been the signature injury pattern of Op HERRICK and, when first seen in the meetings, survival was thought to be unlikely. As the DMS experience has developed along with training, equipment and techniques, good outcomes have been achieved on a regular basis and scrutiny of cases reaching the mortality meeting is intense.

A further study of the DOW cases dying at the UK Role 4 is in progress to determine if there are any specific lessons to be learnt from this sub-group. A similar project is also ongoing into ‘unexpected survivors’ over a longer period than described previously.4 While tactical issues were the most common factor identified in the cases graded S1–3 and each case has been examined individually, a more in-depth study of the group is required as a whole to identify if there are any key learning points that may inform clinical practice or force protection.