Non-compressible haemorrhage from within the torso and junctional regions constitutes the leading cause of potentially preventable death on the battlefield. It can be defined as haemorrhagic shock arising from injury to named torso vessels, pulmonary parenchyma, high grade solid organ injury and/or disruption of the bony pelvis. Data from the US Department of Defence Trauma Registry demonstrate a torso injury rate of 12.7% with 17.1% of casualties exhibiting torso injury and shock. The overall mortality is 18.7%, with major arterial injury and pulmonary injury identified as independent predictors of mortality on multivariate analysis. The UK Joint Theatre Trauma Registry reports similar findings with the greatest burden of mortality occurring prior to hospital admission (75.0%), a rate that has remained unchanged over a decade of war. Injury from improvised explosive devices (IEDs) in particular are associated with non-compressible haemorrhage, frequently causing traumatic lower extremity amputation in combination with torso injury. Contemporary surgical strategy relates to early operative haemorrhage control in patients presenting with shock. In patients sustaining a circulatory arrest, resuscitative thoracotomy and aortic cross clamping can be used to control inflow and increase cardiac afterload. The UK experience over 5 years at Camp Bastion demonstrated a mortality of 78.5%, with greatest survival observed in patients with the shortest time to thoracotomy. In patients sustaining lower extremity amputation following IED injury, 1 in 5 require a laparotomy for proximal vascular control, with less than half requiring further intra-abdominal intervention. There is a pressing need for a haemorrhage control and resuscitation adjunct in non-compressible haemorrhage that can be deployed prior to or as an adjunct to operative haemorrhage control. Resuscitative endovascular balloon occlusion of the aorta (REBOA) is a technique that can occlude the aorta without the need for an operating theatre. It is an experimental technique, so its effect on survival and physiology is unknown. In a porcine model of uncontrolled pelvic haemorrhage, infra-renal REBOA was shown to be as effective as chitosan gauze in the setting of normal coagulation. However, REBOA was associated with a significantly greater survival in a coagulopathic setting. Similar results were obtained when using a porcine model of abdominal haemorrhage in conjunction with thoracic REBOA. In both studies, balloon occlusion demonstrated a significant improvement in systolic blood pressure and other haemodynamic measures compared to the no-occlusion control groups. Having demonstrated a survival and haemodynamic benefit in uncontrolled haemorrhage models, the metabolic and inflammatory consequences of thoracic REBOA were characterised in further detail using a porcine model of controlled hypovolaemic shock. Occlusion for 30 and 90 minutes was associated with a significant lactate burden when compared to animals undergoing shock alone. However, following resuscitation with blood and intravenous fluid, normal physiology was restored within 6 hours. The inflammatory sequelae were studied following 30, 60 and 90 minutes of shock and occlusion. Increasing occlusion time resulted in an escalating release of interleukin-6 which manifest clinically as an increase in ARDS and need for vassopressor support. In order to develop a fluoroscopy free REBOA system, a series of human studies were undertaken to examine the relationship between an external measure of torso height and aortic length in order to guide insertion length. A retrospective examination of computed tomography in male trauma patients demonstrated a correlation between torso height and aortic length. This was confirmed by a prospective study which was also used linear regression to develop equations predictive of insertion length. Finally, the UK Joint Theatre Trauma Registry was used to determine the need for REBOA in a population of UK military personnel injured over 10 years of conflict. Of 1317 severely injured patients 70.2% had no indication, 11.2% had a contra-indication and 18.5% had an injury pattern indication for REBOA. Of those with an indication for REBOA, 66 (27.0%) patients died en-route to hospital and 29 (11.9%) died in-hospital. In conclusion, non-compressible haemorrhage constitutes a significant burden of potentially preventable battlefield mortality. REBOA is a technique that can be used in the thoracic or infra-renal aorta as a haemorrhage control and resuscitation adjunct, prior to operative haemorrhage control. While associated with a significant survival advantage in models of uncontrolled haemorrhage, it is associated with a significant metabolic penalty, although with resuscitation this can be ameliorated successfully.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:631018 |
| Date | January 2014 |
| Creators | Morrison, Jonathan James |
| Publisher | University of Glasgow |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://theses.gla.ac.uk/5669/ |
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