Effect of resuscitation strategies on coagulation following haemorrhage and blast exposure

Abstract

Approximately one-third of trauma patients are coagulopathic on arrival to the emergency department. Acute traumatic coagulopathy and systemic inflammatory responses are serious secondary consequences of severe trauma and are linked to increased morbidity and mortality. Early tissue hypoxia is a major component in the aetiology of both complications. New resuscitation strategies are aimed at improving tissue oxygenation in the pre-hospital phase, and may attenuate coagulopathy and inflammatory sequelae. This is of particular importance in military personnel who suffer complex injuries, often from blast exposure, and may have extended evacuation times. This thesis evaluates the effect of a novel hybrid (NH) resuscitation strategy on coagulation and inflammation. Terminally anaesthetised pigs were randomised to one of two injury strands of haemorrhage +/- blast injury; initially resuscitated with 0.9% Saline to a hypotensive systolic blood pressure of 80mmHg for one hour. This was followed by either a return to a normotensive pressure (110mmHg) (NH) or a continuation at the hypotensive level. Over both injury strands NH significantly reduced Prothrombin Time, PT (mean proportion of baseline: 1.40±0.05 vs. 1.80±0.09; p=0.001) and interleukin-6 (IL6) levels (mean 1106±153 vs. 429±79 pg/ml; p=0.001) compared to the hypotensive groups. PT was positively correlated with IL6 (p=0.002) and base deficit (p=0.0004). These findings indicate that improving tissue oxygenation reduces the coagulation derangement and the pro-inflammatory response. No difference in coagulopathy was found between injury strands although blast did cause greater inflammation. Early identification of coagulopathic casualties is essential and a separate feasibility field study was preformed to assess the use of thromboelastometry in a deployed military hospital, evaluating the degree of coagulopathy in battlefield casualties and to monitor the coagulation status during the resuscitation process. In conclusion, NH attenuated the acute traumatic coagulopathy and inflammatory responses and therefore should be considered when an extended casualty evacuation is enforced.