Abstract
Introduction Damage Control orthopaedic techniques have been proposed in the seriously injured with primary external fixation of long bone fractures, reducing the ‘second hit’ of surgery. We have developed a large animal (ovine) model for the study of major trauma.
Aim To clarify the sequence of pulmonary and systemic physiological responses over a 24-hour period following injury, comparing the effects of primary external femoral fixation to intramedullary stabilisation to better quantify the ‘second hit’ of these surgical techniques.
Methods Under terminal anaesthesia bilateral femoral diaphyseal fractures were produced using a mechanical pneumatic actuator (ram). Hypovolaemic shock was maintained for 4 hours before fluid resuscitation and surgical stabilisation.
24 sheep were randomised into 4 groups and monitored for 24 hours following injury:
Group 1 – Control Group (effects of general anaesthesia only)
Group 2 – Control Group for Trauma (injury but no long bone stabilisation)
Group 3 – Damage control group (Injury and external fixation)
Group 4 – Early total care (Injury and reamed intra-medullary stabilisation)
Outcome measures: Embolic load (Mayo score) using transoesophageal echocardiography; serum markers of coagulation (prothrombin time, activated partial thromboplastin time and fibrinogen levels) and inflammation (interleukin 6). Bronchoalveolar lavage to assess total cell count and cell differential to quantify the proportion of neutrophils present.
Results A sustained embolic shower was detected with each femoral fracture (mean Mayo score of 5 and 5.5 respectively). Intramedullary reaming and nailing produced further embolic events with a mean score of 2.5 and 1.5 respectively. Mean prothrombin time increased from a pre-fracture mean of 12 in each group to 18.8 (group 1) 20.7 (group 2); 24.8 (group 3); 31.1 (group 4). Alveolar lavage samples taken at 0, 4 and 24 hours following injury indicated a progressive neutrophilia developing in each group with a count pre-fracture of 4.3 increasing to 55.75 (group 1); 40 (group2); 49 (group3) and 31.7 (group 4) by 24 hours following injury.
Discussion The effects of damage control techniques in this model appear to be a reduced stimulation of the extrinsic coagulation system. An additional embolic hit was detected secondary to intramedullary reaming and nail insertion. Localised lung inflammation seems to develop in all groups with no significant differences seen due to treatment.
Theses abstracts were prepared by Professor Roger Lemaire. Correspondence should be addressed to EFORT Central Office, Freihofstrasse 22, CH-8700 Küsnacht, Switzerland.
