1. Defining acute aortic syndrome following trauma: are abbreviated injury scale (AIS) codes a useful surrogate descriptor? Field ML, Bashir M, Sastry P, Cuerden R, Richens D Aortic rupture Intimal tear IMH http://www.lightlabimaging.com/gallery/cvpstill.html http://uk.wrs.yahoo.com Acute aortic syndrome. Heart 2001;85:365–368

2. Background Vehicle related blunt traumatic aortic injury typically results in exsanguination and fatality A small percentage of patients sustain a lesser, partial thickness aortic injury or contained rupture, allowing transfer to hospital The spectrum of aortic injuries included in the description of acute aortic syndrome include: intimal tear, intramural haematoma, localised dissection, contained and uncontained rupture

3. Objective To use Abbreviated Injury Scale (AIS) codes, used in trauma data bases, as a surrogate marker for entities within the spectrum of acute aortic syndrome Hypothesis The kinematics of injury are distinct for partial thickness intimal tears and mural haematoma versus full thickness rupture

4. Results I – Abbreviated Injury Scales (AIS) codes AIS codeAISDescription 4202994thoracic aorta, NFS 4202024thoracic aorta, intimal tear, no disruption 4202045thoracic aorta, intimal tear, with aortic valve involvement 4202064thoracic aorta, laceration, NFS, (perforation, puncture) 4202084thoracic aorta, laceration, minor 4202105thoracic aorta, laceration, major 4202125thoracic aorta, laceration, major, with aortic root or valve involvement 4202145thoracic aorta, laceration, major, with paraplegia not due to direct spinal cord trauma 4202165thoracic aorta, laceration, major, with hemorrhage confined to mediastinum 4202186thoracic aorta, laceration, major, with hemorrhage not confined to mediastinum Intimal injury Mural injury Rupture

5. AAS matched to AIS codes

6. Methods As part of the UK Cooperative Crash Injury Study, which performs detailed vehicle related crash scene analysis, including equivalence test speed (ETS), seatbelt usage, seat position and impact direction, we examined victims with aortic injuries categorised by AIS codes 420200 to 420299

7. Estimation of combined impact speeds in the Laboratory using vehicle deformation to calculate Estimated Test Speed (ETS)

8. Results Of over 16000 analysed crashes in the UK-CCIS database, 132 involved aortic injuries. Using AIS codes as surrogate markers there were: – 9 initimal tears, –22 intramural haematomas, –42 localised dissections/ contained ruptures –41 uncontained ruptures Taking this selective group of 132 vehicle related fatalities with BTAI, we were able to relate entities within the spectrum of acute aortic disease to kinematics and mechanism of injury. Risk of partial thickness aortic injuries is higher in front and far side impacts while full thickness uncontained ruptures are more likely in near side impacts.

9. Results: Position in car AIS codeAISDescriptionFront rowSecond rowUnknownTotal 4202024intimal tear, no disruption819 4202045intimal tear, with aortic valve involvement0 4202064laceration, NFS, (perforation, puncture)92112 4202084laceration, minor9110 4202105laceration, major29332 4202125laceration, major, with aortic root or valve involvement11 4202145laceration, major, with paraplegia not due to direct spinal cord trauma0 4202165laceration, major, with hemorrhage confined to mediastinum171119 4202186laceration, major, with hemorrhage not confined to mediastinum36541 4202994NFS718 116115132

10. Result: Direction of impact AIS codeAISDescriptionFrontSide LeftSide RightTotal 4202024intimal tear, no disruption213 4202045intimal tear, with aortic valve involvement0 4202064laceration, NFS, (perforation, puncture)22 4202084laceration, minor2316 4202105laceration, major53513 4202125laceration, major, with aortic root or valve involvement11 4202145laceration, major, with paraplegia not due to direct spinal cord trauma0 4202165laceration, major, with hemorrhage confined to mediastinum15511 4202186laceration, major, with hemorrhage not confined to mediastinum66315 4202994NFS113 19 1574

11. Relationship between Estimated Test Speed and Abbreviated Injury Score

12. Conclusions AIS codes may be matched to intimal tear, intramural haematoma, localized dissection and contained/ uncontained rupture Mechanism of injury differs for entities within the spectrum of acute aortic syndrome Risk of partial thickness injury is higher in frontal and far side impacts while rupture is more common in near side impacts Refinement of “Thoracic Vascular” AIS codes in light of our current understanding of acute aortic syndromes would further aid analysis