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 Acute aortic syndrome. Heart 2001;85:365–368

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

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

Results I – Abbreviated Injury Scales (AIS) codes AIS codeAISDescription thoracic aorta, NFS thoracic aorta, intimal tear, no disruption thoracic aorta, intimal tear, with aortic valve involvement thoracic aorta, laceration, NFS, (perforation, puncture) thoracic aorta, laceration, minor thoracic aorta, laceration, major thoracic aorta, laceration, major, with aortic root or valve involvement thoracic aorta, laceration, major, with paraplegia not due to direct spinal cord trauma thoracic aorta, laceration, major, with hemorrhage confined to mediastinum thoracic aorta, laceration, major, with hemorrhage not confined to mediastinum Intimal injury Mural injury Rupture

AAS matched to AIS codes

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 to

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

Results Of over 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.

Results: Position in car AIS codeAISDescriptionFront rowSecond rowUnknownTotal intimal tear, no disruption intimal tear, with aortic valve involvement laceration, NFS, (perforation, puncture) laceration, minor laceration, major laceration, major, with aortic root or valve involvement laceration, major, with paraplegia not due to direct spinal cord trauma laceration, major, with hemorrhage confined to mediastinum laceration, major, with hemorrhage not confined to mediastinum NFS

Result: Direction of impact AIS codeAISDescriptionFrontSide LeftSide RightTotal intimal tear, no disruption intimal tear, with aortic valve involvement laceration, NFS, (perforation, puncture) laceration, minor laceration, major laceration, major, with aortic root or valve involvement laceration, major, with paraplegia not due to direct spinal cord trauma laceration, major, with hemorrhage confined to mediastinum laceration, major, with hemorrhage not confined to mediastinum NFS

Relationship between Estimated Test Speed and Abbreviated Injury Score

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