Aetiology of Traumatic Shock in an <scp>A</scp> ustralian Level 1 Trauma Centre

OBJECTIVE: Resuscitation of traumatic shock (TS) is reflexively oriented towards haemorrhage control, reflecting its contribution to early preventable mortality. While the mechanisms of shock are well established, the relative frequency of haemorrhagic, non-haemorrhagic, indeterminate, and mixed aetiologies in blunt-predominant cohorts is less well characterised. This study aimed to identify and rank the causes of TS among adult major trauma (MT) patients managed at an Australian Level 1 trauma centre. METHODS: A retrospective cohort study (Dec 2022-Jan 2025) identified MT patients meeting a pragmatic clinical definition of TS based on early physiological parameters. Structured chart review assigned one or more causes of shock using a predefined hierarchy spanning haemorrhagic, non-haemorrhagic, and indeterminate categories. Causes were ranked by frequency and stratified by injury mechanism. RESULTS: Of 3667 MT patients, 324 (8.8%) met TS criteria. Shocked patients were younger, more severely injured, and had higher in-hospital mortality (22.5% vs. 9.1%). Blunt trauma predominated (86.7%). Pooled haemorrhagic mechanisms accounted for 66.3% of primary aetiologies (64.8% blunt; 76.2% penetrating), leaving approximately one-third of cases attributable to non-haemorrhagic or indeterminate causes. The primary cause was indeterminate in 14.8%, more frequent after blunt than penetrating injury (16.0% vs. 7.1%). Multiple contributory causes were identified in 44.0% of cases. CONCLUSION: While haemorrhage remained the dominant aetiology of traumatic shock, approximately one-third of cases were attributable to non-haemorrhagic, indeterminate, or mixed mechanisms, with these proportions higher following blunt injury. These findings argue against an exclusively haemorrhage-centred diagnostic approach in blunt-predominant trauma systems and support routine consideration of alternative and coexisting aetiologies during early resuscitation.