Introduction/Hypothesis: In trauma patients, the significance of initial prehospital vital signs in predicting resuscitation needs on arrival to hospital is unclear. Changes in vital signs are frequently unreported during transport. We hypothesize that initial prehospital vital signs may underestimate need for urgent interventions after hospital arrival.

Methods:We retrospectively reviewed all adult trauma activations at a single Level 1 trauma center over a 24-month period from January 2017 to December 2018. Shock index (SI) was calculated using initial prehospital and arrival vital signs. Severity of shock was categorized as level 1 (none, SI

Results:2224 patients (prehospital shock level 1 or 2, n=2036, level 3, n=159 and level 4, n=29) were included. All level 4 patients died prior to arrival and were excluded. 37% of level 1 and 2 patients had worsened shock on arrival compared to 7% of level 3 patients (p=0.001). For level 1 and 2 prehospital shock, worsened shock was associated with urgent intervention (level 1: 17%[W] vs 8%[U/I], p=0.0001; level 2: 22%[W] vs 11%[U/I], p=0.02). For level 3 shock, worsened shock was not associated with urgent intervention (27%[W] vs 30% [U/I], p=0.9). In level 1 and 2 patients, the massive transfusion protocol was used more frequently with worsening shock (level 1: 5%[W] vs 0.5%[U/I], p

Conclusions: More than one third of patients with mild or no prehospital shock experience worsening shock on arrival. Initial prehospital vital signs may not provide enough data to anticipate resuscitation needs. Better communication of prehospital data during transport may represent an opportunity to improve trauma care.