Background: A ruptured abdominal aortic aneurysm (rAAA) is a life-threatening condition, with high mortality rates. The Shock Index (SI) is an easy tool and a useful predictor of hemodynamic instability in trauma patients. We aimed to assess the predictive and prognostic value of the SI for patients with a suspected rAAA in the prehospital and hospital setting.
Methods: This was a retrospective, observational, single-center study. Patients >18 years old who visited the emergency department with a suspected rAAA between January 2009 and December 2018 were included. Prehospital and hospital SI were calculated and analyzed for its predictive value on the presence of a rAAA, need for packed cells (PCs) and mortality.
Results: A total of 313 patients met the inclusion criteria, of which 71 patients (22.6%) presented with a rAAA. Prehospital and hospital SI were significantly increased in the rAAA group. A SI ≥ 1.0 was estimated as an optimal cutoff point for the presence of a rAAA (AUROC 0.74, 95% CI 0.67-0.82; p < 0.001) with an adjusted Odds Ratio (OR) of 5.3 (95% CI 2.13-13.39) for the prehospital SI and an adjusted OR of 18.2 (95% CI 5.83-56.73) for the hospital SI. Both prehospital and hospital SI ≥ 1.0 were associated with a higher need for PCs and amount of PCs (p < 0.05). A hospital SI ≥ 1.0 was associated with higher in-hospital mortality rates (39.0% vs 68.0%, p = 0.022).
Conclusions: The prehospital and hospital SI were significantly elevated in the rAAA group. As such, the SI showed promising results as a predictive and prognostic tool, with SI ≥ 1.0 as cutoff point.
Keywords: emergency medical services; prehospital; rAAA; ruptured abdominal aortic aneurysm; shock index; triage.