Prehospital shock index predicts 24-h mortality in trauma patients with a normal shock index upon emergency department arrival.

ABSTRACT

BACKGROUND: The shock index (heart rate divided by systolic blood pressure) of trauma patients upon emergency department arrival predicts blood loss and death. However, some patients with normal shock indices (0.4 < shock index <0.9) upon emergency department arrival also have poor prognoses. This study aimed to determine whether abnormal prehospital shock indices in trauma patients with normal shock indices upon emergency department arrival were predictors of a high risk of mortality. METHODS: We conducted a retrospective cohort study of emergency department-admitted trauma patients from 2004 to 2017. The study included 89,495 consecutive trauma patients aged ≥16 years, with Abbreviated Injury Scale score of ≥3, who were transported to the emergency department directly from the field and had a normal shock index upon emergency department arrival. According to the prehospital shock index scores, the patients were categorized into low shock index (≤ 0.4), normal shock index, and high shock index (≥0.9) groups. Odds ratios and 95% confidence intervals were calculated using logistic regression analysis. RESULTS: The 89,495 patients had a median age of 64 (interquartile range 43-79) years, and 55,484 (62.0%) of the patients were male. There were 1350 (1.5%) 24-h deaths in total; 176/4263 (4.1%), 1017/78,901 (1.3%), and 157/6331 (2.5%) patients were in the low, normal, and high prehospital shock index groups, respectively. The adjusted odds ratios for 24-h mortality compared with the normal shock index group were 1.63 (95% confidence interval 1.34-1.99) in the low shock index group and 1.62 (95% confidence interval 1.31-1.99) in the high shock index group. CONCLUSION: Trauma patients with abnormal prehospital shock indices but normal shock indices upon emergency department arrival are at a higher risk of 24-h mortality. Identifying these indices could improve triage and targeted care for patients.