Shock index for prehospital sepsis recognition

Abstract

The authors of this study aimed to assess the effectiveness of prehospital shock index (SI) and modified shock index (MSI) as predictors for sepsis and related outcomes. They aimed to determine whether the SI and MSI correlated with hyperlactatemia, which is considered a marker of sepsis severity and a predictor of poor prognosis. This was a prospective cohort study including all adult patients transported by our county EMS system as per our system’s prehospital sepsis protocol. The study was approved by our medical school’s institutional review board. The study cohort included 1,426 patients. Of these, 969 had an elevated SI. The initial SI ranged from 0.260 to 2.840, with a median of 1.11, and 68% had a “positive” SI (>1.0). The initial MSI ranged from 0.336 to 3.727, with a median of 1.465, and 74% of the cohort had a “positive” MSI (<0.7, or >1.3). Of the patients, 92% had repeat vitals during transport, and the second SI was elevated in 41%. The study found that patients with an elevated SI were significantly more likely to have an elevated lactate (P=0.0309) and be admitted for sepsis (P<0.0001, 95% CI 0.1038 to 0.2714). Patients with an elevated serum lactate were significantly more likely to die during their hospital stay (P<0.0001, 95% CI 0.1503 to 0.3210) with an odds ratio of 2.38 (95% CI 1.59 to 3.56). The study data suggest that an elevated shock index >1 can be used as a surrogate marker for elevated lactate, which in turn correlates with sepsis and poor outcomes following sepsis.