Shock Index

Why Use

Blood pressure and heart rate, when used individually, fail to accurately predict the severity of hypovolemia and shock in major trauma. Massive transfusion of blood products can be associated with significant risk if initiated on the wrong patient. Identifying patients at risk for massive transfusion can be difficult, and objective measures like the Shock Index can help. Shown to be more sensitive than the ABC Score for Massive Transfusion ( Schroll 2018 ).

When to Use

Consider in the following scenarios: Patients presenting with hemorrhage and trauma, to identify patients at increased risk for transfusion. Patients requiring endotracheal intubation, to help identify groups of patients at risk of post-intubation hypotension. Patients with suspected sepsis (found to be as sensitive as the SIRS criteria to identify patients at risk for sepsis, Berger 2013 ); however, note that a large RCT showed that use of the Shock Index to guide fluid resuscitation in sepsis did not demonstrate a mortality improvement ( ProCESS Investigators 2014 ).

Formula

Pearls / Pitfalls

There are currently no large scale prospective studies validating the use of the Shock Index to guide resuscitative intervention. Shown to correlate with higher risk of mortality (likelihood ratio 5.67) and hospitalization (LR 6.64) at a cutoff of >1.3 ( Al Jalbout 2019 ). A pediatric age-adjusted Shock Index (SIPA) better differentiates severely injured children (up to 16 years of age) ( Acker 2015 ).

Critical Actions

Accuracy of Shock Index in identifying trauma patients in need of massive blood transfusion has not yet been prospectively investigated.