Google Search: Shock Index Calculator

Posted on June 30, 2026 by Tom Wade MD

Today, I review a Google Search page on the Shock Index Calculator and link to some of the resources on the above page.

All that follows are some of the links and information on the above web page.

AI Overview

The Shock Index (SI) is a quick clinical tool used to assess hemodynamic instability and detect early or “occult” shock. It is calculated by dividing your patient’s heart rate (HR) by their systolic blood pressure (SBP):

MDCalc +4

How to Interpret the Shock Index

A normal, healthy resting shock index typically ranges from 0.5 to 0.7.

Medscape Reference +1
  • < 0.7: Normal or reassuring hemodynamics.
  • 0.7 – 0.9: Borderline/Watch closely ; values ≥ 0.8 serve as early warning signs of cardiovascular stress.
  • ≥ 0.9 – 1.0: High-risk physiology. Commonly used as the threshold for hemodynamic instability, predicting a high likelihood of ICU admission, mortality, or the need for a massive blood transfusion.
    ShockCalcs +2
Variations and Bedside Calculators
To use digital, interactive tools that automatically calculate the traditional Shock Index, Modified Shock Index (MSI), or Pediatric Shock Index (SIPA), you can use the following clinical calculators:
  • Traditional Shock Index: Available on MDCalc or Omni Calculator.
  • Modified Shock Index (MSI): Replaces systolic blood pressure with Mean Arterial Pressure (MAP) for better sensitivity and specificity in detecting vascular tone . You can use the PulmTools Hemodynamics Tool or ShockCalcs.
  • Pediatric Age-Adjusted (SIPA): A version used to predict mortality in children aged 4-16 with blunt trauma. Available on MDCalc.

MDCalc Shock Index: May be a more sensitive indicator of occult shock, especially in trauma or acute hemorrhage.

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).

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).

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).

Related Calculators

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