Last updated October 9, 2026 · Report an error
The Shock Index (SI) = Heart Rate / Systolic Blood Pressure, originally described by Allgower & Burri (1967). The commonly cited normal range is roughly 0.5-0.7; higher values are used in the literature as a marker that may suggest hemodynamic compromise. This tool reports the reference ratio only — it does not diagnose shock or any condition. For general reference and educational purposes only. Consult a doctor for actual clinical assessment.
How it works
Enter heart rate (bpm) and systolic blood pressure (mmHg). The tool divides the two.
- Enter heart rate (bpm).
- Enter systolic blood pressure (mmHg).
- Click Calculate to see your results.
Examples
Heart rate 80 bpm, systolic BP 120 mmHg
SI = 80/120 = 0.667 — within the commonly cited normal range.
Who should use it
- Rapid bedside calculation during initial patient assessment.
- Emergency medicine and nursing education.
Industry applications
- Emergency medicine reference
- Nursing and paramedic education
Advantages
- Simple, transparent division using two commonly available vital signs.
- Widely referenced in emergency medicine literature as a rapid bedside ratio.
Limitations
- A screening ratio, not a diagnosis of any specific condition.
- Affected by many factors (e.g. baseline fitness, medications) beyond acute hemodynamic status.
Common mistakes to avoid
- Treating an elevated shock index as a confirmed diagnosis of shock rather than a screening signal.
- Using diastolic blood pressure instead of systolic in the formula.
Best practices
- Track shock index alongside other vital signs and clinical context rather than as a standalone number.
Tips
- Interpret shock index alongside the full clinical picture and vital sign trend, not as a standalone value.
Frequently asked questions
Yes, with no signup and no limit on how many calculations you run.
Values above the commonly cited normal range (roughly 0.5-0.7) are referenced in the literature as a marker that may suggest hemodynamic compromise, but this tool reports the ratio only — it does not diagnose shock or any other condition.
Allgower M & Burri C, "Schockindex", Deutsche Medizinische Wochenschrift, 1967.
No — this is a reference ratio, not a diagnosis. Consult a doctor for actual clinical assessment.