What is a normal shock index?

A normal shock index is between 0.5 and 0.7 in healthy adults. Values below 0.6 are generally considered normal hemodynamics. Values above 1.0 suggest significant hemodynamic compromise.

What does a shock index above 1.0 mean?

A shock index above 1.0 indicates significant hemodynamic instability and is associated with increased mortality in trauma and sepsis. It suggests the heart rate is exceeding the systolic blood pressure, a sign of compensated or decompensated shock.

What is the modified shock index (MSI)?

The modified shock index divides heart rate by mean arterial pressure (MAP) instead of systolic BP. Some studies suggest MSI is a more sensitive predictor of outcome in certain patient populations, particularly in obstetric emergencies.

Can shock index be used for children?

Standard adult shock index thresholds do not apply to pediatric patients due to different normal heart rate and blood pressure ranges by age. Age-adjusted pediatric shock index (SIPA) tools should be used for children.

Is shock index a definitive diagnostic tool?

No. The shock index is a screening and triage tool, not a definitive diagnosis. It should be interpreted alongside clinical examination, lab values, and other vital signs. A normal SI does not rule out serious illness.

Shock Index Calculator

Enter heart rate and systolic blood pressure to calculate shock index and assess hemodynamic stability.

Vital Sign Inputs

Heart Rate (bpm)

bpm

Systolic Blood Pressure (mmHg)

mmHg

Diastolic Blood Pressure (mmHg, optional — for MSI)

mmHg

Formula Reference

SI = Heart Rate (bpm) ÷ Systolic BP (mmHg)

MSI = Heart Rate ÷ Mean Arterial Pressure

MAP = (SBP + 2 × DBP) ÷ 3

Thresholds: <0.6 Normal • 0.6–0.9 Mildly elevated • 0.9–1.3 Elevated • >1.3 Severely elevated. For clinical use only; not a substitute for professional medical judgment.

Summary

Enter heart rate and systolic blood pressure to calculate shock index and assess hemodynamic stability.

How it works

Enter the patient's heart rate in beats per minute (bpm).
Enter the systolic blood pressure in mmHg.
The shock index is calculated as heart rate divided by systolic blood pressure.
Results are categorized: normal (<0.6), mildly elevated (0.6–0.9), elevated (0.9–1.3), severely elevated (>1.3).
The modified shock index (heart rate divided by mean arterial pressure) is also shown for reference.

Use cases

Rapid triage of trauma patients in the emergency department.
Monitoring hemodynamic status in patients with suspected sepsis.
Early detection of occult shock in patients with normal blood pressure.
Assessing response to fluid resuscitation over serial measurements.
Perioperative monitoring of patients at risk for hemodynamic instability.
Evaluating severity of hemorrhage in obstetric emergencies.

Frequently Asked Questions

Last updated: 2026-09-19 · Reviewed by Nham Vu

Shock Index Calculator

Vital Sign Inputs

Shock Index (SI)

Modified Shock Index (MSI)

Formula Reference

Summary

How it works

Use cases

Frequently Asked Questions

Shock Index Calculator

Use the Shock Index Calculator

Vital Sign Inputs

Shock Index (SI)

Modified Shock Index (MSI)

Formula Reference

Summary

How it works

Use cases

Frequently Asked Questions