shock_index: Shock Index (SI)

In cliot: Clinical Indices and Outcomes Tools

Shock Index (SI)

Description

Calculates the Shock Index (SI), a bedside assessment tool used to evaluate the hemodynamic stability of patients, particularly in trauma or acute critical illness. It is defined as the ratio of heart rate to systolic blood pressure.

Usage

shock_index(heart_rate, systolic_bp)

Arguments

heart_rate	Numeric. Heart rate in beats per minute (bpm).
systolic_bp	Numeric. Systolic blood pressure in mmHg.

Details

The formula is:

SI = \frac{HR}{SBP}

Normal values typically range from 0.5 to 0.7. Values > 0.9 are associated with increased risk of mortality, need for massive transfusion, and occult shock even when blood pressure appears normal.

Value

A list containing:

Shock_Index	The calculated index value.
Interpretation	Clinical context regarding the score (Normal, Elevated, High).

References

Allgöwer M, Burri C. Shock index. Dtsch Med Wochenschr. 1967;43:1-10. Rady MY, Smithline HA, Blake H, Nowak R, Rivers E. A comparison of the shock index and ordinary vital signs to identify trauma patients with extensive major injury. Ann Emerg Med. 1994;24(4):685-690.

Examples

# Example 1: Normal
# HR 70, SBP 120
# SI = 0.58
shock_index(70, 120)

# Example 2: High Risk (Occult Shock)
# HR 110, SBP 100
# SI = 1.1
shock_index(110, 100)

cliot documentation built on Dec. 1, 2025, 1:06 a.m.