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Shock Index

Purpose: To use the shock index to identify patients who may need more intensive care even though the vital signs may appear stable or not markedly abnormal.

Description

The Shock Index (SI) is the ratio of the heart rate to systolic blood pressure. The index is a sensitive indicator of left ventricular dysfunction and can become elevated following a reduction in left ventricular stroke work. It can be used in the Emergency Department and Intensive Care Unit to identify patients needing a higher level of care despite vital signs that may not appear strikingly abnormal.


shock index =

= (heart rate in beats per minute) / (systolic blood pressure in mm Hg)

 

Interpretation:

• normal: 0.5 to 0.7

• An elevated shock index (> 0.9) was found helpful by Rady et al (1994) to identify patients in the Emergency Department requiring admission and/or intensive care despite apparently stable vital signs.

• Persistent elevation of the SI has been associated with poor outcome in critically ill patients.

• An elevated SI may be an early warning sign for impending shock even when vital signs appear normal.


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Specialty

Objective

ICD-10