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Overview :
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.
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