Shock Index

I attended a CME recently where I heard a term I had never heard before.


The shock index (SI) is heart rate divided by systolic blood pressure. The normal range is 0.5 to 0.7.

The shock index has been shown to be a predictor of increased likelihood of shock, hospital admission, and mortality.

Someone is likely at risk for shock if their SI is over 0.8.

If my systolic blood pressure is 120 and my heart rate is 60, my SI is 0.5.
If my systolic is 120 and my heart rate is 120, my SI is 1.0 –in the danger zone.

While most paramedics can just look at a patient and tell you whether or not they are in shock, the shock index can help raise concern for someone in who is at risk for decompensation.

Here’s some studies on the shock index.

A prehospital shock index for trauma correlates with measures of hospital resource use and mortality

Shock index in patients with traumatic solid organ injury as a predictor of massive blood transfusion protocol activation

Here’s a great article on shock.

Approach to Shock


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