The Cardiovascular
ToolsCalculators

Shock Index

Heart rate divided by systolic blood pressure to flag occult shock.

Shock Index
Heart rate
bpm
Systolic blood pressure
mmHg
Complete the fields above to see the result.

When to use

  • Screening for occult haemorrhagic or septic shock when vital signs individually look reassuring.

Formula

Shock index = heart rate / systolic blood pressure. Normal 0.5-0.7; values >=0.9 suggest circulatory compromise.

Pearls and pitfalls

  • More sensitive than heart rate or blood pressure alone for early shock.
  • A modified shock index (HR / mean arterial pressure) is sometimes used as an alternative.

References

  1. Allgower M, Burri C. Dtsch Med Wochenschr. 1967;92(43):1947-50.