Shock index

Shock index (SI)[1]


  • Used when HR and SBP do not predict severity of hypovolemia in early stages
  • May be used as secondary triage tool in mass casualty incidents[2]
  • 0.5-0.7 is normal
  • >0.70-0.75 for occult shock or requirement of life-saving intervention

Simple Shock Index (sSI) was recently proposed. Subtracting SBP from HR is a good SI substitute. Working with integers is easier than dividing them, improving value availability.[3]

See Also


  1. Levitan, Richard M. Fundamentals of Airway Management. 3rd ed. Irving, TX: Emergency Medicine Residents' Association, 2015.
  2. Vassallo J et al. Usefulness of the Shock Index as a secondary triage tool. J R Army Med Corps. 2015 Mar;161(1):53-7.
  3. Kamikawa Y, Hayashi H. Equivalency between the shock index and subtracting the systolic blood pressure from the heart rate: an observational cohort study. BMC Emergency Medicine. 2020 Dec;20:1-8.