Shock index is the ratio of heart rate to systolic blood pressure. In horses it should be interpreted as an adjunct to examination, perfusion assessment and serial monitoring rather than as a standalone diagnosis.
Formula
Heart rate ÷ systolic blood pressure
What is the equine shock index?
The shock index combines two routinely available cardiovascular measurements into a dimensionless ratio.
A rising value may reflect increasing cardiovascular compromise, but the result is influenced by pain, excitement, medication, arrhythmia, measurement technique and underlying disease.
How should it be used?
Use the result alongside mucous membrane colour, capillary refill time, pulse quality, mentation, temperature, lactate and repeated haemodynamic measurements.
Serial values are often more informative than a single isolated measurement.
Limitations
This calculator does not establish a diagnosis of shock and should not delay urgent treatment.
Blood pressure methodology and patient movement can materially affect the result.
References
- Use current equine emergency and critical-care guidance and patient-specific clinical judgement.