Blood pressure and heart rate, when used individually, fail to accurately predict the severity of hypovolemia and shock in major trauma.
It has been studied in patients either at risk of or experiencing shock from a variety of causes: trauma, hemorrhage, myocardial infarction, pulmonary embolism, sepsis, and ruptured ectopic pregnancy.
Calculate SI: HR divided by SBP
| Level of Shock | Shock Index |
| No Shock | <0.6 |
| Mild Shock | ≥0.6 to <1.0 |
| Moderate Shock | ≥1.0 to <1.4 |
| Severe Shock | ≥1.4 |
