Which term best matches the definition 'the ratio of heart rate to systolic blood pressure'?

• A. Homeostatic Failure
• B. Shock Index
• C. Critical Perfusion
• D. Cellular Death

Answer: (B)

The ratio of heart rate to systolic blood pressure is called the Shock Index. It’s calculated by dividing heart rate by systolic BP, giving a quick read on how well perfusion is being maintained. As someone moves into shock, heart rate tends to rise to keep cardiac output up, while systolic blood pressure tends to fall, so this ratio increases. Normal values are roughly in the 0.5–0.7 range; higher values signal hemodynamic instability. For example, a heart rate of 110 with a systolic BP of 100 yields an SI of about 1.1, suggesting significant impairment, while a heart rate of 70 with a systolic BP of 120 gives about 0.58, indicating stable perfusion. This index is especially handy in emergency and trauma settings for rapid assessment and prognosis. The other terms don’t describe this specific ratio and are not used to quantify the immediate balance between heart rate and blood pressure.