Hemodynamics

Shock Index Calculator

Heart rate over systolic pressure; a rising value can flag shock before blood pressure falls.

Reviewed by Alex G, BSN, RN, CEN, CCRN, CMC, NREMT-P · From the Reference tab of the app

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Formula

HR / SBP

How it is used

• Shock index = HR ÷ SBP. Above 1 marks instability: it is one trigger for massive transfusion in trauma, and it flags instability in GI bleeding and PE.
• A shock index of 0.9 or more before intubation is a risk factor for post-intubation hypotension; have fluids and a vasopressor ready.
• Heart rate rises and pulse pressure narrows before systolic pressure falls, so the index can climb while the blood pressure still looks normal.
• In pregnancy the normal obstetric shock index is higher, about 0.7–0.9 (Le Bas 2014).

Same formula as the app. Open it in the web app.

Related one-pagers

• Shock Types at a GlanceActivate massive transfusion early: ABC score ≥2 (penetrating injury, SBP ≤90, HR ≥120, positive FAST) or shock index >1.
• Pulmonary EmbolismTrend HR, BP, shock index (HR ÷ SBP >1), lactate, urine output, O₂ need; escalate early
• Trauma: Primary and Secondary SurveyHypotension first appears in class III. Age, beta-blockers and pacemakers blunt tachycardia, so add shock index (HR ÷ SBP; worry near 1), lactate and base deficit.
• Airway and RSIHypotension, shock index ≥ 0.9 · Lost sympathetic tone; less venous return · Vasopressor running; push-dose drawn; lower dose

Related calculators

• Cardiac Index (CI)
• Cardiac Output (Fick Principle)
• Cerebral Perfusion Pressure (CPP)
• Mean Arterial Pressure (MAP)
• Oxygen Delivery (DO₂)
• Pulmonary Vascular Resistance (PVR)
• QTc (Bazett)
• Stroke Volume (SV)

For education and exam preparation only. Follow your institution’s protocols. For education and exam preparation only. Verify results independently and follow your local protocols and medical direction. Not a substitute for clinical judgment.