Traditional Shock Index Calculator (HR/SBP)

Traditional Shock Index is heart rate in beats per minute divided by systolic blood pressure in mmHg. This page keeps full calculation precision and displays the resulting ratio to two decimals. It reports traditional SI only.

Sources: [1]

The original traditional ratio is heart rate divided by systolic blood pressure. Modified SI instead uses mean arterial pressure, but it is a separate construct and is not calculated here.

Sources: [1, 9]

The quotient is meaningful only when both readings describe the same assessment context. Do not combine a heart rate and pressure from different times, devices, clinical states, or units.

Sources: [1, 2]

Approximately 0.5–0.7 is a historical adult literature context, while 0.9 or 1.0 were studied in selected adult emergency, trauma, infection, and outcome cohorts. They are not universal normal/abnormal boundaries or diagnostic cutoffs.

Sources: [1, 2, 3]

Study populations, outcomes, medications, baseline blood pressure, and measurement conditions differ. A numerical ratio alone cannot supply a universal diagnosis, severity class, or treatment threshold.

Sources: [4, 5, 6]

No. In sepsis research, SI ≥1 was more specific than sensitive in some cohorts; a value below 1 cannot exclude clinically important risk. A single ratio must be interpreted with the full assessment.

Sources: [5]

No. A higher ratio can be a supportive observation, but it does not determine shock type, blood loss, sepsis, postpartum haemorrhage, severity, or treatment by itself.

Sources: [4, 5, 7]

Yes. Medicines can blunt heart-rate response, and age, baseline hypertension, comorbidity, and blood-pressure treatment can change the relationship between the ratio and outcomes. No replacement cutoff is supplied.

Sources: [6]

An irregular or paced heart rate may not represent the expected physiologic response. This page supplies no dedicated adjustment or cutoff for those contexts.

Sources: [6]

Pregnancy changes haemodynamics. In the WHO/FIGO/ICM 2025 postpartum-haemorrhage standard, SI >1 is only one abnormal sign within a criterion paired with objective blood-loss findings; it does not alone diagnose postpartum haemorrhage or decide treatment.

Sources: [7, 11]

No. Adult study context does not transfer to children. SIPA is a separate pediatric age-adjusted construct and is not calculated here.

Sources: [8]

Traditional SI is heart rate divided by systolic blood pressure. Modified SI uses mean arterial pressure, Age SI multiplies traditional SI by age, and SIPA is pediatric age-adjusted. They are distinct measures; this calculator reports traditional SI only.

Sources: [8, 9, 10]

Comparable paired measurements over time can add context to the clinical assessment. This calculator reports one submitted ratio and does not interpret a trend or create a monitoring plan.

Sources: [2, 5]

Those values were used as strata in particular trauma or obstetric observational cohorts. They are not shown as a universal threshold ladder on this page and must not be transferred to other populations or outcomes.

Sources: [9, 11]

No. It does not choose fluids, blood products, medication, surgery, triage level, or discharge. Use the relevant clinical pathway and full patient assessment.

Sources: [4, 7]