Calculates shock index from heart rate and systolic blood pressure in an obstetric patient. This guide explains the formula, use and limitations.
Overview
Calculates shock index from heart rate and systolic blood pressure in an obstetric patient.
Clinical Significance
A rising index may support early recognition of haemodynamic compromise, but thresholds vary and urgent clinical assessment takes priority.
When to Use
- Use when the calculation is relevant to the clinical question.
- Confirm that the population and units match the validated method.
- Use current and reliable measurements.
How It Is Calculated
- Shock index = heart rate ÷ systolic blood pressure.
Interpretation
- A rising index may support early recognition of haemodynamic compromise, but thresholds vary and urgent clinical assessment takes priority.
- Interpret alongside the full clinical picture and current guidance.
Worked Example
Enter the required measurements in the stated units. MedicalC then applies: Shock index = heart rate ÷ systolic blood pressure.
Patient Considerations
- Consider age, body size, pregnancy, organ function and treatment effects where relevant.
- Repeat the calculation when inputs or clinical status materially change.
Limitations
- Accuracy depends on the quality and units of the entered data.
- The equation may not be validated in every patient population.
- This tool does not replace clinical judgement or specialist advice.
Clinical Pearls
- Check units before calculating.
- Document the source and timing of each input.
- Use trends where clinically appropriate.
Common Mistakes
- Mixing SI and conventional units.
- Using non-contemporaneous measurements.
- Treating the output as a diagnosis or prescription.
Evidence Base
The implemented calculation follows the published or guideline-based relationship: Shock index = heart rate ÷ systolic blood pressure.
Frequently Asked Questions
What does the Obstetric Shock Index calculator do?
Calculates shock index from heart rate and systolic blood pressure in an obstetric patient.
Can the result be used alone?
No. Use it as decision support with clinical assessment and current guidance.
Why might the result be misleading?
Incorrect units, poor measurement quality or use outside the validated population can produce misleading results.
Should it be recalculated?
Recalculate when relevant measurements or the clinical condition change.
References
- Le Bas A, et al. Use of the shock index to identify haemodynamic compromise in postpartum haemorrhage. Int J Gynaecol Obstet. 2014. — Primary publication, guideline or established source supporting the calculation.
Reviewed by: MedicalC Clinical Editorial Team
Last reviewed: July 2026