RSBI Calculator

Calculate the Rapid Shallow Breathing Index (RSBI) to assess weaning readiness from mechanical ventilation. This tool helps clinicians evaluate respiratory function in ventilated patients.

How to Use This Calculator

Measure the patient's respiratory rate during a spontaneous breathing trial
Measure the average tidal volume during the same period
Select the appropriate patient category for context-specific interpretation
Click Calculate to determine the RSBI and interpret the results

Formula Used

RSBI = Respiratory Rate (breaths/min) ÷ Tidal Volume (L)

Where:

RSBI = Rapid Shallow Breathing Index
Respiratory Rate = Number of breaths per minute
Tidal Volume = Volume of air inhaled or exhaled in one breath (in liters)

Interpretation:

RSBI < 105 breaths/min/L: Likely to succeed in weaning from mechanical ventilation
RSBI ≥ 105 breaths/min/L: Likely to fail weaning from mechanical ventilation

Example Calculation

Real-World Scenario:

A 65-year-old patient on mechanical ventilation is being evaluated for extubation. During a spontaneous breathing trial, the patient's respiratory rate is 24 breaths/min and tidal volume is 350 mL.

Given:

Respiratory Rate = 24 breaths/min
Tidal Volume = 350 mL = 0.35 L

Calculation:

RSBI = 24 ÷ 0.35 = 68.6 breaths/min/L

Result: The RSBI is 68.6 breaths/min/L, which is below the threshold of 105. This patient is likely to succeed in weaning from mechanical ventilation.

Why This Calculation Matters

Clinical Applications

Predicting weaning success from mechanical ventilation
Reducing duration of mechanical ventilation
Identifying patients at risk of extubation failure
Optimizing ventilator management strategies

Key Benefits

Simple, non-invasive bedside assessment
Helps reduce complications of prolonged ventilation
Supports evidence-based clinical decision-making
Can be performed without specialized equipment

Common Mistakes & Tips

RSBI should be measured during a spontaneous breathing trial with minimal or no pressure support. Measuring with significant pressure support can artificially lower the RSBI and give a false sense of security about weaning readiness.

RSBI should be measured over a consistent time period, typically 1 minute. Using different time intervals for respiratory rate and tidal volume measurements can lead to inaccurate results. Both parameters should be measured simultaneously.

Frequently Asked Questions

The Rapid Shallow Breathing Index was developed by Yang and Tobin in 1991. Their study showed that RSBI was a better predictor of weaning success than traditional parameters like maximal inspiratory pressure or minute ventilation.

While RSBI is widely used, its predictive value may vary in different patient populations. It may be less accurate in patients with neuromuscular disease, chronic respiratory failure, or those who have been on prolonged mechanical ventilation. Clinical judgment should always accompany RSBI measurements.

Studies have shown that RSBI is one of the most accurate single predictors of weaning success. However, using RSBI in combination with other parameters (such as oxygenation, hemodynamic stability, and mental status) provides the most comprehensive assessment of weaning readiness.

References & Disclaimer

Medical Disclaimer

This calculator is for educational purposes only and should not replace professional medical judgment. RSBI is just one component of a comprehensive weaning assessment. Always consult with qualified healthcare professionals for clinical decision-making.

References

Yang KL, Tobin MJ. A prospective study of indexes predicting the outcome of trials of weaning from mechanical ventilation. - N Engl J Med. 1991;324(21):1445-1450.
Weaning from Mechanical Ventilation - StatPearls - Comprehensive review of weaning parameters and protocols
Epstein SK. Weaning from Mechanical Ventilation. - JAMA. 2017;318(13):1235-1236.

Accuracy Notice

RSBI has a sensitivity of approximately 0.97 and specificity of 0.64 for predicting weaning failure. However, its predictive value may vary based on patient characteristics and measurement conditions. This calculator provides a mathematical calculation only and does not substitute for clinical assessment.

About the Author

Kumaravel Madhavan

Web developer and data researcher creating accurate, easy-to-use calculators across health, finance, education, and construction and more. Works with subject-matter experts to ensure formulas meet trusted standards like WHO, NIH, and ISO.

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