Patients who cannot breathe on their own tend to breathe fast and shallow. Yang and Tobin showed in 1991 that an RSBI below 105 predicted successful extubation. It is one part of a broader weaning assessment.
How to use the RSBI Calculator
- Respiratory rate
- Tidal volume
Results update as you type, and every field accepts the units shown in its menu.
How it works
Measure respiratory rate and average tidal volume over about one minute of spontaneous breathing.
Inputs explained
| Field | What to enter |
|---|---|
| Respiratory rate | In breaths/min |
| Tidal volume | Units: mL, L, fl oz |
Example values
How the main result changes when Respiratory rate changes and everything else stays at the example values above:
| Respiratory rate (breaths/min) | RSBI (breaths/min/L) |
|---|---|
| 11 | 28 |
| 16.5 | 41 |
| 22 | 55 |
| 27.5 | 69 |
| 33 | 83 |
| 44 | 110 |
Health note: this calculator is for education and screening only and is not a diagnosis or treatment advice. Discuss your results with a qualified clinician.
Formula
RSBI = respiratory rate (breaths/min) ÷ tidal volume (L)
< 105: weaning likely to succeed · ≥ 105: likely to fail
Worked example
Inputs — Respiratory rate: 22 breaths/min; Tidal volume: 400 mL.
Results — RSBI = 55 breaths/min/L.
Key terms
- RSBI
- Rapid shallow breathing index (f/VT).
Frequently asked questions
What is a good RSBI?
Below 105; many units also look for values below 80.
Is RSBI enough to decide extubation?
No – mental status, secretions, cough and oxygenation also matter.
When should RSBI be measured?
During a spontaneous breathing trial on minimal support.