RSBI Calculator
Calculate the Rapid Shallow Breathing Index using respiratory rate and tidal volume. RSBI is one piece of ventilator weaning assessment and helps identify a rapid, shallow breathing pattern.
Calculator
Calculate RSBI
Formula: RSBI = RR ÷ VT in liters. Enter VT in mL or L; the calculator converts for you.
RSBI
—
breaths/min/L
Enter RR and VT to calculate RSBI.
Formula
RSBI Formula
RSBI = RR ÷ VT in liters
Example: RR 24, VT 350 mL
350 mL = 0.35 L
RSBI = 24 ÷ 0.35 = 69 breaths/min/L
Example: RR 24, VT 350 mL
350 mL = 0.35 L
RSBI = 24 ÷ 0.35 = 69 breaths/min/L
RT Memory Trick
Rapid + Shallow Makes the Number Higher
RSBI increases when respiratory rate is high and tidal volume is low.
Remember:
Fast breathing on top, small breath size on bottom. A rapid shallow pattern drives RSBI upward.
Fast breathing on top, small breath size on bottom. A rapid shallow pattern drives RSBI upward.
Interpretation
How to Interpret RSBI
| RSBI | General Meaning | Clinical Context |
|---|---|---|
| < 105 | More favorable weaning screen | Often considered more consistent with possible spontaneous breathing trial success. |
| ≥ 105 | Less favorable weaning screen | Suggests rapid shallow breathing pattern and possible weaning difficulty. |
| Any RSBI | Not a standalone decision | Must be interpreted with oxygenation, ventilation, mental status, hemodynamics, secretion burden, and work of breathing. |
Clinical Pearl
RSBI Is a Screen, Not a Guarantee
RSBI can help identify rapid shallow breathing, but extubation readiness depends on much more than one number.
Look at oxygenation
FiO₂, PEEP, SpO₂, PaO₂, and overall stability.
FiO₂, PEEP, SpO₂, PaO₂, and overall stability.
Look at ventilation
PaCO₂, pH, minute ventilation, and respiratory pattern.
PaCO₂, pH, minute ventilation, and respiratory pattern.
Look at airway protection
Mental status, cough, secretions, and aspiration risk.
Mental status, cough, secretions, and aspiration risk.
Look at endurance
Work of breathing, fatigue, hemodynamics, and SBT tolerance.
Work of breathing, fatigue, hemodynamics, and SBT tolerance.
Common Student Mistakes
Avoid These Errors
Using VT in mL without converting
RSBI requires VT in liters. The calculator converts mL automatically.
RSBI requires VT in liters. The calculator converts mL automatically.
Treating RSBI as pass/fail extubation
RSBI is one screening tool, not the whole weaning decision.
RSBI is one screening tool, not the whole weaning decision.
Ignoring work of breathing
A patient can have an acceptable RSBI but still look clinically tired.
A patient can have an acceptable RSBI but still look clinically tired.
Ignoring airway protection
Extubation also depends on cough, secretions, mentation, and airway safety.
Extubation also depends on cough, secretions, mentation, and airway safety.
Continue Learning
Connect RSBI to Ventilator Weaning
Use RSBI alongside oxygenation, ventilation, mechanics, mental status, hemodynamics, and spontaneous breathing trial performance.