Respiratory

Rapid Shallow Breathing Index (RSBI) Calculator

Respiratory rate divided by tidal volume in liters during spontaneous breathing, a weaning readiness index.

Reviewed by Alex G, BSN, RN, CEN, CCRN, CMC, NREMT-P · From the Reference tab of the app

Turn on JavaScript to use this calculator, or open it in the web app.

Formula

RSBI = respiratory rate (breaths/min) ÷ tidal volume (L)
Tidal volume in L = mL ÷ 1000
Threshold: under 105 predicts success, 105 or more predicts failure

Reference: Under 105 favors weaning success

How it is used

• Yang and Tobin measured rate and tidal volume over 1 minute of breathing off the ventilator; pressure support and PEEP lower the value, so readings taken on support are not comparable (Yang & Tobin 1991).
• As a stand-alone test it is moderately sensitive and poorly specific: pooled sensitivity 83% and specificity 58% for extubation success (Trivedi 2022).
• Using the RSBI to decide on weaning lengthened weaning (3.0 vs 2.0 days) without fewer failures (Tanios 2006); readiness is judged by a spontaneous breathing trial and the whole patient.

Key points

• Do not delay a spontaneous breathing trial on the RSBI alone, and do not extubate on a good RSBI without checking airway protection, secretions and mental status.

Same formula as the app. Open it in the web app.

Related one-pagers

• Ventilator Modes and SettingsRSBI = RR ÷ Vt in liters; under 105 favors success. Still tested, though AARC 2024 says it isn't needed before an SBT.
• Ventilator Liberation and TracheostomyRSBI = RR ÷ Vt in liters; under 105 favors success (sensitivity 0.97, specificity 0.64; Yang and Tobin 1991). Not needed before an SBT (AARC 2024).
• Airway and RSIRapid shallow breathing index · f/VT under 105 (Yang and Tobin 1991)
• ABG Interpretation in 6 Steps

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• Minute Ventilation
• O₂ Extraction Ratio

For education and exam preparation only. Follow your institution’s protocols. For education and exam preparation only. Verify results independently and follow your institution’s protocols. Not a substitute for clinical judgment.