RSBI Assessment

The RSBI is calculated immediately after switching to spontaneous breathing (e.g., T-piece) and helps predict extubation success.

Respiratory rate (breaths/min)

Tidal volume (mL)

Use average spontaneous tidal volume over 1 minute.

Results

RSBI

43 breaths/min/L

RR ÷ (VT in liters)

Tidal volume (L)

0.42

Converted from entered mL

Interpretation:

Very low RSBI—consider possible over-assist; evaluate effort.

RSBI <105 has high sensitivity for successful extubation but should be combined with comprehensive weaning criteria.

How to Use This Calculator

Evaluate RSBI after 1 minute on T-piece or low-level pressure support. Ensure patient is awake, hemodynamically stable. Use ventilator spirometry or handheld respirometer to capture tidal volume; count breaths manually or via monitor. Combine RSBI with gas exchange, strength, airway protection, and mental status before extubation decisions.

Formula

Rapid Shallow Breathing Index (RSBI) = Respiratory rate (breaths/min) ÷ Tidal volume (liters).

Reference: Yang KL, Tobin MJ. N Engl J Med. 1991.

Frequently Asked Questions

Use the average spontaneous tidal volume recorded during a weaning trial. Avoid values during coughing or speaking. Yes—ensure the patient is awake enough to breathe spontaneously. Excess sedation can mask respiratory distress. Yes, RSBI applies to tracheostomy weaning as well; interpret alongside secretion management and airway protection. Very low VT inflates RSBI, signaling high risk of failure. Optimize lung mechanics (bronchodilators, recruitment) before retrying. RSBI is validated in adults. Pediatric weaning uses different indices tailored to age and size.