What is the RSBI and what value indicates readiness for weaning?

• A. RSBI equals respiratory rate divided by tidal volume in liters
• B. RSBI equals tidal volume divided by respiratory rate
• C. RSBI equals respiratory rate multiplied by tidal volume in liters
• D. RSBI equals respiratory rate / tidal volume (L); <105 suggests readiness for weaning

Answer: (D)

The RSBI is the breathing pattern index that compares how fast you breathe to how much air you move with each breath. It’s calculated as respiratory rate divided by tidal volume in liters: RSBI = RR / VT (L). A lower RSBI means you’re breathing more efficiently (not too fast and not too shallow), which suggests you may tolerate weaning from mechanical ventilation. The commonly used threshold is less than 105 breaths per minute per liter; values below this indicate readiness for weaning, while higher values point to a higher risk of weaning failure. For example, RR 18 with VT 0.5 L gives 36, well under 105.