How to Calculate Breathing Rate
What is Breathing Rate?
Respiratory rate (RR) is breaths per minute; tidal volume (TV) is volume per breath. Minute ventilation = RR × TV. Normal resting: 12–20 breaths/min, 400–600ml tidal volume. Increased RR is one of the earliest signs of physiological deterioration.
Step-by-Step Guide
- 1Minute ventilation (MV) = RR × Tidal volume
- 2Alveolar ventilation = (TV − dead space) × RR
- 3Anatomical dead space ≈ 1ml per lb body weight (~150ml for average adult)
- 4Dead space does not participate in gas exchange
Worked Examples
Input
RR=15 breaths/min · TV=500mL
Result
MV = 7.5 L/min · Alveolar ventilation ≈ 5.25 L/min
(500-150)×15=5,250ml alveolar ventilation
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