ventilation
V̇E = VT × RR
Normal: 5–8 L/min
Normal: 0.4–0.6 L
Normal: 12–20 breaths/min
Minute ventilation is the total volume of gas moved in and out of the lungs per minute. It is the product of tidal volume and respiratory rate. Not all of this volume participates in gas exchange — a portion (dead space ventilation) ventilates airways that do not contact pulmonary capillaries. Minute ventilation is the primary determinant of PaCO₂.
Monitor during mechanical ventilation to ensure adequate CO₂ clearance. A rising minute ventilation requirement (patient breathing fast to maintain normal CO₂) indicates increasing CO₂ production or dead-space ventilation. Used to guide weaning — patients who need VE > 10–12 L/min rarely wean successfully.
Normal adult
→ 7.0 L/min
Normal minute ventilation
Metabolic acidosis compensation
→ 19.6 L/min
Very high VE — indicates severe metabolic acidosis requiring compensatory hyperventilation
PaCO₂ is inversely related to alveolar ventilation: increasing V̇E decreases PaCO₂, decreasing V̇E increases PaCO₂. Target minute ventilation in adults: 6–8 L/min. VE > 12 L/min predicts weaning failure. VE requirements rise with fever, sepsis, and metabolic acidosis (compensatory hyperventilation).