0.0396
1.98
L/min
1,980
mL/min
118.8
L/h
2,851.2
L/day
0.0396
1.98
L/min
1,980
mL/min
118.8
L/h
2,851.2
L/day
The Carbon Dioxide Production calculator determines VCO₂, the rate at which an organism produces carbon dioxide through metabolic processes. CO₂ is a primary end product of cellular respiration, generated when carbon-containing fuels are oxidized in the citric acid cycle. Measuring VCO₂ is essential for calculating the respiratory quotient and total energy expenditure via indirect calorimetry.
This tool computes VCO₂ from the difference between expired and inspired CO₂ concentrations multiplied by the ventilation rate. Combined with VO₂ measurements, VCO₂ enables determination of substrate utilization patterns and metabolic rate in both clinical and research settings.
CO₂ production rate is calculated from ventilation and CO₂ fraction differences:
VCO₂ = Flow Rate × (FeCO₂ - FiCO₂)
FeCO₂ is the CO₂ fraction in expired air (typically 3.5-5% at rest) and FiCO₂ is the CO₂ fraction in inspired air (approximately 0.04% or 400 ppm in ambient air). The result is given in both liters and milliliters per minute.
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Results
At rest with 6 L/min ventilation, VCO₂ is about 238 mL/min. Combined with a resting VO₂ of approximately 300 mL/min, this gives an RQ of about 0.8.
Inputs
Results
During intense exercise, both ventilation and expired CO₂ fraction increase. VCO₂ reaches nearly 4 L/min, reflecting dramatically increased metabolic activity.
VCO₂ is used in indirect calorimetry to determine energy expenditure and substrate utilization in critically ill patients. It helps guide nutritional support, preventing both overfeeding (which increases CO₂ and ventilatory demand) and underfeeding. In mechanically ventilated patients, VCO₂ monitoring helps optimize ventilator settings.
Yes, temporarily during intense exercise above the anaerobic threshold, VCO₂ exceeds VO₂ because excess CO₂ is produced from buffering of lactic acid by bicarbonate. This gives an RQ greater than 1.0. Similarly, overfeeding with carbohydrates promotes lipogenesis, which also produces excess CO₂.
Ambient atmospheric CO₂ is approximately 0.04% (400 ppm), though this varies by location and indoor conditions. In well-ventilated spaces, FiCO₂ ranges from 0.03-0.05%. In poorly ventilated rooms, it can reach 0.1% or higher. The inspired fraction is subtracted to measure only metabolically produced CO₂.
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