Adjustment of Stores of Carbon Dioxide During Voluntary Hyperventilation

¹ Fellow in Medicine
² Section of Physiology

Adjustments of body stores of carbon dioxide were studied during voluntary hyperventilation for 1 hour at a constant rate by trained subjects. Healthy men eliminated from their stores an average of 161 ml. of CO₂ per mm. of mercury decrease in mixed venous tension, corresponding to a partial dissociation slope for body stores of 2.05 ml./mm./kg. Increasing the respiratory minute volume by about 50 per cent for 1 hour produced elimination of 1.5 to 2.5 liters of CO₂ in excess of the metabolic production, which is a small part of the 100 or more liters estimated to be present in the body. The elimination of stores during a period of 1 hour did not appear to proceed at a single exponential rate, which is consistent with the presence of multiple storage sites or pools that exchange at different rates. In unsteady states, such as may exist during development of or recovery from CO₂ retention and narcosis, the arterial CO₂ tension may not adequately reflect the tissue levels.