Is it better to increase the tidal volume or respiratory rate?
Hyperventilation results from increases in both tidal volume and respiratory rate. The best combination depends on the patient’s pulmonary physiology and the presence of restrictive lung disease, chronic obstructive pulmonary disease, etc. The only caveat is that the tidal volume must be greater than 500 ml when the rebreathing loop is fully extended. If there is difficulty in achieving hyperventilation, check the inspiratory flow limit and inspiratory pressure limit settings on the ventilator. Tidal volumes significantly greater than 760 mls tend to slow the rate of rise in end tidal CO2, because part of the exhaled CO2 moves out of the rebreathing loop and into the breathing circuit. If the end tidal CO2 does not rise rapidly, consider reducing the tidal volume and increasing the respiratory rate.
