Abstract
When the controlled ventilation was performed with the aid of the mechanical ventilator connected to the anesthesia machine under general anesthesia according to the calculated respiratory condition to keep the arterial Pco2 to the predicted value, arterial Pco2 sometimes showed lower value than expected.
We examined this discrepancy and the results were as followes.
1) Resperatory volume indicated on the ventilator was inaccurate. Mostely, this volume was smaller than the actual volume which came out from the ventilator.
2) Changes in the fresh anesthetic gaseous flow into the circle of the anesthesia machine also altered the resperatory volume.
3) Therefore, respiratory condition has to be set up not on the ventilator but on the patient himself.
