Ventilation volume as a stimulus to spontaneous ventilation after prolonged artificial ventilation

The observations reported in this paper are intended to determine whether the ventilation volume imposed during artificial ventilation has an effect on subsequent spontaneous ventilation. It reports investigations on paretic patients in which the tidal volume imposed during artificial ventilation was varied, but the end-tidal PCO2 and the ventilatory frequency were kept constant. A variable volume of external dead space was introduced during artificial ventilation. Periods of spontaneous ventilation were subsequently permitted, and during these periods the external dead space was small. The effect has been observed of these changes in imposed tidal volume on the ventilation subsequently chosen by the patient when breathing spontaneously, and on his response to C02 added to the inspired air.