[Regulation of respiration in assisted ventilation]

Based on knowledge of the control of external respiration, the physiological reactions are discussed which should be evoked proprioceptively and chemoreceptively by an assisting respirator's disturbances of spontaneous breathing movements. The following possible states are discriminated: 1. "no adaption": the respiratory motor system does not remain passive during the machine's stroke; 2. "passive adaption": the respiratory motor system remains passive during the respirator's stroke; to changes of the blood gas-status, only the breathing frequency responds, but in just the same manner as during spontaneous ventilation; 3. "active adaption": the ventilatory motor apparatus remains passive during the respirator's operation; changes of the blood gases are responded to by the breathing frequency only, but in a manner different to spontaneous breathing and which compensates for the invariability of the fixed stroke-volume. - Related to these 3 states, consequences concerning the efficiency of chemical respiratory control can be derived which should reveal themselves during experimental manipulation of the blood gas partial pressures. Accordingly, the CO2-response curves of minute ventilation, breathing frequency and tidal-volume generated in 9 healthy, awake and cooperative subjects during spontaneous breathing and assisted (stroke-volume controlled) respiration with gas mixtures of 0, 3 and 6% CO2 were investigated and compared. (In each subject assisted ventilation with 2 or 3 different stroke-volumes was performed. The smallest stroke-volume equalled the medium tidal-volume of spontaneous ventilation. Every stroke-volume produced its particular CO2-response curve). Hence it follows that with assisted ventilation, using a stroke-volume larger than the spontaneous tidal-volume, the subjects maintain a state between "passive" and "active adaption".(ABSTRACT TRUNCATED AT 250 WORDS)