[Comparative studies on the efficiency of ventilation by engström-respirator ER 300 (author's transl)].

The efficiency of ventilation provided by the Engstrom-Respirator ER 300 was examined in 35 patients under general anaesthesia and relaxation during normoventilation and hyperventilation of 15% and 30%. For criteria the acid-base-status of arterial blood was used. There was a tendency to acidosis in all kinds of ventilation, probably as a consequence of surgical effects. During normoventilation the acid-base-status showed changes of low hyperventilation which are desired for security. During hyperventilation of 15% and 30%, arterial pCO2 was reduced to 30 and 27 Torr. Both situations showed no advantage over normoventilation. Using the Engstron-Respirator, normoventilation should be preferred during general anesthesia. Higher degrees of hyperventilation should be avoided because of their effects in lowering cerebral blood flow.