[The effect of prolonged inspiration time and PEEP on compliance and gas exchange in ventilated patients (author's transl)].

The effect of prolonged inspiration time and PEEP on compliance, haemodynamics and gas exchange was studied on 15 patients, who were ventilated because of respiratory distress syndrome. The patients were ventilated by the Servoventilator 900 BR connected with a calculation unit. The inspiration time varied from 35 to 70%, the PEEP from 0 to 20 cm H2O. All patients were ventilated with constant tidal volumes (10-15 ml/kg b.w.). The compliance rose from 48 ml/H2O (ZEEP) to 61,5 ml/cm H2O (PEEP + 8 ml H2O). A further increase of PEEP caused a decrease of compliance to 48 ml/cm H2O (PEEP + 20 cm H2O). A prolongation of inspiration time of up to 53% showed an augmentation of compliance from 48 ml/cm H2O to 53 ml/cm H2O. Both modes of assisted ventilation caused an improvement of alveolar ventilation. The simultaneous consideration of various parameters of gas exchange, compliance and haemodynamics guaranteed the optimal mode of ventilation and minimal side effects.