A COMPUTER-PROGRAM FOR AUTOMATIC-MEASUREMENT OF RESPIRATORY MECHANICSIN ARTIFICIALLY VENTILATED PATIENTS

A program for automatic and periodic determination of respiratory mech anics in artificially ventilated patients is described. Airway pressur e and flow signals are obtained from the ventilator in the controlled ventilation mode with constant flow inflation and end-inspiratory paus e. Periodically, the program records both signals for a given time and it delimits a ventilatory cycle and its components out of this record . Then, four mechanical parameters of the respiratory system are calcu lated: (1) R(init), the resistance obtained with the end-inflation occ lusion technique; (2) E(rs), the elastance (inspiratory) calculated fr om the slope of the airway pressure profile during inflation; (3) tau, the expiratory time constant; (4) PEEP, the global positive end expir atory pressure. All parameter measurements have been evaluated in expe rimental conditions, and are in good agreement with reference values. The complete software includes the display of the signals and of the t rends together with automatic disk file backups. An additional program allows one to display the trends again and to create table text files containing all the recorded data for further analysis. The system pro ved to work in ICU and anaesthesia patients with various ventilators.