| Abstract | We describe a simple, low cost technique for computerized
measurements of compliance of the respiratory system (Crs) by airway
occlusion technique in intubated newborn infants. Tidal
volumes of 5, 7.5, and 10 mL/kg were injected from a calibrated syringe into
the endotracheal tube via a three-way stop cock and a t-piece. Airway
pressure was measured by means of a differential pressure transducer. The
analog pressure signal was fed into an optically isolated signal conditioning
termination panel and an analog input board which was connected to the PC
bus. The signal was amplified and A/D converted by the input board and
processed by the digital computer. Crs was determined as the
ratio of the injected tidal volume to the difference between the
endexpiratory pressure and the pressure at airway occlusion. The software is
written in Turbo Pascal (Borland Int.) and includes a patient data base and
facilities for system configuration, calibration of transducers, data
acquisition, handling, calculation of Crs, reporting and archive storage.
Data sampling frequency may be individually set at 60 to 200 Hz. Synchronous
measurements in 10 newborn infants using analog pressure
amplification and polygraphic recording showed that pressures were correctly
determined by the computer and that amplitude and frequency
response of the pressure recordings were adequate. |