Evaluation of Indices for Respiratory Mechanics from an Automated System

Abstract

The traditional monitoring of respiratory mechanics in patients treated with ventilators includes airway pressure and expired volume minute by minute (Widemann et al. 1984). Semistatic compliance and resistance can be calculated from these parameters (Jonson et al. 1975). Automatic calculation and presentation of lung mechanics has become possible with the use of bedside monitors. Multipatient systems for automatic calculation of these parameters have been described (Matell et al. 1983: Baehrendtz et al. 1980: Brandt and Frank 1980). Reference values for lung mechanics calculated with the aid of such a system in anesthetized patients without pulmonary disease have been published (Carvalhas 1983). However, the influence of various diseases on monitored respiratory-mechanics parameters has, to our knowledge not been systematically studied. In order to establish the influence of common pulmonary disorders on mechanical variables of the lung, automatic respiratory monitoring was carried out in four well defined groups of patients who could be expected to have different lung-mechanical properties. Sampled variables were examined for inter-group differences. In addition, we wanted to test whether a more complex computer-calculated index gave better diagnostic seperation than conventional parameters.