Noninvasive method for measuring respiratory system compliance during pressure support ventilation

摘要

Purpose: To date, few methods have been accepted for assessing the respiratory system compliance (Crs) in patients under assisted ventilation at the bedside. The aim of this study was to evaluate our adaptive time slice method (ATSM) to continuously calculate the Crs. Methods: One breath is divided into several time periods (slices). For each slice, a compliance value Ci is calculated. The slice width is adapted according to the confidence interval of Ci. After all Ci values are obtained and the outliers are eliminated, the Crs of this breath is calculated as the mean value of the remainder of Ci's. Seven patients with Chronic Obstructive Pulmonary Disease were evaluated during pressure support ventilation. The results are compared with the values calculated with the transdiaphragmatic pressure (Pdi). Results: 95±4% of the recorded data could be analyzed with ATSM. In 6 patients out of 7, the results delivered with ATSM and with Pdi had similar variation (standard deviation) and accuracy (difference<20%). They were strongly correlated (weighted correlation coefficient = 0.86, p<10−5) with a mean difference of 3.22 ml/mbar. Conclusions: The ATSM is a robust method and able to provide accurate Crs in spontaneously breathing patients during pressure support ventilation noninvasively without extra instrumentation or complicated maneuvers.