title: Noninvasive method for measuring respiratory system compliance during pressure support ventilation.
abstract: OBJECTIVE
  To date, few methods have been accepted for assessing the respiratory system compliance (C(rs)) 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 C(rs).
  
  
  METHODS
  One breath is divided into several time periods (slices). For each slice, a compliance value C(i) is calculated. The slice width is adapted according to the confidence interval of C(i). After all C(i) values are obtained and the outliers are eliminated, the C(rs) of this breath is calculated as the mean value of the remainder of C(i)'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 (P(di)).
  
  
  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 P(di) 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 C(rs) in spontaneously breathing patients during pressure support ventilation noninvasively without extra instrumentation or complicated maneuvers.
authors.affiliation: Department of Biomedical Engineering, Furtwangen University, D-78054 VS-Schwenningen, Germany. zhanqi.zhao@hs-furtwangen.de
authors.forename: Zhanqi
authors.initials: Z
authors.lastname: Zhao
authors.forename: Marcus
authors.initials: M
authors.lastname: Eger
authors.forename: Thomas
authors.initials: T
authors.lastname: Handzsuj
authors.forename: V Marco
authors.initials: VM
authors.lastname: Ranieri
authors.forename: Lorenzo
authors.initials: L
authors.lastname: Appendini
authors.forename: Cosimo
authors.initials: C
authors.lastname: Micelli
authors.forename: Knut
authors.initials: K
authors.lastname: Moller
mesh_terms: D006801:Humans; D008170:Lung Compliance; D011175:Positive-Pressure Respiration; D029424:Pulmonary Disease, Chronic Obstructive / Q000503:physiopathology*; D015656:Respiratory Mechanics