Gravitational distribution of regional opening and closing pressures, hysteresis and atelectrauma in ARDS evaluated by e
- PDF / 1,316,651 Bytes
- 8 Pages / 595.276 x 790.866 pts Page_size
- 50 Downloads / 223 Views
Open Access
RESEARCH
Gravitational distribution of regional opening and closing pressures, hysteresis and atelectrauma in ARDS evaluated by electrical impedance tomography Gaetano Scaramuzzo1, Elena Spinelli2, Savino Spadaro1, Alessandro Santini3, Donatella Tortolani1, Francesca Dalla Corte1, Antonio Pesenti2,4, Carlo Alberto Volta1, Giacomo Grasselli2,4 and Tommaso Mauri2,4*
Abstract Background: The physiological behavior of lungs affected by the acute respiratory distress syndrome (ARDS) differs between inspiration and expiration and presents heterogeneous gravity-dependent distribution. This phenomenon, highlighted by the different distribution of opening/closing pressure and by the hysteresis of the pressure–volume curve, can be studied by CT scan, but the technique expose the patient to radiations, cannot track changes during time and is not feasible at the bedside. Electrical impedance tomography (EIT) could help in assessing at the bedside regional inspiratory and expiratory mechanical properties. We evaluated regional opening/closing pressures, hysteresis and atelectrauma during inspiratory and expiratory low-flow pressure–volume curves in ARDS using electrical impedance tomography. Methods: Pixel-level inspiratory and expiratory PV curves (PVpixel) between 5 and 40 cmH2O were constructed integrating EIT images and airway opening pressure signal from 8 ARDS patients. The lower inflection point in the inspiratory and expiratory PVpixel were used to find opening (OPpixel) and closing (CPpixel) pressures. A novel atelectrauma index (AtI) was calculated as the percentage of pixels opening during the inspiratory and closing during the expiratory PV curves. The maximal hysteresis (HysMax) was calculated as the maximal difference between normalized expiratory and inspiratory PV curves. Analyses were conducted in the global, dependent and non-dependent lung regions. Results: Gaussian distribution was confirmed for both global OPpixel (r2 = 0.90) and global CPpixel (r2 = 0.94). The two distributions were significantly different with higher values for OPpixel (p
Data Loading...
