Application of regional mechanical power monitored by electrical impedance tomography during positive end-expiratory pressure titration in acute respiratory distress syndrome patients

Abstract

Objective To investigate regional gas distribution and regional mechanical power during positive end-expiratory pressure (PEEP) titration in acute respiratory distress syndrome (ARDS) patients using electrical impedance tomography (EIT). Methods Ten ARDS patients admitted to Peking Union Medical College Hospital from November 2018 to February 2019 and receiving invasive mechanical ventilation were studied. A descending PEEP trial (15-0 cmH2O, 1 cmH2O=0.098 kPa) in 3 cmH2O steps was monitored by EIT, with lung images divided into four ventral-to-dorsal horizontal regions of interest (ROIs) 1 and 2 represent non-dependent areas, while ROIs 3 and 4 represent dependent areas). Gas distributions in the four regions were recorded, with which regional mechanical powers in each region were calculated. Results With PEEP decreasing from 15 cmH2O to 0 cmH2O, tidal volumes significantly decreased in dependent areas (F=5.611, P<0.001), but significantly increased in non-dependent areas (F=5.587, P<0.001). Ventilation shifted from dorsal regions to ventral regions during the descending PEEP trial. With PEEP decreasing from 15 cmH2O to 0 cmH2O, global mechanical power decreased significantly (F=19.601, P<0.001); mechanical power decreased significantly in ROIs 2-4 (F=4.130, P=0.003; F=30.690, P<0.001; F=16.744, P<0.005) but did not change significantly in ROI 1 (F=0.460, P=0.804). Conclusions Regional mechanical power can be monitored by EIT. Global mechanical power decreases during the descending PEEP trial, while regional mechanical power may increase in some cases, which may help in the selection of PEEP. Key words: Electrical impedance tomography; Mechanical power; Positive end-expiratory pressure; Respiratory distress syndrome, adult