Electrical impedance tomography to set high pressure in time-controlled adaptive ventilation

TCAV (Time controlled adaptive ventilation), a combination of settings applied to the APRV (airway pressure release ventilation) mode, provides personalized ventilation tailored to the lung condition in ARDS (acute respiratory distress syndrome). The objective was to evaluate whether electrical impedance tomography (EIT) could serve as a tool for guiding P_high level in TCAV for ARDS patients.

Eleven patients with moderate or severe ARDS were enrolled in a prospective single-center study in 2023. Patients were monitored with EIT (PulmoVista 500). P_high trial was conducted from 34 to 18 cmH₂O, with 4-cmH₂O P_high decrements every 5 min. Driving pressure was maintained constant by adjusting T_low. Best EIT-derived-P_high was defined as the pressure at the crossing point between overdistension and collapse curves.

C_RS was significantly higher at P_high 18 cmH2O with 43 [32-50] mL/cmH2O than at P_high 34 with 20 mL/cmH2O [14-24], p < 0.005. Highest P_high levels caused significant overdistension in the anterior region and anterior compliance is significantly lower at P_high 34 with 10 [6-11] mL/cmH2O than at P_high 22 cmH2O with 18 [13-25] mL/cmH2O. Best EIT-derived P_high were 18, 22, 26 cmH₂O for four, five and two patients respectively.

EIT enabled detection of regional ventilation distribution on TCAV during a decremental P_high trial and thus enabled the determination of a best EIT-derived-P_high through an individualized approach, achieving best compromise between overdistension and collapse. The observed overdistention variability highlights the necessity of P_high level personalization on TCAV.