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

INTRODUCTION

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 Phigh level in TCAV for ARDS patients.

METHODS

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

RESULTS

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

CONCLUSION

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