Methodological considerations in personalized methods for PEEP optimization with electrical impedance tomography

Excerpt

We have read with interest the recently published article by Pavlovsky and colleagues [1]. The authors examined patients with ARDS during a decremental PEEP trial performed with steps of 3 cmH₂O from 20 to 5 cmH₂O. Airway and esophageal pressures as well as electrical impedance tomography (EIT) data were recorded simultaneously. Four different approaches were then applied to identify the ’optimum PEEP’ value from the recordings of each patient by determining those PEEP levels of the PEEP trial at which (1) the plateau pressure was 28–30 cmH₂O, (2) the positive expiratory transpulmonary pressure reached its minimum (’positive P_LE’), (3) the center of ventilation (CoV) was closest to 0.5 and (4) the relative lung overdistension and collapse curves crossed (’crossing point’). The latter two values were derived from the EIT data. With the exception of the ’crossing point’ and ’positive P_LE’, the calculated ’optimum PEEP’ values varied significantly from each other, and none of the values was correlated to the recruitment-to-inflation ratio (R/I_est), as calculated from the change in end-expiratory lung impedance between PEEP of 5 and 15 cmH₂O. …