The impact of PEEP-guided electrical impedance tomography on oxygenation and respiratory mechanics in moderate-to-severe ARDS: a randomized controlled trial

Abstract

Electrical impedance tomography (EIT)-guided positive end-expiratory pressure (PEEP) titration may optimize ventilation and reduce ventilator-induced lung injury in acute respiratory distress syndrome (ARDS). We compared EIT-guided PEEP with low PEEP/FiO₂ strategy in patients with moderate-to-severe ARDS. In this randomized controlled trial, 108 patients with PaO₂/FiO₂ below 200 mmHg were allocated to EIT-guided PEEP after a recruitment maneuver (n = 56) or low PEEP/FiO₂ strategy (n = 52). Patients in the EIT group underwent PEEP titration guided by the intersection point between alveolar overdistension and collapse during a decremental PEEP trial. Primary outcomes were oxygenation (PaO₂/FiO₂) and static compliance. Secondary outcomes included mortality, ventilator-free days, ICU stay, barotrauma, rescue therapies, and sequential organ failure assessment (SOFA) score changes. On day 1, oxygenation was higher with EIT (mean PaO₂/FiO₂ 180 vs. 159 mmHg; p = 0.036). Static compliance was greater at both day 1 (26 vs. 23 mL/cmH₂O; p = 0.016) and day 2 (27 vs. 24 mL/cmH₂O; p = 0.029). Driving pressure was lower with EIT at day 1 (16 vs. 17 cmH₂O; p < 0.001) and day 2 (15 vs. 17 cmH₂O; p = 0.005). SOFA scores improved more in the EIT group (day 1: - 1 vs. 0, p = 0.013; day 2: - 1 vs. - 0.5, p = 0.015). Twenty-eight-day mortality was lower with EIT (29 vs. 44%), although not statistically significant (p = 0.090). ICU stay, ventilation duration, barotrauma, ECMO use, and rescue therapies were similar. Benefits were most pronounced in patients with severe ARDS. EIT-guided PEEP improved oxygenation, lung mechanics, and reduced organ dysfunction in moderate-to-severe ARDS, particularly in severe cases. It showed a trend toward reduced mortality and may serve as a practical bedside tool for lung-protective ventilation. Larger multicenter trials are needed to confirm its clinical benefits.Trial registration: ClinicalTrials, NCT06733168. Registered on 13/12/2024, https://clinicaltrials.gov/study/NCT06733168 .

Keywords: ARDS; Electrical impedance tomography; Oxygenation; PEEP; Respiratory mechanics.

Fig. 1

Determination of recommended PEEP using EIT-based analysis. The recommended PEEP level is identified at the intersection between the cumulative collapse (white) and overdistension (yellow) curves, representing the balance point that minimizes both atelectasis and overinflation. In this example, the recommended PEEP was determined to be 16 cmH₂O.

Fig. 2

Flow chart of the study.

Fig. 3

Oxygenation. Ratio of arterial partial pressure of oxygen to fraction of inspired oxygen (PaO₂/FiO₂; A) and arterial partial pressure of oxygen (PaO₂; B). Data are presented as mean ± SD. Differences were analyzed using two-way repeated-measures ANOVA with Bonferroni’s post hoc test. *p < 0.05 (between groups).

Fig. 4

Respiratory mechanics. Positive end-expiratory pressure (PEEP; A), plateau pressure (Pplat; B), static compliance of the respiratory system (Cstat; C), and driving pressure (Pdriv; D). Data are presented as median [range] or mean ± SD. Differences were analyzed using the Mann–Whitney U test (A) and two-way repeated-measures ANOVA with Bonferroni’s post hoc test (B–D). *p < 0.05, **p < 0.001 (between groups).

Fig. 5

Kaplan–Meier 28-day survival curves for the EIT and control groups.

Fig. 6

Changes in the ratio of arterial partial pressure of oxygen to fraction of inspired oxygen (ΔPaO₂/FiO₂) and static compliance of the respiratory system (ΔCstat), subgrouped by ARDS severity on day 1 (A,C) and day 2 (B,D). Data are presented as mean ± SD. Differences were analyzed using Student’s t-test. Numbers inside the bars indicate the number of participants.