This is a prospective, single-center, randomized controlled trial designed to evaluate
the effects of PEEP settings guided by electrical impedance tomography (EIT) on clinical
outcomes in patients with moderate to severe ARDS undergoing lung-protective ventilation.
Adult intubated patients with moderate to severe ARDS will be enrolled in the study.
Patients in the intervention group will receive PEEP titrated using EIT with a stepwise
decremental PEEP trial, while those in the control group will have PEEP set based on the
FiO2-PEEP table. Other ventilator parameters will be managed according to the ARDSnet
protocol.
The primary outcomes are blood oxygenation and pulmonary mechanics. Secondary outcomes
include 28-day mortality, ventilator-free and shock-free days at 28 days, length of ICU
and hospital stay, rate of successful weaning, the proportion requiring rescue therapies,
complications, respiratory variables, and the Sequential Organ Failure Assessment (SOFA)
score.
Before initiating recruitment maneuver, all patients were placed on mechanical
ventilation set according to the ARDS network strategy for 10 minutes, ensuring SpO2 of
88-95%, PaO2 of 55-80 mmHg, and a mean arterial pressure (MAP) ≥ 65 mmHg.
Patients received sedation and neuromuscular blockade to achieve full
synchronization with the ventilator (RASS ≤ -3).
The mode was set to Pressure-Controlled Ventilation (PCV): ΔP = 15 cmH2O, which was
maintained constant during the recruitment maneuver, while FiO2, PEEP, and
respiratory rate were kept as previously set.
PEEP was incrementally increased by 5 cmH2O every minute: from 10 to 15, to 20, and
finally to 25 cmH2O, with a maximum pressure limit of 40 cmH2O.
Following the recruitment maneuver at the final PEEP level, the process of
identifying the optimal PEEP was initiated.
Then, PEEP will be set to 20 cmH2O and gradually decreased by 2 cmH2O every 30
seconds until it reached 6 cmH2O or SpO2 dropped to ≤ 80%.
Selection of optimal PEEP: The optimal PEEP was defined as the intersection point
between the alveolar overdistension and collapse curves as measured by the EIT
system.
- Termination Criteria: If persistent hypotension (mean arterial pressure
decrease > 15 mmHg) or sustained hypoxemia (SpO2 < 85% for at least 1 minute)
occurs during the recruitment maneuver maneuver, the procedure is terminated,
and ventilator settings are returned to the parameters used prior to the
recruitment maneuver.
Low FiO2 - PEEP table In the control group, patients set PEEP by low FiO2-PEEP table
based on ARDSnet protocol.