EIT-Guided PEEP Optimization in Trauma and Postoperative ARDS

Official title

Electrical Impedance Tomography-Guided Positive End-Expiratory Pressure Optimization in Patients With Trauma-Related and Postoperative Acute Respiratory Distress Syndrome

Overview

Acute respiratory distress syndrome (ARDS) remains a serious and often fatal complication in patients following severe trauma or major surgery. Mechanical ventilation is essential for supportive care in this population, but may aggravate lung injury when suboptimal ventilatory settings are applied. Positive end-expiratory pressure (PEEP) is crucial for maintaining alveolar recruitment; however, optimal PEEP selection in trauma- or postoperative-associated ARDS remains uncertain. Electrical impedance tomography (EIT) enables bedside, real-time assessment of regional ventilation and may support optimal PEEP titration by balancing alveolar overdistension and collapse. This study compares EIT-guided PEEP optimization with the conventional low FiO₂-PEEP strategy in terms of oxygenation and respiratory mechanics in patients with moderate to severe ARDS following trauma or surgery.

Detailed description

This single-center, prospective, randomized controlled trial was designed to evaluate whether EIT-guided PEEP titration improves clinical outcomes in patients with trauma- or postoperative-associated ARDS. Adult intubated patients with moderate to severe ARDS were enrolled.

Patients in the intervention group received PEEP settings guided by electrical impedance tomography, whereas those in the control group were managed according to the lower PEEP/FiO₂ table of the ARDS Network. Other ventilatory parameters and oxygenation targets were set in accordance with ARDS Network recommendations. Supportive care and post-trial PEEP management followed standard ARDS treatment protocols.

The primary outcomes included oxygenation and respiratory mechanics. The secondary outcomes comprised 28-day survival, ventilator-free days at day 28, length of ICU and length of hospital stay, rate of successful ventilator weaning, use of adjunctive therapies (prone positioning, neuromuscular blockade, ECMO), newly developed barotrauma (pneumothorax, pneumomediastinum, and subcutaneous emphysema) excluding cases attributable to invasive procedures) and changes in the SOFA score.

In the intervention group, PEEP was titrated under the guidance of electrical impedance tomography (EIT) according to a protocol:

* Preparation: patients underwent airway suctioning and were deeply sedated (RASS ≤ -3) to abolish spontaneous breathing. PEEP titration was performed using an EIT system (Enlight 2100, Timpel SA, Brazil), with a silicone belt containing 32 surface electrodes positioned at the fourth to fifth intercostal space in accordance with the manufacturer's instructions. * Pressure-controlled ventilation was applied with an inspiration pressure set at 15 cmH₂O and a set PEEP of 24 cmH₂O, with a maximum airway pressure limit of 40 cmH₂O. Ventilator settings were maintained for 30 seconds with an FiO₂ of 1.0. A decremental PEEP trial was then performed by reducing PEEP in 2 cmH₂O every 30 seconds until a PEEP of 6 cmH₂O was reached or the SpO₂ decreased to ≤ 80%. * The EIT-guided optimal PEEP was defined as the PEEP level corresponding to the intersection point of the collapse and overdistension curves.

Criteria for discontinuing: PEEP titration was terminated if any of the following occurred: a sustained decrease in mean arterial pressure of \> 20 mmHg from baseline, SpO₂ \< 88%, or the onset of new cardiac arrhythmias. If the event of discontinuation of the procedure, all ventilator settings were reverted to those applied prior to initiation of the PEEP titration.

In the control group, PEEP was set directly and adjusted according to the lower PEEP/FiO₂ table of the ARDS Network.

Interventions

• Device EIT-giuded PEEP
  Device: electrical impedance tomography system (Enlight 2100, Timpel SA, Brazil). \- Patients underwent airway suctioning and were deeply sedated (RASS ≤ -3) to abolish spontaneous breathing. PEEP titration was performed using an EIT system (Enlight 2100, Timpel SA, Brazil), with a silicone belt containing 32 surface electrodes positioned at the fourth to fifth intercostal space in accordance with the manufacturer's instructions. Pressure-controlled ventilation was applied with an inspiration
• Device Control
  PEEP was set and adjusted according to the lower PEEP/FiO₂ table of the ARDS Network

Primary outcome measures

• Oxygenation [Time frame: at day 0, 1, 2, 3]
• Pulmonary Mechanics [Time frame: at day 0, 1, 2, 3]

Secondary outcome measures (7)

• Ventilator free days [Time frame: up to 28 days]
• Length of ICU stay [Time frame: up to 28 days]
• Length of mechanical ventilated days [Time frame: up to 28 days]
• Barotrauma [Time frame: up to 28 days]
• Rescue therapies [Time frame: up to 7 days]
• SOFA [Time frame: at day 0, 1, 2, 3]
• Mortality [Time frame: up to 28 days]

Eligibility criteria

Inclusion criteria

• Mechanically ventilated surgical intensive care patients with trauma- or postoperative-associated moderate to severe ARDS, as defined by the 2023 Global Definition of ARDS.

Exclusion criteria

• Age <18 or >90 years.
• Severe acute brain injury or acute stroke with Glasgow Coma Scale <8.
• Thoracic trauma with pneumothorax or pneumomediastinum.
• End-stage diseases under palliative care (e.g., metastatic cancer, cirrhosis, end-stage renal disease).
• Severe multiorgan failure with expected survival <7 days.
• Conditions requiring prolonged mechanical ventilation (e.g., Guillain-Barré syndrome, cervical spinal cord injury).
• Contraindications to hypercapnia (e.g., elevated intracranial pressure, acute coronary syndrome).
• Prior use of advanced respiratory therapies (e.g., ECMO, inhaled nitric oxide, prone positioning, high-frequency ventilation).
• Pregnancy, breastfeeding, or skin lesions at electrode placement sites.
• Implanted electrical devices interfering with EIT (e.g., pacemaker, ICD).
• Known allergy to electrode materials.
• Refusal to participate or concurrent enrollment in another study

Criteria are shown verbatim from the registry (in English). Final eligibility is always assessed by the study center.

Healthy volunteers: No

Study design

Allocation

Randomized

Model

Parallel assignment

Masking

Open label

Primary purpose

Treatment

Study locations

Vietnam · 1 center

• Center for Anesthesia and Surgical Intensive Care, Viet Duc University Hospital — Hanoi

Publications

• Costa EL, Borges JB, Melo A, Suarez-Sipmann F, Toufen C Jr, Bohm SH, Amato MB. Bedside estimation of recruitable alveolar collapse and hyperdistension by electrical impedance tomography. Intensive Care Med. 2009 Jun;35(6):1132-7. doi: 10.1007/s00134-009-1447-y. Epub 2009 Mar 3. PMID 19255741
• Jimenez JV, Weirauch AJ, Culter CA, Choi PJ, Hyzy RC. Electrical Impedance Tomography in Acute Respiratory Distress Syndrome Management. Crit Care Med. 2022 Aug 1;50(8):1210-1223. doi: 10.1097/CCM.0000000000005582. Epub 2022 May 23. PMID 35607967
• Gao Y, He H, Chi Y, Frerichs I, Long Y, Zhao Z. Electrical impedance tomography guided positive end-expiratory pressure titration in critically ill and surgical adult patients: a systematic review and meta-analysis. BMC Pulm Med. 2024 Nov 23;24(1):582. doi: 10.1186/s12890-024-03394-y. PMID 39580405

Identifiers

NCT: NCT07313644 · MinhGMHS 1879/GCN-HMUIRB

Primary sources (government registries)

• ClinicalTrials.gov (US NIH)

View this study on ClinicalTrials.gov ↗