PEEP Titration Guided by Electrical Impedance Tomography in Laparoscopic Surgery The PEaRL Study

Official title

Personalized PEEP Titration Guided by Electrical Impedance Tomography in Patients Undergoing Laparoscopic Surgery: A Randomized Controlled Trial - The PEaRL Study

Overview

Background: Laparoscopic surgery has gained widespread adoption due to its minimally invasive nature, offering advantages such as reduced postoperative pain, shorter hospitalization, and faster functional recovery compared with traditional open surgery. Nevertheless, postoperative respiratory complications remain a major source of morbidity. Factors such as general anesthesia, the Trendelenburg position, and CO₂ pneumoperitoneum can impair respiratory mechanics, reduce total lung capacity, and promote atelectasis, leading to compromised gas exchange. Rationale: Positive end-expiratory pressure (PEEP) is routinely applied to prevent alveolar collapse and improve oxygenation during mechanical ventilation. However, the use of standardized, non-individualized PEEP levels may be suboptimal, as inappropriate settings can cause alveolar overdistension or persistent collapse. Personalized PEEP titration, tailored to patient-specific lung mechanics, has recently emerged as a promising strategy to minimize ventilator-induced lung injury (VILI). Methods and Tools: Electrical Impedance Tomography (EIT) is a non-invasive, bedside monitoring technique that enables real-time assessment of regional lung ventilation. By evaluating ventilated and non-ventilated lung areas, EIT can guide PEEP optimization and support individualized ventilatory management. Recent studies suggest that EIT-guided PEEP titration improves respiratory parameters and reduces atelectasis in patients undergoing major surgery. Objective: The present study aims to evaluate the efficacy of EIT-guided PEEP personalization in patients undergoing laparoscopic and robotic surgery. Primary endpoints include improvements in regional ventilation, respiratory system compliance, and intraoperative gas exchange, as well as postoperative pulmonary function.

Detailed description

Laparoscopic surgery has become an increasingly widespread surgical approach due to its minimally invasive nature, which allows for reduced postoperative pain, shorter hospital stays, and faster functional recovery compared to traditional open surgery. However, despite these advantages, laparoscopic procedures are not free from postoperative respiratory complications, which remain among the leading causes of postoperative morbidity. The combination of general anesthesia, the Trendelenburg position, and insufflation of CO₂ into the abdominal cavity can alter respiratory mechanics, reduce total lung capacity, and promote the development of atelectatic areas, resulting in impaired gas exchange (1-2).

Positive end-expiratory pressure (PEEP) is a widely used strategy to prevent alveolar collapse and improve oxygenation during mechanical ventilation. Nevertheless, the application of a standardized, non-individualized PEEP level may not be optimal for all patients, and an inappropriate PEEP setting may lead to alveolar overdistension or persistence of collapsed areas (3). Recently, personalized PEEP titration has gained attention as a method to tailor ventilation settings to individual patient characteristics, thereby minimizing the risk of ventilator-induced lung injury (VILI) (4).

Electrical Impedance Tomography (EIT) is a non-invasive, bedside imaging technique that enables real-time assessment of the regional distribution of pulmonary ventilation. EIT allows continuous monitoring of the effects of PEEP on both ventilated and non-ventilated lung regions and can guide the optimization of individualized PEEP levels to improve ventilation distribution and reduce the risk of respiratory complications (5-6). Recent studies have shown that the use of EIT-guided PEEP personalization in patients undergoing major surgery can improve respiratory parameters and reduce atelectasis formation (7-8). Specifically, EIT enables the performance of a PEEP trial, during which the device identifies areas of alveolar overdistension or collapse in response to PEEP changes, thereby guiding personalized ventilatory settings.

However, the application of this technique in the context of laparoscopic surgery remains limited. This study aims to evaluate the effectiveness of EIT-guided PEEP personalization in patients undergoing laparoscopic and robotic procedures, with the goal of improving regional ventilation, respiratory system compliance, and intraoperative gas exchange, as well as postoperative pulmonary function.

Interventions

• Device A PEEP trial performed with the PulmoVista® 500 (Dräger, Lübeck, Germany) is a procedure designed to identify the optimal level of positive end-expiratory pressure
  During the trial, stepwise adjustments of PEEP are made while EIT provides real-time, bedside visualization of ventilation distribution across different lung regions. Typically, the protocol involves a recruitment maneuver followed by incremental and/or decremental PEEP steps (for example, in 2-3 cmH₂O intervals). At each step, EIT measures changes in regional impedance, which reflect variations in local lung aeration and ventilation. By analyzing these parameters, clinicians can determine the

Primary outcome measures

• Static respiratory system compliance [Time frame: - Baseline (after anesthesia induction) - T1 (After Trendelemburg position and induction of pneumoperitoneum) - T2 (After PEEP trial) - T3 (90 minutes after PEEP trial) - T4 (180 minutes after PEEP trial) - T5 (Before end of anesthesia)]

Eligibility criteria

Inclusion criteria

• scheduled for laparoscopic abdominal surgery
• informed consent signed

Exclusion criteria

• COPD
• Acute respiratory failure
• Hemodynamic instability
• Pregnancy
• Contraindications for EIT device

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

Prevention

Study locations

Italy · 1 center

• Department of Anesthesia and Intensive Care Medicine — Milan

Publications

• Ma X, Fu Y, Piao X, De Santis Santiago RR, Ma L, Guo Y, Fu Q, Mi W, Berra L, Zhang C. Individualised positive end-expiratory pressure titrated intra-operatively by electrical impedance tomography optimises pulmonary mechanics and reduces postoperative atelectasis: A randomised controlled trial. Eur J Anaesthesiol. 2023 Nov 1;40(11):805-816. doi: 10.1097/EJA.0000000000001901. Epub 2023 Sep 13. PMID 37789753
• Rauseo M, Spadaro S, Mirabella L, Cotoia A, Laforgia D, Gaudino G, Vinella F, Ferrara G, Gattullo A, Tullo L, Cinnella G. Electrical Impedance Tomography during Abdominal Laparoscopic Surgery: A Physiological Pilot Study. J Clin Med. 2023 Dec 1;12(23):7467. doi: 10.3390/jcm12237467. PMID 38068519
• Jiang L, Deng Y, Xu F, Qiao S, Wang C. Individualized PEEP guided by EIT in patients undergoing general anesthesia: A systematic review and meta-analysis. J Clin Anesth. 2024 Jun;94:111397. doi: 10.1016/j.jclinane.2024.111397. Epub 2024 Jan 25. PMID 38278058
• Pavlovsky B, Desprez C, Richard JC, Fage N, Lesimple A, Chean D, Courtais A, Mauri T, Mercat A, Beloncle F. Bedside personalized methods based on electrical impedance tomography or respiratory mechanics to set PEEP in ARDS and recruitment-to-inflation ratio: a physiologic study. Ann Intensive Care. 2024 Jan 5;14(1):1. doi: 10.1186/s13613-023-01228-4. PMID 38180544
• 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
• Chen L, Yu K, Yang J, Han X, Liu L, Li T, Miao H. Electrical impedance tomography-guided positive end-expiratory pressure titration for perioperative oxygenation and postoperative pulmonary complications: A systematic review and meta-analysis. Medicine (Baltimore). 2024 Dec 27;103(52):e40357. doi: 10.1097/MD.0000000000040357. PMID 39969340
• Scaramuzzo G, Priani P, Ferrara P, Verri M, Montanaro F, La Rosa R, Cammarota G, Volta CA, Spadaro S. Longitudinal changes of electrical impedance tomography-based best PEEP in obese patients undergoing laparoscopic surgery: A prospective physiological study. Anaesth Crit Care Pain Med. 2025 Sep;44(5):101569. doi: 10.1016/j.accpm.2025.101569. Epub 2025 Jun 13. PMID 40518045

Identifiers

NCT: NCT07289113 · CET 341-2025

Primary sources (government registries)

• ClinicalTrials.gov (US NIH)

View this study on ClinicalTrials.gov ↗