Chest EIT for Lung Ventilation and Perfusion
- In ICU
- Tue, 21 Oct 2025
Electrical impedance tomography (EIT) represents a significant advancement in respiratory monitoring as a non-invasive, radiation-free imaging technique that enables real-time bedside assessment of lung ventilation and perfusion. Despite growing clinical evidence and expanding applications over the past seven years since the first international consensus in 2017, there remains a lack of standardised protocols and evidence-based guidelines for EIT use in adult critically ill patients.
An international study, conducted by the REspiratory and Critical Care medicine EIT study (RECCE) group, aimed to establish comprehensive, evidence-based recommendations for clinical application of chest EIT in adult intensive care settings.
The research team assembled an international multidisciplinary steering committee comprising intensivists, physicians, biomedical engineers, guideline methodologists, and biostatisticians with expertise in EIT clinical applications. They conducted a systematic literature search, screening 11,159 abstracts and reviewing 242 relevant publications focusing on chest EIT applications for lung ventilation and perfusion in adults.
A Delphi consensus process involved two online survey rounds with an expanded group of 25 international experts from 12 countries. Strong consensus was defined as greater than 95% expert agreement, consensus as 75-95% agreement, and no consensus as less than 75% agreement.
The comprehensive review generated 14 clinical questions resulting in 87 evidence-based recommendations across three main dimensions: data acquisition and analysis, clinical applications, and future perspectives. The consensus outcomes were impressive: 15 recommendations achieved strong consensus (100% agreement), 70 recommendations reached consensus (75-95% agreement), and only two recommendations failed to reach consensus.
The evidence quality varied considerably: only 3 of 87 recommendations were graded as high-quality evidence (A grade), 47 recommendations were moderate quality (B grade), and 37 recommendations were based on lower quality evidence (C-D grade). This distribution highlights both the growing body of EIT research and the urgent need for higher-quality studies, particularly multicentre randomised controlled trials.
Core Recommendations
Data Acquisition Standards: The panel established that electrodes should be placed at the 4th-5th intercostal spaces for optimal EIT chest examination, with the 3rd-4th intercostal spaces as the primary alternative when necessary. Electrodes must maintain direct skin contact without interposition of drapes or tubes. When comparing EIT examinations across different occasions, identical belt positioning is essential. The effects of electrode placement and body position on lung ventilation images must be considered when comparing results.
Electrode-Skin Contact and Obesity Considerations: Contact impedance should remain below vendor-specific thresholds and stable over time to ensure high-quality imaging. Electrode gel, spray, or other solutions can enhance contact quality. Obesity impacts lung contour and area in functional EIT images but does not affect EIT's ability to provide continuous dynamic lung ventilation monitoring. Inflatable air mattresses should not alternate chamber pressure during EIT recordings to avoid contact changes.
Volume Assessment: Changes in end-expiratory lung impedance (EELI) reliably reflect changes in lung volume at end-expiration, though only changes from baseline should be reported, not absolute values. The absolute EELI value cannot be compared between individuals or within individuals across interrupted measurements. Critically, changes in tidal impedance variation correlate with changes in tidal volume and can be calibrated to calculate volume-impedance ratios.
PEEP Titration and Recruitment: EIT proves valuable for assessing recruitability and recruitment manoeuvre efficacy. The regional respiratory compliance approach (Costa approach) for PEEP titration calculates relative compliance changes rather than absolute values. Regional compliance loss toward higher PEEP levels indicates relative overdistension, while loss toward lower PEEP indicates relative derecruitment. The "optimal PEEP" can be defined at the crossover point of relative hyperdistension and collapse curves, depending on patient-specific needs and clinical goals.
Perfusion Assessment: For contrast-enhanced EIT perfusion assessment, a 10ml bolus of hypertonic (5-10%) saline is commonly used as contrast agent, administered during at least 8 seconds of breath holding. This method effectively detects regional perfusion defects from pulmonary embolism and ventilation-perfusion mismatches from various etiologies.
Clinical Applications: EIT demonstrates utility in identifying regional ventilation abnormalities from various causes, including pleural effusion, pneumothorax, and obstructive lung diseases. It quantitatively evaluates effects of prone and lateral positioning on lung ventilation, aeration, perfusion, and ventilation-perfusion matching. EIT can guide weaning processes by evaluating regional lung ventilation changes during spontaneous breathing trials and helps detect patients at risk for self-inflicted lung injury through pendelluft identification.
Ventilation Management and Outcomes: High-quality evidence (A-1b grade) supports that individualised mechanical ventilation with EIT has potential for improving outcomes in ARDS patients, though further study is required. EIT-guided PEEP improves oxygenation compared to fixed PEEP in surgical patients. The technology also proves helpful for individualising PEEP and tidal volume during veno-venous ECMO therapy.
This consensus statement demonstrates that evidence and expert agreement support EIT's application in detecting dynamic pulmonary abnormalities and inhomogeneities that may significantly influence clinical management and diagnosis.
The panel emphasised that proper training is required for adequate EIT image analysis and data interpretation. Future technological development should focus on multi-layer electrode systems for 3D imaging, automated validity assessment, unified technical specifications for perfusion imaging, and reference values based on large sample populations. Clinical trials must confirm how EIT-guided ventilation strategies influence patient outcomes and establish how to guide clinical decisions based on regional ventilation and perfusion abnormalities.
Source: The Lancet
Image Credit: iStock
References:
He H et al. (2025) Recommendations for lung ventilation and perfusion assessment with chest electrical impedance tomography in critically ill adult patients: an international evidence-based and expert Delphi consensus study. The Lancet. 89(103575).
