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

Background: Electrical impedance tomography (EIT) is a non-invasive, radiation-free imaging technique that allows for monitoring of lung ventilation and perfusion at the bedside. However, there is a lack of evidence-based and international expert consensus statement of EIT clinical applications in adult critically ill patients. The purpose of this study was to provide evidence-based and expert consensus recommendations for lung ventilation and perfusion assessment with chest EIT in adult critically ill patients. Methods: A English literature search was conducted of MEDLINE, EMBASE, Web of Science and Cochrane Library databases between January 1, 1990, and J March 22, 2024. Eligible literature included systematic reviews, meta-analyses, cohort/clinical trials, case reports and review articles that focused on chest EIT application for lung ventilation and perfusion in adult population. The animal studies were excluded. An international global panel of intensivists, physicians, biomedical engineers with expertise in the field of EIT clinical applications, guideline methodologists and biostatisticians, was convened. The Oxford Centre of Evidence Based Medicine's Levels of Evidence method was used to rate the quality of evidence and the strength of recommendations. Subsequently, with a Delphi process (two online surveys at June 3 and September 13, 2024), a group of expanded global experts from 12 different countries developed recommendations. We defined a strong consensus as agreement of >95% experts, consensus as agreement of 75-95% experts and no consensus as agreement<75%. The study is registered with PREPARE, PREPARE-2024CN166. Findings: The final 14 questions generated a total of 11,159 abstracts, of which 242 publications were identified relevant to develop 87 recommendations. The 87 statements focused on data acquisition and analysis, clinical application, and future perspectives were developed and modified. Twenty experts in the expanded group completed the survey in the first round, and eighteen experts in the expanded group completed the survey in the second round. At the end of the Delphi process, 15 recommendations were identified as strong consensus, 70 recommendations as consensus, and two recommendations did not reach consensus. The statements with strong consensus were focused on data acquisition, analysis, training and interpretation, assessment of posture effect on lung ventilation, lung perfusion and ventilation/perfusion match, and the statements without agreement were focused on regional ventilation delay ratio, perfusion assessment with heart-beat related EIT signal. Recommendations were mostly based on moderate quality of evidence (3/87 was A grade, 47/87 was B grade, 37/87 was C-D grade of recommendation). Interpretation: Our study provides evidence-based recommendations with high consensus for using chest EIT for lung ventilation and perfusion in adult critically ill patients. Evidence and expert consensus supports the application of EIT in the detection of dynamic pulmonary abnormalities and inhomogeneities, which may significantly influence clinical management and final diagnosis. High quality evidence is urgently needed for the development of EIT guidelines in the future. Funding: National High-Level Hospital Clinical Research Funding, National Key Research and Development Program, National Natural Science Foundation of China, Peking Union Medical College Hospital Talent Cultivation Program Category C.