Non-apnea Saline-contrast EIT for Lung Perfusion Imaging in Spontaneously Breathing Patients: A Prospective Cross-over Study

Title: Validating the Accuracy of Lung Blood Flow Monitoring Without Breath-Holding Under Spontaneous Breathing Support

Purpose: The purpose of this study is to evaluate the accuracy of a new Electrical Impedance Tomography (EIT) technique that measures lung blood flow (perfusion) without requiring patients to hold their breath. We aim to determine if this "non-apnea" method provides results consistent with the current clinical gold standard (the "pause" method).

Background: EIT is a non-invasive bedside tool used to monitor lung function. The traditional method for measuring lung blood flow requires patients to hold their breath for 5-8 seconds during a saline injection to avoid interference from breathing. However, many patients-especially those using a nasal cannula, high-flow nasal oxygen (HFNO), or pressure support ventilation (PSV)-must maintain continuous spontaneous breathing and find it difficult or unsafe to hold their breath. If a "non-apnea" method is proven accurate, it will make monitoring safer and easier for these patients.

What the Study Involves: The study includes stable adult patients who are breathing spontaneously. Each patient undergoes two measurements in a randomized order:

Standard Reference (Pause Method): Measurement taken during a brief, guided breath-hold.

Test Method (Non-Apnea Method): Measurement taken during normal, uninterrupted breathing while receiving respiratory support (Nasal Cannula, HFNO, or PSV).

Expected Significance: By comparing the lung images and ventilation/perfusion (V/Q) data from both methods, this study seeks to validate the reliability and precision of the non-apnea approach. This would allow clinicians to assess lung health in spontaneously breathing patients without interrupting their natural breathing rhythm.