Feasibility Study of Vascular Pulsatile EIT Lung Perfusion Imaging for V/Q-matched Dynamic Non-invasive Monitoring

OBJECTIVES Ventilation/perfusion (V/Q) matching is an important indicator for assessing lung functional status. Existing techniques for assessing V/Q in the clinic are unable to meet the demand for continuous monitoring at the bedside, and are accompanied by invasive and infected risks. Therefore, the present study is based on our team's newly developed high-performance electrical impedance tomography (EIT) system, and explores the feasibility of its use for non-invasive assessment of V/Q at the bedside by acquiring and imaging pulmonary blood flow pulsation signals and combining them with pulmonary ventilatory impedance information. METHODS Domestic pigs under anaesthesia (N = 8, 17.50 ± 1.51 kg) were used as experimental subjects, and continuous lung EIT imaging data acquisition was performed at 40 fps through different positions and apnoea states in pigs. By analysing the vascular pulsation impedance information, lung perfusion-related information was extracted and combined with lung ventilation impedance information to establish a vascular pulsation V/Q assessment method. In addition, the method of monitoring pulmonary perfusion by hypertonic saline (5 ml of 10% NaCl) was used as a ‘standard’ for control experiments. RESULTS The V/Q results obtained by both methods changed significantly with changes in body position and respiratory status. When the body position changed from supine to prone, both methods showed a decrease in V/Q values ( p < 0.05 ). When the respiratory pause status was changed from end-expiratory pause period to end-inspiratory pause period, both methods showed an increase in V/Q values ( P < 0.05 ). The Kappa values for both methods were 0.492, p < 0.05 , for postural and 0.586, p < 0.05 , for during apnoea.This demonstrated the consistency of the results of the two methods in assessing V/Q. CONCLUSIONS Finally, the EIT imaging based on the vascular pacing method can effectively assess V/Q changes caused by alterations during different positions and apnoea, with results consistent with the hypertonic saline method. The vascular pulsatility method is expected to be a novel bedside monitoring and assessment method to guide and improve V/Q.