Abstract Rationale Reliable non-invasive continuous dynamic monitoring of pulmonary perfusion remains a significant challenge in critically ill, mechanically ventilated patients. Although saline contrast electrical impedance tomography (EIT) is an established method for perfusion assessment, it requires breath-holding maneuvers, which limits its applicability for continuous monitoring. We hypothesized that a non-invasive pulse wave EIT method, which extracts perfusion signals from cardiogenic impedance variations, could provide a practical alternative without these constraints. Methods In a prospective observational study, we enrolled sedated, mechanically ventilated critical ill patients without pre-existing lung disease. Simultaneous perfusion measurements were obtained using both pulse wave method and saline contrast method at positive end-expiratory pressure (PEEP) levels of 5. Collect EIT data, respiratory mechanics, and hemodynamic parameters. Results The study found a high level of agreement between the pulse wave method and saline contrast method (expiratory breath-hold) in measuring pulmonary perfusion distribution (r = 0.986, p 0.001). Repeated measurements demonstrated excellent internal consistency and measurement stability of the pulse wave method across all four lung regions, with intraclass correlation coefficients (ICCs) ranging from 0.946 to 0.967. In contrast, the saline contrast method showed poor agreement in perfusion distribution when measurements were taken under different breath-hold conditions (expiratory vs. inspiratory apnea) in the same subjects (ICC0.5). Moreover, injection of hypertonic saline both during inspiratory breath-hold and without breath-holding, a sustained reduction in pulmonary baseline impedance was observed. We found that this baseline impedance drop did not resolve even after the resumption of mechanical ventilation. No such impedance drop was observed when saline was injected during inspiratory breath-hold. (Figure 1.) Conclusions This study demonstrates that pulse wave EIT shows high concordance with the traditional saline contrast method in assessing pulmonary perfusion distribution, while offering superior measurement reproducibility and stability. The technique overcomes the reliance on breath-holding and avoids the persistent impedance artifact induced by hypertonic saline, demonstrating strong potential as a non-invasive, reliable, and practical tool for real-time bedside monitoring of lung perfusion. This abstract is funded by: None
Tian et al. (Fri,) studied this question.