Real-time non-invasive monitoring of pulmonary embolism based on dynamic EIT technology: a new method

Abstract

Background The assessment and monitoring of pulmonary embolism is a key factor in guiding the treatment of critically ill patients. To date, bedside methods used clinically to estimate the physiological correlates of pulmonary embolism (pulmonary blood flow perfusion) are often unreliable or require invasive testing. The aim of this study was to explore a new method for assessing pulmonary embolism detection and non-invasive real-time monitoring based on a high-performance electrical impedance tomography system that acquires imaging of pulmonary blood flow pulsation signals. Methods An anaesthetised porcine model (N = 12) was selected for a before-and-after self-control experiment, and the pulmonary perfusion changes induced before and after pulmonary embolism (artificially induced) were continuously monitored by the vascular pulsatility method (VPM), from which the amplitude, maximal slope (both positive and negative), and waveform area were extracted as indicators for assessing the status of the local pulmonary perfusion. In addition, the degree of ventilation-perfusion matching of the lungs was assessed in conjunction with the analysis of lung ventilation areas. A conventional invasive hypertonic saline (5 ml of 10% NaCl) imaging technique was used as a control to assess the actual pulmonary embolism. Results Areas of perfusion defects before and after embolisation by the vascular pulsatile method showed a high degree of concordance with hypertonic saline in terms of images and indices. All pulmonary blood flow pulsatility indices were significantly reduced in the embolised region relative to the pre-embolisation period, with the most significant changes in waveform area and amplitude during the end-expiratory pause (P < 0.001). Ventilation blood flow matching indices extracted in combination with regional ventilation also showed significant differences, with the most significant changes in ventilation blood flow matching% and deadspace ventilation fraction% (P < 0.001). Conclusions Vascular beat-based EIT imaging methods can be used to assess characteristic changes in pulmonary perfusion before and after embolisation, and this approach is expected to provide new ideas for non-invasive bedside monitoring of pulmonary embolism.