Introduction: Invasive and non-invasive respiratory support is titrated based on whole-lung measures of respiratory function like plateau pressure, esophageal pressure, partial pressure of CO2, and oxyhemoglobin saturation and clinical ones like chest rise and work of breathing. Radiological studies like chest X-ray and CT provide static assessment of lung aeration and distention, and technique like electrical impedance tomography can provide regional assessments of aeration. However, there are no tools to dynamically assess lung strain as is common practice in echocardiography where speckle mapping is used to quantify myocardial strain. This was identified as a high priority goal of the European Society of Intensive Care (ESICM) and the European Society of Paediatric and Neonatal Intensive Care (ESPNIC). Methods: Using publicly available R image processing and analysis tools and assisted with Claude Artificial Intelligence for coding, we developed a tool to quantify regional lung strain in recorded point of care lung ultrasound images and validated using an anesthetized and mechanically ventilated pig with different tidal volumes and comparing different lung regions. Results: After optimization of the tool, both period and amplitude of centroid movement were consistent with repeated measures and with measures of different regions of the pig lung. Amplitude increased with increasing tidal volume sequentially from 4 to 10 mL/kg. Tracking of movement yielded hysteresis loops of the different regions of lung allowing comparison of lung tissue movement within and between images. Conclusions: Although further optimization is required, this approach could be useful in minimizing lung injury and titrating respiratory support during invasive and non-invasive mechanical ventilation.
Walters et al. (Sun,) studied this question.