Ultrasound Strain Measurements for Evaluating Local Pulmonary Ventilation

Local lung function is difficult to evaluate, because most lung function estimates are either global in nature (e.g., pulmonary function tests) or require equipment that cannot be used at a patient's bedside, such as computed tomography. Yet, local function measurements would be highly desirable for many reasons. Recently, we were able to track displacements of the lung surface during breathing. We have now extended these results to measuring lung strains during respiration as a means of assessing local lung ventilation. We studied two human volunteers and 14 mice with either normal lung function or experimentally induced pulmonary fibrosis. The differences in strains between the control, normal mice and those with pulmonary fibrosis were significant (p < 0.0001), whereas the strains measured in the human volunteers closely matched linear strains predicted from the literature. It may be possible to use ultrasonography to assess local lung ventilation in a clinical setting.