Shift of the Mediastinum with Respiration

A Bronchospirometric Study in Pulmonary Tuberculosis

¹ Associate Professor, Department of Medicine, Chicago Medical School
² Associate Attending Physician, Department of Thoracic Medicine, Michael Reese Hospital and Medical Center

Mediastinal shift during respiration was observed in 28 per cent of 800 patients with advanced pulmonary tuberculosis; roentgenographic and pulmonay data were analyzed in 75 consecutive patients selected from this series. A group of 61 patients without mediastinal shift served as controls. The patients with mediastinal shift had more severe impairment of ventilatory function than the controls and bronchospirometry showed greater inequality of lateralization of this impairment. Mediastinal shift was classified as obstructive, restrictive or combined, depending on the ventilatory defect in the lung producing the mediastinal shift. Bronchospirometry showed significantly greater impairment of function of the lung producing the shift in the restrictive than in the obstructive group. In all groups, oxygen uptake of the lung responsible for the mediastinal shift was impaired more than ventilation or vital capacity. Shift of the mediastinum with respiration cannot be produced experimentally during bronchospiromety if thoracic bellows function on the side of bronchial occlusion is impaired and adequate transmediastinal pressure gradients are not developed. Mediastinal shift cannot occur if the mediastinum is fixed due to pleural or parenchymal lung disease, but mediastinal fixation was rarely observed.