Volumes of: (A) the thoracic cavity, (B) the intra‐thoracic organs, (C) right lung and (D) left lung, measured using MRI, in non‐sternotomised pigs and in sternotomised pigs before (0 mmHg) and after the application of negative pressure wound therapy of −75, −125 and −175 mmHg. The results are presented as mean values ± standard error on the mean. Note how the volumes of the thorax and intra‐thoracic organs decrease upon the application of negative pressure, most prominently upon the change from 0 to −75 mmHg. Further increases in negative pressure only result in minor reduction in volume.