Changes in lung lobar volume and bronchial deformity after right upper lobectomy

To explore the anatomical repositioning of the middle lobe following right upper (RU) lobectomy, we measured the lobar volumes of the lung and the branching angles of the airway, and defined their changes after RU lobectomy in a rabbit model. Groups A1 (n=10) and A2 (n=10) were control groups and groups B1 (n=10) and B2 (n=10) underwent RU lobectomy. Casting material was introduced into the airway and a heart-lung bloc was removed form the thoracic cavity in all groups. In groups A1 and B1, the volume of each lobe of the bilateral lungs was measured, while in groups A2 and B2, bronchial casts were made and the branching angles of the airway were measured. The volume ratio of the right upper lobe (RUL) to the total lung was 12.0 ± 0.4% in group A1; however, after RU lobectomy, the volume ratio of the right middle lobe (RML) to the total lung increased from 8.7 ± 0.6% in group A1 to 13.5 ± 0.8% in group B1. The volume of the left lung also increased from 43.0 ± 0.5% in group A1 to 48.8 ± 1.1% in group B1. The angle between the truncus intermedius and the RML bronchus was significantly smaller in group B2, at 109.0 ± 3.5°, than in group A2, in which it was 138.5 ± 1.7°. The angle between the RML bronchus and the coronal plane was 57.5 ± 2.5° in group A2 and 33.5 ± 3.3° in group B2. Our method of measuring the bronchial branching angle subsequent to RU lobectomy proved useful to illustrate postoperative positional changes and expansion of the remaining lobes.