Table 1 Goals for sequential segmental treatment

Treat less lung volume per session as compared to the lobar treatment sessions in VAPOR

The rate of SAEs increases as volume of lung treated increases [11]. Reducing volume per session is expected to reduce the rate of SAEs.

Treat a larger amount of lung volume per patient as compared to patients in VAPOR

Change in FEV₁ is related to the amount of diseased lung tissue treated per patient. Increasing the volume of diseased lung to be treated per patient is expected to result in an improvement of pulmonary function and efficacy [16–18].

Treat the most diseased segments in the upper lobes

The NETT demonstrates that reducing the more diseased upper lobes allow healthier lower lobes to expand yielding the best benefit. It is therefore hypothesized that targeting more diseased portions (segments) of the upper lobe should allow the least diseased regions of the upper lobes, in addition to the lower lobes, to expand [17, 19].

Preserve least diseased segments of the upper lobes

Emphysematous tissue is typically not homogeneous (equivalently diseased) throughout the lung or lobe. Preserving the least diseased segments allowing them to expand is expected to improve gas exchange in the upper lobes.