Effects of lung volume reduction surgery on distribution of ventilation and perfusion.

Lung volume reduction surgery (LVRS) results in functional improvements in most patients. The mechanisms behind the improvements are not clear. We hypothesized that reduced inequalities in ventilation to perfusion ratio (V/Q) may be a contributing explanation. Nine patients who underwent LVRS were investigated by ventilation and perfusion scintigrams before and after surgery. In addition, 8 healthy subjects were investigated once. The relative ventilation, perfusion and V/Q were calculated in 1 x 1 cm lung elements. Normal range of the element count-rate was determined by the corresponding results in the normal subjects. Results of this small study show a significant effect of LVRS on V/Q, with reduction of shunt-like elements. We conclude that the functional improvement after LVRS to some extent may be explained by decreased V/Q inequality.