The objective of this randomized study is to compare the effect of two controlled chest tube protocols on the duration of air leak and fluid drainage following pulmonary lobectomy or segmentectomy by using an electronic regulated chest drainage system (Thopaz). Previous studies have suggested that the amount of negative pressure used at the level of the chest drainage device may affect the duration of air leak, but the results have been inconsistent, however as revealed in more recent studies understanding of the physics of chest drainage devices may have been confounded by lack of regulation of the pleural pressure.