Purpose : Shoulder arthroscopy requires a large of irrigation for a better surgical view, resulting in circulatory overload. This study was performed to p rove whether pulmonary edema will be lead by a large of irrigation . Materials and Methods : General anesthesia with interscalene block was induced before operation. The primary outcome was ultrasound evaluation of B lines from the time before nerve block to the time 10 hours after operation. The secondary outcomes included oxygenation index, arterial partial pressure of carbon dioxide, visual analogue scale, muscle strength grade. Results : A total of 93 patients were evaluated. Before surgery, B lines failed to be detected. While the highest total incidence of B lines was 49.4%, occured at 4 hours after surgery. The highest incidence s of severe and moderate pulmonary edema were 3.2% (P=0.081) and 9.7% (P=0.002), respectively. B lines were also found on both the affected and healthy side. During operation, the incidence of type 1 respiratory failure was 5.4% (P=0.023) and that of both type 1 and 2 respiratory failure were 6.5% (P=0.013). Pain was relieved in 6 hours after surgery (VAS<3). At 12 hours after operation, the VAS of resting and motion were 4.68±2.27, 6.90±2.43, respectively. While the grade of muscle strength was 4.48±0.51 at 12 hours after operation. Conclusions : There is a high incidence of pulmonary edema in shoulder arthroscopy, and ultrasound is an convenient tool to evaluate this complication . Pain is relieved in 6 hours after surgery by nerve block. While muscle strength can also recover at 12 hours after surgery.