## 4 Discussion  
With the advancement of surgical techniques and equipment, VATS surgery can be easily adapted for the management of PSP. Despite the use of minimally invasive incisions, the field of anesthesia still aims to further minimize the damage to patients during a surgery. There are many studies comparing methods of anesthesia, specifically comparing GA with a double-lumen endotracheal tube with epidural anesthesia [2; 11; 12; 13]. However, there have only been a few studies comparing postoperative clinical outcomes in patients with pneumothorax who underwent surgery under general and local anesthesia [10]. This study reviewed many variables to compare postoperative clinical outcomes in patients who underwent surgery for PSP under GA and LA at our center. The surgical technique was more or less similar between the two groups: wedge resection of blebs was done with shallow shaving so as not to have excessive tension in the resection area, followed by visceral coverage using Neoveil@with glue. However, intraoperative management should be different for the two groups; in the case of GA, the exposed lung can be expanded by the anesthesiologist whenever required (if oxygen saturation decreases or if vital signs become unstable). However, with LA, the gradually collapsed lung cannot be expanded, even in a critical situation, unless the incision is sealed. Then, locking ports with valves at the entrance (usually used in laparoscopic surgery) need to be placed--which could make the lung expand due to the negative pressure through the ports at the end of the operation. In the study reported here, we did not perform mechanical or chemical pleurodesis after resection, since mechanical pleurodesis could lead to bleeding and chest pain and chemical pleurodesis could cause acute lung injury due to pulmonary dissemination of talc particles. Recent studies have shown that pneumothorax generally occurs in visceral pleural lesions and that visceral strengthening should be aimed for to prevent recurrence, rather than adhesion between visceral and parietal pleura. Furthermore, mechanical or chemical pleurodesis was not preferable for reducing postoperative pain. Performing thoracic surgery under LA can induce iatrogenic pneumothorax, resulting in desaturation, or, due to the manipulation of the lung parenchyma, activate the cough reflex--both of which increase the difficulty of the procedure by impeding easy manipulation. Therefore, unnecessary manipulation of the lung tissue should be minimized. It follows that planning ahead is important, using preoperative chest CT images to locate the blebs and plan the placement of ports. The total duration of hospital stay was significantly shorter for the LA group than for the GA group--a result of the decreased time interval from admission to operation and operation to discharge. The interval between admission and operation was short because surgery under LA is the easiest way to arrange the schedule in our center. The interval between operation and discharge was significantly shorter for the LA group than for the GA group, which made a difference to the total duration of hospital stay. The duration of postoperative chest tube drainage especially was relatively shorter in the LA group than in the GA group and could be predicted from early independent ambulation and lung rehabilitation and early cessation of postoperative air leakage. Reviewing the relationships between the clinical outcomes and the perioperative findings shows that the recurrence rate was significantly lower in cases operated upon with local anesthesia. There was no correlation between the various operative techniques, the operative time, or the length of resected lung parenchyma and the rate of recurrence. However, we hypothesize that some differences between the two groups during lung expansion had an impact on the rate of recurrence; this hypothesis is based on several articles that have shown that the neogenesis of bullae causes recurrences of the pneumothorax.