“…The exact pathogenetic mechanism for the entry of the air, in shoulder arthroscopy, is not clearly known. Nevertheless, it can be considered, that the transitional changes of the pressure emerged in the subacromial space throughout the whole invasive procedure, compared to the atmospheric pressure, facilitate the entry of the air through the lateral portals, causing possible injury to the pleura in association with the invasive handlings, thus leading to pneumothorax occurrence [21][22][23]. During the arthroscopic technique, the subacromial space is dilated, due to pressure exerted from the injected fluid with the use of an infusion pump, in order to establish a good field of view and most important an appropriate working space.…”