A: An intraoperative photo shows a schematic diagram of the new technique. If the covering film becomes convex this suggests that there is positive pressure in the thoracic space. B: A diagram showing the intraoperative view of (A). C: At the end of the procedure, if the transparent film has re-entered the inner side, this suggests the presence of negative pressure in the thoracic space (C). D: A diagram showing the intraoperative view of (C).