Positive Intrapleural Pressure with Carbon Dioxide May Limit Intraoperative Pulmonary Arterial Bleeding: Verification by Animal Model

Purpose: Intraoperative complications, especially unexpected bleeding, are of great concern in the safety of thoracoscopic surgery. We investigated the hemostatic efficacy and safety of positive intrapleural pressure (PIP) with carbon dioxide insufflation by assessing the amount of blood loss in a pulmonary arterial hemorrhage model.Methods: An ex vivo experimental model of saline flow into a swine vessel was created in a container simulating a chest cavity. From the results, in vivo experiments (swine model) were conducted to compare the pulmonary arterial bleeding volume while applying PIP.Results: In the ex vivo experiment, regardless of the incision type, the outflow volumes did not significantly differ at flow pressures of 20, 30, and 40 mmHg. At each flow pressure, the outflow volumes at 10, 15, and 20 mmHg of positive pressure in the container were significantly smaller than those of the control (p = 0.027, p = 0.002, and p = 0.005, respectively). Similarly, the in vivo experiments showed that bleeding decreased as intrapleural pressure increased (slope = −0.22, F = 55.13, p