Hemodynamic responses to intrapleural insufflation with hemipulmonary collapse

Background: The hemodynamic effects of carbon dioxide (CO2) insufflation wi th hemipulmonary collapse were studied in consecutive thoracoscopic harvest s of the left or right internal mammary artery (IMA), which were used for v ideo-assisted coronary artery bypass grafting. Methods: Thirty-eight patients (30 male, eight female) with a mean age of 6 9.5 +/- 11.5 years were selected, and 33 left and five right IMA were harve sted thoracoscopically. After hemipulmonary collapse was established by sin gle-lung ventilation, low-flow (2-3 L/min) CO2 was delivered at a constant intrapleural pressure of 8-10 mmHg. Using electrocardiography, a radial art erial catheter, a Swan-Ganz catheter, and transesophageal echocardiography, we obtained values for seven hemodynamic variables. Baseline data were col lected during bilateral lung ventilation. Each variable was then measured d uring hemipulmonary collapse and insufflation. The significance of any chan ges was established with Student's t-test after correcting for baseline dif ferences. Results: Insufflation facilitated IMA harvest by expanding the pleural spac e between the anterior chest wall and heart. Mean insufflation times were 4 0.8 +/- 12.2 min on the left and 33.5 +/-8.5 min on the right. Significant increases from the baseline values were observed in the mean central venous pressure (L:4.7-9.0 mmHg, R: 5.1-14.0 mmHg, p<0.05), the pulmonary arteria l pressure (L: 11.3-17.3 mmHg, R: 12.1-19.9 mmHg, p<0.05), and the pulmonar y capillary wedge pressure (L: 7.2-10.5 mmHg, R: 6.5-10.0 mmHg, p <0.05). O n the right, but not on the left, slight decreases were noted in the mean a rterial pressure and cardiac index (71.3-62.6 mmHg, 2.01-1.76 L.min(-1).M-2 , p<0.05). Conclusions: The hemodynamic effect resulting from one-lung collapse plus l ow-flow CO, insufflation at 8-10 mmHg for 30-40 min is mild in both hemitho races, although the impact is greater on the right.