Hemodynamic effects of carbon dioxide insufflation under single-lung ventilation during thoracoscopy

Background. The hemodynamic effects of carbon dioxide insufflation under single-lung ventilation were studied in 22 consecutive thoracoscopic harvests of the left internal mammary artery, which was used for minimally invasive coronary artery bypass grafting. Methods. An electrocardiograph, arterial catheter, Swan-Ganz catheter, and transesophageal echocardiograph were used to monitor seven hemodynamic variables. Baseline data were obtained during ventilation of both lungs and the measurements were repeated after the left lung was collapsed and at 5 and 30 minutes after hemithorax insufflation with low-flow (2 to 3 L/minute) carbon dioxide gas was begun. The intrapleural pressure was maintained at 8 to 10 mm Hg. Results. Thoracoscopic harvest of the internal mammary artery was completed in all cases with a mean insufflation time of 44 ± 12 minutes. There were no significant changes in the mean arterial pressure, heart rate, cardiac index, and left ventricular ejection fraction throughout the procedure, whereas the central venous pressure, mean pulmonary arterial pressure, and pulmonary capillary wedge pressure (p< 0.05 for each variable) during insufflation. Conclusions. Low-flow carbon dioxide insufflation into the left hemithorax with an intrapleural pressure of 8 to 10 mm Hg under selective right-lung ventilation does not compromise the human heart with normal to moderately depressed function and can be an efficacious adjunct in specific thoracoscopic procedures.