The Cardiopulmonary Effects of Single-Lung Ventilation and Carbon Dioxide Insufflation During Thoracoscopic Internal Mammary Artery Harvesting

Abstract

Background: Thoracoscopic internal mammary artery harvesting has become an integral part of minimally invasive coronary artery bypass operations. The technique involves the use of single-lung ventilation and carbon dioxide insufflation to maximize exposure and facilitate rapid dissection. The hemodynamic and pulmonary effects of this technique have not been extensively studied.
Methods: Seventy-five consecutive patients undergoing a minimally invasive coronary artery bypass operation were prospectively studied intra-operatively. Sixty-six left and nine right thoracoscopic IMA harvests were performed in patients with ejection fractions ranging from 12 to 70%. Carbon dioxide insufflation was utilized in the range of 8 to 12mm Hg and the effects on cardiovascular and pulmonary performance were recorded to disk every sixty seconds.
Results: Carbon dioxide insufflation in combination with single-lung ventilation increases central venous pressure and pulmonary artery pressure. At higher levels of insufflation pressure, negative effects are seen on systemic blood pressure, cardiac output and left ventricular stroke work. These effects can be aggravated by hypovolemia and a poor preoperative left ventricular ejection fraction.
Conclusions: Single-lung ventilation and carbon dioxide insufflation greatly enhances the technical ease of thoracoscopic internal mammary artery harvest. While safe in the majority of patients, CO2 insufflation should be used cautiously in hypovolemic patients and patients with poor left ventricular function.