BACKGROUND: To visualize adequately the intrathoracic structures, creation of an artificial pneumothorax by carbon dioxide (CO2) insufflation under positive pressures has been advocated during thoracoscopic surgery. We hypothesized that positive-pressure insufflation during thoracoscopy would cause significant hemodynamic and ventilatory compromise. METHODS: Thirty patients underwent general anesthesia with a single lumen endotracheal tube and placement of an arterial line. Noninvasive cardiac output monitoring was done on both the side of the neck and chest. Baseline measurements of hemodynamic indices and arterial blood gas analysis (ABGA) were taken before CO2 insufflation. Data was obtained at 5 minutes after CO2 insufflation. ABGA was taken 5 minutes after CO2 deflation. RESULTS: Insufflation of CO2 resulted in an increase in heart rate (HR), mean arterial pressure (MAP), and systemic vascular resistance index (SVRI). Whereas cardiac index (CI), accelerated contractility index (ACI), PH, and arterial oxygen saturation (SaO2) were decreased. CONCLUSIONS: Positive pressure insufflation of CO2 during thoracoscopy resulted in hemodynamic and arterial blood gas changes. Therefore, we propose that low pressure (< 10 mmHg) insufflation is a safe adjunct to routine thoracoscopic surgical procedures.