Reliable noninvasive parameters for early detection of cardiopulmonary compromise induced by carbon dioxide thoracoretroperitoneum in minimally invasive thoracolumboendoscopic spine surgery

Background: Using a novel endoscopic retroperitoneal approach for thoracolu mbar anterior spine fusion, we examined the cardiopulmonary effects of the inevitably associated carbon dioxide (CO2) thoracoretroperitoneum and evalu ated noninvasive parameters, which may provide early and adequate recogniti on of cardiopulmonary dysfunction. Methods: Under balanced anesthesia and paralysis, six pigs subjected to end oscopic CO2 thoracoretroperitoneal spine fusion underwent extensive pulmona ry and hemodynamic online monitoring throughout the operative procedure. Op en thoracophrenolumbotomy in six pigs served as a control procedure. Results: In contrast to unchanged cardiopulmonary parameters during open th oracolumbar spine surgery, CO2 rhoracoretroperitoneum caused significant hy percapnia, hypoxia, and acidemia with concomitant tachycardia, pulmonary hy pertension, and systemic hypotension. Ventilatory adjustment, CO2 evacuatio n, or both promptly reversed the cardiopulmonary effects. Noninvasively ass essed end-tidal CO2, peak respiratory pressure, and heart rate were early c lues for detecting the tension pneumothorax-like cardiopulmonary dysfunctio n, as indicated by a significant correlation with the invasively assessed p ulmonary hemodynamic parameters and arterial blood gases. Conclusions: During endoscopic thoracolumbar spine fusion, CO2 thoracoretro peritoneum induces cardiopulmonary dysfunction, which, however, can be dete cted reliably by changes in end-tidal CO2, peak respiratory pressure, and h eart rate, and which can be corrected immediately by appropriate ventilator y adjustments. Therefore, endoscopic CO2 thoracoretroperitoneal spine fusio n might not necessarily require extraordinarily extensive and invasive moni toring of systemic and pulmonary hemodynamics, but ventilatory adjustment a nd intrathoracic pressure evacuation should be readily available to reexpan d the lung, and to facilitate rapid normalization of hemodynamic conditions .