Rapid, Non-Invasive Determination of Cardiac Output at Rest by CO2 Rebreathing Using a Computerized System: Application in Normal Adults and Patients with Cardiac Disease

In 1909 Pleschl described an indirect method for measuring mixed venous carbon dioxide tension (\(P\bar{v}\) CO2). Application of this technique led to the development of non-invasive determination of cardiac output (CO) by carbon dioxide rebreathing (CO2RB). Clinical utilization of this method, however, has been limited because of technical considerations: expired gas must be collected and analyzed; and various calculations, including correction formulas, are necessary2,3.