Titration of continuous positive airway pressure by real-time dual oximetry

The clinical utility of combined pulse and pulmonary artery oximetry (dual oximetry) in titrating continuous positive airway pressure (CPAP) therapy was tested in 17 patients with acute respiratory failure. The level of CPAP was altered in 2.5 cmH2O increments and decrements, while conventional measurements of cardiopulmonary function and continuous dual oximetry were performed. Then, optimum CPAP levels were selected using both techniques independently. The difference in optimum CPAP determined by the two methods was 0 cmH2O in ten of 17 patients, less than or equal to 2.5 cmH2O in 14 of 17 patients, and 5.0 to 7.5 cmH2O in the remaining three patients. When a difference existed, CPAP level determined with dual oximetry was consistently lower than the level selected by conventional means. The results indicate that the estimates of venous admixture and oxygen utilization coefficient obtained using dual oximetry provide sufficient information for rapid and accurate titration of CPAP in the majority of patients with acute respiratory failure.