Non-invasive extended hemodynamic monitoring. Reduction of circulatory risk situations

Background. Cardiac output and the cardiac index (CI) are not routinely monitored during major abdominal surgery for economic as well as medical reasons. This practice, however, might be changed by the application of newer non-invasive technologies like the partial CO2 rebreathing method based on the inverse Fick's principle. In this prospective randomized study we investigated the impact of a non-invasive monitoring of CI on the incidence of hemodynamic instability and interventions by the attending anesthesiologist during major abdominal surgery. Patients and methods. Additionally to routine hemodynamic monitoring we measured CI using the partial CO2 rebreathing method in 28 patients (9 female, 19 male) undergoing major abdominal surgery. In group I the anesthesiologists were aware of the results of the extended hemodynamic monitoring and in group II the attending anesthesiologist was blinded to the information obtained by these measurements of CI. Results. Groups did not differ with regard to the baseline hemodynamic parameters. We obtained 923 measurements in both groups and 95 situations of hemodynamic instability (CI < 2.5 l/minxm(2)) were detected in group I compared to 147 situations in group II (p < 0.05). There were significantly more hemodynamic interventions in group I than in group II (p < 0.0001). The cardiac index remained higher in group I in comparison to group II (p < 0.0001). Measurement of CI was the only method to detect situations of hemodynamic instability in our setting. Conclusion. The incidence of hemodynamic instability was significantly reduced during major abdominal surgery when anesthesiologists were aware of the measurement results of extended hemodynamic monitoring.