Novel parameters for predicting fluid responsiveness during the mini fluid challenge and ability of the cardiac power index: an observational cohort study

Background/aim: The percentage change in the stroke volume index (SVI) due to the mini fluid challenge (MFC) (MFC-ASVI%) used commonly in daily practice. However, up to 20% of patients remain in the gray zone of this variable. Thus, it was aimed to compare the MFC-ASVI% and the percentage change in the cardiac power index (CPI) due to the MFC (MFC-ACPI%) with the baseline values of the pulse pressure variation (PPV) and stroke volume variation (SVV) in terms of their abilities to predict fluid responsiveness.Materials and methods: The SVI, CPI, SVV, and PPV were recorded before 100 mL of isotonic saline was infused (MFC), after MFC was completed, and after an additional 400 mL of isotonic saline was infused to complete 500 mL of fluid loading (FL). Patients whose SVI increased more than 15% after the FL were defined as fluid responders.Results: Sixty-seven patients completed the study and 35 (52%) of them were responders.The areas under the receiver operating characteristics curves for the MFC-ASVI% and MFC-ACPI% (0.94; 95% CI: 0.86-0.99 and 0.89; 95% CI: 0.79-0.95, respectively) were significantly higher than those for the SVV and PPV (0.63; 95% CI: 0.50-0.75 and 0.55; 95% CI: 0.42-0.67, respectively) (p < 0.001 for all of the comparisons). The gray zone analysis revealed that the MFC-ASVI% values of 12 patients were in the gray zone. Of the 12, the MFC-ACPI% values of 7 patients were outside of the gray zone.Conclusion: Fluid responsiveness can be predicted more accurately using the MFC-ASVI% and MFC-ACPI% than using the SVV and PPV. Additionally, concomitant use of the MFC-ASVI% and MFC-ACPI% is recommended, as this approach diminishes the number of patients in the gray zone.