Monitoring Variations in Stroke Volume Enables Precise Evaluation of Fluid Resuscitation in Patients with Septic Shock on Pressure Support Ventilation

Purpose: To determine whether stroke volume variation (SVV) is a useful indicator of fluid resuscitation in patients with septic shock on pressure support ventilation. Subjects: We assessed 37 patients with septic shock who were fitted with FloTrac sensors (Edwards Lifesciences Ltd., Tokyo, Japan), hospitalized between October 2011 and August 2013 and managed using pressure support ventilation. Methods: This is a prospective, observational, pilot study. Lactate (Lac), IVC diameter, IVC variation (ΔIVC), stroke volume index (SVI), and SVV (mean value at one hour) during initial fluid resuscitation were measured and the SVV value was continuously monitored. These parameters were measured again when the SVV curve decreased and flattened (stable SVV). Fluctuations in SVV during initial fluid resuscitation and stability were analyzed using fast Fourier transformation. Result: The mean values of Lac, IVC diameters, and SVV during initial fluid therapy vs. stable SVV were 6.0 vs. 1.8 mmol/L, 11 vs. 19 mm, and 18.6 vs. 8.8%, respectively (p < 0.001). Fluctuations in SVV curves calculated by fast Fourier transformation resulted in a Lorentzian spectrum. The amplitude of all curves peaked at a frequency of 0 and became significantly lower when SVV was stable than during fluid therapy (1.3% vs. 3.7%; p < 0.001). Conclusion: Continuous monitoring of SVV trends enables precise evaluation of fluid resuscitation in patients with septic shock on pressure support ventilation.