Mini-fluid challenge to predict fluid responsiveness measured by Vigileo FloTrac.

Carlos Moreno, Sandra Beltrán de Heredia, Felipe Unigarro, Laia Bosch, Laura Castelltort, Carlos A García-Bernedo
Anesthesiology Department. Hospital del Mar (PSMAR). Barcelona

Background and objective of study:
Fluid challenge (FC) is a test that allows the physician to assess fluid responsiveness1. Classical FC is defined as a fluid administration of 300-500 mL in 30 minutes. Fluid responsiveness is defined as an increase in systolic volume greater than 10% after a FC. An increase in aortic blood flow measured by transthoracic echocardiography (TTE) after an infusion of 100 mL colloid (mini-FC) can predict fluid responsiveness2. Our objective was to determine if the administration of 100ml can predict fluid responsiveness measuring the stroke volume index (SVI) with Vigileo FloTrac.

Materials and methods:
A prospective study was conducted in our institution during the past year, (February–December 2016). Inclusion criteria was: patients admitted to the surgical intensive care unit (SICU) with clinical diagnosis of septic or hypovolemic shock; we excluded patients with history of cardiac arrhythmias, valvular heart disease or severe ventricular dysfunction.
SVI was measured by the Vigileo FloTrac system before infusion of fluids (baseline), after 100 ml (1 min), 300 ml (15 min) and 500 ml (15 min) of colloidal infusion (gelatin of Gelofusine). Patients were considered to be fluid responders when SVI increase> 10% from baseline. We used gelafundin 4% to perform the FC.
SVI changes in each dose stage (100, 300 and 500 ml) from baseline were compared using the McNemar test.
Patients treated with vasopressors drugs (norepinephrine) were included but no change in drug dose was made during fluid test.

Results and Discussion:
Twenty two critically ill patients were included: mean age was 73.8 years (SD+/- 9.2), 60% male; shock etiology was: 45.5% septic and 54.5% hypovolemic. 14 patients (63.3%) were receiving norepinephrine (mean dose 0.3 micg/kg*min, SD +/- 0.4).
There were no significant differences in patient characteristics, tidal volume or plateau pressure (VT >8 ml / kg, <13 ml / kg, plateau pressure <8cmH20).
Mean SVI at baseline was 28.8 mL (SD +/- 6.9), 31 mL (SD +/- 7.1) after 100 mL, 33 mL (SD +/- 7.1) after 300 mL and 34 mL (SD +/- 8) after 500 mL.
SVI increase >10% from baseline after a mini-FC predicted and increase of SVI >10% after a classical FC of 500 mL but not after 300 mL (p=0.0143, p=0.1797 respectively). SVI increase >10% had a positive predictive value of 100% but just a negative predictive value of 54% to predict fluid responsiveness after a classical FC.
The mini-FC approach monitoring SVI measured by Vigileo FloTrac could detect fluid responders but a negative mini-FC might be carefully interpreted. High dose of vasopressors in our population could be a potential source of errors3. Another limitation of our study is the small sample included.

1-Maurizio Cecconi, Anthony K. Parsons and Andrew Rhodes; What is a fluid challenge? Curr Opin Crit Care. 2011 Jun;17 (3):290-5.
2- Muller L1, Toumi M, Bousquet PJ, Riu-Poulenc B, Louart G, Candela D, Zoric L, Suehs C, de La Coussaye JE, Molinari N, Lefrant JY; AzuRéa Group.  An Increase in Aortic Blood Flow after an Infusion of 100 ml Colloid over 1 Minute Can Predict Fluid Responsiveness.  Anesthesiology. 2011 Sep;115(3): 54 1-7.
3- Monnet X, Anguel N, Jozwiak M, Richard C, Teboul J-L. Third-generation FloTrac/Vigileo does not reliably track changes in cardiac output induced by norepinephrine in critically ill patients. Br J Anaesth. 2012 Apr; 108(4):615-622.


11 / Mini-fluid challenge to predict fluid responsiveness measured by Vigileo FloTrac.