Brachial artery peak velocity variation to predict fluid responsiveness in mechanically ventilated patients

INTRODUCTION: Although several parameters have been proposed to predict the hemodynamic response to fluid expansion in critically ill patients, most of them are invasive or require the use of special monitoring devices. The aim of this study is to determine whether noninvasive evaluation of respiratory variation of brachial artery peak velocity flow measured using Doppler ultrasound could predict fluid responsiveness in mechanically ventilated patients. METHODS: We conducted a prospective clinical research in a 17-bed multidisciplinary ICU and included 38 mechanically ventilated patients for whom fluid administration was planned due to the presence of acute circulatory failure. Volume expansion (VE) was performed with 500 mL of a synthetic colloid. Patients were classified as responders if stroke volume index (SVi) increased ≥ 15% after VE. The respiratory variation in Vpeak(brach )(ΔVpeak(brach)) was calculated as the difference between maximum and minimum values of Vpeak(brach )over a single respiratory cycle, divided by the mean of the two values and expressed as a percentage. Radial arterial pressure variation (ΔPP(rad)) and stroke volume variation measured using the FloTrac/Vigileo system (ΔSV(Vigileo)), were also calculated. RESULTS: VE increased SVi by ≥ 15% in 19 patients (responders). At baseline, ΔVpeak(brach), ΔPP(rad )and ΔSV(Vigileo )were significantly higher in responder than nonresponder patients [14 vs 8%; 18 vs. 5%; 13 vs 8%; P < 0.0001, respectively). A ΔVpeak(brach )value >10% predicted fluid responsiveness with a sensitivity of 74% and a specificity of 95%. A ΔPP(rad )value >10% and a ΔSV(Vigileo )>11% predicted volume responsiveness with a sensitivity of 95% and 79%, and a specificity of 95% and 89%, respectively. CONCLUSIONS: Respiratory variations in brachial artery peak velocity could be a feasible tool for the noninvasive assessment of fluid responsiveness in patients with mechanical ventilatory support and acute circulatory failure. TRIAL REGISTRATION: ClinicalTrials.gov ID: NCT00890071