Respiratory variations in aortic blood flow predict fluid responsiveness in ventilated children

Abstract

Objective: To investigate whether respiratory variations in aortic blood flow velocity (ΔVpeak ao), systolic arterial pressure (ΔPS) and pulse pressure (ΔPP) could accurately predict fluid responsiveness in ventilated children. Design and setting: Prospective study in a 18-bed pediatric intensive care unit. Patients: Twenty-six children [median age 28.5 (16-44) months] with preserved left ventricular (LV) function. Intervention: Standardized volume expansion (VE). Measurements and main results: Analysis of aortic blood flow by transthoracic pulsed-Doppler allowed LV stroke volume measurement and on-line ΔVpeak ao calculation. The VE-induced increase in LV stroke volume was > 15% in 18 patients (responders) and < 15% in 8 (non-responders). Before VE, the ΔVpeak ao in responders was higher than that in non-responders [19% (12.1-26.3) vs. 9% (7.3-11.8), p = 0.001], whereas ΔPP and ΔPS did not significantly differ between groups. The prediction of fluid responsiveness was higher with ΔVpeak ao [ROC curve area 0.85 (95% IC 0.99-1.8), p = 0.001] than with ΔPS (0.64) or ΔPP (0.59). The best cut-off for ΔVpeak ao was 12%, with sensitivity, specificity, and positive and negative predictive values of 81.2%, 85.7%, 93% and 66.6%, respectively. A positive linear correlation was found between baseline ΔVpeak ao and VE-induced gain in stroke volume (rho = 0.68, p = 0.001). Conclusions: While respiratory variations in aortic blood flow velocity measured by pulsed Doppler before VE accurately predict the effects of VE, ΔPS and ΔPP are of little value in ventilated children. © 2008 Springer-Verlag.