Background: Rapid prediction of the effect of volume expansion is crucial in unstable patients receiving mechanical ventilation. Both radial artery pulse pressure variation (ΔPP) and change of aortic blood flow peak velocity are accurate predictors but may be impractical point-of-care tools.
Purpose: We sought to determine whether respiratory changes in the brachial artery blood flow velocity (ΔVpeak-BA) as measured by internal medicine residents using a hand-carried ultrasound (HCU) device could provide an accurate corollary to ΔPP in patients receiving mechanical ventilation.
Methods: Thirty patients passively receiving volume-control ventilation with preexisting radial artery catheters were enrolled. The brachial artery Doppler signal was recorded and analyzed by blinded internal medicine residents using a HCU device. Simultaneous radial artery pulse wave and central venous pressure recordings (when available) were analyzed by a blinded critical care physician.
Results: A Doppler signal was obtained in all 30 subjects. The ΔVpeak-BA correlated well with ΔPP (r = 0.84) with excellent agreement (weighted κ, 0.82) and limited intraobserver variability (2.8 ± 2.8%) [mean ± SD]. A ΔVpeak-BA cutoff of 16% was highly predictive of ΔPP ≥ 13% (sensitivity, 91%; specificity, 95%). A poor correlation existed between the CVP and both ΔVpeak-BA (r = − 0.21) and ΔPP (r = − 0.16).
Conclusions: The HCU Doppler assessment of the ΔVpeak-BA as performed by internal medicine residents is a rapid, noninvasive bedside correlate to ΔPP, and a ΔVpeak-BA cutoff of 16% may prove useful as a point-of-care tool for the prediction of volume responsiveness in patients receiving mechanical ventilation.