Respirophasic carotid artery peak velocity variation as a predictor of fluid responsiveness in mechanically ventilated patients with coronary artery disease.

BACKGROUND: We studied respirophasic variation in carotid artery blood flow peak velocity (ΔVpeak-CA) measured by pulsed wave Doppler ultrasound as a predictor of fluid responsiveness in mechanically ventilated patients with coronary artery disease.

METHODS: Forty patients undergoing elective coronary artery bypass surgery were enrolled. Subjects were classified as responders if stroke volume index (SVI) increased ≥15% after volume expansion (6 ml kg(-1)). The ΔVpeak-CA was calculated as the difference between the maximum and minimum values of peak velocity over a single respiratory cycle, divided by the average. Central venous pressure, pulmonary artery occlusion pressure, pulse pressure variation (PPV), and ΔVpeak-CA were recorded before and after volume expansion.

RESULTS: PPV and ΔVpeak-CA correlated significantly with an increase in SVI after volume expansion. Area under the receiver-operator characteristic curve (AUROC) of PPV and ΔVpeak-CA were 0.75 [95% confidence interval (CI) 0.59-0.90] and 0.85 (95% CI 0.72-0.97). The optimal cut-off values for fluid responsiveness of PPV and ΔVpeak-CA were 13% (sensitivity and specificity of 0.74 and 0.71) and 11% (sensitivity and specificity of 0.85 and 0.82), respectively. In a subgroup analysis of 17 subjects having pulse pressure hypertension (≥ 60 mm Hg), PPV failed to predict fluid responsiveness (AUROC 0.70, P=0.163), whereas the predictability of ΔVpeak-CA remained unchanged (AUROC 0.90, P=0.006).

CONCLUSIONS: Doppler assessment of respirophasic ΔVpeak-CA seems to be a highly feasible and reliable method to predict fluid responsiveness in mechanically ventilated patients undergoing coronary revascularization.

CLINICAL TRIAL REGISTRATION: NCT 01836081.