Point-of-care ultrasound for the prediction of fluid responsiveness in off-pump coronary artery bypass grafting surgery: a comparison between carotid Doppler peak systolic velocity and inferior vena cava distensibility index: a prospective observational trial.

Abstract

Background: Evidence remains inconclusive regarding the ability of the inferior vena cava (IVC) distensibility index and common carotid Doppler flow velocity parameters to predict fluid responsiveness before off-pump cardiac surgery. Therefore, we sought to evaluate the relationship between the IVC distensibility index, common carotid Doppler flow velocity parameters, and fluid responsiveness during off-pump coronary artery bypass surgery. Methods: In this prospective observational study conducted at Ain Shams University Hospitals (Cardiothoracic Academy), 30 adult patients (ejection fraction > 45%) scheduled for off-pump coronary artery bypass surgery after an 8-h fasting period were enrolled. Following induction of anesthesia, a fluid challenge of 5 ml/kg crystalloid was administered. Hemodynamic variables (mean arterial pressure, heart rate, central venous pressure, IVC distensibility index, common carotid Doppler peak velocity, and transthoracic cardiac output [CO]) were recorded before and after fluid loading. An increase in CO of > 15% after the fluid challenge indicates fluid responsiveness. Results: Sonographic measurements demonstrated statistically significant changes in CO following fluid loading. However, neither the change in the IVC distensibility index (ΔIVC) nor the change in carotid Doppler peak systolic velocity (ΔVpeakCCA) demonstrated adequate discriminatory ability to differentiate fluid responders from non-responders in this cohort. Conclusions: Point-of-care ultrasound parameters, including the IVC distensibility index and carotid Doppler velocity, showed limited value for predicting fluid responsiveness in off-pump cardiac surgery and, therefore, should not be used in isolation to guide perioperative fluid administration.