Prediction of Preload Responsiveness by the Change in Carotid Peak Velocity Variation with Tidal Volume Challenge

Background and Aims: Tidal volume (TV) challenge was shown to improve the reliability of pulse pressure variation (PPV) in predicting volume responsiveness. Carotid peak velocity (CPV) has similar potential to predict volume responsiveness. This study compared the performance of CPV and PPV in predicting volume responsiveness following a TV challenge. Methodology: In patients with haemodynamic instability, baseline CPV and PPV were measured at 6 ml/kg (CPV6 and PPV6) and 8 ml/kg TV (CPV8 and PPV8), and the changes (∆CPV (6–8) and ∆PPV (6–8)) were recorded. The TV was then reduced to 6 ml/kg. After fluid bolus (6 ml/kg), change in cardiac output (CO) measured with trans thoracic echocardiogram by more than 15% was considered volume response. Results: Among the 42 patients studied, the mean PPV6 and CPV 6 were 18.94 ± 5.61 and 76.40 ± 13, respectively, whereas mean PPV8 and CPV8 were 23 ± 6.06 and 79.86 ± 13.5. Mean ∆CPV (6–8) and ∆PPV (6–8) were 4.15 ± 1.4 and 3.61 ± 1.6. The absolute change in CPV and PPV after TV challenge predicted fluid responsiveness with AUROC (with 95% CIs) of 0.71 (95% CI: 0.55–0.88), and 0.84 (95% CI: 0.6–0.95), respectively. Conclusions: The prediction of volume responsiveness by change in CPV variation is similar to change in PPV following TV challenge.