Changes in Respiratory Variation of Velocity-Time Integral and Peak Velocity of Left Ventricular Outflow Tract after Tidal Volume Challenge Predict Fluid Responsiveness in Elderly Patients with Low Tidal Volume Ventilation: A Prospective Observational Study.

Objective: We hypothesized that changes in respiratory variation of velocity-time integral (ΔVTI) and peak velocity (ΔVpeak) of left ventricular outflow tract after tidal volume challenge (TVC) better predict fluid responsiveness in elderly patients with low tidal volume ventilation.

Design: A prospective observational study.

Setting: A tertiary teaching hospital.

Participants: Ninety-six critically ill elderly patients without arrhythmias under mechanical ventilation were enrolled in this study.

Interventions: TVC was performed by increasing the tidal volume from 6 to 8 mL/kg of predicted body weight. Passive leg raising was performed to identify fluid responders (increase in stroke volume >10%).

Measurement and main results: Pulse pressure variation (PPV), ΔVTI, and ΔVpeak were measured before and 1 minute after TVC. Receiver operating characteristic curves and gray zones were used to assess the ability of changes in PPV (ΔPPV_TVC), ΔVTI (ΔVTI_TVC), and ΔVpeak (ΔVpeak_TVC) after TVC to predict fluid responsiveness. The mean age was 75 years, and 75% were male. Forty-five (46.9%) patients were the responders. The area under the receiver operating characteristic curves for ΔPPV_TVC to predict fluid responsiveness was 0.89 (95% confidence interval 0.82-0.95, p < 0.001), including 43.8% of patients in the gray zone. ΔVTI_TVC and ΔVpeak_TVC predicted fluid responsiveness with AUCs of 0.96 (95% CI 0.90-0.99, p < 0.001) and 0.94 (95% CI 0.87-0.98, p < 0.001), including 11.5% and 19.8% of patients in the gray zones, respectively.

Conclusion: In elderly patients with low tidal volume ventilation, ΔVTI_TVC and ΔVpeak_TVC predicted fluid responsiveness accurately and better than ΔPPV_TVC.