Predicting Fluid Responsiveness Using Pulse Pressure Variation after Tidal Volume Challenge in Postoperative Patients Receiving Lung Protective Ventilation: A Clinical Trial

Abstract Background: Lung protective ventilation with low tidal volume is beneficial in patients with intermediate to high risk of postoperative pulmonary complications. However, during low tidal volume ventilation, pulse pressure variation (PPV) and stroke volume variation (SVV) do not predict fluid responsiveness. We aimed to determine whether changes in PPV and SVV after transient increases in tidal volume can predict fluid responsiveness in these patients. Methods: We recorded 22 measurements from 15 patients who experienced postoperative acute circulatory failure. We performed a tidal volume challenge by transiently increasing tidal volume (VT) from 6 to 8 mL/kg (VT6–8), 8 to 10 mL/kg (VT8–10), and 6 to 10 mL/kg (VT6–10) of patients' predicted body weight. The change in PPV (∆PPV) at VT6–8 (∆PPV6–8), VT8–10 (∆PPV8–10), VT6–10 (∆PPV6–10) and the change in SVV (∆SVV) at VT6–8 (∆SVV6–8), VT8–10 (∆SVV8–10), and VT6–10 (∆SVV6–10) were recorded. Patients were classified as fluid responders if there was an increase in stroke volume of more than 10% after a fluid bolus. Results: Following the tidal volume challenge, ∆PPV and ∆SVV failed to predict fluid responsiveness, with areas under the receiver operating characteristic curves (with 95% confidence intervals) of 0.49 (0.23–0.74), 0.54 (0.29–0.79), 0.52 (0.28–0.77) for ∆PPV6–8, ∆PPV8–10, and ∆PPV6–10, and 0.55 (0.30–0.80), 0.55 (0.31–0.80), and 0.59 (0.34–0.84) for ∆SVV6–8, ∆SVV8–10, and ∆SVV6–10, respectively. Conclusions: Changes in PPV and SVV after the tidal volume challenge did not predict fluid responsiveness in postoperative patients with low tidal volume ventilation. Trial registration: This trial was registered with Clinicaltrials.in.th, TCTR20190808003.