Assessment of Fluid Responsiveness in Prone Neurosurgical Patients Undergoing Protective Ventilation: Role of Dynamic Indices, Tidal Volume Challenge, and End-Expiratory Occlusion Test

Abstract

BACKGROUND: In patients in the prone position, the reliability of pulse pressure variation and stroke volume variation (PPV and SVV) and the use of functional hemodynamic tests to predict fluid responsiveness have not previously been established. Perioperatively, in this setting, optimizing fluid management can be challenging, and fluid overload is associated with both intraoperative and postoperative complications. We designed this study to assess the sensitivity and specificity of baseline PPV and SVV, the tidal volume (VT) challenge (VTC) and the end-expiratory occlusion test (EEOT) in predicting fluid responsiveness during elective spinal surgery. METHODS: The study protocol was started during a period of intraoperative hemodynamic stability after prone positioning and before the administration of any vasopressor: (1) at baseline, the controlled ventilation was set at 6 mL/kg of predicted body weight (PBW) (T 0); (2) patients underwent the first EEOT (EEOT6) by interrupting the mechanical ventilation for 30 seconds; (3) the ventilation was set again at 6 mL/kg PBW for 1 minute (T 1); (4) the VTC was applied by increasing the VT up to 8 mL/kg PBW for 1 minute; (5) the ventilation was kept at 8 mL/kg PBW for 1 minute (T 2); (6) a second EEOT (EEOT8) was performed; (7) the VT was reduced back to 6 mL/kg PBW for 1 minute (T 3); (8) a fluid challenge of 250 mL of Ringer’s solution was infused over 10 minutes. After each step, a complete set of hemodynamic measurements was recorded. RESULTS: Neither PPV and SVV values recorded at T 3 nor the EEOT6 or the EEOT8 predicted fluid responsiveness. The change in PPV after VTC application predicted fluid responsiveness with an area under the curve of 0.96 (95% confidence interval, 0.87–1.00), showing a sensitivity of 95.2% and a specificity of 94.7%, using a cutoff increase of 12.2%. The change in SVV after VTC application predicted fluid responsiveness with an area under the curve 0.96 (95% confidence interval, 0.89–1.00) showing a sensitivity of 95.2% and a specificity of 94.7%, using a cutoff increase of 8.0%. A linear correlation between stroke volume index changes after fluid challenge administration and the changes in PPV and SVV after VTC application was observed (r = 0.71; P < .0001 and r = 0.68; P < .0001, respectively). CONCLUSIONS: In prone elective neurosurgical patients, the baseline values of PPV and SVV and the EEOT fail to predict fluid responsiveness, while the VTC is a very reliable functional hemodynamic test and could be helpful in guiding intraoperative fluid therapy.

Assessment of Fluid Responsiveness After Tidal Volume Challenge During Pressure-Controlled Ventilation Volume Guaranteed: An observational study

“…Moreover, the AUCs of PPV 8 and SVV 8 are also lower than those in studies conducted in patients ventilated with the VCV mode. Nevertheless, it has been showed that the AUCs of ΔPPV 6 − 8 and ΔSVV 6 − 8 in this study were not signi cantly different with those in previous studies [26][27][28]. Simultaneously, the correlation between the ΔPPV 6 − 8 and ΔSVV 6 − 8 after the TVC application and ΔCI after FC administration ( Fig.…”

Update on the assessment of fluid responsiveness

“…Myatra et al [25] showed that the absolute changes in PPV and SVV induced by a tidal volume challenge were good predictors of fluid responsiveness, with AUCs of 0.99 and 0.97, respectively (threshold, PPV: 3.5%, SVV: 2.5%). In another recent study [26], the absolute changes in PPV and SVV after a tidal volume challenge showed acceptable predictabilities for fluid responsiveness, with high sensitivity and specificity even with patients in the prone position. Although the tidal volume challenge cannot be used in patients with spontaneous breathing, open-chest conditioning, or arrhythmia, this intervention can be a useful method to assess fluid responsiveness in the perioperative period under other circumstances.…”

PPV May Be a Starting Point to Achieve Circulatory Protective Mechanical Ventilation

“…The study also found that during the increase in VT, if the absolute value of PPV increases by ≥3.5%, the fluid responsiveness can be predicted quite accurately (AUROC curve, 0.99) ( 30 ). Messina et al ( 31 ) conducted a tidal volume challenge (TVC) in the prone position patients, that is, increasing the tidal volume from 6 to 8 ml/kg in a short period of time, and attempting to use pulse pressure variability and stroke volume variability to assess the fluid responsiveness of a patient. In addition, the studies have pointed out that when the PPV of a patient is >13%, the passive leg raising tests are performed.…”