Tidal volume challenge to predict fluid responsiveness in the operating room: An observational study

Area of Science:

• Critical care medicine
• Anesthesiology
• Cardiovascular physiology

Background:

• Pulse pressure variation (PPV) and stroke volume variation (SVV) are unreliable for predicting fluid responsiveness during protective ventilation strategies.
• Functional hemodynamic tests are necessary to overcome the limitations of traditional methods.

Purpose of the Study:

• To evaluate the efficacy of a tidal volume challenge (VTC) and the end-expiratory occlusion test (EEOT) in predicting fluid responsiveness.
• To assess these functional hemodynamic tests in neurosurgical patients undergoing protective ventilation.

Main Methods:

• An interventional prospective study was conducted on supine elective neurosurgical patients.
• The protocol involved baseline EEOT, VTC with increased tidal volume (8ml/kg PBW), a second EEOT, and fluid challenge administration.
• Changes in PPV, SVV, cardiac index (CI), and stroke volume index (SVI) were recorded.

Main Results:

• PPV and SVV at baseline and during 6ml/kg PBW ventilation did not predict fluid responsiveness.
• A 13.3% increase in PPV after VTC predicted fluid responsiveness with 94.7% sensitivity and 76.1% specificity.
• EEOT at 8ml/kg PBW showed a 3.6% increase in CI (89.4% sensitivity, 85.7% specificity) and a 4.7% increase in SVI (89.4% sensitivity, 85.7% specificity) predicted fluid responsiveness.

Conclusions:

• Changes in PPV and SVV after VTC reliably predict fluid responsiveness.
• These VTC-derived changes are comparable to CI and SVI changes from EEOT at 8ml/kg PBW.
• Both VTC and EEOT at higher tidal volumes are effective in predicting fluid responsiveness in neurosurgical patients.