[Does fasting influence preload responsiveness in ASA 1 and 2 volunteers?]

Area of Science:

• Anesthesiology
• Critical Care Medicine
• Cardiovascular Physiology

Background:

• Traditional views linked preoperative fasting to fluid depletion and potential hemodynamic instability.
• Recent evidence challenges this, suggesting a more restrictive fluid management approach.
• Uncertainty persists regarding the actual hemodynamic impact of preoperative fasting.

Purpose of the Study:

• To investigate the hemodynamic effects of preoperative fasting.
• To evaluate changes in preload indices before and after fasting.
• To assess the reliability of dynamic preload indices in spontaneously breathing patients.

Main Methods:

• Observational, analytic, prospective, longitudinal study.
• 31 ASA 1 and ASA 2 volunteers underwent echocardiography before and after ≥6h fasting.
• Static and dynamic preload indices were measured and compared.

Main Results:

• Static preload indices showed high variability with fasting.
• Dynamic preload indices remained consistent, showing no significant change.
• Aortic velocity time integral (VTI) variation during passive leg raise reliably indicated preload changes.

Conclusions:

• Preoperative fasting does not significantly alter preload or Frank-Starling curve position in conscious volunteers.
• Transaortic VTI variation with passive leg raise is a robust dynamic index for preload responsiveness.
• Findings support current recommendations for preoperative fasting duration.