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

Area of Science:

• Anesthesiology
• Critical Care Medicine
• Cardiovascular Physiology

Background:

• Traditional preoperative fasting protocols aimed to prevent hemodynamic instability.
• Recent evidence challenges the necessity of prolonged fasting, suggesting potential for restrictive fluid management.
• The precise hemodynamic impact of preoperative fasting remains debated.

Purpose of the Study:

• To investigate the hemodynamic effects of preoperative fasting on fluid status and preload.
• To evaluate the reliability of dynamic preload indices in assessing fluid responsiveness.

Main Methods:

• Observational, prospective, longitudinal study involving 31 ASA 1 and ASA 2 volunteers.
• Echocardiographic examinations performed before and after a minimum 6-hour fasting period.
• Comparison of static and dynamic preload indices, including aortic velocity time integral (VTI) variation with passive leg raise.

Main Results:

• Static preload indices showed high variability with fasting.
• Dynamic preload indices demonstrated consistency, indicating no significant change in preload.
• Aortic VTI variation with passive leg raise was the most reliable indicator of preload responsiveness.

Conclusions:

• Preoperative fasting does not significantly alter preload or position on the Frank-Starling curve in conscious volunteers.
• Transaortic VTI variation during passive leg raise is a robust dynamic index for preload responsiveness in spontaneously breathing patients.