Minimal fixed flow anesthesia for off-pump coronary artery bypass surgery: A parallel randomized trail

Area of Science:

• Anesthesiology
• Cardiovascular Surgery
• Respiratory Physiology

Background:

• Off-pump coronary artery bypass grafting (OPCABG) requires careful anesthetic management.
• Maintaining adequate oxygenation is critical during OPCABG procedures.
• Fixed minimal fresh gas flow (FGF) anesthesia is being explored as an efficient method.

Purpose of the Study:

• To evaluate the safety and efficacy of fixed minimal FGF anesthesia (0.5 L/min) for oxygenation during OPCABG.
• To compare the use of pure oxygen versus an oxygen-air mixture (FiO2 0.8) as carrier gas.
• To identify patient factors influencing oxygenation during minimal FGF anesthesia.

Main Methods:

• A randomized, prospective, single-center study involving 208 patients undergoing OPCABG.
• Patients received endotracheal inhalational anesthesia with fixed minimal FGF.
• Anesthesia was induced with either sevoflurane or isoflurane, with carrier gas being pure oxygen or an oxygen-air mixture (FiO2 0.8).

Main Results:

• In the trial groups using an oxygen-air mixture, inhaled oxygen concentration dropped below 0.4 in 28.8% of cases.
• Body surface area (BSA) and patient age were significant predictors of low oxygen concentration.
• Patients with BSA > 2.3 m² had a significantly higher risk of inadequate oxygenation (Exp(B) = 183).

Conclusions:

• Fixed minimal FGF anesthesia with an oxygen-air mixture (FiO2 0.8) may be insufficient for patients with larger BSA (>2.0 m²).
• Using pure oxygen as the carrier gas with fixed minimal FGF is a safer and more reliable method for maintaining oxygenation.
• Anesthetic protocols should consider patient BSA to ensure adequate oxygenation during minimal FGF anesthesia in OPCABG.