Low-flow anaesthesia with desflurane: kinetics during clinical procedures

Area of Science:

• Anesthesiology
• Pharmacokinetics
• Respiratory Physiology

Background:

• Low-flow anesthesia offers economic and environmental benefits.
• Desflurane is a volatile anesthetic agent used in various surgical procedures.
• Optimizing anesthetic delivery is crucial for patient safety and resource management.

Purpose of the Study:

• To determine inspired and end-tidal desflurane concentrations.
• To evaluate these concentrations during low-flow anesthesia.
• To assess the impact of fresh gas inflows (1.0 and 2.0 L/min) with a fixed vaporizer setting (5%).

Main Methods:

• Prospective, randomized study with 56 patients.
• Patients underwent elective surgery with expected anesthesia duration of at least 120 minutes.
• Inspired and end-tidal desflurane concentrations were measured at fixed fresh gas flows and vaporizer settings.

Main Results:

• Significant differences (P < 0.001) were observed between inspired and end-tidal desflurane concentrations in both 1.0 L/min (4.54% vs. 4.37%) and 2.0 L/min (4.76% vs. 4.58%) groups.
• End-tidal/inspired ratios were consistently high (0.96) at 120 minutes.
• Higher fresh gas flow (2.0 L/min) resulted in a higher end-tidal concentration (0.87 of vaporizer setting at 1.0 L/min, increasing by 0.05 at 2.0 L/min).

Conclusions:

• Significant differences exist between inspired and end-tidal desflurane concentrations at 1.0 and 2.0 L/min fresh gas flows.
• The ratio of inspired to end-tidal concentrations remained consistent across tested flows.
• Findings provide insights into desflurane pharmacokinetics under low-flow anesthesia conditions.