Low-flow anaesthesia with a fixed fresh gas flow rate

Area of Science:

• Anesthesiology
• Pharmacology

Background:

• Traditional low flow anesthesia (LFA) uses high fresh gas flow during the wash-in period to achieve target anesthetic concentrations.
• This study investigates an alternative LFA protocol for desflurane anesthesia.

Purpose of the Study:

• To evaluate the safety and efficacy of a fixed 1 L/min fresh gas flow for desflurane anesthesia, including the wash-in and maintenance phases.
• To assess the feasibility of this method in obese patients.

Main Methods:

• 104 patients undergoing general anesthesia received desflurane with a fixed 1 L/min fresh gas flow after intubation.
• Vaporizer was set at 18%; time to reach 0.7 minimum alveolar concentration (MAC) was recorded.
• Hemodynamic variables, fraction of inspired oxygen (FIO2), MAC, and Bispectral Index (BIS) were monitored.

Main Results:

• The average time to reach 0.7 MAC was 2.9 ± 0.5 minutes.
• Initial MAC and BIS values were 0.7 and 39 ± 8.5, respectively; no patient exceeded a BIS of 60.
• Hemodynamics remained stable, FIO2 stayed above 30%, and average desflurane consumption was 0.33 ± 0.05 mL/min.

Conclusions:

• Fixed 1 L/min fresh gas flow desflurane anesthesia is effective, safe, and economical.
• This LFA method simplifies anesthetic delivery without requiring high initial fresh gas flows.