Effect of fresh gas flow on isoflurane concentrations during low-flow anaesthesia.
The effect of fresh gas flow (FGF) on isoflurane concentrations at given vaporizer settings during low-flow anaesthesia was investigated. Ninety patients (American Society of Anaesthesiologists physical status I or II) were randomly allocated to three groups (FGF 1 l/min, FGF 2 l/min and FGF 4 l/min). Anaesthesia was maintained for 10 min with vaporizer setting isoflurane 2 vol% and FGF 4 l/min for full-tissue anaesthetic uptake in a semi-closed circle system. Low-flow anaesthesia was maintained for 20 min with end-tidal isoflurane 1.5 vol% and FGF 2 l/min. FGF was then changed to FGF 1 l/min, FGF 2 l/min or FGF 4 l/min. Measurements during the 20-min period showed that inspired and end-tidal isoflurane concentrations decreased in the FGF 1-l/min group but increased in the FGF 4-l/min group compared with baseline values. No haemodynamic changes were observed. Monitoring of anaesthetic concentrations and appropriate control of vaporizer settings are necessary during low-flow anaesthesia.
Park
J-Y
JY
Department of Anaesthesiology, Korea University Anam Hospital, Seoul, Korea.
Kim
J-H
JH
Kim
W-Y
WY
Chang
M-S
MS
Kim
J-Y
JY
Shin
H-W
HW
D000328:Adult; D000769:Anesthesia, Inhalation / Q000379:methods*; D018685:Anesthetics, Inhalation / Q000008:administration & dosage*; D001794:Blood Pressure; D005260:Female; D006339:Heart Rate; D006439:Hemodynamics; D006801:Humans; D007432:Intraoperative Period; D007530:Isoflurane / Q000008:administration & dosage*; D008875:Middle Aged; D013990:Tidal Volume
D018685:Anesthetics, Inhalation; D007530:Isoflurane