Intravenous anesthesia


Anesthesia and Pain Medicine. 2002 Dec. 6(4): 206-213
ⓒ Korean Society for Intravenous Anesthesia
Comparison of the Condition of Laryngeal Mask Insertion According to Methods of Target-controlled Infusion of Propofol
Hee Jung Baik, M.D., Jong Hak Kim, M.D., Choon Hi Lee, M.D., Ja Yoon Tae, M.D.,
Department of Anesthesiology, College of Medicine, Ewha Womans University, Seoul, Korea.

BACKGROUND: We evaluated the condition of laryngeal mask airway (LMA) insertion produced by a infusion method, in which initial target plasma concentration (Cpt) of propofol was 11 microgram/ml and target- controlled infusion (TCI) was stopped at the start of LMA insertion when effect-site concentration (EC) reached 2.5 microgram/ml, as compared with TCI set at 6 microgram/ml of Cpt.
METHODS: The sixty six ASA physical status 1 and 2 patients were randomly divided into two groups, group 1 (n = 33) received TCI of propofol with 6 microgram/ml of Cpt and group 2 (n = 33) received TCI with 11 microgram/ml of Cpt initially and then TCI was stopped at the start of LMA insertion. LMA was inserted when the EC reached 2.5 microgram/ml, which was displayed on the infusion pump. The conditions of LMA insertion and hemodynamic responses were evaluated until 3 minutes after LMA insertion. Total dose of propofol, EC, and elapsed time since the start of TCI were recorded at five times: at the loss of consciousness and eyelash reflex, at 2.5 microgram/ml of EC, and immediately, 1 minute, and 3 minutes after the insertion of LMA.
RESULTS: The conditions of LMA insertion such as mouth opening, gagging, coughing, laryngospasm, overall ease were excellent in group 2 as compared with group 1 significantly (P < 0.05). When the EC reached 2.5 microgram/ml, the administered total dose and elapsed time were significantly larger and shorter in group 2 (3.2 +/- 0.0 mg/kg and 91 +/- 12 sec), respectively, than those in group 1 (2.1 +/- 0.1 mg/kg and 140 +/- 4 sec). Immediately after insertion of LMA, the EC in group 2 (3.6 +/- 0.2 microgram/ml) was significantly higher than that in group 1 (3.0 +/- 0.1 microgram/ml) (P < 0.05). But there were no significant differences in hemodynamic responses between two groups.
Conclusions: A method in which initial Cpt of propofol was 11 microgram/ml and TCI was stopped at the start of LMA insertion, improved the condition of LMA insertion without aggravation in hemodynamic responses as compared with TCI set at 6microgram/ml of Cpt.
Key words : Effect-site concentration, laryngeal mask airway, plasma concentration, propofol,target- controlled infusion
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