Comparison of Laryngeal Tube Insertion Condition according to Effect-Site Concentration during Target-Controlled Infusion (TCI) of Propofol

Hur, Min Jung; Kim, Yun Jin; Baik, Hee Jung; Kim, Jong Hak

Abstract

BACKGROUND: The aim of the study was to compare the laryngeal tube (LT) insertion conditions at 3.0 and 3.5microgram/ml effect site concentrations (ECs) during anesthesia induction using the target-controlled infusion (TCI) of propofol.
METHODS
The forty patients were randomly divided into two groups. The patients received TCI of propofol with a 6.0 microgram/ml target plasma concentration (Cpt) and then an LT was inserted without the aid of a muscle relaxant when the predicted EC reached 3.0microgram/ml (group 1) or 3.5microgram/ml (group 2). The conditions of LT insertion, i.e., mouth opening, gagging, coughing, head or limb movement, laryngospasm, and overall ease, and hemodynamic responses were evaluated 3 min after midazolam injection, at loss of consciousness and eyelash reflex, and immediately before, immediately after, 1 min after, and 3 min after LT insertion. We also compared times required to insert LTs, cuff volumes, and incidences of blood staining and of postoperative sore throat.
RESULTS
The conditions of LT insertion, except laryngospasm and overall ease, were not significantly different in the two groups. The incidence of laryngospasm in group 1 (25%) was significantly higher than in group 2 (0%) and group 2 was better than group 1 in terms of overall ease of insertion (P<0.05). No significant differences were observed between the two groups in terms of hemodynamic responses. Minimum cuff volume to 60 cmH2O was 64.0 +/- 8.3 ml in Group 1 and 63.9 +/- 6.5 ml in Group 2, and time required for LT insertion was 21.0 +/- 11.0 sec in Group 1 and 24.7 +/- 16.6 sec in Group 2. Postoperative sore throat and blood stain incidences were not significantly different in the two groups.
CONCLUSIONS
After induction with 6microgram/ml of Cpt using propofol TCI for LT insertion, LT insertion at 3.5microgram/ml of EC provided a lower incidence of laryngospasm and better overall ease than insertion at 3.0microgram/ml of EC.