Target Effect-site Controlled Infusion of Propofol by Schnider Model: Comparison of Gender and Age / 대한마취과학회지

BACKGROUND: We investigated effect-site median effective concentration (EC50) of propofol for loss of consciousness and effect-site concentration at each anesthetic stage and awakening time to compare the differences by gender or age of patients using Schnider model. METHODS: Total 91 patients were allocated into 4 groups: male patients aged 18-34 year (Group 1), male patients aged 35-55 years (Group 2), female patients aged 18-34 years (Group 3) and female patients aged 35-55 years (Group 4). The effect-site EC50 for loss of consciousness was calculated and the effect-site concentration of propofol at each anesthetic stage and the awakening time of each group were recorded. RESULTS: The effect-site EC50 of propofol for loss of consciousness was 4.53 +/- 0.30microgram/ml, 4.60 +/- 0.25microgram/ml, 4.13 +/- 0.39microgram/ ml and 4.47 +/- 0.65microgram/ml in group 1, 2, 3, and 4, respectively. The effect-site concentrations in male patients aged 18-34 years were significantly higher than those in female patients. The awakening time of female patients aged 35-55 years was shorter than that of male patients. CONCLUSIONS: There were no significant differences of effect-site EC50 for the loss of consciousness of propofol with target effect-site controlled infusion by Schnider model among the groups. However the effect-site concentrations and the awakening time of propofol by Schnider model showed differences in patients' gender and age.

The Clinical Investigation on Laryngeal Mask Airway Intracuff Pressure Monitoring / 대한마취과학회지

BACKGROUND: This study was undertaken to analyze the necessity of deflating cuff volume to maintain intracuff pressure of the laryngeal mask airway (LMA) under 44 mmHg in general anesthesia with propofol and N2O. METHODS: In 168 surgical patients, LMA was inserted (male: #5, female: #4) and the cuff was sealed with air under positive pressure ventilation with 7-8 ml/kg of tidal volume. After measuring the initial intracuff pressure (P0), the intracuff volume (V0) of LMA and peak inspiratory pressure (PIP0), N2O (50%) was administered, and the time for the intracuff pressure to reach a pressure of 44 mmHg (T44), the intracuff volume for the intracuff pressure to reduce to P0 (Vdef), the N2O inhaled time and the number of patients who needed deflation were recorded. RESULTS: P0, V0, PIP0 were 24+/-7.5 mmHg, 17+/-2.8 ml, 13+/-3.8 cmH2O in males and 27+/-8.2 mmHg, 14+/-2.3 ml, 13+/-4.0 cm H2O in females, respectively. The number of patients who needed cuff deflation after inhaling N2O was 17 (18.5%) in males and 36 (47.4%) in females. T44 and Vdef were 27+/-16 min, 1.9+/-0.8 ml in males and 26+/-21 min and 1.3+/-0.6 ml in females, respectively. The necessity for LMA cuff deflation was related to P0, V0, and the N2O inhaled time in males and to P0 and the N2O inhaled time in females (P <0.05). CONCLUSIONS: In anesthesia with N2O, if the initial intracuff pressure of LMA is high and the duration of anesthesia prolonged, careful monitoring of the intracuff pressure is necessary.