SummaryThe purpose of this study was to determine the effect-site concentration of remifentanil that would provide optimal conditions for successful laryngeal mask airway insertion during a target-controlled infusion (TCI) of propofol at 3.5 lg.ml )1 without the use of neuromuscular blockade. Five minutes after propofol infusion, remifentanil was infused at a dose determined by a modified Dixon's up-and-down method. Five minutes after remifentanil infusion, the laryngeal mask was inserted.The effect-site concentration of remifentanil for successful laryngeal mask insertion in 50% of adults (EC 50 ) was 3.04 (SD 0.49) ng.ml )1 during a TCI of 3.5 lg.ml )1 propofol without neuromuscular blockade. From the probit analysis, the EC 50 and EC 95 of remifentanil were 2.84 ng.ml )1 (95% CI 2.09-3.57 ng.ml) and 3.79 ng.ml )1 (95% CI 3.26-9.25 ng.ml )1 ), respectively.

Percutaneous radiofrequency ablation (RFA) is a useful and safe procedure for treating hepatic neoplasm. However, liver RFA causes severe pain, which thereby increases the demand for monitored anesthesia care (MAC). Here, we compared the efficacy and safety of propofol and dexmedetomidine, which are commonly administered during MAC when performing RFA to assess hepatic neoplasm.In this randomized controlled trial, 40 patients were randomly allocated to 2 groups for elective RFA. Patients received either dexmedetomidine (group D) or propofol (group P). Both groups received the continuous infusion of remifentanil for pain control. The primary outcomes were opioid consumption and differences in partial pressure of arterial carbon dioxide (PaCO2) between pre- and postprocedure RFA. In addition, hemodynamic parameters, patient satisfaction, and interventional radiologist satisfaction were determined.There were significant differences in opioid consumption (50.1 ± 16.8 ng/kg/min [group D] vs 71.2 ± 18.7 ng/kg/min [group P]; P = 0.001) and delta PaCO2 (10.4 ± 6.4 mm Hg vs 17.2 ± 9.2 mm Hg, respectively; P = 0.016). Moreover, respiratory rates were significantly different between groups during RFA (P < 0.001). However, blood pressure and heart rate did not significantly change during RFA. Neither patient nor interventional radiologist satisfaction was significantly different between groups.Dexmedetomidine provides better respiratory stability and reduces opioid consumption in comparison with propofol when administered under MAC when performing RFA for hepatic neoplasm.

Major laparoscopic pelvic surgery requires steep Trendelenburg position with pneumoperitoneum for a long time. We investigated the effect of Trendelenburg position with pneumoperitoneum on diaphragmatic excursion and lung compliance during major laparoscopic pelvic surgery using M-mode sonography. Twenty patients undergoing elective pelviscopic radical hysterectomy were included in this study. Diaphragmatic excursion was measured at the following time points; after sedation, after intubation, 90 minutes after Trendelenburg position with pneumoperitoneum, and after operation with recovery of muscle relaxation. And lung compliance was measured using anesthetic machine under general anesthesia; after the intubation, 90 minutes after Trendelenburg position with pneumoperitoneum and after operation with recovery of muscle relaxation. In order to detect postoperative pulmonary complication, postoperative chest radiography was checked. Static lung compliance, dynamic lung compliance and diaphragmatic excursion were decreased during operation (P < 0.001, respectively). At the end of the operation with recovery of muscle relaxation, reduced diaphragmatic movement was not recovered as its excursion after sedation (P < 0.001). In conclusion, lung compliance was decreased following transiently decreased diaphragmatic excursion during major laparoscopic pelvic surgery.