The effect of dexmedetomidine pretreatment on the median effective bolus dose of propofol for facilitating laryngeal mask airway insertion.

BACKGROUND: We designed this study to investigate the effect of dexmedetomidine (1 µg/kg) pretreatment on the median effective dose (ED50) of propofol for facilitating successful laryngeal mask airway (LMA) insertion compared to propofol alone. METHODS: Forty patients were randomized to either the control group (n = 21) or the dexmedetomidine group (n = 19). After infusion of normal saline or dexmedetomidine 1 µg/kg over 10 min, 1 % lidocaine 0.5 mg/kg, followed by propofol 2.5 mg/kg was administered and the laryngeal mask airway was inserted without muscle relaxants. The ED50 of propofol for successful LMA insertion was determined by the modified Dixon's up-and-down method. The ED50 and ED95 were also calculated using an isotonic regression method, based on the pooled adjacent-violators algorithm-adjusted response rate, and the confidential interval (CI) was estimated using a bootstrap approach. RESULTS: The ED50 of propofol for smooth insertion of the LMA was significantly higher in the control group than in the dexmedetomidine group (3.1 ± 0.4 vs 1.9 ± 0.3 mg/kg, P < 0.001). From isotonic regression analysis using a bootstrap approach, the ED50 and ED95 of propofol was 2.9 mg/kg (83 % CI 2.5-3.3 mg/kg) and 3.9 mg/kg (95 % CI 3.5-4.0 mg/kg) in the control group, and 1.8 mg/kg (83 % CI 1.8-2.1 mg/kg) and 2.4 mg/kg (95 % CI 2.0-2.5 mg/kg) in the dexmedetomidine groups, respectively. The apnea time was not significantly different between the two groups. CONCLUSIONS: Pretreatment with dexmedetomidine 1 µg/kg could reduce the propofol requirement by 38 % for facilitating LMA insertion without prolonged respiratory depression and hemodynamic instability.

Pain related to robotic cholecystectomy with lower abdominal ports: effect of the bilateral ultrasound-guided split injection technique of rectus sheath block in female patients: A prospective randomised trial.

BACKGROUND: Robotic cholecystectomy (RC) using port sites in the lower abdominal area (T12-L1) rather than the upper abdomen has recently been introduced as an alternative procedure for laparoscopic cholecystectomy. Therefore, we investigated the time course of different components of pain and the analgesic effect of the bilateral ultrasound-guided split injection technique for rectus sheath block (sRSB) after RC in female patients. METHODS: We randomly assigned 40 patients to undergo ultrasound-guided sRSB (RSB group, n = 20) or to not undergo any block (control group, n = 20). Pain was subdivided into 3 components: superficial wound pain, deep abdominal pain, and referred shoulder pain, which were evaluated with a numeric rating scale (from 0 to 10) at baseline (time of awakening) and at 1, 6, 9, and 24 hours postoperatively. Consumption of fentanyl and general satisfaction were also evaluated 1 hour (before discharge from the postanesthesia care unit) and 24 hours postoperatively (end of study). RESULTS: Superficial wound pain was predominant only at awakening, and after postoperative 1 hour in the control group. Bilateral ultrasound-guided sRSB significantly decreased superficial pain after RC (P < 0.01) and resulted in a better satisfaction score (P < 0.05) 1 hour after RC in the RSB group compared with the control group. The cumulative postoperative consumption of fentanyl at 6, 9, and 24 hours was not significantly different between groups. CONCLUSIONS: After RC with lower abdominal ports, superficial wound pain predominates over deep intra-abdominal pain and shoulder pain only at the time of awakening. Afterwards, superficial and deep pain decreased to insignificant levels in 6 hours. Bilateral ultrasound-guided sRSB was effective only during the first hour. This limited benefit should be balanced against the time and risks entailed in performing RSB.