Effect of remifentanil on three effect-site concentrations of propofol and their relationship during electroencephalography at loss of response, at maximum alpha power, and at onset of burst suppression: a prospective randomized trial.

PURPOSE: The effect-site concentration (Ce) at loss of response (Ce-LOR) to propofol closely correlates both with Ce as electroencephalographic alpha power becomes highest (Ce-alpha) and with Ce at onset of burst suppression (BS) (Ce-OBS), when no opioids are administered. Co-administration of opioids dose-dependently decreases Ce-LOR. We investigated the influence of remifentanil on the relationship between these three Ces. METHODS: After receiving approval from our local ethical committee, with written informed consent, we enrolled 90 participants (ASA-PS I or II) who were scheduled for elective surgery. Participants were randomly assigned to three groups: constant remifentanil Ce 0 ng/ml (Remi_0); 1 ng/mL (Remi_1); and 2 ng/mL (Remi_2). We recorded both raw EEG and EEG-derived parameters on a computer. After reaching remifentanil equilibrium, we administered propofol using a target-controlled infusion pump such that propofol Ce increased to about 0.3 µg/mL/min. After determining Ce-LOR, we administered 0.6 mg/kg of rocuronium and started mask ventilation. The study protocol ended after observation of BS. RESULTS: Three participants were excluded. Ce-LOR in each group (Remi_0, Remi_1, Remi_2) was 2.00 ± 0.58 µg/mL, 1.43 ± 0.49 µg/mL, and 1.37 ± 0.42 µg/mL. Ce-alpha was 2.91 ± 0.63 µg/mL, 2.30 ± 0.41 µg/mL, and 2.12 ± 0.39 µg/mL. Ce-OBS was 3.80 ± 0.69 µg/mL, 3.25 ± 0.68 µg/mL, and 2.90 ± 0.57 µg/mL. In three other instances, Ce was decreased by remifentanil. Generalized linear model analysis revealed that remifentanil had no influence on the relationship between the three Ces. CONCLUSION: During propofol anesthesia, even low concentrations of remifentanil shifted concentration-related electroencephalographic changes.

Use of Sugammadex in a Patient with Myotonic Dystrophy Undergoing Laparoscopic Cholecystectomy.

A 37-year-old female patient with myotonic dystrophy was scheduled for laparoscopic cholecystectomy for gall stone under general anesthesia with continuous propofol infusion. Rocuronium was administered with careful monitoring using TOF- Watch®, measuring train-of-four count (Tc), TOF ratio (Tr), and posttetanic count The total amount of rocuronium was 70 mg ; 0.6 mg .kg⁻1 for anesthetic induction and 0.3 mg .kg⁻1 when Tc exceeded 1. When the operation was completed, Tc was 4, Tr was uncountable and she showed reaction to calling her name. Then sugammadex 2 mg .kg⁻1, rapidly antagonized the neuromuscular block, such that the Tr recovered to 100% but tidal volume was 250 ml in 3 minutes. Additional dorsage of sugammadex, 2 mg .kg⁻1, was required for tidal volume to recover to 530 ml. After 20 minutes of first administration of sugammadex, we extubated the tracheal tube without respiratory depression. To avoid respiratory depression, we did not use postoperative opioids. Intraoperative transversus abdominis plane block and postoperative thoracic epidural block with ropivacaine were successful for postoperative pain relief.