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Background: Phase lag entropy (PLE) is a novel anesthetic depth indicator that uses four-channel electroencephalography (EEG) to measure the temporal pattern diversity in the phase relationship of frequency signals in the brain. The purpose of the study was to evaluate the anesthetic depth monitoring using PLE and to evaluate the correlation between PLE and bispectral index (BIS) values during propofol anesthesia., Methods: In thirty-five adult patients undergoing elective surgery, anesthesia was induced with propofol using target-controlled infusion (the Schneider model). We recorded the PLE value, raw EEG, BIS value, and hemodynamic data when the target effect-site concentration (Ce) of propofol reached 2, 3, 4, 5, and 6 μg/ml before intubation and 6, 5, 4, 3, 2 μg/ml after intubation and injection of muscle relaxant. We analyzed whether PLE and raw EEG data from the PLE monitor reflected the anesthetic depth as the Ce of propofol changed, and whether PLE values were comparable to BIS values., Results: PLE values were inversely correlated to changes in propofol Ce (propofol Ce from 0 to 6.0 μg/ml, r 2  = - 0.83; propofol Ce from 6.0 to 2.0 μg/ml, r 2  = - 0.46). In the spectral analysis of EEG acquired from the PLE monitor, the persistence spectrogram revealed a wide distribution of power at loss of consciousness (LOC) and recovery of consciousness (ROC), with a narrow distribution during unconsciousness. The power spectrogram showed the typical pattern seen in propofol anesthesia with slow alpha frequency band oscillation. The PLE value demonstrated a strong correlation with the BIS value during the change in propofol Ce from 0 to 6.0 μg/ml (r 2  = 0.84). PLE and BIS values were similar at LOC (62.3 vs. 61.8) (P > 0.05), but PLE values were smaller than BIS values at ROC (64.4 vs 75.7) (P < 0.05)., Conclusions: The PLE value is a useful anesthetic depth indicator, similar to the BIS value, during propofol anesthesia. Spectral analysis of EEG acquired from the PLE monitor demonstrated the typical patterns seen in propofol anesthesia., Trial Registration: This clinical trial was retrospectively registered at ClinicalTrials.gov at October 2017 (NCT03299621).

Background: There are limited data regarding the efficacy and safety of remifentanil sedation for diagnostic bronchoscopy. The aim of this study was to evaluate the clinical efficacy and safety of remifentanil by comparing it with those of conventional drugs, midazolam and propofol., Methods: A retrospective study of 186 patients who underwent diagnostic bronchoscopy at Chonbuk National University Hospital was performed. Patients were classified into the remifentanil group and midazolam/propofol group according to the drugs used during bronchoscopy., Results: Of the 186 patients, 111 patients received remifentanil and 75 received midazolam/propofol during the bronchoscopy. The proportion of patients who required bronchoscopy for endobronchial inspection alone was significantly higher in the midazolam/propofol group than in the remifentanil group (93.3% vs. 73.0%; p <  0.001). In contrast, the proportion of patients who required more invasive procedures, such as bronchoscopic biopsy, bronchoalveolar lavage, or transbronchial lung biopsy, was significantly higher in the remifentanil group than in the midazolam/propofol group (27.0% vs. 6.7%; p <  0.001). The recovery time was significantly shorter in the remifentanil group than in the midazolam/propofol group (mean 6.4 min vs. 11.6 min, p <  0.001). There were no significant differences between the groups with regard to safety events including desaturation, hypotension, and arrhythmia., Conclusions: Despite the higher proportion of patients who underwent more invasive procedures in the remifentanil group than in the midazolam/propofol group, there was no significant difference in safety events between the groups. Those in the remifentanil group also demonstrated a faster recovery time than those in the midazolam/propofol group.