Propofol Affects Different Human Brain Regions Depending on Depth of Sedation(△) / 中国医学科学杂志(英文版)

<p><b>OBJECTIVE</b>To investigate the effect of propofol on brain regions at different sedation levels and the association between changes in brain region activity and loss of consciousness using blood oxygen level-dependent functional magnetic resonance imaging (BOLD-fMRI) and bispectral index (BIS) monitoring.</p><p><b>METHODS</b>Forty-eight participants were enrolled at Peking Union Medical College Hospital from October 2011 to March 2012 and randomly assigned to a mild or a deep sedation group using computer- generated random numbers. Preliminary tests were performed a week prior to scanning to determine target effect site concentrations based on BIS and concomitant Observer's Assessment of Alertness/Sedation scores while under propofol. Within one week of the preliminary tests where propofol dose-response was established, BOLD-fMRI was conducted to examine brain activation with the subject awake, and with propofol infusion at the sedation level.</p><p><b>RESULTS</b>Mild propofol sedation inhibited left inferior parietal lobe activation. Deep sedation inhibited activation of the left insula, left superior temporal gyrus, and right middle temporal gyrus. Compared with mild sedation, deep propofol sedation inhibited activation of the left thalamus, precentral gyrus, anterior cingulate, and right basal nuclei.</p><p><b>CONCLUSION</b>Mild and deep propofol sedation are associated with inhibition of different brain regions, possibly explaining differences in the respective loss of consciousness processes.</p>

Psychedelic effects of subanesthetic doses of ketamine / 中国医学科学院学报

<p><b>OBJECTIVE</b>To study the psychedelic effects in healthy volunteers when given subanesthetic dose of ketamine.</p><p><b>METHODS</b>Thirteen male healthy volunteers aged 24-39 years were enrolled. All subjects received subanesthetic doses of ketamine using target control infusion. A stepwise series of target plasma concentrations (0, 100, 200, and 300 ng/ml) were maintained for 20 minutes each. Visual analogue scale (VAS) of mechanical pain by von Frey hair was evaluated, and then the volunteers completed a VAS rating of 13 symptom scales. Pictures were shown to them at the same time. Heart rate, mean blood pressure, and SpO2 were monitored throughout the infusion.</p><p><b>RESULTS</b>During the process of analgesia, ketamine produced dose-related analgesic effects. With the increase of ketamine dose, some psychedelic effects became more obvious and the memory impairment became worse stepwisely.</p><p><b>CONCLUSION</b>Target control infusion of subanesthetic doses of ketamine produce obvious psychedelic effects in healthy volunteers.</p>

Comparison of cerebral state index and bispectral index accuracies in sedation monitoring during target control infusion of midazolam / 中国医学科学院学报

<p><b>OBJECTIVE</b>To compare the accuracies of cerebral state index (CSI) and bispectral index (BIS) in sedation monitoring during target control infusion of midazolam.</p><p><b>METHODS</b>Twenty informed adult male volunteers were intravenously administered with midazolam through plasma target control infusion from 30ng/ml (in increments of 10ng/ml every time) until they became unresponsive to tactile stimulation (i. e., mild prodding or shaking). The BIS and CSI were continuously recorded simultaneously. Sedation was assessed using the Observers' Assessment of Alertness/Sedation (OAA/S) scale at each time when Ct equaled to Ce. The electroencephalogram (EEG) parameters were correlated with the OAA/S scores using nonparametric Spearman's correlation analysis. The prediction probabilities were calculated at the points of lost of verbal contact (LVC) and lost of responses to stimulus (LOR). BIS05, BIS50, BIS95, and CSI05, CSI50, CSI95 were also calculated for LVC and LOR.</p><p><b>RESULTS</b>BIS and CSI were well correlation with OAA/S scales during both the onset and recovery phases. When the sedation level increased, BIS and CSI progressively decreased. The prediction probabilities of BIS and CSI were 84%, 74% for LVC and 79%, 68% for LOR, while the BIS05, BIS50, and BIS95 as well as CSI05, CSI50, and CSI95 were 85.5, 60.6, and 35.7 (for BISs) and 82.2, 65.2, and 30.3 (for CSIs) at the point of LVC and 79.7, 47.6, and 15.6 (for BISs) and 75.9, 43.4, and 11 (for CSIs) at the point of LOR.</p><p><b>CONCLUSIONS</b>Both CSI and BIS seem to be useful parameters for assessing midazolam-induced sedation. BIS is superior in the prediction of LVC and LOR.</p>