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>

Effects of propofol on brain activation in respond to mechanical stimuli / 中国医学科学院学报

<p><b>OBJECTIVE</b>To observe the effects of different concentrations of propofol on brain regions activated by mechanical stimuli, and then to investigate the analgesic effect of propofol.</p><p><b>METHODS</b>Twenty healthy male volunteers were randomly divided into two groups: light anesthesia group (group L) (BIS 60-80) and deep anesthesia group (group D)(BIS 40-60). Propofol was administrated by target controlled infusion system in pilot study. The target effect site concentration (ESC) of propofol was defined as the average of the ESC from BIS 80 to 60 or BIS 60 to 40 in group L or group D respectively. Mechanical stimuli were applied using von Frey filaments at the center of the left foot, and the pain threshold and VAS scores were evaluated. fMRI examinations were taken 1 week after pilot study with the following sequences: structure imaging+ functional imaging: functional imaging=stimulus sequence+propofol sequence, in which the stimulus sequence was 6 × (20 s on + 20 s off). This sequence was repeated after propofol sequence.</p><p><b>RESULTS</b>As shown by fMRI, in group L, active brain regions of (the second stimulation-the first stimulation, P2-P1) were seen in cingulate gyrus, thalamus, and cerebellum, while active brain regions of (P1-P2) were seen in temporal lobe, frontal gyrus, and occipital lobe. In group D, the active brain region of (P2-P1) was only seen in cerebellum, while active brain regions of (P1-P2) were seen in cingulate gyrus and thalamus. Active brain regions of (deep-low) with propofol infusion in response to vFFs stimulation were observed in cerebellum.</p><p><b>CONCLUSIONS</b>Propofol at different concentrations has different effect on the activation of brain regions. It may exert its analgesic effect via different mechanisms.</p>

Pharmacokinetic and pharmacodynamic characteristics of the domestic sevoflurane for transabdominal hysterectomy / 中国医学科学院学报

<p><b>OBJECTIVE</b>To evaluate the clinical efficacy of domestic sevoflurane by comparing the pharmacokinetic and pharmacodynamic characteristics of domestic sevoflurane and an imported product.</p><p><b>METHODS</b>Eighty patients undergoing general anesthesia for transabdominal hysterectomy were equally randomized into domestic sevoflurane group and imported sevoflurane group. The following data were recorded and compared: vital signs; change of sevoflurane concentrations in the induction period and recovery period; the time when inhaled sevoflurane concentration reached half of the pre-set concentration of the vaporizer; the time when the end-tidal sevoflurane concentration reached half of the pre-set concentration of the vaporizer; the time when the end-tidal sevoflurane concentration reached half of inhaled sevoflurane concentration; the time of the end-tidal sevoflurane concentration reached 0. 8 MAC in the induction period; the recovery time; the extubation time; and time to recovery of consciousness.</p><p><b>RESULTS</b>The general conditions of the two groups were not significantly different. The pharmacokinetic and pharmacodynamic parameters at the intra-operative time points as well as the minimal alveolar concentration, the inspired and end-tidal sevoflurane concentrations, and the time to recovery of consciousness also showed no significant differences between the two groups.</p><p><b>CONCLUSION</b>The domestic sevoflurane has similar pharmacokinetic and pharmacodynamic characteristics as the imported products. It can serve as a cost-effective product for transabdominal hysterectomy.</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>