Can bispectral index or auditory evoked potential index predict implicit memory during propofol-induced sedation? / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Some patients still suffer from implicit memory of intraoperative events under adequate depth of anaesthesia. The elimination of implicit memory should be a necessary aim of clinical general anaesthesia. However, implicit memory cannot be tested during anaesthesia yet. We propose bispectral index (BIS) and auditory evoked potential index (AEPI), as predictors of implicit memory during anaesthesia.</p><p><b>METHODS</b>Thirty-six patients were equally divided into 3 groups according to the Observer's Assessment of Alertness/Sedation Score: A, level 3; B, level 2; and C, level 1. Every patient was given the first auditory stimulus before sedation. Then every patient received the second auditory stimulus after the target level of sedation had been reached. BIS and AEPI were monitored before and after the second auditory stimulus presentation. Four hours later, the inclusion test and exclusion test were performed on the ward using process dissociation procedure and the scores of implicit memory estimated.</p><p><b>RESULTS</b>In groups A and B but not C, implicit memory estimates were statistically greater than zero (P < 0.05). The implicit memory scores in group A did not differ significantly from those in group B (P > 0.05). Implicit memory scores correlated with BIS and AEPI (P < 0.01). The area under ROC curve is BIS > AEPI. The 95% cutoff points of BIS and AEPI for predicting implicit memory are 47 and 28, respectively.</p><p><b>CONCLUSIONS</b>Implicit memory does not disappear until the depth of sedation increases to level 1 of OAA/S score. Implicit memory scores correlate well with BIS and AEPI during sedation. BIS is a better index for predicting implicit memory than AEPI during propofol induced sedation.</p>

Investigation and analysis of incidence of awareness in patients undergoing cardiac surgery in Beijing, China / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Awareness under general anesthesia is a serious complication which leads to psychiatric disorders. The incidence of awareness in patients undergoing cardiac surgery has been reported in as many as 1.5% - 23% in foreign countries. But so far, medical literature about awareness during cardiac surgery is still rare in China. Therefore, we investigated the incidence of awareness in patients undergoing different kinds of cardiac surgery, the phases when awareness occurred and the effect of cardiopulmonary bypass on the incidence of awareness in coronary artery bypass grafting in Beijing.</p><p><b>METHODS</b>Patients' recall of awareness during cardiac surgery was assessed. One hundred patients undergoing coronary artery bypass grafting (CABG) in Chaoyang Hospital, Beijing, one hundred patients undergoing CABG and one hundred patients undergoing valve replacement or septal defect repair in Fuwai Hospital, Beijing, were interviewed 3-6 days after surgery. Every report about patients on recall of awareness was recorded. An independent research team, blinded to patients' surgery and anesthesia, assessed every report of awareness.</p><p><b>RESULTS</b>The incidence of awareness of patients received CABG under cardiopulmonary bypass (CPB), off -pump CABG, septal repair or valve replacement under CPB was 4.7% (5 of 106 cases), 9.6% (9 of 94 cases) and 4% (4 of 100 cases), respectively. CPB did not greatly affect the incidence of awareness during the period of CABG (P > 0.05). The incidence of awareness of patients who received CABG under CPB did not increase significantly, in comparison with that of patients who received septal repair or valve replacement under CPB in Fuwai Hospital (P > 0.05). Awareness easily occurred before bypass grafting or CPB.</p><p><b>CONCLUSIONS</b>Awareness mainly occurs before bypass grafting or CPB in cardiac surgery. Most cases with awareness have auditory perceptions. CPB is not a main factor which affects the incidence of awareness of CABG. Surgical types do not affect the incidence of awareness of patients under CPB.</p>

Effects of isoflurane inhalation during reperfusion on different degrees of global cerebral ischemiareperfusion injury in rats / 中华麻醉学杂志

Objective Isoflurane preconditioning has been shown to protect against cerebral ischemia-reperfusion(I/R)injury.The purpose of this study was to investigate if isoflurane inhalation during reperfusion hasany protective effects.Methods Fourty-two SD rats weighing 318-365 g were randomly divided into 3 groups:sham group(n=6),control group(n=18)and isoflurane group(n=18).Control group and isoflurane groupwere further divided into 10,15 and 20 rain ischernia subgroups(subgroup A,B,C,n=6).In isoflurane group1.4% isoflurane in air was inhaled immediately after reperfusion was started for 30 min.Two days before theexperiment the animals were anesthetized with intraperitoneal chloral hydrate 300 mg?kg~(-1).Microdialysis catheterwas inserter into right hippocampns using stereotactic technique and fixed.BIS microelectrodes were placed in thebrain.Vertebral arteries were permanendy occluded by electric coagulation.Bilateral common carotid arteries wereexposed and atranmatic sutures were placed around them.Globol cerebral ischemia was produced by tighteningcarotid sutures and maintained for 10,15 or 20 min(subgroup A,B,C).Cerebral iscbemia was confirmed by lossof righting reflex,dilated pupils,loss of light reflex,BIS=0 and isoelectric potential on EEG.Carotid sutureswere then released for reperfusion.Isoflurane inhalation was started right after the beginning of reperfusion andmaintained for 30 min.Neurologlc outcome was assessed by motor performance according to Combs(0-10,0=severe dysfunction,10=no dysfunction)at 24 h,48 h and 72 h of reperfusion.Microdialysis samples werecollected before during and 0-15,15-30,30-45 and 45-60 min after ischemia for determination of glutamateconcentration.Three days after ischemia the animals were sacrificed and brains were removed for microscopicexamination of hippocampns CA1 region.The number of apoptotic(TUNEL positive)neurons were counted and thepercentage(the number of TUNEL positive neurons/the total number of neurons)was calculated.Results Theglutamate content in hippocampus was significantly lower in isoflurane group than in control group duringreperfusion(P