Propofol Affects Different Human Brain Regions Depending on Depth of Sedation(△).

OBJECTIVE: 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. METHODS: 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. RESULTS: 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. CONCLUSION: Mild and deep propofol sedation are associated with inhibition of different brain regions, possibly explaining differences in the respective loss of consciousness processes.

Urgent tracheal resection and reconstruction assisted by temporary cardiopulmonary bypass: a case report.

Severe tracheal stenosis can not only cause critical medical problems such as severe shortness of breath, hypoxia, and even orthopnea, but also impose overwhelming challenges on the physicians, particularly the anesthesiologist. Life-threatening airway obstruction can make the patient's gas exchange extremely difficult.Though several options could be offered regarding the treatment of tracheal stenosis, normally, tracheal resection and following reconstruction is the first choice for severe airway stenosis. Successful surgical intervention relies on the close communication and cooperation between surgeons and anesthesiologists. In these cases, airway management is the top issue for the anesthesiologist, and the level of difficulty varies with stenosis location, severity of stenosis, and surgical technique. Extracorporeal membrane oxygenation (ECMO), or cardiopulmonary bypass (CPB), is rarely utilized for the surgery, but for those impossible airways due to nearly complete tracheal obstruction, ECMO or CPB could be the final choice for anesthesiologists. Here we report a case of successful urgent airway management for tracheal resection and reconstruction assisted by temporary CPB.

[Non-inferiority study of lornoxicam to patient-controlled analgesia in patients after hysterectomy].

OBJECTIVE: To evaluate the non-inferiority of lornoxicam to fentanyl in patient-controlled intravenous analgesia after hysterectomy. METHODS: In this prospective randomized controlled study, 117 patients who suffered from moderate to severe pain i.e. pain visual analogue scale (VAS) ≥4 after hysterectomy were allocated to receive lornoxicam (Group L) or fentanyl (Group F) for patient-controlled analgesia. The patients were given a loading dose of lornoxicam 4 mg or fentanyl 50 µg after the enrollment according to the patients' grouping and connected to the patient-controlled analgesia device containing lornoxicam 0.4 g/L or fentanyl 5 mg/L with bolus dose set at 2.5 mL and lockout interval set at 10 min. Pain scores were rated using VAS at 6, 12, and 24 h postoperatively. Pain intensity difference (PID) was the difference between pain scores rated immediately after surgery and 6, 12 and 24 h postoperatively. The sum of pain intensity difference over 24 h (SPID-24) was the sum of PID at 6, 12 and 24 h. non-inferiority could be claimed if the lower limit of the 95% confidence interval (CI) for SPID-24 difference between the two groups was greater than pre-specified non-inferiority margin -3. RESULTS: No difference was detected for pain scores at any time point between the two groups. SPID-24 were 12.0±6.1 and 10.2±5.4 (P>0.05). SPID-24 difference between the two groups was 0.66, 95%CI -1.24 to 2.56, and the lower limit greater than non-inferiority margin -3. Adverse effects, such as nausea, vomiting, and drowsiness were significantly less in lornoxicam group than in fentanyl group (P<0.05). CONCLUSION: Lornoxicam is not inferior to the equivalent dose of fentanyl with regard to the margin pre-specified at -3 in reducing moderate to severe postoperative pain after hysterectomy.

[Effect of subanaesthetic dose of ketamine on mechanical stimulus on brain regions].

OBJECTIVE: To investigate the effect of subanaesthetic dose of ketamine on mechanical stimulus on brain regions. METHODS: Totally 13 healthy male volunteers were enrolled in this study, in whom 0 and 100 ng/ml ketamine were administrated by target controlled infusion system in pilot study. After von Frey filaments (vFFs) 300 g were used as mechanical stimuli, Visual Analogue Scale scores were evaluated. Functional magnetic resonance imaging (fMRI)was taken 1 week after pilot study at the following sequences: structure imaging + functional imaging (stimulus sequence with 300 g vFFs, ketamine sequence); stimulus sequence = 6×(20s on + 20s off), with target concentration of ketamine at 0,100 ng/ml.fMRI result was processed by SPM2 and Metlab 7.01 software package. RESULTS: Posterior cerebellum lobe and corpus callosum were inhibited at 100 ng/ml under vFFs stimulus, whereas cingulate gyrus, middle frontal gyrus, inferior parietal lobule, occipital lobe, and posterior cerebellum lobe were activated at 100 ng/ml under vFFs stimulus. CONCLUSIONS: Ketamine 100 ng/ml exerts its effect on pain related brain regions. It can both activate and inhibit these brain regions, with the activating effect being the primary effect.

[An audit of perioperative fluid management and electrolyte monitoring in children undergoing surgery for scoliosis].

OBJECTIVE: To audite and compare the perioperative practices of intravenous fluids and electrolyte & glucose monitoring in children undergoing operations for scoliosis in 2008, 2010, prior to and after the publication of guideline in 2009. METHODS: Retrospective audit was conducted at Peking Union Medical College Hospital, a tertiary referral teaching hospital in Beijing, China. Children under 14 years old with scoliosis treated surgically in 2008 and 2010 were recruited. The following data were collected from medical files: age, gender, weight, duration of hospitalization, concurrent illness, operation, anesthesia, fluid prescribed during perioperative fasting period, electrolyte monitoring and postoperative pain control, etc. RESULTS: Among 235 American Society of Anesthesiologists (ASA) I-II cases, 75 children received dextrose 5% or saline 0.9% during the preoperative fasting period. Intraoperatively, the anesthesiologists preferred dextrose 5% or saline 0.9% in children under 6 years old (n = 15, 2008; n = 15, 2010) and Ringer's solution in those aged 6 - 14 years (n = 84, 2008; n = 94, 2010) and hypotonic fluid was not used. And 82.3% and 94.3% of them received electrolyte examinations preoperatively. The electrolyte results were unavailable postoperatively in 27/122 (in 2008) and 13/113 (in 2010) and serum electrolytes were not assessed before fluid treatment postoperatively. Electrolytes were monitored only once in 82.3% (in 2008) and 70.5% (in 2010) patients. Compared with the preoperative concentration of sodium ion, the mean decrease was approximately 2.0 mmol/L at Day 1 postoperation. Hyponatremia at Day 1 postoperation in 2010 was more common than that in 2008 (26.2% vs 23.6%; P = 0.044). But no significant difference existed between the incidence of hyperglycemia of the same day in 2008 and that in 2010 (P = 0.306). CONCLUSION: Compared with that in 2008, our recent practice of intravenous fluid prescription and electrolyte monitoring is ill-consistent with the recommendations in 2009. Implementation of optimal perioperative fluid management is warranted.

Effects of propofol on brain activation in respond to mechanical stimuli.

OBJECTIVE: 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. METHODS: 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. RESULTS: 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. CONCLUSIONS: Propofol at different concentrations has different effect on the activation of brain regions. It may exert its analgesic effect via different mechanisms.

[Suppressive effect of propofol on low-voltage-activated calcium currents in rat hippocampal neurons].

OBJECTIVE: To investigate the effect of propofol on the low-voltage-activated calcium currents [ICa(LVA)] in rat hippocampal neurons. METHODS: Hippocampal neurons were prepared from Wistar rats and cultured. ICa(LVA) was recorded using whole cell patch clamp technique. Different concentrations of propofol were added to the culture. The effect of propofol on ICa(LVA) was evaluated. RESULTS: ICa(LVA) was inhibited by propofol in a concentration-dependent manner. Propofol 3 µmol /L had no effect on ICa(LVA). Propofol 10, 30, 100 and 300 µmol/L reduced peak ICa(LVA) by (12.6 ± 4.1)%, (29.2 ± 5.7)%, (36.6 ± 5.3)%, (31.6 ± 2.6)% respectively with a mean IC50 of 16.8 µmol/L and Hill coefficient of 0.15. The V1/2 of activation curve was shifted from (-10 ± 1 )mV to (-11 ± 2 )mV. K was 12 ± 1 and 8 ± 1. The V1/2 of inactivation curve was shifted from (-25 ± 1) mV to (-25 ± 5) mV. K was 15 ± 1 and 16 ± 3. CONCLUSION: Propofol produces significant inhibition of ICa (LVA) calcium currents in the central neurons which may partly explain the anesthefic action of propofol on the central nervous system.

[Preventive efficacy of ondansetron and granisetron for postoperative nausea and vomiting in high risk patients].

OBJECTIVE: To compare the efficacy of ondansetron and granisetron in the prevention of postoperative nausea and vomiting (PONV) in high-risk patients. METHODS: Totally 200 patients with three key risk factors for PONV (female, non-smoking and postoperative opioid use) were equally randomized into ondansetron group and granisetron group. Ondansetron (4 mg) or granisetron (3 mg) was intravenously administered upon the completion of surgery. The episodes of nausea and vomiting were observed for 24 hours after surgery. RESULTS: A significantly greater proportion of patients in granisetron group achieved a complete response (i.e., no PONV or rescue medication) during the first 24 hours postoperatively versus those in ondansetron group (62.6% vs. 46.9%, respectively; P=0.048). There were no significant differences in terms of postoperative nausea incidences (42.9% vs. 34.3%, respectively), postoperative vomiting incidences (25.5% vs. 20.2%, respectively) and postoperative rescue anti-emetics incidences (19.4% vs. 15.2%, respectively) (P>0.05). CONCLUSION: Granisetron is more effective than ondansetron in preventing PONV in high-risk patients during the first 24 hours postoperatively.

[Pharmacokinetic and pharmacodynamic characteristics of the domestic sevoflurane for transabdominal hysterectomy].

OBJECTIVE: To evaluate the clinical efficacy of domestic sevoflurane by comparing the pharmacokinetic and pharmacodynamic characteristics of domestic sevoflurane and an imported product. METHODS: 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. RESULTS: 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. CONCLUSION: The domestic sevoflurane has similar pharmacokinetic and pharmacodynamic characteristics as the imported products. It can serve as a cost-effective product for transabdominal hysterectomy.

[Suppression effect of ketamine on transient outward potassium currents in rathippocampal neurons].

OBJECTIVE: To investigate the effect of ketamine on the transient outward potassium currents [IA] using whole-cell patch clamp technique. METHODS: Pyramidal neurons were enzymatically isolated from Wistar rat hippocampus. The effect of ketamine on the [IA] was assessed using whole-cell patch clamp technique. Different concentrations of ketamine were added and potassium currents were measured. RESULTS: [IA] was inhibited by ketamine in a concentration-dependent manner. 10 micromol/L ketamine had no effect on [IA]. The four concentrations of ketamine (30, 100, 300, 1000 micromol/L) reduced peak [IA] currents by (11+/-2)%, (22+/-3)%, (45+/-5)%, (53+/-5)% respectively, with a mean IC50 of (130+/-24) micromol/L and Hill coefficient of 1.19+/-0.56. The V1/2 of activation curve was shifted from (-8.70+/-0.13) mV to (-11.2+/-2.10) mV (n=8, P<0.05). The V1/2 of inactivation curve was shifted from (-75.53+/-7.98) mV to (-91.94+/-11.85) mV (n=8, P<0.05). CONCLUSION: Ketamine produces significant inhibition of potassium currents in the central neurons, which may least partly explain at the action of ketamine.

[Effect of ketamine on high-voltage-activated calcium currents in rat hippocampal neurons].

OBJECTIVE: To investigate the effect of ketamine on the high-voltage-activated calcium currents (ICa(HVA)) in rat hippocampal neurons. METHODS: Neurons were cultured from Wistar rat hippocampus. ICa(HVA) was recorded using whole-cell patch clamp technique. After application with ketamine at different concentrations (10, 30, 100, 300, and 1000 µmol/L), the effect of ketamine on ICa(HVA) was evaluated. RESULTS: ICa(HVA) was inhibited by ketamine in a concentration-dependent manner. Ketamine at 10 µmol/L showed no effect on ICa(HVA). Four concentrations of ketamine (30, 100, 300,and 1000 µmol/L) reduced the peak ICa(HVA) currents by (17.5 ∓ 4.5)%, (25.5 ∓ 6.9)%, (38.5 ∓ 4.1)%, and (42.3 ∓ 4.6)% respectively,with a mean half maximal inhibitory concentration of 68.2 µmol/L and Hill coefficient of 0.47. The maximal activation membrane potential was shifted to (5.3 ∓ 0.8) from (5.4 ∓ 0.9). The half maximal activation membrane potential of inactivation curve was shifted from(-26.7 ∓ 3.9) mV to(-32.8 ∓ 4.2) mV. CONCLUSION: Ketamine can remarkably inhibit calcium currents in the central neurons,which may explain at least partly the action of ketamine on central nervous system.

[Application of propofol target controlled infusion combined with dribbled and nebulized lidocaine in tracheal intubation under spontaneous respiration].

OBJECTIVE: To evaluate the value of propofol target-controlled infusion combined with dribbled and nebulized lidocaine in tracheal intubation under spontaneous breathing. METHODS: Totally 40 elective surgery patients to accept tracheal intubation under unconsciousness and spontaneous breathing were randomly divided into 2 groups: 6-8 cm of endotracheal tube was inserted subglottic ally in the complete intubation group (n=20) while 3-4 cm was inserted temporarily in the partial intubation group (n=20). RESULTS: The tracheal intubation was successfully completed under spontaneous breathing in all patients; meanwhile,the hemodynamic status was stable without any severe respiratory complications. Eleven patients suffered from moderate coughing response in the complete intubation group while no such response was noted in the partial intubation group (P<0.01). CONCLUSIONS: Application of propofol target-controlled infusion combined with dribbled and nebulized lidocaine provides a good condition for tracheal intubation under unconsciousness and spontaneous breathing. The partial intubation can effectively prevent the occurrence of coughing response.

[Effects of naloxone on the expression of stem cell factor and C-kit receptor in combined oxygen-glucose deprivation of primary cultured human embryonic neuron in vitro].

OBJECTIVE: To explore the effects of naloxone on the expression of c-kit receptor (c-kit R) and its ligand stem cell factor (SCF) in human embryo neuronal hypoxic injury. METHODS: Serum-free cerebral cortical cultures prepared from embryonic human brains were deprived of both oxygen and glucose which would set up an environment more likely with that of in vivo ischemic injury. Neurons in 24-well culture plates were randomly divided into four groups: control group, hypoxia group, naloxone 0.5 microg/ml group and naloxone 10 microg/ml group. MTT assay and biological analysis were performed to study the cell death and the changes of extracellular concentrations of lactate dehydrogenase (LDH) after combined oxygen-glucose deprivation. Neurons in 25 ml culture flasks were also randomly allocated into four groups as previously described. Intracellular total RNA were extracted at different time points: pre-hypoxia, immediately after hypoxia, and 3, 6, 12, and 24 hours after reoxygenation. The changes of SCF/c-kit R mRNA expression in hypoxic neurons treated with different concentrations of naloxone pre and post oxygen-glucose deprivation were determined with RT-PCR. RESULTS: The cell vitality detected by MTT assay decreased significantly in hypoxia group and naloxone 0.5 microg/ml group when compared with control group (P<0.01), while no significant difference was found between naloxone 0.5 microg/ml group and hypoxia group or between naloxone 10 microg/ml group and control group. Extracellular concentration of LDH significantly increased in hypoxia group (P<0.05), while no difference was found between naloxone 0.5 microg/ml group and control group, between naloxone 0.5 microg/ml and hypoxia group, or between naloxone 10 microg/ml and control group (all P>0.05). Immediately after oxygen-glucose deprivation, the expression of SCF/c-kit R mRNA increased significantly (P<0.01). Among those the expression of SCF presented a distribution of double-peak value within 24 hours. After treated with different concentrations of naloxone, the peak value of each group were delayed to appear and went down with the increasing of naloxone concentration. The peak values in all treated groups were significantly different from that in control group (P<0.01). CONCLUSIONS: The expression of SCF/c-kit R mRNA increases at the early stage after combined oxygen-glucose deprivation. Naloxone 0.5 microg/ml can attenuate cell injuries and regulate the expression of SCF/c-kit R. Naloxone may protect neurons by modulating the expressions of some cytokines.

[Effects of residual paralysis after a single intubating dose of rocuronium on postoperative pulmonary function of patients undergoing laparoscopic gynecological surgeries].

OBJECTIVE: To evaluate the residual paralysis after a single intubating dose of rocuronium and its effect of residual paralysis after a single dose of rocuronium on the postoperative pulmonary function of patients undergoing laparoscopic gynecological surgeries. METHODS: Sixty American Society of Anesthesiologists (ASA) I - II patients undergoing laparoscopic gynecological surgeries were randomly divided into rocuronium (R) group (n = 30) and rocuronium + neostigmine (R + N) group (n = 30).All patients received midazolam (0.02 mg/kg), fentanyl (1 microg/kg), propofol(1.5-2 mg/kg), and rocuronium (0.6 mg/kg) to facilitate tracheal intubation and no more relaxant thereafter. Anesthesia was maintained with isoflurane and nitrous oxide in oxygen (N(2)O:O(2) = 1:1). At the end of the procedure, neuromuscular blockade was not reversed in R group, while antagonism was accomplished with neostigmine (0.04 mg/kg) and atropine (0.02 mg/kg) in R + N group. Immediately after tracheal extubation and on arrival in the PACU, the train-of-four (TOF) ratio at the adductor pollicis of all patients were measured using acceleromyography. Forced vital capacity (FVC), forced expiratory volume in one second (FEV(1)), and peak expiratory flow rate (PEFR) of all patients were measured using spirometry before surgery, after administration of midazolam and fentanyl, immediately after tracheal extubation, on arrival in the PACU, and after the TOF ratio recovered to 1.0. The TOF ratio and pulmonary function between two groups were compared. RESULTS: Immediately after tracheal extubation and on arrival in the PACU, the mean TOF ratio in R group was significantly lower than that in R + N group (P < 0.05). The mean time to achieve TOF ratio of 0.9 and 1.0 in R group was significantly longer than in R + N group (P < 0.05). Immediately after tracheal extubation and on arrival in the PACU, FVC, FEV(1), and PEFR were significantly lower in R group than in R + N group (P < 0.05). FVC, FEV(1), and PEFR after administration of midazolam and fentanyl and after TOF ratio recovered to 1.0 were significantly lower than the baseline values in all patients (P < 0.01). CONCLUSIONS: After a single intubating dose of rocuronium, residual paralysis exists in the majority of patients undergoing laparoscopic gynecological surgeries. The pulmonary function is impaired after the surgery, even after recovery of TOF ratio to 1.0.

[Psychedelic effects of subanesthetic doses of ketamine].

OBJECTIVE: To study the psychedelic effects in healthy volunteers when given subanesthetic dose of ketamine. METHODS: 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. RESULTS: 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. CONCLUSION: Target control infusion of subanesthetic doses of ketamine produce obvious psychedelic effects in healthy volunteers.

[Effects of atracurium pretreatment with magnesium on speed of onset, duration, and recovery of neuromuscular blockade].

OBJECTIVE: To determine the effects of atracurium pretreatment with magnesium on speed of onset, duration, and recovery of neuromuscular block. METHODS: Thirty patients who were undergoing elective gynecologic laparoscopic examination and treatments under general anesthesia were randomized into magnesium group (n = 15) and control group (n = 15). Before induction of general anesthesia, patients in magnesium group intravenously received MgSO4 30 mg/kg in saline within 5 minutes, and patients in control group received the same volume of saline without MgSO4. In both groups, the train-of-four (TOF) responses to stimuli of the ulnar nerve were measured at intervals of 12 seconds. Anesthesia was induced with Fentanyl and Propofol through target controlled infusion (TCI), and tracheal intubation was performed with 0.5 mg/kg atracurium after stabilization of the electromyography recording. The onset time of muscle relaxation, clinical duration of action, recovery index, and recovery time were recorded. To determine serum magnesium and calcium levels, blood samples were collected before MgSO4/saline infusion and at the end of operation. Haemodynamic changes and other responses during induction were also recorded. RESULTS: The onset time from the end of injection to maximum neuromuscular blockade was significantly shorter in magnesium group than in control group (P < 0.01). Duration of relaxant action, recovery index, and recovery time in magnesium group were significantly prolonged than in control group (P < 0.01). Serum magnesium level significantly decreased after management (P < 0.01), and there was also a decrease trend in magnesium group. No change of serum calcium levels in both groups was observed. No adverse event was reported. CONCLUSION: Prior administration of magnesium sulphate can increase the onset speed of atracurium and prolong the duration of atracurium-induced neuromuscular blockade.

[Effects of melatonin on the voltage-gated delayed rectifier potassium channels of cultured hippocampal neurons of new-born rats].

OBJECTIVE: To investigate the effects of melatonin on voltage-gated delayed rectifier potassium channels. METHODS: Hippocampus neurons were obtained from newborn Wistar rat and cultured. Primary cultured for 7 to 12 days of new-born Wistar rat were selected as objectives. Patch clamp whole-cell recording technique was used on the hippocampus neurons cultured for 7 to 12 day. to record the delayed rectifier potassium current to analyze the basic electrophysiological characteristics. The effects of melatonin of the concentrations of 1 nmol/L, 10 nmol/L, 100 nmol/L, 1 mol/L, 10 mol/L, 100 mol/L, and 1 mmol/L on the amplitudes and kinetics of delayed rectifier potassium currents were investigated. RESULTS: With different voltage protocols and specific blockers of potassium channel (4-AP and TEA) a delayed rectifier potassium current that activated and inactivated slowly and had the outward rectifying characteristics (Ik) from the outward potassium currents in cultured new-born hippocampus neurons was separated. The effect of melatonin on the delayed rectifier channel was rapid, reversible and voltage-dependent Melatonin had no effect on the kinetic characteristics of the I -V curve. Melatonin increased the potassium current concentration-dependently. 1 - 100 nmol/L melatonin increased the amplitude of potassium current gradually; the effects of 1 - 100 micromol/L melatonin on the potassium current increased concentration-dependently, while the action of 1 mmol/L melatonin decreased. CONCLUSION: Melatonin reversibly increases the rectifier delayed potassium currents of the cultured hippocampus neurons of new-born rat. This may be involved in some aspects of physiological and pathological significance of potassium currents.

[Comparison of cerebral state index and bispectral index accuracies in sedation monitoring during target control infusion of midazolam].

OBJECTIVE: To compare the accuracies of cerebral state index (CSI) and bispectral index (BIS) in sedation monitoring during target control infusion of midazolam. METHODS: 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. RESULTS: 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. CONCLUSIONS: Both CSI and BIS seem to be useful parameters for assessing midazolam-induced sedation. BIS is superior in the prediction of LVC and LOR.

[A randomized double-blind study of prevention of postoperative nausea and vomiting with ondansetron, tropisetron, or granisetron in patients undergoing general anesthesia].

OBJECTIVE: To compare the efficacy of different 5-hydroxytryptamine 3 receptor antagonists in the prevention of postoperative nausea and vomiting (PONV) in patients undergoing general anesthesia. METHODS: Totally 360 patients, American Society of Anesthesiologists (ASA) grade I - II, aged 18-75 years, and having received elective operation with endotracheal intubation general anesthesia, were randomly divided into three double-blind groups: ondansetron group, tropisetron group, and granisetron group, with 120 patients in each group. Before anesthesia induction, patients were intravenously given ondansetron (4 mg), tropisetron (5 mg), or granisetron (3 mg), respectively. The episodes of nausea and vomiting were recorded for 24 hours after operation. RESULTS: No significant differences were observed in the terms of complete inhibition rate of PONV among ondansetron group (70.0%), tropisetron group (68.6%), and granisetron group (72.9%) within 24 hours postoperatively (P >0.05), and so did postoperative nausea incidences (22.5%, 25.4%, and 20.3%, respectively), and postoperative vomiting incidences (10.0%, 13.6%, and 8.5%, respectively) (P > 0.05). No remarked antiemetic-related adverse effects were observed within 24 hours postoperatively. CONCLUSION: Intravenous ondansetron (4 mg), tropisetron (5 mg), or granisetron (3 mg) before anesthesia induction can prevent PONV with similar efficacy and safety.

[Protective endotracheal intubation to reduce endotracheal bacterial contamination].

OBJECTIVE: To initially observe the effect of classical endotracheal intubation on endotracheal bacterial contamination and evaluate the validity of protective endotracheal intubation on reducing endotracheal bacterial contamination. METHODS: Ninety elective patients undergoing general anesthesia for hysterectomy were randomly assigned to two equal groups. Group II received endotracheal intubation protected by sterilized transparent sleeve while group I correspondingly adopted unprotective classical endotracheal intubation. Endotracheal swab sampling and bacterial counting were performed on the principle of aseptic processing before endotracheal intubation and extubation, respectively. RESULTS: Bacteria were found in 62 of 180 samples. The difference of bacterial counting between before extubation and before intubation was (-0.3 +/- 35.6) 100 CFU/ ml in group II, lower than that in group I, which was (21.4 +/- 56.7) 100 CFU/ml (P<0.05). CONCLUSION: Endotracheal bacterial contamination may be caused by unprotective classical endotracheal intubation and could be reduced by protective endotracheal intubation.