Objective To investigate the influences of carbon dioxide (CO2) pneumoperitoneum and operation position on intraocular pressure (IOP) during laparoscopic surgery under general anesthesia. Methods Thirty-six patients were divided into two groups of udergoing laparoscopic pelvic surgeries (group A) and udergoing laparoscopic cholecytectomies(group B) with 18 cases each. The patients in group A were operated under 25 degrees head-down position and those in group B under 25 degrees head-up position. IOP was recorded before surgery(T0), at 5 min after tracheal intubation (T1), 5 min after CO2 pneumoperitoneum(T2), 5 min(T3) and 30 min(T4) after body position changed and the time of normal PETCO2 regained(T5). Results IOP was remarkably decreased after induction of general anesthesia in both groups. IOP of group A raised to (21.0±1.6) mm Hg at T4, which was dropped to (14. 6±1.6) mm Hg at T5. IOP of group B raised to (12.1±2.9) mm Hg at T4,which was dropped to (11.1±1.2) mm Hg at T5. Changes of IOP of both groups were positively correlated with the changes of PETCO2. Conclusion IOP can be decreased remarkably after induction of general anesthesia with propofol. The head-up position and normal range of PETCO2 are the two important factors to avoid an increase of IOP in surgical patients under general anesthesia.

Objective To evaluate the efficacy of small dose of dexmedetomidine for prevention of the adverse effects caused by carboprost in the patients undergoing caesarean section.Methods Forty parturients,of ASA physical status Ⅰ or Ⅱ,aged 26-30 yr,weighing 63-71 kg,scheduled for elective caesarean section under epidural anesthesia,were equally and randomly divided into control group (C group) or carboprost group (D group) by using a random number table.After delivery of the fetus,all the patients received iv infusion of 20 U oxytocin and carboprost 250 μg was injected into the myometrium simultaneously.In group D,after a loading dose of dexmedetomidine 0.1 μg/kg,dexmedetomidine was infused at a rate of 0.4 μg· kg-1 · h-1 starting from 1 min prior to carboprost injection until the end of surgery,while the equal volume of normal saline was given in group C.Adverse effects such as dyspnea,facial flushing,nausea,vomiting,hypertension and tachycardia were recorded.The OAA/S scores and time for breastfeeding initiation were also recorded at the end of surgery and 2 h after surgery.Results Compared with group C,the incidence of dyspnea,facial flushing,nausea,vomiting,hypertension and tachycardia was significantly decreased in D group.There was no significant difference in OAA/S score and the time for breastfeeding initiation after surgery between the two groups.Conclusion Small-dose dexmedetomidine (loading dose 0.1 μg/kg,followed by infusion at 0.4 μg· kg-1 · h-1 until the end of surgery) infused before carboprost administration is helpful in preventing the adverse gastrointestinal and cardiovascular reactions caused by carboprost in the patients undergoing caesarean section.

Objective To investigate the placental transfer and neonatal effects of dexmedetomidine during the cesarean section under general anesthesia.Methods Thirty-eight nulliparous parturients,of American Society of Anesthesiologists physical status Ⅰ or Ⅱ,aged 22-37 yr,weighing 56-82 kg,who were at full term with a singleton fetus,scheduled for elective caesarean section under general anesthesia,were randomly divided into 2 groups (n=19 each) using a random number table:dexmedetomidine group (group D) and normal saline group (group N).In group D,dexmedetomidine was infused in a loading dose of 0.6 μg/kg starting from 10 min before induction of anesthesia,followed by an infusion of 0.4 μg · kg-1 · h-1 until peritoneal closure.Group N received the equal volume of normal saline.Blood samples were collected from the maternal artery (MA),umbilical vein (UV),and umbilical artery (UA) for blood gas analysis and for determination of plasma dexmedetomidine concentrations (CMA,CUV and CUA) by high-performance liquid chromatography-mass spectrometry,and CUV/CMA and CUA/CUV were calculated.Apgar scores were recorded at 1 and 5 min after delivery,and the occurrence of respiratory depression was also recorded.The I-D interval (the time from administration of anesthetics to delivery) and U-D interval (the time from incision of the uterus to delivery) were recorded.Results There were no significant differences in the blood gas analysis parameters in blood samples collected from the MA,UV and UA,I-D interval,U-D interval,and Apgar scores between the two groups (P＞0.05).No neonatal respiratory depression was found in both groups.In group D,CMA,CUV and CUA were 471±119,359±88 and (321±78) ng/ml,respectively,CUV/CMA was 0.76±0.06,and CUA/CUV was 0.89±0.03.Conclusion Although the metabolism of dexmedetomidine is little after easy placental transfer,dexmedetomidine has no adverse effects on the newborn during the cesarean section under general anesthesia.

Objective To explore the neonatal effects and efficacy of dexmedetomidine on haemodynamics during cesarean section under general anesthesia.Methods Thirty-eight ASA Ⅰ or Ⅱ parturients with a single baby at full term in vertex presentation,scheduled for cesarean section under general anesthesia,were randomly divided into 2 groups (each group of 19 patients) by random digits table method:dexmedetomidine group and normal saline group.The patients in dexmedetomidine group received an intravenous infusion loading dose of 0.6 μ g/kg of dexmedetomidine,starting 10 min before induction of anesthesia,following with an intravenous infusion 0.4 μ g/ (kg ·h) of dexmedetomidine until peritoneal closure.The patients in normal saline group received an intravenous infusion of isovolumic of normal saline.Recording the systolic blood pressure (SBP),diastolic blood pressure (DBP) and heart rate (HR) before infusion (T0) and 10 min after the start of infusion (T1),at tracheal intubation (T2),at delivery of the baby (T3),15 min after delivery (T4),at end of operation (T5),at extubation (T6) and 15 min after extubation (T7).The blood of umbilical vein and umbilical artery was drawn for gas analysis,and the Apgar scores at 1 and 5 min were also recorded after delivery.Results The level of SBP,DBP and HR at T0 had no significant difference between two groups (P ＞ 0.05).In dexmedetomidine group,the level of SBP,DBP and HR were significantly higher at T2 than those at T0 [(136 ± 12) mmHg (1 mmHg =0.133 kPa) vs.(124 ± 9) mmHg,(83 ± 10) mmHg vs.(72 ± 6) mmHg,(93 ± 11) times/min vs.(81 ± 8) times/min] (P ＜ 0.05).In normal saline group,the level of SBP,DBP and HR at T2-6 [(151 ± 14),(137 ± 11),(132 ± 10),(132 ±9),(142± 13)mmHgvs.(125 ±9)mmHg;(94±13),(85±9),(80±8),(80±9),(86±11)mmHgvs.(74 ±7) mmHg; (122 ±15),(105 ±12),(90 ±9),(89 ± 10),(97 ±11) times/min vs.(81 ±9) times/min] were significantly lower (P ＜ 0.05).Compared with normal saline group,the level of SBP,DBP and HR were lower in dexmedetomidine group at T2-6(P ＜ 0.05).There were no significant difference not only about the blood gas analysis of umbilical vein and umbilical artery,but also about the Apgar scores at 1 and 5 min after delivery (P ＞ 0.05).Conclusion Administration of dexmedetomidine is effective in maintaining the maternal haemodynamic during the cesarean section under general anesthesia without adverse neonatal effects.

Objective To investigate the efficacy and safety of acute normovolemic hemodilu-tion for pregnant women with total placenta pravia and accreta.Methods Fifty-two pregnant women with placenta praevia and accreta were randomly divided into three groups.Groups A and B received ANH or AHH before the operation while group C received the normal treatment.The total blood loss,transfusion of allogeneic blood and preoperative and postoperative routine blood test were recor-ded;the infants’umblical artery blood samples were taken immediately after birth,and 1 min,5 min Apgar scores and the blood gas was analyzied.Results There were no significant difference in the general condition,operation duration,blood loss among the three groups;the transfusion of allogeneic blood in groups B and C were much more than group A (P <0.05);the postoperative hemoglobin and hematocrit and the count of plateletsin in group A were better than groups B and C (P <0.05),while there were no statistically difference between groups B and C;there were not only seldom difference in the Apgar scores of 1 min and 5 min,but also barely change in the blood gas analysis of umbilical ar-tery in new borns from the three groups.Conclusion ANH could play an important role in the pre-vention of postpartum hemorrhage without doing any harm to the mother and infant.

Objective To investigate the factors affecting pulse transit time during anesthesia. Methods Sixty cases of gastrointestinal surgery under general anesthesia were investigated.The pulse transit time (PTT),BP and HR were measured at the time before and after intravenous anes-thesia induction,and at the time before and after the injection of vasoactive drugs,respectively. Results Compared to at the time before injection,HR,SBP and DBP increased significantly,and PTT decreased significantly (P <0.01 )at the time after injection of atropine and ephedrine.Com-pared to at the time before injection,HR and PTT increased significantly,while SBP and DBP de-creased significantly (P < 0.01 )at the time after injection of nicardipine.While HR and PTT de-creased significantly,and SBP,DBP increased significantly (P <0.01 )with the injection of pheny-lephrine.Obvious negative correlation between SBP and PTT was observed before and after induc-tion;meanwhile,only weak correlation between DBP and PTT was observed,and no obvious correla-tion between HR and PTT was detected.SBP and PTT were well negatively correlated with the injec-tion of atropine,ephedrine,nicardipine or phenylephrine.Conclusion All the PTT changes during anesthesia were found to be negatively correlated with the systolic blood pressure.

Objective To evaluate the efficacy of dexmedetomidine mixed with ropivacaine for epidural anesthesia in the patients.Methods Forty-six patients, of ASA physical status Ⅰ or Ⅱ , aged 36-58 yr, weighing 48-77 kg, scheduled for elective hysterectomy under epidural anesthesia, were randomly divided into 2 groups (n =23 each) according to the random number table: normal saline + ropivacaine group (R group) and dexmedetomidine + ropivacaine group (DR group).Epidural anesthesia was performed at L2,3interspace.The catheter was inserted into the epidural space.A mixture of 0.75％ ropivacaine 15 ml and dexmedetomidine 1 μg/kg was injected epidurally in DR group.A mixture of 0.75％ ropivacaine 15 ml and normal sline 2 ml was injected epidurally in R group.The onset time of sensory block, maximum level of sensory block, and duration of sensory block were recorded.The modified Bromage scale, Ramsay sedation score and intraoperative traction reaction were assessed.The occurrence of dexmedetomidine-related cardiovascular events and respiratory depression, and epidural anesthesia-related adverse events within 2 h after operation was recorded.Results Compared with R group, the onset time of sensory block was significantly shortened, the duration of sensory block was prolonged, the maximum level of sensory block and Ramsay sedation score were increased, the degree of intraoperative traction reactions was lessened, and the incidence of shivering was decreased in DR group (P ＜ 0.05).No patients developed dexmedetomidine-related adverse events.Conclusion Epidural dexmedetomidine 1 μg/kg significantly optimize the efficacy of ropivacaine when used for epidural anesthesia in the patients.

Objective To study the optimal dose of dexmedetomidine for preventing of shive-ring during caesarean section under epidural anesthesia.Methods One hundred and twenty ASA Ⅰ orⅡ parturients with a single baby at full term in vertex presentation,scheduled for caesarean section under continuous epidural anesthesia,were randomly divided into 4 groups (n=30 each):group D1, group D2,group D3 and group N (control group).After delivery of the baby,The group D1,group D2 and group D3 were received an intravenous infusion loading dose of 0.2μg/kg,0.5μg/kg and 0.8μg/kg of dexmedetomidine within 10 minutes respectively,and following with an intravenous infusion 0.4 μg·kg-1·h-1 of dexmedetomidine until peritoneal closure.The group N received an intravenous infusion 0.1 ml·kg-1·h-1 of normal saline.Results The incidence and degree of shivering in group D2 and group D3 were lower than those in group D1 and group N(P<0.05),but there were no statistics differences between group D2 and group D3.Conclusion Administration of dexmedetomidine can re-duce the occurrence of shivering during caesarean section under epidural anesthesia,and a loading dose of 0.5 μg/kg of dexmedetomidine is the optimal dose.

Objective To evaluate the effect of preloading the epidural space with normal saline (NS) on the incidence of injury to blood vessel by epidural catheter placement for cesarean section. Methods One hundred and fifty parturients with a single baby at full term in vertex presentation scheduled for cesarean section under continuous epidural anesthesia were randomly divided into 3 groups ( n = 50 each): Ⅰ group control; Ⅱ group NS needle attached to a 5 ml syringe. Loss of resistance was used to identify the epidural space. In group Ⅰ no fluid was injected into the epidural space before insertion of catheter; while in group Ⅱ and Ⅲ NS 5 ml with or without whom blood or blood tinted fluid was withdrawn from epidural catheter was recorded. Results The number of patients in whom blood or blood tinted fluid was withdrawn from epidural catheter was significantly lower in group Ⅱand Ⅲ than in group Ⅰ but was not significantly different between group Ⅱ and Ⅲ. Conclusion Preloading the epidural space with 5 ml NS can reduce the incidence of injury to blood vessel induced by insertion of epidural

Objective To investigate the effect of dexamethasone on the toxicity of bupivacaine in murine neurons.Methods Murine neuroblastoma cell line N2a was obtained from ATCC cell bank (USA). The cells were cultured in 10% fetal cow serum/MEM culture medium and divided into 4 groups voup I control (Con); group II bupivacaine ( Bup); group Ⅲ dexamethasone (Dex) and group IV Dex + Bup. The culture medium contained bupivacaine 900 μmol/L in group Bup and dexamethasone 1 μmol/L in group Dex respectively. In group Dex + Bup ( IV ) Bup was added to the culture medium with a final concentration of 900 μmol/L at 12 h after pretreatment with Dex 1 μmol/L. The cells were inoculated in 24 well plates (0.5 ml in each well, 24 wells in each group) and 10 cm culture dishes (7 ml in each dish, 4 dishes in each group). The release rate of LDH was calculated and the morphology of the cells and nucleus condensation (by Hoechst 3334224 fluorescent staining) was detected at 9 h of incubation in 24 well plates. The mitochondrial transmembrane potential (by JC-1 assay) and phosphorylation of Akt and ERKs (by Western blot) were measured at 5 h of incubation in 24 well plates and in culture dishes respectively. ResultsBupivacaine caused severe damage to the N2a cells as evidenced by increase in LDH release and nucleus condensation (apoptosis), dephosphorylation of Akt and ERKs, decrease in mitochondrial transmembrane potential and severe morphological changes. Dexamethasone pretreatment significantly attenuated bupivacaine-induced neurotoxicity. Conclusion Dexamethasone can protect N2a cells from bupivacaine-induced neurotoxicity through stabilization of mitochondrial transmembrane potential and inhibition of dephosphorylation of Akt and ERKs.