Objective To observe the effects of ventilation with low tidal volume and positive end-expiratory pressure (PEEP)in different periods on the postoperative pulmonary function and short-term prognosis in aged patients undergoing abdominal surgery.Methods Sixty aged patients undergoing selective open abdominal surgery scheduled for general anesthesia,21 males and 39 fe-males,were randomized into 3 groups (n =20).Patients in group A received PEEP 1 h after the be-ginning of surgery;patients in group B received PEEP 1 h before tracheal extubation;patients in group C received PEEP intraoperatively.The secretion score in preoperative,postoperative 24 h and 72 h respectively,and the arterial blood gas analysis indexes (PaCO 2 ,PaO 2 ,A-aDO 2 ,PaO 2/FiO 2 calculation)in postoperative 1 h and 24 h were recorded.Results Compared with preoperative,in postoperative 1 h,PaCO 2 increased obviously in all groups,PaO 2 decreased in group B,A-aDO 2 in-creased in group A (P <0.05);in postoperative 24 h,PaCO 2 was significantly increased in group B and C,PaO 2/FiO 2 decreased in group B (P <0.05).Compared with postoperative 1 h,in postopera-tive 24 h,PaCO 2 and A-aDO 2 decreased obviously in group A (P <0.05).There were no differences in postoperative secretions score in between the 3 groups.Conclusion Low tidal volume combined short-range PEEP in different periods of surgery may improve postoperative pulmonary oxygenation. But they had no obvious help with postoperative pulmonary complications.

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 evaluate the effect of acute plateletpheresis (APP) and back-transfusion on platelet activation in the patients undergoing open heart surgery with cardiopulmonary bypass (CPB).Methods Forty patients,aged 35-64 yr,with body mass index within the normal range,of ASA physical status Ⅱ or Ⅲ (NYHA Ⅱ or Ⅲ),scheduled for elective cardiac valve replacement under CPB,were randomly divided into 2 groups (n =20 each) using a random number table:control group (group C) and APP group.In group APP,after induction of anesthesia,APP was performed,packed red blood cells and platelet-poor plasma were transfused back to the patient after termination of the previous cycle,and another cycle was started simultaneously.Platelet-rich plasma (PRP) was harvested and transfused back to the patient after termination of CPB and neutralization of heparin with protamine.Before induction of anesthesia (baseline),after APP and before heparinization,after neutralization of heparin with protamine and before back-transfusion of PRP,at the end of operation,and at 24 h after operation,venous blood samples were collected for determination of the expression of CD62p and PAC-1 in inactivated platelets and activated platelets by adenosine diphosphate (ADP).After APP and before heparinization,and after neutralization of heparin with protamine and before back-transfusion of PRP,the expression of CD62p and PAC-1 in inactivated platelets and ADP-activated platelets was detected in the whole blood and PRP in group APP.Results Compared with C group,the expression of CD62p and PAC-1 in inactivated platelets was down-regulated at the end of operation,and the expression of CD62p and PAC-1 in ADP-activated platelets was upregulated in APP group.The expression of CD62p and PAC-1 in inactivated platelets was down-regulated in PRP,and the expression of CD62p and PAC-1 in ADP-activated platelets was up-regulated in PRP as compared with those in the whole blood.Conclusion APP can not induce platelet activation,however,platelet back-transfusion can enhance platelet activation in the patients undergoing open heart surgery with CPB.

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 evaluate the effect of dexmedetomidine on left ventricular function in patients undergoing coronary artery bypass grafting (CABG) by transesophageal echocardiography (TEE).Methods The study was a prospective,randomized and placebo-control clinical trial.Eighty patients undergoing CABG with cardiopulmonary bypass (CPB) were divided into dexmedetomidine group (group D)and control group (group C) by random digits table method with 40 cases each.A loading dose of dexmedetomidine 0.5 μg/kg was injected intravenously 10 min after induction followed by infusion at 0.4 μ g/(kg· h) until the end of operation in group D,while equal volume of normal saline was given in group C.Left ventricular function was assessed by transesophageal echocardiography before the infusion of dexmedetomidine (T1),at the end of the infusion of loading dose (T2),before CPB (T3) and at the end of the operation (T4).Results Compared with those at T1,left ventricular ejection fraction and fractional area change decreased significantly [(58.0 ± 12.0)％,(60.0 ± 9.6)％ vs.(63.0 ± 8.6)％ and (46.0 ± 9.3)％,(48.0 ± 8.4)％ vs.(51.0 ± 6.7)％] (P ＜ 0.05 or ＜ 0.01),E/A ratio increased significantly (1.05 ± 0.27,1.07 ±0.31 vs.0.98 ±0.19)(P ＜0.05 or ＜0.01) and myocardial performance index (MPI) decreased significantly (0.46 ± 0.14,0.45 ± 0.12 vs.0.51 ± 0.14) (P ＜ 0.05) at T2 and T3 in group D,while stroke volume was not significantly changed (P＞ 0.05).Compared with that in group C,E/A ratio and rapid filling fraction in group D was significantly higher [1.06 ± 0.18 vs.0.97 ± 0.18,(62.0 ± 7.1)％ vs.(58.0 ± 7.3)％],and S/D ratio and MPI was significantly lower at T4(1.17 ± 0.21 vs.1.29 ± 0.22,0.43 ± 0.15 vs.0.50 ± 0.15),and there were significant differences (P ＜ 0.05).There was no difference in the parameters indicating left ventricular systolic function (P ＞ 0.05).Conclusions Dexmedetomidine restrains left ventricular systolic function in the patients undergoing CABG,but does not decrease the cardiac output,and improve relaxation dysfunction of left ventricular diastolic function.Global left ventricular function is improved by dexmedetomidine after CABG.

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 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 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.