Propofol-controlled infusion technique in assessing the safe dosage for sedation during epidural anesthesia

Yingmin Cai; Pengbin Liu; Jinxin Song; Rongliang Xue

摘要：BACKGROUND:Epidural anesthesia requires a convenient and accurate method to determine the plasma concentration of the given subsidiary drug.The target-controlled infusion(TCI)technique,controlling infusion pump by computer,has been used.Intravenous jnjection of propofol was given for the purpose of measunng plasma concentrations and to observe the effects of different target concentrations on the memory,consciousness,hemodynamics and blood gases of patients,in order to find a safe dosage for sedation in epidural anesthesia.OBJECTIVE:To observe the influence of different target concentrations on the memory,consciousness,hemodynamics and blood gases of patients accepted epiduml anesthesia.DESIGN:A randomized and controlled study.SETTING:Department of Anesthesiology,the Second Affiliated Hospital,Medical College of Xi'an Jiao Tong University.PARTICIPANTS:The expenment was conducted in the Department of Anesthesiology,the Second Affiliated Hospital,Medical College of Xi'an Jiao Tong University from June 2005 to June 2006.Fifty patients underwent surgery for lower abdomen and lower limbs were selected,including 30 males and 20 females,30-60 years old with an average of(46±6)years,weighling(65.8±8.5)kg,and American Society of Anesthesiology(ASA)gradling of Ⅰ-Ⅱ.All the patients were informed and agreed with the items for detection.METHODS:All the patients were given diazepam(10 mg)and atropine(0.5 mg)intramusculady 30 minutes before surgery.They were placed supinely and given oxygen inhalation,their blood pressure,heart rate and blood oxygen saturation were determined,then an epidural puncture was made in the left lateral decubitus position with hands crossed over knees.The patients were in a horizontal position and a radial artery puncture was done,after the epidural cathetar was positioned into epidural space.Blood of radial artery was drawn to get a blood gas,a linked HP multi-functional monitor was used to monitor blood pressure(radial artery),pulse,oxygen saturation and electrocardiogram continuously.TCI instillation begun and plasma concentrations with 1.0,1.5,2.0.2.5,3.0 mg/L were set up.Epidural anesthesia was discontinued and the operation was completed.When target concentrations were achieved the state of consciousness,the blood pressure,heart rate,oxygen saturation and blood gas results were recorded immediately,and Compared with the measurements taken before surgery.The length of time to awakenling after surgery was noted and a follow-up survey was done on the next day to record the patients'memory about the surgery.MAIN OUTCOME MEASURES: :①Effects of different target concentrations of propofol on Consciousness,memory,blood pressure,heart rate,respiratory frequency,oxygen saturation and blood gases;②Recovery of orientation after surgery.RESULTS:All the 50 enrolled patients were involved in the analysis of results.①Effects of different target concentrations of pmpofol on consciousness and memory:When the target concentration of propofol reached 1.0 mg/L.30 cases(60%)lost Consciousness,5 cases(10%)had consciousness at that time,but could not remember anythling about the surgery afterwards,and the other 15 cases(30%)Could remember the Conditions about the surgery,which was significantly different from those before the surgery.When the target concentration of propofol reached 1.5 mg/L,45 cases(90%)lost consciousness,and all had complete amnesia.When the target concentration of propofol reached 2.0 mg/L,all the patients were unconscious and amnesia.②Effects of different target concentrations of prepofol on blood pressure and heart rate:When the target concentration of propofol reached 1.5-3.0 mg/L.the systolic pressures were(100.34±9.76),(94.32±6.58),(85.12±6.98)and (78.56±4.76)mm Hg(1 mm Hg=0.133 kPa)respectively,which were all lower than that before surgery [(129.00±10.18)mm Hg,P＜0.05-0.01];The diastolic pressures were(56.44±7.67),(50.72±9.72),(49.78±4.80)and(40.34±6.98)mm Hg respectively,which were all lower than that before surgery [(78.88±9.76)mm Hg,P＜0.05-0.011:The heart rates were(98.78±8.76),(108.34±7.85),(110.56±4.72)and(112.56±9.87)beats/min,which were all higher than that before surgery [(87.87±8.88)beats/min,P＜0.05-0.01].③Effects of different target concentrations of propofol on respiratory rate,oxygen saturation and blood gases:When the target concentration of propofol was 1.0 and 1.5 mg/L,the oxygen saturations were higher than that before surgery[(97.65±4.67)%,(97.64±7.23)%,(97.34±5.87)%,P＜0.05]:When the target concentration of propofol was 2.5 and 3.0 mg/L,the oxygen saturations were lower than that before surgery [(88.67±14.73)%.(86.76±16.78)%,(97.34±5.87)%,P＜0.05].When the target concentration of propofol was 2.0,2.5 and 3.0 mg/L,the respiratory frequencies were(18.62±4.52),(18.76±5.98)and(18.46±4.87)beats/min,which were all higher than that before surgery [(13.23±2.45)beats/min,P＜0.05];When the target concentration of propofol was 3.0 mg/L,the Ph value was lower than that before surgery (7.28±9.68,7.36±9.67,P＜0.05),the CONLUSION:TCI assessment showed that propofol under the target concentrations 1.5-2.0mg/Lwas optimal for apidural anesthesia.