Median Effective Target Plasma Concentration Research Articles

Effect of neoadjuvant chemotherapy for ovarian cancer on sedative potency of propofol and oxycodone for anesthesia induction

Objective To evaluate the effect of neoadjuvant chemotherapy for ovarian cancer on the sedative potency of propofol and oxycodone for anesthesia induction. Methods Sixty-eight American Society of Anesthesiologists physical status Ⅰor Ⅱ patients, aged 40-64 yr, with body mass index of 20-30 kg/m2, scheduled for elective radical resection of ovarian cancer with general anesthesia, were divided into into 2 groups(n=34 each)according to whether the patients received neoadjuvant chemotherapy before surgery: neoadjuvant chemotherapy group(groupⅠ)and non-chemotherapy group(group Ⅱ). Patients received 3 cycles of chemotherapy(21 days for 1 cycle), chemotherapy regimen was paclitaxel and carboplatin, and patients underwent surgery after 3 weeks of chemotherapy in group Ⅰ.Anesthesia was induced with Ⅳ oxycodone 0.2 mg/kg.Propofol was given by target-controlled infusion 4 min later, and the effect-site concentration(Ce)of propofol was determined by up-and-down technique, with the initial Ce 1.0 μg/ml and the ratio between the two successive Ces 1.09.The median-effective target plasma concentration(EC50)and 95% confidence interval of propofol causing loss of consciousness were calculated using Probit analysis. Results The EC50 and 95% confidence interval of propofol causing loss of consciousness were 1.22 μg/ml(1.14-1.30 μg/ml)and 1.74 μg/ml(1.57-3.19 μg/ml)in group Ⅰ and group Ⅱ, respectively.Compared with group Ⅱ, the EC50 of propofol causing loss of consciousness was significantly decreased in group Ⅰ(P<0.05). Conclusion Neoadjuvant chemotherapy for ovarian cancer can enhance the sedative potency of propofol and oxycodone for anesthesia induction. Key words: Oxycodone; Chemotherapy, adjuvant; Propofol; Sedation

Effects of different doses of dexmedetomidine administered intranasally on EC50 of propofol inhibiting responses to laryngeal mask airway insertion in pediatric patients

Objective To evaluate the effects of different doses of dexmedetomidine administered intranasally on the median effective target plasma concentration(EC50)of propofol inhibiting responses to laryngeal mask airway(LMA)insertion in the pediatric patients. Methods American Society of Anesthesiologists physical statusⅠor Ⅱ pediatric patients of both sexes, aged 1-3 yr, with body mass index of 20-26 kg/m2, scheduled for elective surgery under general anesthesia, were divided into 3 groups using a random number table: control group(group C), dexmedetomidine 1 μg/kg group(group D1)and dexmedetomidine 2 μg/kg group(group D2). At 20 min before induction of anesthesia, dexmedetomidine 1 and 2 μg/kg(diluted to 1 ml in normal saline)were intranasally administered in DI and D2 groups, respectively, and the equal volume of normal saline was intranasally administered in group C. Children were separated from their parents at 20 min after intranasal administration and admitted to the operating room.The target plasma concentration of propofol was determined by modified Dixon′s up-and-down method.The initial target plasma concentration of propofol was set at 5.4 μg/ml.The target plasma concentration of propofol was increased/decreased by 10% in the next patient according to the response to LMA insertion, and the ratio between the two successive concentrations was 1.1.Patients′ sedation status and LMA acceptance were evaluated when patients were separated from their parents.Patient′s satisfaction with sedation and with LMA acceptance was recorded.Probit analysis was used to calculate the EC50 of propofol inhibiting responses to LMA insertion. Results Compared with group C, the satisfactory rates of sedation and LMA acceptance were significantly increased, and EC50 of propofol inhibiting responses to LMA insertion was decreased in D1 and D2 groups(P<0.05). Compared with group D1, the satisfactory rates of sedation and LMA acceptance were significantly increased, and the EC50 of propofol inhibiting responses to LMA insertion was decreased in group D2(P<0.05). Conclusion Dexmedetomidine 1 and 2 μg/kg administered intranasally both can decrease the EC50 of propofol inhibiting responses to LMA insertion in the pediatric patients, and 2 μg/kg produces better efficacy. Key words: Dexmedetomidine; Administration, intranasal; Propofol; Dose-response relationship, drug; Laryngeal masks; Child

Median effective target plasma concentration of remifentanil inhibiting responses to skull-pin placement when combined with propofol in female patients undergoing neurosurgery

Objective To determine the median effective target plasma concentration (EC50) of remifentanil inhibiting responses to skull-pin placement when combined with propofol in the female patients undergoing neurosurgery. Methods Sixteen female patients, aged 20-60 yr, with body mass index of 18-30 kg/m2, of American Society of Anesthesiologists physical status Ⅰor Ⅱ, scheduled for elective neurosurgery under general anesthesia, were enrolled in this study.Anesthesia was induced with propofol and remifentanil given by target-controlled infusion and iv rocuronium 0.6 mg/kg.The target plasma concentration (Cp) of remifentanil and propofol was set at 5 ng/ml and 3 μg/ml, respectively.At 3 min after tracheal intubation, the target Cp of remifentanil was adjusted and set at 5 ng/ml in the first patient.The skull-pin was placed after the target effect-site and plasma concentrations were balanced.The Cp increased/decreased by 20% each time in the next patient depending on whether or not the response to skull-pin placement was positive.The ratio between the two successive concentrations was 1.2.The response to skull-pin placement was defined as positive when heart rate and/or mean arterial pressure increased by 20% of the baseline value within 1 min after placement.The EC50 and 95% confidence interval of remifentanil required to inhibit responses to skull-pin placement were calculated when combined with propofol. Results The EC50 (95% confidence interval) of remifentanil required to inhibit responses to skull-pin placement was 3.74 (3.43-4.09) ng/ml when combined with propofol. Conclusion When combined with propofol, the EC50 of remifentanil inhibiting responses to skull-pin placement is 3.74 ng/ml in the female patients undergoing neurosurgery. Key words: Piperidines; Propofol; Female; skull-pin; Dose-response relationship, drug; Drug delivery systems

Effect of age on potency of propofol inhibiting visceral pain during gastroscopy

Objective To evaluate the effect of age on the median-effective target plasma concentration (EC50) of propofol inhibiting body movement evoked by gastroscopy in the patients.Methods Ninety adult patients of both sexes,of ASA physical status Ⅰ or Ⅱ,with body mass index 19-25 kg/m2,scheduled for elective gastroscopy,were divided into 3 groups according to age (n =30 each):18-39 yr group (Ⅰ group),40-64 yr group (Ⅱ group) and 65-85 yr group (Ⅲ group).In Ⅰ,Ⅱ,Ⅲ groups,propofol was given by target-controlled infusion with the initial target concentrations of 2.5,2.0 and 1.5 μg/ml,respectively,and gastroscopy was performed when the target concentration was achieved.Body movement was defined as the directional movement in head or four extremities during gastroscopy.The target plasma concentration of propofol was determined by up-and-down sequential trial.Each time the plasma concentration of propofol increased/decreased by 0.5 μg/ml in the next patient depending on whether or not body movement developed.The EC50 and 95 ％ confidence interval of propofol inhibiting gastroscopy-evoked body movement were determined using Probit analysis.Results The EC50 (95 ％ confidence interval) of propofol was 4.2(3.8-4.5),4.1(3.7-4.4) and 2.4(1.8-2.7) μg/ml in Ⅰ,Ⅱ and Ⅲ groups,respectively.There was no significant difference in the EC50 of propofol between group Ⅱ and group Ⅰ.The EC50 of propofol was significantly lower in group Ⅲ than in Ⅰ and Ⅱ groups.Conclusion Age affects propofol-induced analgesia in patients with visceral pain,and the potency of propofol inhibiting visceral pain during gastroscopy in the elderly patients is significantly enhanced as compared with that in the young and middle-aged patients. Key words: Age factors ; Viscera ; Pain ; Propofol ; Dose-response relationship, drug

Optimum dose of fentanyl for gastroscopy in elderly patients when combined with propofol

Objective To evaluate the effects of different doses of fentanyl on the median effective target plasma concentration (EC50) of propofol inhibiting body movement evoked by gastroscopy in the elderly patients.Methods Ninety patients of both sexes,aged 75-89 yr,with a body mass index of 19-25 kg/m2,of ASA physical status Ⅱ or Ⅲ,scheduled for elective gastroscopy,were randomly divided into 3 groups (n =30 each):control group (group C) and different doses of fentanyl groups (F0.5 and F1.0 groups).Fentanyl 0.5 and 1.0 μg/kg were injected intravenously in F0.5 and F1.0 groups,respectively.Propofol was then administered by target-controlled infusion.The initial target plasma concentrations (Cps) of propofol were 2.0,1.5 and 1.0 μg/ml in C,F0.5 and F1.0 groups,respectively.Gastroscopy was performed after the target effect-site and plasma concentrations were balanced.Body movement was defined as movement in head or four extremities during gastroscopy.The target Cp of propofol was determined by up-and-down sequential trial.Each time the Cp increased/decreased by 0.5 μg/ml in the next patient depending on whether or not body movement developed.The EC50 and 95 ％ confidence interval (CI) of propofol inhibiting gastroscopy-evoked body movement were determined using Probit analysis.Results The EC50 (95 ％ CI) of propofol was 2.24 ng/ml (1.67-2.47 ng/ml) in group C,1.79 (1.55-1.95) μg/ml in group F0.5,and 1.13 (1.08-1.62) μg/ml in group F1.0.There was no significant difference in the EC50 of propofol between F0.5 and C groups.The EC50 of propofol was significantly lower in F1.0 group than in C and F0.5 groups.Conclusion When combined with propofol,fentanyl 1.0 μg/kg is recommended for gastroscopy in the elderly patients. Key words: Aged; Fentanyl; Dose-response relationship, drug; Propofol; Gastroscopy

Median effective target plasma concentration of remifentainil inhibiting body movement evoked by puncture during brachial plexus block in pediatric patients

Objective To determine the median effective target plasma concentration (Cp50) of remifentainil inhibiting body movement evoked by puncture during brachial plexus block in pediatric patients.Methods Pediatric patients of both sexes,aged 5-12 yr,who grown normally,scheduled for elective forearm or hand surgery,were enrolled in this study.Children were premedicated with oral midazolam 0.2 mg/kg at 30 min before anesthesia.The initial target Cp of remifentainil was 5.0 ng/ml.The target Cp was determined by up-and-down sequential method.Each time Cp increased/decreased by 20％ in the next patient depending on the response of the previous patient to puncture.The ratio between the two successive concentrations was 1.2.The puncture was performed after the target effect-site and plasma concentrations were balanced.Body movement was defined as puncture-induced movement of truncus,limbs and/or head and neck.The Cp50 and 95 ％ confidence interval of remifentainil were calculated by Dixon method.Results Cp50 of remifentainil inhibiting body movement evoked by puncture during brachial plexus block was 3.9 ng/ml,and 95 ％ confidence interval was 3.6-4.2 ng/ml.Conclusion Cp50 of remifentainil inhibiting body movement evoked by puncture during brachial plexus block is 3.9 ng/ml in pediatric patients. Key words: Piperidines; Motor activity; Dose-response relationship, drug; Drug delivery systems; Child; Brachial plexus; Nerve block

Effects of gender on median effective target plasma concentration of propofol inhibiting responses to laryngeal mask airway insertion

Objective To evaluate the effects of gender on the median effective target plasma concentration (EC50) of propofol inhibiting responses to laryngeal mask airway (LMA) insertion in patients.Methods Fiftyfive ASA physical status Ⅰ or Ⅱ patients,aged 20-60 yr,with body mass index 18-25 kg/m2,requiring LAM insertion,undergoing elective surgery,were divided into 2 groups according to the gender:male group (group M,n =27) and female group (group F,n =28).Propofol was given by target-controlled infusion.Anesthesia was induced with target-controlled infusion of propofol.The concentration of propofol was determined by using modified Dixon's up-and-down method.The initial target plasma concentration of propofol was 3.0 μg/ml (group M) or 2.7μg/ml (group F) and the ratio between the 2 successive concentrations was 1.1.Fentanyl 1 μg/kg was injected intravenously at about 10 min of propofol target-controlled infusion.LMA was inserted after the effect-site and plasma concentrations were balanced.The positive response to LMA insertion was defined as development of swallowing,coughing,biting LMA,body movement and laryngospasm during insertion.When the response to LMA insertion was positive,the concentration of propofol was increased in the next patient and when the response was negative,the concentration was decreased in the next patient.The EC50 and 95 ％ confidence interval of propofol inhibiting responses to LMA insertion were calculated.Results The EC50 (95 ％ confidence interval) of propofol was 3.11 (2.92-3.30) μg/ml in group F and 2.70 (2.55-2.85) μg/ml in group M (/ ＜ 0.05).Conclusion The EC50 of propofol inhibiting responses to LMA insertion is higher in female patients than in male patients. Key words: Sex factors; Propofol; Laryngeal masks; Drug delivery systems; Dose-response relationship, drug

Effects of remifentanil infused at different rates on median effective target plasma concentration of propofol inhibiting responses to laryngeal mask airway insertion in pediatric patients

Objective To compare the effects of remifentanil infused at different rates on median effective target plasma concentration (EC50) of propofol inhibiting responses to laryngeal mask airway (LMA) insertion and determine the optimum infusion rate of remifentanil when used for fiberoptic bronchoscopy in pediatric patients.Methods Eighty-four ASA Ⅰ or Ⅱ pediatric patients,aged 7 months-3 years,scheduled for elective fiberoptic bronchoscopy,were randomly assigned into 3 groups (n =28 each):normal saline group (group C),remifentanil infused at 3 ng· kg-1 ·min-1 group (group R1) and remifentanil infused at 5 ng· kg-1 · min-1 group (group R2).Responses to LMA insertion were defined as body movement and/or bucking during insertion.The initial target plasma concentrations of propofol were 5.2,4.8 and 4.4 μg/ml in groups C,R1 and R2,respectively.The target plasma concentration of propofol was determined by up-and-down sequential allocation.Each time the target plasma concentration increased/decreased by 0.2μg/ml.EC50 and 95 ％ confidence interval of propofol blunting responses to LMA insertion were determined by probit method.Results EC50 (95 ％ confidence interval) of propofol was 5.03 (4.92-5.12) μg/ml,4.71 (4.58-4.84) μg/rnl and 4.46 (4.20-4.94) μg/ml in groups C,R1 and R2,respectively.There was no significant difference in EC50 of propofol between groups R1 and C (P ＞ 0.05).EC50 of propofol was significantly lower in group R2 than in groups C and R1 (P ＜ 0.05).Conclusion The infusion rate of remifentanil should not be lower than 5 ng· kg-1· min-1 when combined with propofol in pediatric patients undergoing fiberoptic bronchoscopy. Key words: Piperidines; Infusions, intravenous; Propofol; Dose-response relationship, drug; Child ; Anesthesia, general; Bronchoscopy

Median effective target plasma concentration of propofol inhibiting response to laryngeal mask airway insertion when combined with dexmedetomidine

Objective To determine the median effective target plasma concentration （EC50） of propofol inhibiting the response to laryngeal mask airway （LMA） insertion when combined with dexmedetomidine. Methods ASA Ⅰ or Ⅱ patients of both sexes, aged 20-60 yr, with body mass index 20-25 kg/m2 , scheduled for surgeries under general anesthesia, were studied. E C50 of propofol was determined by modified Dixon＇s up-and-down sequential experiment. After dexmedetomidine 1.0 μg/kg was infused over 10 min, propofol was infused by targetcontrolled infusion. The initial target plasma concentration of propofol was set at 3.0μg/ml. LMA was inserted when the target effect-site concentration of propofol and target plasma concentration of propofol reached the balance and BIS value was 50-60. Each time the target concentration increased/decreased by 0.2 μg/ml according to the occurrence of the response to LMA insertion. The response to LMA insertion was defined as the occurrence of coughing, body movement, laryngospasm or systemic voluntary movement. EC50 and 95 % confidence interval （CI） of propofol for inhibition of the response to LMA insertion were calculated. Results The ECs0 of propofol required for inhibition of the response to LMA insertion was 2.351 （95% CI 1.737-2.600） μg/ml when combined with dexmedetomidine 1：0μg/kg.Conclusion The EC50 of propofol inhibiting the response to LMA insertion is 2.351 μg/ml when combined with dexmedetomidine. Key words: Dexmedetomidine ; Propofol ; Drug delivery systems ; Laryngeal masks

Effects of ovarian cycle on medlan-effecttve target plasma concentration of propofol TCI caused loss consciousness

Objective To evaluate the effects of ovarian cycle on median-effective target plasma concentration (EC50) of propofol administered by target controlled infusion (TCI) caused loss consciousness.Methods Forty ASA I or II patients who had age 20 - 39 (28.5 ± 4.8) years and were scheduled for elective gynecologic laparoscopic surgery were divided into 2 groups (n =20 each group) : The follicular phase group (F group, serum progesterone concentration O.31 1.52 ng/ml) and luteal phase group (L group, serum progesterone concentration 5.16 ～ 18.56 ng/ral).No premedication was administered.Propofol was administered by TCI.TCI system was incorporated with Marsh pharmacokinetic model.EC50 was determined by up-and-down sequential trial.The target phsma concentration (Cp) was set at 3.5 μg/ml in the fh-st patient in each group.Each time, Cp was increased/decreased by 10％ in the next patient depending on whether or not the loss consciousness occurred.Results The ECho and 95％ confidence interval of propofol TCI caused loss consciousness were 4.76 (4.52 -5.00) μg/ml in group F, 4.18(3.88 ～4.52)μg/ml in group L.EC50in group L was significantly lower than in group F (t =6.23, P ＜0.01).Conclusions As loss consciousness occurred, median-effective target plasma concentration of propofol in luteal phase was lower than that in follicular phase. Key words: Menstrual cycle; Anesthesia, general; Propofol/PK

Effects of gender and age on median-effective target plasma concentration of propofol TCI causing respiratory depression

Objective To evaluate the effects of gender and age on median-effective target plasma concentration(EC50)of propofol administered by target controlled infusion(TCI)causing respiratory depression.Methods Eighty ASA Ⅰ or Ⅱ patients aged 40-79 yr,with body mass index 18-25 kg/m2.undergoing general anesthesia were divided into 4 groups(n=20 each):1 middle-aged male group(MA);Ⅱ middle-aged female group(FA);Ⅲold male group(MO) and Ⅳo ld female group(FO).No premedication was administered.Propofol Was administered by TCI for 15 min,using TCI system incorporating Marsh pharmacokinetic model.EC50 Was determined by up-end-down sequential trial.The target plasma concentration(Cr)was set at 3.1μg/ml in the first Patient in each group.Each time Cr increased/decreased by 10%in the next patient depending on whether or not the respiratory depression occurred.Respiratory depression was defined as RR<8 bpm,Vr≤5 ml/kg,end-tidal PCO2≥50 mm Hg,SaO2≤94%and/or apnea≥15s.Results The EC50 and 95%confidence interval of propofol TCI causing respiratory depression were 6.40(6.09-6.72)μg/ml in group MA,5.93(5.54-6.34)μg/ml group FA,4.58(4.32-4.91)μg/ml in group MO and 4.37(4.14-4.61)μg/ml in group FO.EC50 was significantly lower in group FO than in group FA and in group MO than in group MA,but there Was no significant difference in EC50 between group MA and group FA or between group MO and FO. Conclusion The potency of propofol given by TCI causing respiratory depression is increased in the old patients as compared with the middle-aged patients and is not related to sex. Key words: Age factors; Sex factors; Propofol; Respiratory insufficiency; Drug delivery systems; Dose-response relationship, drug