Intravenous sedation with target-controlled infusion (TCI) in patients with difficult airways

Tracheal intubation was facilitated with an intubating laryngeal mask (ILM) in two patients with difficult airways. Target-controlled infusion (TCI) of propofol and fentanyl was used for sedation during placement of an ILM. An ILM was inserted smoothly. Spontaneous ventilation and oxygenation were well maintained throughout the induction. Both patients were satisfied with intravenous sedation using TCI for awake instrumentation of their airways.     

Anesthetic management of a hyper-obese patient by target-controlled infusion (TCI) of propofol and fentanyl]

We gave total intravenous anesthesia to an over-100% hyper-obese patient using target-controlled infusion (TCI) of propofol and fentanyl. To keep him asleep, we maintained his BIS in a range of 40 to 60 by adjusting the target concentration of propofol. For the target concentration of fentanyl, we chose 2 ng.ml-1 at incision and 1.6 ng.ml-1 during the operation. At the patient's emergence from anesthesia, his estimated blood concentration of propofol was 1.51 micrograms.ml-1 and his BIS was 80. The relationship between BIS value and effect-site concentration of propofol was almost the same as that assessed in ordinary adults of a normal weight. We conclude that the estimated concentration of propofol is a good indicator of the effect of propofol and that TCI is a useful technique in obese patients as well as in ordinary adults.     

Manual compared with target-controlled infusion of propofol

We studied 160 ASA I-II patients, anaesthetized with propofol by infusion, using either a manually controlled or target-controlled infusion system. Patients were anaesthetized by eight consultant anaesthetists who had little or no previous experience of the use of propofol by infusion. In addition to propofol, patients received temazepam premedication, a single dose of fentanyl and 67% nitrous oxide in oxygen. Each consultant anaesthetized 10 patients in sequential fashion with each system. Use of the target-controlled infusion resulted in more rapid induction of anaesthesia and allowed earlier insertion of a laryngeal mask airway. There was a tendency towards less movement in response to the initial surgical stimulus and significantly less movement during the remainder of surgery. Significantly more propofol was administered during both induction and maintenance of anaesthesia with the target-controlled system. This was associated with significantly increased end-tidal carbon dioxide measurements during the middle period of maintenance only, but recovery from anaesthesia was not significantly prolonged in the target- controlled group. With the exception of a clinically insignificant difference in heart rate, haemodynamic variables were similar in the two groups. Six of the eight anaesthetists found the target-controlled system easier to use, and seven would use the target-controlled system in preference to a manually controlled infusion. Anaesthetists without prior experience of propofol infusion anaesthesia quickly became familiar with both manual and target-controlled techniques, and expressed a clear preference for the target-controlled system.      

Setting targets for sedation with a target-controlled propofol infusion

We studied 30 unpremedicated patients undergoing muscle biopsy under femoral nerve block to determine sedation levels reached with a Diprifusor target-controlled propofol infusion, in order to establish the equivalent of the ED50 for different levels of depth of sedation. Infusion was started at 0.8 microg x ml(-1) and altered by increments of 0.1 microg x ml(-1) after equilibrium between target and calculated concentrations, until the desired level of sedation was reached. The ED50 target propofol concentrations for sedation at sedation levels 2 (drowsy), 3 (drowsy, responds to verbal stimulation) and 4 (responsive to physical stimulation only) were 1.0 microg x ml(-1), 1.6 microg x ml(-1) and 2.1 microg x ml(-1), respectively. At sedation level 3, several patients exhibited spontaneous movement, hindering surgery. Oxygen supplementation is recommended for sedation at level 4.     

Remifentanil concentration during target-controlled infusion of propofol

After institutional approval and with written informed consent, eight surgical patients were infused intravenously with remifentanil at 250 ngkg lean body mass (LBM)(-1) x min(-1) for 30 min. Cardiovascular and respiratory parameters were recorded and arterial blood samples were taken at regular intervals. In each patient, the same protocol was repeated 40 min later during propofol infused to a target concentration of 3.0 microg x ml(-1). Blood concentrations of remifentanil and propofol were assayed using capillary gas chromatography and high performance liquid chromatography techniques respectively. The number of subjects enrolled was determined by testing the successive areas under the remifentanil time-concentration curve (AUC) for significant difference or non-difference using sequential analysis. The median measured propofol concentration was 3.5 (range: 2.6-4.5) microg x ml(-1) which did not change significantly during the second remifentanil infusion. The median AUC during propofol infusion was greater than control in all subjects, although there was considerable variation of 94.4 (64.3-129.6) versus 64.6 (34.8-126.9) ng x ml(-1) x min; P=0.008, n=8. After 30 min, there was no significant difference in remifentanil concentration during propofol infusion when compared with remifentanil alone of 4.6 (3.2-5.7) versus 3.8 (1.6-4.9) ng x ml(-1); P=0.73, n=8. Co-administration of propofol and remifentanil may result in greater remifentanil concentrations than when remifentanil is infused alone.     

Target controlled infusion (TCI): applications of the "TCI visual" program in anesthesia and sedation with propofol

BACKGROUND: Systems for Target Controlled Infusion accepting not only patient' data, like Diprifusor, but also a pharmacokinetic model have not been available in Italy in the last years. Therefore a program which controls a Pilot Anesthesia Vial pump and accepts any pharmacokinetic model was developed and applied to propofol infusion for anaesthesia and sedation. METHODS: Two versions of the Visual TCI program have been developed. The first, at intervals, supplies the anaesthetist with the values for the pump; the second directly interacts with the pump. The program also supplies the anaesthetist with the current amount of drug in each compartment and with the estimated awakening time. DESIGN: preliminary prospective study. SETTING: operatory theatre and Intensive Care Unit in a University Hospital. Patients: 6 patients undergoing total intravenous anaesthesia with propofol and fentanyl for abdominal surgery; 6 patients undergoing sedation with propofol in an Intensive Care Unit (the first 4-hour period was taken into account). Interventions: propofol infusion was regulated by the Visual TCI program. The first version was employed in three patients of each group and the second one in the others. Hypo- and hypertensive episodes (systolic pressure less than 80 mmHg or higher than basal value plus 25%) were recorded during anaesthesia and sedation. Propofol concentration was measured in plasma three times at defined intervals and per cent differences between measured and computer-calculated values (Predictive error, PE) were calculated. RESULTS: No hypo- or hypertensive episodes were recorded. PE was 27.4 +/- 17.9%. CONCLUSIONS: The program was easily employed, caused no inconvenience, and its use was associated with a remarkable cardiovascular stability. PE distribution was acceptable on the ground of the criteria reported in the literature. The program can be applied to drugs other than propofol, with both two and three compartment pharmacokinetic models and the anaesthetist can choose the most suitable model for the patient.     

异丙酚效应室靶控输注与血浆靶控输注的比较

目的 观察人工流产手术使用效应室靶控输注异丙酚时的药效学变化,并与血浆靶控输注比较。方法 50例患者随机分成效应室靶控(E)和血浆靶控(B)两组,给予芬太尼1μg·kg~(-1)后分别以4μg·ml~(-1)(E组)和6μg·ml~(-1)(B组)的靶浓度输注异丙酚,观察起效时间、恢复时间、脑电频谱(BIS)值以及心率(HR)、血压(BP)、脉搏氧饱和度(SpO_2)。结果 E组起效时间及恢复时间均显著短于B组(P<0.01),而BIS值差异无显著性(P>0.05),同时E组的SpO_2显著低于B组(P<0.05)。结论 效应室靶控和血浆靶控同样适用于人工流产手术,并且起效快、恢复快,但同时应注意其呼吸抑制作用。     

丙泊酚靶控输注用于内窥镜逆行胰胆管造影的麻醉

目的 比较丙泊酚靶控输注与恒速输注用于内窥镜逆行胰胆管造影麻醉的效果差异.方法 选择接受内窥镜逆行胰胆管造影(endoscopic retrograde cholangiopancreatography,ERCP)患者67例,随机分为靶控组(n=35)与恒速组(n=32). 麻醉开始予芬太尼1μg/kg静脉注射,靶控组以丙泊酚按血浆靶浓度3 mg/L～6 mg/L诱导.待成功入镜后减至诱导浓度的1/2维持,必要时每次增减0.5 mg/L来加深或减浅麻醉;微泵组以丙泊酚1.5 mg/kg～2.5 mg/kg手工匀速推注至睫毛反射消失为诱导量,入镜后减至6mg·kg~(-1)·h~(-1)～9mg·kg~(-1)·h~(-1)泵注维持.两组均以术中体动反应调节麻醉深度.记录两组内泊酚总用量、手术时间、患者入睡时间、苏醒时间、不良事件发生率及术者、患者满意度并作统计分析.结果 靶控组呼吸抑制例数较少,术者满意度较高,差异有统计学意义.结论 靶控输注丙泊酚用于内窥镜逆行胰胆管造影麻醉呼吸抑制发生率低,靶浓度数值便于经验交流,操作简便.值得推广.     

靶控输注异丙酚在脑脊液中药物浓度的实验研究

目的 研究靶控效应室浓度输注异丙酚时脑脊液浓度、效应室浓度以及BIS之间的相互关系,探讨靶控效应室浓度输注的准确性。方法 选择成年健康杂种犬12只,以3μg/ml为效应室靶浓度进行靶控输注15min。取脑脊液用高效液相色谱荧光检测法测定异丙酚的浓度。同时监测BIS以及血液动力学和呼气末CO2。结果 靶控效应室浓度输注后,模拟血浆浓度与效应室浓度在10.9min时达到平衡,并维持在3μg/ml的靶浓度水平。15min停止输注后模拟血浆和效应室浓度逐渐衰减。脑脊液峰值浓度约为0.29±0.14μg/ml,但各时点的浓度值均比效应室浓度低（P<0.05）,平均为效应室浓度的18·7％。BIS与脑脊液浓度均在5min达到峰值,而效应室浓度相对滞后。且BIS与脑脊液浓度的相关性（γ=0.9195）优于效应室浓度（γ=0.554）。给药后犬的血压下降但未出现严重的心血管副作用。结论 靶控效应室浓度输注异丙酚时,效应室浓度与BIS的变化不完全一致可能是药代动力学参数造成的差异。脑脊液浓度与BIS相关较好,比血药浓度更能反映效应部位的药代学特征。     

Laryngeal mask insertion during target-controlled infusion of propofol

STUDY OBJECTIVE: To compare the Laryngeal Mask Airway (LMA; The Laryngeal Mask Airway Co., Ltd., Nicosia, Cyprus) insertion conditions produced by 6 and 8 microg/mL of target plasma concentrations (Cpt) during the induction of anesthesia with target-controlled infusion (TCI) of propofol. DESIGN: Randomized, prospective, single-blind, clinical study. SETTING: University hospital. PATIENTS: 44 ASA physical status I and II patients, 16 to 54 years of age, weighing between 45 and 100 kg, undergoing minor surgery in which the use of LMA was indicated. INTERVENTIONS: Patients were randomly divided into two groups (1 and 2) of 22 to compare the effects of different propofol concentrations. Three minutes after intravenous (IV) injection of midazolam 0.04 mg/kg, group 1 and 2 received TCI of propofol with 6 and 8 microg/mL of Cpt, respectively. LMA was inserted when the effect-site concentration (EC) reached 2.5 microg/mL, which was displayed on the infusion pump. MEASUREMENTS: The LMA insertion conditions (mouth opening, gagging, coughing, head or limb movement, laryngospasm, overall ease of insertion) were assessed, and hemodynamic responses were evaluated until 3 minutes after LMA insertion. Total dose of propofol, EC, and elapsed time since the start of TCI were recorded at five times: at the loss of consciousness and eyelash reflex, at 2.5 microg/mL of EC, and immediately, 1 minute, and 3 minutes after the insertion of LMA. MAIN RESULTS: There was no significant difference between the two groups in insertion conditions, despite the significantly larger total dose and shorter elapsed time (2.6 +/- 0.08 mg/kg and 109 +/- 5.0 s) in Group 2 than those (2.1 +/- 0.02 mg/kg and 140 +/- 4.1 s) in Group 1 at 2.5 microg/mL of EC (p < 0.05). Systolic and diastolic blood pressure decreased and heart rate increased significantly throughout the study period in both groups (p < 0.05). But there was a significant decrease in arterial pressure in Group 2 compared with Group 1 1 and 3 minutes after the insertion (p < 0.05). CONCLUSIONS: Induction with 8 microg/mL of Cpt, compared with 6 microg/mL, allowed earlier LMA insertion but, could not improve the conditions for LMA insertion and required more careful attention to the decrease in blood pressure after LMA insertion.     

靶控输注雷米芬太尼和丙泊酚静脉麻醉临床性能评价

目的观察不同年龄对雷米芬太尼靶控输注（TCI）药代动力学模型参数的影响、分析靶浓度与实测浓度的差值并评价TCI系统的性能。方法60例上腹部手术患者随机分为A组（28岁-44岁,n=20）,B组（45岁-64岁,n=30）,C组（65岁-80岁,n=20）。全麻诱导设定丙泊酚血浆靶控浓度3 mg／L,雷米芬太尼7μg／L。意识消失后给予维库溴铵0．1 mg／kg气管插管后行机械通气。气管插管后丙泊酚的靶控浓度降至2．5 mg/L,雷米芬太尼靶控浓度维持不变。术中调节丙泊酚的量使BIS指数维持在45-55。TCI开始后5 min、10 min、20 min、40 min、60 min、80 min、100 min、120 min抽取动脉血检测雷米芬太尼血药浓度。采用执行误差（PE）的中位数（MDPE）、执行误差的绝对中位数（MDPAE）及摆动度（wobble）评价TCI系统的性能。结果三组患者各时点血浆雷米芬太尼浓度均明显低于靶浓度。输注后5 min、10 min,C组的血浆雷米芬太尼浓度显著高于A、B组,有统计学差异（P〈0．05）,而其他各时段两组间无统计学差异（P〉0．05）。三组患者TCI系统偏离度（MDPE）在正常范围, MDAPE大于该范围,摆动度也较大。结论TCI时靶控浓度与实测血药浓度差异较大,老年人的药代动力学特征明显不同于青壮年,在国人使用雷米芬太尼TCI静脉麻醉时,应根据不同年龄设定靶控浓度。     

Bispectral index in patients with target-controlled or manually-controlled infusion of propofol

In this prospective, randomized study we compared bispectral index (BIS), hemodynamics, time to extubation, and the costs of target-controlled infusion (TCI) and manually-controlled infusion (MCI) of propofol. Forty patients undergoing first-time implantation of a cardioverter-defibrillator were included. Anesthesia was performed with remifentanil (0.2-0.3 micro g. kg(-1). min(-1)) and propofol. Propofol was used as TCI (plasma target concentration, 2.5-3.5 micro g/mL; n = 20) or MCI (3.0-4.0 mg. kg(-1). h(-1); n = 20). BIS, heart rate, and arterial blood pressure were measured at six data points: T1, before anesthesia; T2, after intubation; T3, after skin incision; T4, after first defibrillation; T5, after third defibrillation; and T6, after extubation. There were no significant hemodynamic differences between the two groups. BIS was significantly lower at T3 and T4 in the TCI group than in the MCI group. The mean dose of propofol was larger in TCI patients (5.8 +/- 1.4 mg. kg(-1). h(-1)) than in the MCI patients (3.7 +/- 0.6 mg. kg(-1). h(-1)) (P < 0.05), whereas doses of remifentanil did not differ. Time to extubation did not differ between the two groups (TCI, 13.7 +/- 5.3 min; MCI, 12.3 +/- 3.5 min). One patient in the MCI group had signs of intraoperative awareness without explicit memory after first defibrillation (BIS before shock, 49; after shock, 83). Costs were significantly less in the MCI group (34.83 US dollars) than in the TCI group (39.73 US dollars). BIS failed to predict the adequacy of anesthesia for the next painful stimulus. IMPLICATIONS: In this prospective, randomized study, bispectral index (BIS), hemodynamics, time to extubation, and costs of target-controlled infusion (TCI) and manually-controlled infusion of propofol were compared. TCI increased the amount of propofol used. BIS failed to predict the adequacy of anesthesia for the next painful stimulus.     

梗阻性黄疸病人靶控输注异丙酚的药代动力学

目的 探讨梗阻性黄疸病人靶控输注（TCI）异丙酚的药代动力学。方法 择期手术病人24例，ASAI或Ⅱ级，按胆红素水平分成3组（n=8），对照组：血清总胆红素（sTBL）〈17.1μmol／L；轻度梗阻性黄疸组（B组）：17．1／μmol／L≤sTBL≤171．1μmol／L；中重度梗阻性黄疸组（C组）：sTBL〉171．1μmol／L。三组均以血浆靶浓度3．0μg／ml TCI异丙酚直至手术结束。分别于以下时点取桡动脉血：TCI开始后0．5、1、2、4、6、8min、麻醉维持过程中每隔15min、停止TCI后即刻、2、4、6、8、10、20、30、40、50、60、90、120、180、240、300、360min，用高效液相色谱荧光法测定血浆异丙酚浓度，用NONMEM软件分析药代动力学参数。结果 TCI异丙酚的群体药代动力学大部分（18／24）最适合用三室模型来描述，小部分（6／24）最适合用二室模型来描述。三组间异丙酚的药代动力学参数比较差异无统计学意义（P〉0．05）。结论 TCI异丙酚药代动力学绝大部分适合用三室模型，小部分适合用二室模型来描述；梗阻性黄疸对异丙酚的药代动力学没有影响。     

丙泊酚复合瑞芬太尼靶控输注在腹腔镜胆囊切除术中的应用

目的:观察丙泊酚复合瑞芬太尼靶控输注全凭静脉麻醉对腹腔镜胆囊切除术血流动力学及术后苏醒时间的影响。方法:50例择期行腹腔镜胆囊切除术的患者均采用丙泊酚复合瑞芬太尼靶控输注全凭静脉麻醉。设定诱导时静注咪达唑仑2mg,先血浆靶控输注瑞芬太尼4ng/ml,1min后血浆靶控输注丙泊酚3μg/ml或3.5μg/ml,患者意识消失后静注维库溴铵0.1mg/kg,3min后气管内插管,插管后丙泊酚靶浓度调至2μg/ml,术中维持根据需要调整丙泊酚靶浓度,以0.2μg/ml递增或递减,瑞芬太尼维持不变。记录诱导前、诱导后2min、插管即刻、插管后5min、气腹时、气腹后5min的收缩压(systolic bloodpressure,SBP)、舒张压(diastolic blood pressure,DBP)、心率(heart rate,HR)及术后呼吸恢复时间、呼之睁眼时间。结果:诱导后2min的SBP、DBP、HR与诱导前差异均有统计学意义(P0.05),气腹时SBP、DBP、HR有所升高,但差异无统计学意义,其他时点经适当调整丙泊酚靶浓度处理后逐渐平稳,术后呼吸恢复时间为(6.5±2.2)min,呼之睁眼时间(8.9±3.1)min。结论:丙泊酚复合瑞芬太尼靶控输注用于腹腔镜胆囊切除术安全,术中血流动力学平稳,术后苏醒快。     

不同年龄患者靶控输注丙泊酚的血药浓度与脑电双频指数值的相关性

目的研究靶控输注丙泊酚镇静时不同年龄患者的丙泊酚血药浓度与脑电双频指数(BIS)值的相关性。方法60例上腹部手术患者随机分为青壮年组(28~45岁,n=30)和老年组(65~80岁,n=30)。全麻诱导设定丙泊酚血浆靶控浓度3mg/L、雷米芬太尼7μg/L。意识消失后给予维库溴铵0.1mg/kg气管插管后行机械通气。术中雷米芬太尼靶控浓度维持不变,气管插后丙泊酚的靶控浓度降至2.5mg/L,术中调节丙泊酚的量使BIS值维持在45~55,并在调节后5min测定丙泊酚血药浓度。结果两组患者一般情况差异无统计学意义。青壮年组实测丙泊酚血药浓度与BIS值无相关性,老年组呈高度负相关(r=-0.64816)。结论青壮年组丙泊酚实测血药浓度与BIS值无相关性,而老年组有明显的负相关,说明在老年患者实测血药浓度可以评估镇静深度。