Effects of low-dose propofol administration on central respiratory drive, gas exchanges and respiratory pattern

The effects of sedative-hypnotic doses of propofol on respiratory drive and pattern have not yet been extensively described. Repeated small boluses of propofol (0.6-0.3 mg.kg-1) were administered to ten ASA I patients undergoing carpal tunnel release using regional anaesthesia. Airway pressure, capnography and pneumotachography were continuously recorded. With respect to basal values, no significant variations of respiratory rate, minute volume, tidal volume, inspiratory and expiratory time, total expiratory cycle, Ti/Ttot, TV/Ti, P0.1, EtCO2 and blood gas analysis were observed. Low doses of propofol, to maintain conscious sedation of light sleep, have not been shown to cause respiratory depression.     

异丙酚减轻大鼠机械通气所致肺损伤

目的探讨异丙酚对大鼠高压力机械通气所致急性肺损伤的影响。方法24只Wistar大鼠随机分为3组（n=8）,采用压力控制机械通气模式通气。A组为对照组,通气模式为PIP=25 cmH2O,PEEP=2 cm H2O;B、C两组为异丙酚组,通气模式同A组,B组输注模式为静注2 mg／kg,继以4 mg·ks^-1·h^-1速度持续输注;C组输注模式为静注5 mg／kg,继以10 mg·kg^-1·h^-1速度持续输注,记录基础时点、1h、2 h、3 h、4 h的MAP、HR和动脉血气。4 h后处死全部大鼠。测量肺组织湿干比、BALF中蛋白含量,观察肺组织病理形态学变化。结果A组MAP、PaO2和pH在4 h时显著降低,与基础值相比有统计学差异（P〈 0．05）,而B、C两组与基础值相比无明显变化。在4h时A组的PaCO2显著升高（P〈0．05）,而B、C两组与基础值相比无明显变化。肺组织湿／干比和BALF中蛋白含量A组亦明显高于B、C两组（P〈0．05）。B、C组间无显著差别。肺组织形态学改变B、C组好于A组,肺组织中性粒细胞浸润程度也较轻。结论异丙酚对机械通气所致急性肺损伤具有保护作用,其机制可能与减少中性粒细胞在肺内浸润有关。     

异丙酚对MPTP损伤的小鼠黑质多巴胺神经元的保护作用

目的　观察异丙酚对 1 甲基 4 苯基 1,2 ,3 ,6 四氢吡啶 (1 methyl 4 phenyl 1,2 ,3 ,6 tetrahydropyridineMPTP)损伤的小鼠纹状体多巴胺神经元的影响以及可能的作用机制。方法　给予Propofol 10 0mg/ (kg·d)后注射MPTP 2 0mg/ (kg·d) ,用药 6d。 12d后分离纹状体应用高效液相 -电化学方法检测纹状体多巴胺、二羟基苯乙酸及高香草酸的含量水平 ,应用12 5I- β-CIT放射性配基和免疫组化的方法检测多巴胺转运蛋白的活性和黑质神经元的损伤情况。结果　异丙酚可增加MPTP模型鼠多巴胺及其代谢产物的含量 ,异丙酚处理组DA ,DOPAC ,HVA的含量分别为 (8.2 417± 1.692 ) μg/ g、(1.3 81± 0 .486) μg/g和 (1.63 3 9± 0 .5 73 ) μg/ g ,与MPTP损伤组比较 ,明显增加。异丙酚亦可抑制黑质酪氨酸羟化酶 (TH)阳性神经元的减少。MPTP组注射MPTP 6d后 ,纹状体DAT为 (5 .3 13± 0 .64 2 )与正常组 (6.992± 0 .5 48) μg/ g比较显著下降 (P <0 .0 1) ,P +M组纹状体DAT为 (6.5 65± 0 .40 5 ) ,明显高于MPTP组 (P <0 .0 1) ,即减轻纹状体内多巴胺转运蛋白密度下降。结论　异丙酚对MPTP损伤的DA神经元具有一定的保护作用 ,其保护作用可能与抑制多巴胺转运蛋白活性有关     

Comparison of induction characteristics of four intravenous anaesthetic agents

The induction characteristics of thiopentone, etomidate and methohexitone have been compared to those of propofol (2,6 di-isopropyl phenol) in unpremedicated patients. Propofol 2.5 mg/kg caused significantly more hypotension, excitatory side effects and pain on injection at the dorsum of hand than thiopentone 5 mg/kg. However, with regard to the latter two sequelae, etomidate 0.3 mg/kg and methohexitone 1.5 mg/kg caused similar or more frequent upset. Propofol 2.0 mg/kg was equipotent with thiopentone 4.0 mg/kg in terms of successful induction of anaesthesia. Hypotension may contraindicate the use of propofol in the hypovolaemic or unfit patient.     

Comparison of computer-controlled administration of propofol with two manually controlled infusion techniques

Ninety women were studied in order to compare dose requirements and quality of anaesthesia between target-controlled infusion and two manually controlled infusion schemes for propofol administration: group I received target-controlled infusion for induction (4 μg.ml⁻¹ target blood concentration, increased by 2 μg.ml⁻¹ after 3 min if consciousness not lost), groups II and III received an induction bolus of propofol at infusion rates of 1200 or 600 ml.h⁻¹, respectively, until loss of consciousness. Anaesthesia was maintained with propofol target-controlled infusion in group I or by constant rate infusion in the other two groups. Computer simulations were used to calculate blood and effect-site propofol concentrations. Mean induction times (SD) were 78 (65) s in group I versus 51 (10) s and 62 (12) s in groups II and III, respectively (p < 0.05 between groups II and III). Mean induction doses were: 1.31 (0.44), 2.74 (0.56) and 1.77 (0.43) mg.kg⁻¹ and mean maintenance doses were 13.4 (3.55), 9.32 (1.71) and 9.97 (1.53) mg.kg⁻¹.h⁻¹ in groups I, II and III, respectively (p < 0.05 between all groups). There was a lower incidence of apnoea in group I than in groups II and III. There were no significant differences between the groups in other objective parameters of anaesthetic quality studied. Computer simulations showed an 'overshoot' in propofol blood and effect-site concentration with manual induction and significantly higher maintenance levels with target-controlled infusion.     

Effects of propofol emulsion and thiopentone on T helper cell type-1/type-2 balance in vitro

We have earlier found increased percentages of T helper cells (CD4-positive lymphocytes) in the blood circulation after propofol infusion anaesthesia. Cytokines interferon-γ (IFNγ) and interleukin-4 (IL-4) are important in the differentiation of T helper cells into subtypes T helper type-1 (Th1) and type-2 (Th2). To study the effects of propofol emulsion, its solvent Intralipid^® and thiopentone on Th1/Th2 balance, measurements of IFNγ and IL-4 production by mononuclear leucocytes were carried out in vitro . As IL-2 has a central role in immune responses to surgery, its production was also measured. Concanavalin A-stimulated mononuclear cells were cultured in the presence of propofol emulsion at 3.5 or 10 μg.ml⁻¹, Intralipid^® 35 or 100 μg.ml⁻¹, or thiopentone 3 μg.ml⁻¹. Cytokine production was measured from the conditioned media of mononuclear cell cultures. Decreased IFNγ (p <0.001) and IL-4 concentrations (p < 0.01) were found in the presence of thiopentone, but IL-2 production was unaffected. By contrast, propofol emulsion or Intralipid^® had no effects on IFNγ, IL-2 or IL-4 concentrations. Propofol 10 μ.ml⁻¹ increased the IFNγ/IL-4 ratio from the control value median 243 (162–562) (25th–75th percentile) to 363 (195–1028) (p < 0.01), but thiopentone decreased it to 145 (60–214) (p < 0.01). These findings show that propofol and thiopentone have different effects in vitro on Th1/Th2 balance and suggest that they have different modulating effects on the immune response.     

The effect of subhypnotic doses of propofol on the incidence of pruritus after intrathecal morphine for Caesarean section

The effect of subhypnotic doses of propofol on intrathecal morphine-induced pruritus was studied in a prospective, randomly allocated, double-blind controlled trial. Fifty-eight women undergoing elective lower segment Caesarean section for a singleton fetus received spinal anaesthesia with 2.5 ml hyperbaric 0.5% bupivacaine and 0.2 mg of preservative-free morphine. They then received propofol 1 ml (10 mg) or Intralipid 1 ml (control group) intravenously after delivery. Pruritus was assessed using a five-point verbal rating scale at hourly intervals for 8 h. A second dose of their allocated treatment drug was administered at the first recording of significant pruritus. The pruritus score was reassessed after 5 min and the treatment was repeated if pruritus remained. There were no differences between the groups in the onset of pruritus or its successful treatment. No adverse side-effects were associated with this dose of propofol. There were no differences in the incidence of post-operative nausea and vomiting between the two groups. Subhypnotic propofol is not an effective treatment for intrathecal morphine-induced pruritus in women following Caesarean section.     

The safety of patient-controlled sedation

We have investigated the safety of a previously described method of patient-controlled sedation in 100 healthy patients presenting for elective surgery. The device used 0.33-ml boluses of propofol (10 mg.ml⁻¹) infused over 6 s with no lockout. All patients attempted to put themselves to sleep by pressing a button on the hand-held device. The oxygen saturation, heart rate, sedation score and airway patency were noted every minute. When the patient stopped pressing the button, the anaesthetist took over the handset and continued pressing the button until the patient became unresponsive. The system allowed rapid sedation. Only five patients were still anxious after 2 min. After 3 min, no patient was still anxious and more than 70 patients had slurred speech. When they stopped pressing the button, 11 patients were judged oversedated, of whom two were unresponsive. One patient's oxygen saturation decreased transiently to 84%: no other patient's oxygen saturation decreased below 90%. There were no other significant changes. We conclude that the system studied works well but carries too high a risk of oversedation for unsupervised use.     

Anaesthetic management during awake craniotomy in a 12-year-old boy

We present our approach to the preoperative preparation and anaesthetic management for awake craniotomy in a 12-year-old boy. Management included conscious sedation with a propofol infusion plus local anaesthetic infiltration of the scalp, periosteum, and dura. The complications which may be encountered during such procedures and their treatments are reviewed.     

异丙酚和七氟醚麻醉对颅内占位病人颅内压的影响

目的:观察异丙酚和七氟醚麻醉对颅内占位病人颅内压的影响.方法:ASA I～II级、格拉斯哥评分15分、行择期开颅手术病人24例,随机分为七氟醚组(n=12)和异丙酚组(n=12).用依托咪酯、芬太尼、琥珀胆碱麻醉诱导.麻醉维持七氟醚组吸入2%七氟醚,异丙酚组先静注异丙酚1.5 mg/kg,后以8～10 mg·kg-1·h-1维持麻醉,记录诱导前、插管后、给药后5,10和20 min的收缩压、舒张压、平均动脉压、心率和脑脊液压,计算脑灌注压值. 结果:异丙酚组给药后5,10和20 min时比诱导前平均动脉压分别下降12.28%、13.36%和9.64%,七氟醚组分别下降8.26%、11.1%和10.94%,两组差异显著(P<0.05);异丙酚组脑灌注压分别下降12.34%、10.76%和11.0%,七氟醚组分别下降4.1%、7.5%和8.54%,两组差异显著(P<0.05).结论:对颅内占位病人异丙酚麻醉维持能使平均动脉压、脑灌注压和颅内压下降.七氟醚麻醉维持对血流动力学影响较轻,但颅内压有轻度升高,在过度通气条件下可用于无颅内高压症状对颅内占位病人的麻醉.