Pharmacokinetics of propofol during continuous infusion for pediatric anesthesia

The blood concentrations of propofol have been examined during anesthesia by continuous infusion of 12 mg/hg/hr. A bolus dose of 3 mg/kg body weight propofol was used to induce anesthesia. The mean concentrations at apparent steady state were in the range of 4.3 to 5.6 micrograms/ml during the infusion. The mean total body clearance, derived from the apparent steady state concentrations in the blood, was 0.0394 litres/kg/minute. The mean propofol blood concentration at awakening was found to be 2.3 micrograms/ml.     

A new method of continuous propofol infusion for total intravenous anesthesia]

Total intravenous anesthesia (TIVA) is recommended to avoid air pollution. However, intermittent administration of anesthetic agents has a large disadvantage of delayed emergence time. We suggested continuous TIVA with propofol, ketamine, vecuronium and buprenorphine (PKBp), and reported that maintenance with continuous intravenous administration of propofol corresponding to the age associated with ketamine (240 micrograms.kg-1.h-1), vecuronium (80 micrograms.kg-1.h-1) and buprenorphine (0.4 microgram.kg-1.h-1) brought rapid emergence and that the last 1/6 of anesthetic time was the point to reduce propofol maintenance dose. In this study, we maintained anesthesia with continuous intravenous administration of propofol using twice step down method every one hour. We conclude that the reduction of propofol maintenance dose for every 1/6 in one hour produces fewer dropout cases.     

A case of coronary artery spasm during epidural anesthesia with continuous infusion of propofol

A 50-year-old male patient was scheduled for left partial pulmonary resection and biopsy. The patient had neither complication nor history of ischemic heart disease. After arriving in the operation room, an epidural catheter was inserted into the epidural space at the T 4-5 intervertebral space. Anesthesia was induced with intravenous propofol 100 mg, fentanyl 100 microgram and vecuronium 6 mg and then a double lumen endotracheal tube was inserted. Anesthesia was maintained with O2 and air (FIO2 0.3-1.0), continuous infusion of propofol, intermittent intravenous administration of fentanyl and epidural injection of 1% lidocaine. Forty-five minutes after the start of operation, ECG showed an elevation of ST segment and soon it passed into ventricular tachycardia and ventricular fibrillation. The patient was treated with cardiopulmonary resuscitation. Fifteen minutes later, ECG returned to sinus rhythm but the elevation of ST segment remained. We considered that these cardiac events were due to coronary spasm, and started continuous infusion of nitroglycerin and nicorandil. One hour later, ST segment returned to normal. The possible inducing factors in this case were altered balance between sympathetic and parasympathetic nervous activity caused by infusion of propofol and epidural block, and alpha-stimulation caused by ephedrine.     

Target-controlled infusion anesthesia with propofol and remifentanil compared with manually controlled infusion anesthesia in mastoidectomy surgeries

Target-controlled infusion (TCI) system is increasingly used in anesthesia to control the concentration of selected drugs in the plasma or at the site of drug effect (effect-site). The performance of propofol TCI delivery when combined with remifentanil in patients undergoing elective surgeries has been investigated. Our aim in this study was to assess the anesthesia profile of the propofol and remifentanil target controlled infusion (TCI) anesthesia as compared to the manually controlled infusion (MCI), in mastoidectomy surgery, where a bloodless field is of utmost importance to the surgeon. Sixty patients, aged 18-60 years ASA I-II enrolled in the study, were divided into two equal groups. Group MCI received propofol and remifentanil by conventional-dose-weight infusion method, and Group TCI received propofol 4 microg/ml and remifentanil 4 ng/ml as effect-site target concentration. The hemodynamic variability, recovery profile, postoperative nausea and vomiting (PONV), surgeons satisfaction were assessed. Results were analyzed by SPSS version 11.5. The two groups were comparable with respect to age, ASA class, sex, weight, basal vital signs, operation time. The blood pressure and pulse were above desired levels in some data points in the MCI Group (P < or = 0.05). The PACU stay time to reach Aldret score of 10 was longer in the MCI Group (42.54 +/- 8 vs 59.01 +/- 6 min) (P < or = 0.05). The PONV was more common in the MCI Group (P < or = 0.05). Surgeon's satisfaction of the surgical field showed no significant differences except when described as "good", more common in the TCI Group. TCI is capable to induce and maintain anesthesia as well as MCI. In some stages of anesthesia, the TCI control of vital signs are better than the MCI. In some stages of anesthesia, the TCI control of vital signs are beter than the MCI. Recovery profile and complication rate and surgeon's satisfactions are more acceptable in the TCI than in the MCI Group.     

Target-controlled propofol infusion for general anesthesia in three obese patients

We report three cases in which the target-controlled propofol infusion technique was used in obese patients for general anesthesia. General anesthesia was induced by intravenous administration of fentanyl 150-300 micrograms and ketamine 50-80 mg and propofol 2 micrograms.ml-1 to achieve a target blood concentration by target-controlled infusion system. Anesthetic maintenance was achieved by ketamine 1 mg.kg-1.h-1 for 1 hour after the induction, propofol at target blood concentration of 2-3.5 micrograms.ml-1 and the intermittent epidural injection of 1.5% lidocaine through an epidural catheter. The surgical procedures were uneventful. The estimated blood concentrations of propofol at emergence from anesthesia calculated by ConGrace ranged from 1.49-1.69 micrograms.ml-1, and it took 230-300 seconds to emerge from anesthesia. The target-controlled propofol infusion technique appears useful to control the depth of anesthesia in obese patients.     

Anesthesia with continuous infusion of propofol in myasthenic patients]

Anaesthesia with atracurium, fentanyl, and continuous intravenous infusion of propofol in two myasthenic patients is described. There were no intra and postoperative problems and operative conditions were considered excellent. This technique offers a safe alternative to inhalational anaesthesia for patients with myasthenia gravis. Monitoring of neuromuscular function is mandatory. The use of atracurium in myasthenic patients and the influence of propofol on neuromuscular transmission are discussed.     

Changes of propofol concentration in cerebrospinal fluid during continuous infusion

We studied the changes in the propofol concentration in the cerebrospinal fluid (CSF) in 14 patients, undergoing elective intracranial procedures, who were anesthetized with propofol administered by target-controlled infusion. During anesthesia, fentanyl and cisatracurium were administered as required. After intubation of the trachea, the lungs of the patients were ventilated to normocapnia with an oxygen-air mixture (FIO(2) = 0.33). Arterial blood and CSF samples (from an intraventricular drain) were collected between 90-180 min after the induction of anesthesia. Blood propofol concentrations were stable, between 5.0 +/- 1.89 and 4.5 +/- 1.7 microg/mL (mean +/- SD). There was a significant decrease in the CSF propofol concentration, from 52.2 +/- 35.01 ng/mL at 90 min to 28.6 +/- 21.9 ng/mL at 150 min (P < 0.05). The CSF propofol concentration at 180 min (21.4 +/- 14.0 ng/mL) was not significantly different from the concentration at 150 min. Some possible reasons for this decrease after commencing continuous intraventricular drainage are discussed. IMPLICATIONS: Propofol concentrations in the cerebrospinal fluid in neurosurgical patients Propofol concentration in cerebrospinal fluid of investigated patients decreased significantly after starting intraventricular drainage, despite relatively steady blood propofol concentrations. These results supplement the limited information about propofol pharmacokinetics in the human central nervous system.     

持续输注丙泊酚药代动力学模型的选择

目的　将四种文献报道的药代动力学模型用于计算机模拟以预测持续输注丙泊酚的 血浆浓度,籍以选择适合中国人的药代动力学模型。方法　选择ASAⅠ～Ⅱ级的择期手术病人16 例,≥65岁(Ⅰ组)病人静脉输注丙泊酚速度60ml/h,<65岁(Ⅱ组)者输注速度75ml/h,抽取动脉血 分析药物血浆浓度,用四种药代动力学模型预测丙泊酚血浆浓度,计算样本加权残差(WR)、绝对值 加权残差(absWR)。结果　Schuttler模型在Ⅰ组病人,中位数加权残差(MDWR)显著小于其他三种 参数(P<0.01),对所有病人输注期间预测浓度 实测浓度的拟合程度最好(P<0.01)。结论　仅 Schuttler药代动力学模型适合用于持续静脉输注丙泊酚期间和停止输注后的药物浓度预测。     

Use of propofol in ophthalmological anesthesia in elderly patients

Forty patients more than 65 years old were anaesthetized with propofol for cataract surgery. Patients were divided into two groups: those intubated after topical oropharyngeal anaesthesia and those intubated after muscle relaxation obtained with suxamethonium. Induction and maintenance of anaesthesia were carried out with 2.5 mg . kg-1 and 4 mg . kg-1 . h-1 respectively. Concurrent use of muscle relaxants had no effect on the action and characteristics of the general anaesthesia or recovery. Relative bradycardia (7%) and arterial hypotension (25%) occurred rapidly following induction and continued during the entire period of anaesthesia despite the systematic infusion of 500 ml of electrolyte solutions. Recovery was extremely rapid. The original Glasgow score was obtained within 20 min. The only negative side-effects were generally late occurring (4-6 h): postanaesthetic nausea or vomiting. Otherwise, tolerance was excellent. Use of propofol was ideal for this type of surgery due to its strong and durable ocular hypotensive effect.     

雷米芬太尼复合丙泊酚静脉麻醉的临床应用

目的观察雷米芬太尼复合丙泊酚静脉麻醉的效果。方法全身麻醉下腰椎手术患者60例,随机均分为雷米芬太尼复合丙泊酚静脉麻醉组(Ⅰ组)和静吸复合麻醉组(Ⅱ组)。雷米芬太尼和丙泊酚的负荷量分别为1μg/kg和1mg/kg,雷米芬太尼以0.5μg·kg-1·min-1速率输注。麻醉中通过增减雷米芬太尼0.1μg·kg-1·min-1输注速率调整麻醉深度。丙泊酚按5∶4∶3方案输注,即5mg·kg-1·h-1输注10min,4mg·kg-1·h-1输注10min,20min后3mg·kg-1·h-1恒速输注。观察两组气管插管反应、麻醉效果、苏醒质量。结果两组麻醉效果相同,均可抑制气管插管反应(P<0.01),且Ⅰ组较Ⅱ组明显(P<0.05)。Ⅰ组苏醒质量较Ⅱ组好(P<0.01),不良反应较Ⅱ组高(P<0.01),术中无知晓。结论雷米芬太尼复合丙泊酚用两个注射泵静脉麻醉,采用负荷量加两种以上速率输注全凭静脉麻醉简便易行。     

靶控输注丙泊酚中长链脂肪乳在小儿麻醉诱导中的应用

目的 探讨靶控输注(TCI)丙泊酚中长链脂肪乳在小儿麻醉诱导中的应用效果.方法 择期行腹部外科和泌尿外科手术患儿30例,年龄3～11岁.丙泊酚起始血浆靶浓度(Cp)为3μg/ml,每隔2分钟递增0.5 μg/ml,直至患儿脑电双频指数(BIS)降至50并稳定2 min后进行气管插管.整个诱导期间患儿面罩吸纯氧3 L/min.记录诱导前、意识消失时(OAA/S评分＝1分)和BIS=50时的SBP、HR、SpO2、RR.气管插管前抽取桡动脉血1 ml测定丙泊酚血浆药物浓度(CRT).结果 与诱导前比较,意识消失时及BIS＝50时的SBP、HR均明显降低(P＜0.05),所有患儿SBP平均下降(7.55±2.50)％,HR平均减慢(16.90±4.10)％.结论 Marsh系统TCI丙泊酚中长链脂肪乳用于小儿麻醉诱导是安全和有效的.